Papers

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Physics General Relativity and Quantum Cosmology

gr-qc Watch General Relativity and Quantum Cosmology

Wednesday 12 August

General Relativity and Quantum Cosmology

Static multipolar Einstein-vector-Gauss-Bonnet black holes

Burkhard Kleihaus and Jutta Kunz

We construct and analyze static multipolar black holes in Einstein-vector-Gauss-Bonnet theory with a quadratic coupling function. The vectorized solutions bifurcate from the Schwarzschild black hole at discrete values of the Gauss-Bonnet coupling, obtained from a perturbative eigenvalue problem on the Schwarzschild background and labelled by the angular multipole number $\ell$. We restrict to the fundamental radial branches. The electric sector contains the known spherically symmetric $\ell=0$ branch as well as axisymmetric branches with $\ell>0$. These electric branches extend to larger values of the coupling. The magnetic sector features a sequence of axisymmetric branches, including the previously found magnetic dipole branch at $\ell=0$. The magnetic branches instead exist only on finite intervals of the coupling, ending at critical solutions. Away from the bifurcation point, nonlinearities generate additional multipoles, but even-$\ell$ and odd-$\ell$ moments remain separated.

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General Relativity and Quantum Cosmology

Taiji Resolving Power for the Transverse Scalar Mode of Gravitational Waves

Bo-Xuan Ge and Zhoujian Cao

We investigate how small a co-propagating transverse-scalar component can be resolved by Taiji in an already identified bright tensor chirp. Using a source-tracked tensor-null response, we formulate the problem in terms of the minimum resolvable scalar strain fraction and evaluate it over the sky. For a one-year benchmark chirp with tensor signal-to-noise ratio $\rho_T=1000$, we find that Taiji can rule out transverse-scalar strain fractions $\epsilon_b\gtrsim0.532\%$ at the all-sky median level. The threshold scales as $\epsilon_{b,\min}\propto\rho_T^{-1}$, so brighter tensor events can probe correspondingly smaller scalar fractions. We further find that this sub-percent resolving power remains predictable under small source-parameter mismatches through the associated tensor-leakage structure.

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General Relativity and Quantum Cosmology

A Nonsingular Logarithmic Bouncing Cosmology in $f(R,T)$ Gravity with Thermodynamic Viability

Anjani, Pankaj Kumar, S.H. Shekh et al. (+1 more)

We present a nonsingular bouncing cosmological model in the framework of modified $f(R,T)$ gravity within a spatially flat Friedmann–Robertson–Walker universe. A logarithmic time-dependent scale factor is assumed to realize a smooth transition from a contracting phase to an expanding phase without encountering an initial singularity. Based on this assumption, the dynamical evolution of the Hubble parameter, deceleration parameter, energy density, and pressure is obtained for various choices of the model and the matter–geometry coupling parameter to confirm the occurrence of a successful bounce. The effective equation of state parameter is examined to characterize the cosmic fluid during different evolutionary phases. The violation of energy conditions, necessary for the realization of the bouncing behavior, is also discussed. The stability of the model is investigated using the squared speed of sound and is found to remain positive within the allowed parameter space, indicating classical stability. Furthermore, constraints on the matter–geometry coupling parameter are obtained by demanding positive energy density, negative pressure, and a viable cosmological evolution. The obtained cosmological constraint on the coupling parameter is also shown to be compatible with the currently available compact-object constraints. The thermodynamic behavior of the model is examined by testing the generalized second law of thermodynamics. The total entropy production rate remains negative during the contracting phase and changes its sign to positive during the expanding phase. However, it becomes singular at the bouncing point, reflecting the breakdown of the standard thermodynamic description during the transition phase.

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All authors Anjani, Pankaj Kumar, S.H. Shekh, Milan Srivastava

General Relativity and Quantum Cosmology

Vishveshwara's waveform revisited: insights from a Keldysh quasinormal mode expansion

Jérémy Besson and José Luis Jaramillo

We revisit Vishveshwara's linear scattering on a Schwarzschild black hole to study the evolution of quasinormal mode activation along the full time-domain waveform. Specifically, by adopting a hyperboloidal approach we cast the scattering problem in a non-selfadjoint dynamics setting where a (Keldysh) resonant expansion in a bi-orthogonal system of quasinormal modes can be readily performed. The calculation reveals the neat correlation of the second peak in Vishveshwara's waveform to the fundamental mode and first overtones, closely following the ringdown waveform pattern of non-linear evolutions. The first peak is completely controlled, for even (Zerilli) perturbations, by the algebraically special mode and the nearby branch cut. This phenomenon is absent for odd (Regge-Wheeler) perturbations. These qualitative features are robust under change of initial data and, we argue, might provide insight into the mechanisms underlying the ringdown activation time in non-linear evolutions.

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General Relativity and Quantum Cosmology

Trapped surface formation via radial boosts

Nathan Thomas Carruth

Work of Christodoulou, Klainerman, Rodnianski, Luk, An, and others has provided a number of results on the dynamical formation of trapped surfaces in vacuum solutions to the Einstein field equations. Since the stability of Minkowski spacetime as proved by Christodoulou and Klainerman implies that `small' initial data to the Einstein vacuum equations must give rise to a solution with no singularities, and hence no trapped surfaces, it has been assumed that dynamical formation of trapped surfaces requires a (hard) large-data existence result for the nonlinear hyperbolic Einstein field equations. In this paper we show, to the contrary, that dynamical trapped surface formation results qualitatively similar to those of Christodoulou and Klainerman-Rodnianski can be obtained from (classical) local, small-data existence results via a scaling we term a radial boost. In the process we also fully elucidate the short-pulse ansatz as a geometric optics ansatz by showing that, in this scaled picture, the so-called incoming shear satisfies, at highest order, a linear wave equation.

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General Relativity and Quantum Cosmology · Cross-listed from hep-th

On-Shell Amplitudes and Black-Hole Perturbations: Exact Reissner-Nordström Mixing

Kento Takahara and Teppei Kitahara

Can flat-space on-shell amplitudes determine the channel basis of a coupled black-hole perturbation problem? We address this question for electromagnetic and gravitational perturbations of a Reissner-Nordström (RN) black-hole. We organize the minimally coupled photon-graviton tree amplitudes off a heavy charged source into a $2\times 2$ channel-space matrix and perform a parity-resolved Jacob-Wick partial-wave projection. For every radiative multipole $\ell \geq 2$ and in both parity sectors, we show that the trace-free fixed-source partial-wave matrix is exactly proportional to the trace-free Moncrief coupling matrix, and therefore selects the same constant spectral projectors. Through a first-Born matching, the amplitudes determine the same eigenspaces in the leading $r^{-3}$ weak-field potential, but not the complete radial potentials. Using the exact classical RN potentials as independent curved-background input, we show that these projectors persist throughout the full radial domain. We also explicitly retain finite-mass effects through $\mathcal{O}(\omega/m)$, finding a nonvanishing commutator with the Moncrief coupling matrix, which shows that the RN-projector alignment is spoiled by genuine two-body recoil effects. As a first step toward rotation, we further extract the representation-independent linear-spin term from a minimally coupled Dirac amplitude. We find that the complete tree-level channel matrix factorizes with a single linear-spin dressing, while the formal $J=2$ block fails to preserve the unchanged RN projectors. This restricted result does not constitute a test of Kerr-Newman separability, but it indicates that a rotating generalization must account for spin-induced angular-mode mixing. We expect that this on-shell method can be extended to more general long-range scattering systems with two asymptotic channels.

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General Relativity and Quantum Cosmology · Cross-listed from astro-ph.IM

LIGO A$^\sharp$: Detector Design and Science Prospects Beyond A+

L. Sun, K. Kuns, B. J. J. Slagmolen et al. (+1153 more)

We present the LIGO A$^\sharp$ detector concept, an upgrade for the LIGO observatories based on room-temperature interferometers beyond the fifth observing run (O5). Building on the A+ sensitivity, A$^\sharp$ targets broadband sensitivity improvements through heavier test masses, improved suspensions and seismic isolation, increased arm-cavity power, enhanced frequency-dependent squeezing, reduced coating thermal noise considering two scenarios, and improved control of mechanical motion and optical modes. We describe the principal design choices, projected noise performance, and corresponding astrophysical prospects. LIGO A$^\sharp$ substantially increases compact-binary detection rates, strengthens population inference, and improves both early-warning times and localization for binary neutron star mergers. The improved sensitivity enables more detailed studies of compact-binary coalescences, including higher-order multipoles, intermediate-mass black holes, remnant black hole ringdown, and the neutron star equation of state. It also broadens the discovery potential for new gravitational-wave sources such as continuous waves and bursts, should enable detection of the stochastic background from compact binary mergers if it remains undetected after O5, and strengthens the role of gravitational-wave detectors as probes of fundamental physics. We discuss key technical challenges and the role of A$^\sharp$ as both a major scientific upgrade for the 2030s and a technology pathfinder for next-generation gravitational-wave observatories, such as Cosmic Explorer.

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All authors L. Sun, K. Kuns, B. J. J. Slagmolen, P. Fritschel, P. Schmidt, B. T. Lantz, S. S. Y. Chua, Divyajyoti, S. W. Ballmer, M. A. Barton, A. V. Cumming, K. L. Dooley, J. C. Driggers, A. Effler, M. Evans, B. Farr, G. González, N. Lu, D. J. Ottaway, C. Palomba, O. J. Piccinni, G. Pratten, S. Raja, A. P. Subhash, P. J. Sutton, K. Toland, R. L. Ward, A. G. Abac, I. Abouelfettouh, K. Ackley, A. Adam, S. Adhicary, D. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, P. Ajith, L. Albers, S. Al-Kershi, S. Al-Shammari, J. A. Alvarez, S. Alvarez-Lopez, O. Amarasinghe, A. Amato, S. An, A. B. Anand, C. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, F. Andrade-Oliveira, M. Andrés-Carcasona, J. L. Andrey, T. Andric, J. Anglin, J. Anna, J. M. Antelis, L. V. da Conceição, T. Aoki, E. Z. Appavuravther, E. A. Appelt, S. Appert, S. K. Apple, K. Arai, M. C. Araya, J. S. Areeda, M. Ramos Arevalo, S. Armstrong, M. Arogeti, S. M. Aronson, K. G. Arun, G. Ashton, S. M. Aston, K. AultONeal, G. Avallone, E. A. Avila, C. Badger, S. Bae, K. A. Baker, T. Baker, M. Ball, S. Banagiri, D. Bankar, T. M. Baptiste, P. Baral, J. C. Barayoga, K. Baric, B. C. Barish, D. Barker, N. Barman, B. Barr, M. Barrios, L. Barsotti, I. Bartos, A. Basalaev, R. Bassiri, J. C. Bayley, A. C. Baylor, P. A. Baynard II, B. Becher, V. M. Bedakihale, A. S. Bell, D. S. Bellie, W. Benoit, F. Bergamin, B. K. Berger, M. Beroiz, C. P. L. Berry, I. Berry, J. Betzwieser, D. Beveridge, N. Bevins, R. Bhandare, R. Bhatt, A. Bhattacharjee, D. Bhattacharjee, S. Bhattacharyya, S. Bhaumik, I. A. Bilenko, G. Billingsley, S. Bini, O. Birnholtz, S. Biscoveanu, A. Bisht, S. Blaber, J. K. Blackburn, L. A. Blagg, C. D. Blair, D. G. Blair, N. Bode, N. Boettner, P. Bogdan, G. N. Bolingbroke, L. D. Bonavena, V. A. Bonhomme, E. Bonilla, M. S. Bonilla, A. Bonino, A. Borchers, S. Bose, V. Bossilkov, T. D. Boybeyi, M. Boyle, M. J. Brady, P. R. Brady, A. Branch, M. Brinkmann, P. Brockill, E. Brockmueller, A. F. Brooks, D. D. Brown, S. Brunett, R. Bruntz, J. Bryant, Y. Bu, A. Buonanno, K. Burtnyk, J. Calderón Bustillo, R. L. Byer, V. A. Cáceres-Barbosa, L. Cadonati, C. Cahillane, A. Calafat, J. D. Callaghan, T. A. Callister, S. R. Callos, V. Cantory, H. Cao, L. A. Capistran, E. Capote, C. Capuano, K. J. Cardona-Martínez, M. Carlassara, J. Yébana Carrilero, G. Carrillo, G. Carullo, S. Caudill, M. Cavaglià, A. Ceja, N. Chabbra, A. Chakraborty, P. Chakraborty, S. Chakraborty, C. Chan, J. C. L. Chan, M. Chan, K. Chang, S. Chao, P. Charlton, C. Chatterjee, Debarati Chatterjee, Deep Chatterjee, M. Chaturvedi, A. Chen, H. Y. Chen, S. Chen, Yanbei Chen, Yiwen Chen, G. Cheng, H. P. Cheng, T. Cheunchitra, H. T. Cheung, S. Y. Cheung, G. Chiarini, M. Chicoine, D. Chintala, S. Choudhary, N. Christensen, Y. K. Chu, B. Cirok, F. Clara, J. A. Clark, T. A. Clarke, A. Claveus, M. R. Claypool, S. M. Clyne, D. E. Cohen, E. Colangeli, O. Cole, G. D. Cole, M. Colleoni, C. G. Collette, J. Collins, S. Colloms, C. M. Compton, G. Connolly, T. R. Corbitt, N. J. Cornish, A. Corsi, L. Cotnoir, R. Cottingham, J. A. Cotturone, M. W. Coughlin, P. Couvares, R. Coyne, J. D. E. Creighton, T. D. Creighton, S. Crook, R. Crouch, J. Csizmazia, T. J. Cullen, Y. Dang, O. Danner, K. Danzmann, K. E. Darroch, C. Darsow-Fromm, L. P. Dartez, R. Das, S. Das, A. Dasgupta, I. Dave, A. Davenport, T. F. Davies, D. Davis, M. C. Davis, E. J. Daw, M. Dax, E. deBruin, M. Deenadayalan, O. M. del Rio, N. Demos, T. Dent, N. DePergola, E. K. Derrick, M. Desai, D. DeSantis, S. Deshmukh, V. Deshmukh, S. Determan, A. Dhani, R. Dhatri, R. Dhurkunde, R. Diab, M. C. Díaz, T. Dietrich, C. Di Fronzo, A. Dmitriev, J. P. Docherty, Z. Doctor, N. Doerksen, E. Dohmen, A. Doke, F. Donovan, S. Doravari, F. Dosopoulou, R. S. Dumbreck, S. Dwivedi, S. E. Dwyer, C. Eassa, M. Eberhardt, M. Ebersold, M. Ebiri, T. Eckhardt, G. Eddolls, J. Eichholz, M. Emma, R. Enficiaud, R. Espinosa, R. C. Essick, H. Estellés, T. Etzel, T. Evstafyeva, J. M. Ezquiaga, S. Fairhurst, X. Fan, A. M. Farah, W. M. Farr, M. Favata, M. Fazio, J. Feicht, M. M. Fejer, J.-N. Feldhusen, J. Fernandes, D. Fernando, T. A. Ferreira, M. Ferrer-Martinez, M. Fishbach, R. P. Fisher, S. K. Fitzgerald, B. Flanagan, S. M. Fleischer, L. S. Fleming, E. Floden, H. Fong, F. Fontinele-Nunes, C. Foo, B. Fornal, P. W. F. Forsyth, A. Franco-Ordovas, J. P. Freed, Z. Frei, R. Frey, W. Frischhertz, V. V. Frolov, M. Fuentes-Garcia, P. Fulda, M. Fyffe, J. R. Gair, V. Galdi, A. Gamboa, S. Gamoji, A. Ganguly, C. García-Quirós, J. W. Gardner, A. Garron, P. A. Garver, V. Gayathri, T. Gayer, J. George, R. George, D. George, O. Gerberding, L. Gergely, Sayantan Ghosh, Shaon Ghosh, Shrobana Ghosh, Suprovo Ghosh, Tathagata Ghosh, J. A. Giaime, K. D. Giardina, D. R. Gibson, C. Gier, J. Glanzer, J. Godfrey, R. V. Godley, O. Godwin, A. S. Goettel, E. Goetz, J. Golomb, P. Goodarzi, S. R. Goode, S. M. Goss-Grubbs, D. W. Gould, K. Govorkova, V. Graham, A. E. Granados, M. Granata, V. Granata, S. Gras, P. Grassia, C. Gray, R. Gray, K. Gray, L. Green, S. R. Green, A. M. Gretarsson, E. M. Gretarsson, D. Griffith, H. Grote, S. Grunewald, A. G. Guerrero, T. Guidry, H. K. Gulati, H. Guo, W. Guo, A. Gupta, I. Gupta, N. C. Gupta, S. K. Gupta, V. Gupta, N. Gupte, N. Guttman, F. Guzman, M. Haberland, E. D. Hall, E. Z. Hamilton, G. Hammond, J. Hanks, C. Hanna, M. D. Hannam, O. A. Hannuksela, H. Hansen, J. Hanson, A. R. Hardison, K. Haris, I. Harley-Trochimczyk, G. M. Harry, I. W. Harry, C.-J. Haster, K. Haughian, J. Hedberg, A. Heffernan, M. C. Heintze, J. Heinzel, F. Hellman, A. F. Helmling-Cornell, O. Henderson-Sapir, M. Hendry, I. S. Heng, M. H. Hennig, C. Henshaw, A. Heranval, M. Heurs, A. L. Hewitt, J. Heyns, D. Hickey, M. Hill, S. Hill, N. A. Holland, K. Holley-Bockelmann, I. J. Hollows, D. E. Holz, K. M. Hoops, M. E. Hoque, D. J. Horton-Bailey, J. Hough, S. Hourihane, N. T. Howard, E. J. Howell, C. G. Hoy, P. Hsi, H. Y. Huang, Y. Huang, A. D. Huddart, B. Hughey, S. Husa, G. A. Iandolo, Y. Inoue, J. Irwin, T. Ishikawa, M. Isi, K. S. Isleif, S. Iwaguchi, M. M. Iwaya, B. R. Iyer, S. J. Jadhav, S. P. Jadhav, K. Jain, A. L. James, K. Jani, S. Jani, N. N. Janthalur, R. Jaume, W. Javed, M. Jensen, W. Jia, J. Jiang, S.-J. Jin, G. R. Johns, N. A. Johnson, M. C. Johnston, R. Johnston, N. Johny, D. H. Jones, D. I. Jones, R. Jones, P. Joshi, S. K. Joshi, J. Ju, L. Ju, I. L. Juarez-Reyes, H. B. Kabagoz, V. Kalogera, M. Kalomenopoulos, S. Kandhasamy, G. Kang, M. Kang, J. B. Kanner, S. J. Kapadia, D. P. Kapasi, A. S. Karia, R. Kashyap, M. Kasprzack, E. Katsavounidis, W. Katzman, R. Kaushik, K. Kawabe, S. Kawamura, D. Keitel, S. A. Kemper, L. J. Kemperman, J. Kennington, R. Kesharwani, J. S. Key, R. Khadela, S. S. Khadkikar, F. Y. Khalili, C. Khamar, F. Khan, M. Khursheed, N. M. Khusid, C. Kim, J. C. Kim, K. Kim, M. H. Kim, Y.-M. Kim, C. Kimball, K. Kimes, M. Kinnear, J. S. Kissel, S. Klimenko, A. M. Knee, N. Knust, S. M. Koehlenbeck, K. Kokeyama, P. Kolitsidou, K. Kompanets, A. K. H. Kong, A. Kontos, K. Kopczuk, L. M. Koponen, M. Korobko, X. Kou, N. Kouvatsos, D. B. Kozak, V. Kringel, N. V. Krishnendu, S. Kroker, K. Kruska, G. Kuehn, D. Kukla, Achal Kumar, Anil Kumar, Dhruv Kumar, Praveen Kumar, Prayush Kumar, Rahul Kumar, Rakesh Kumar, Ravi Kumar, V. Kumar, N. Kuntimaddi, K. Kwan, G. Lacaille, D. Laghi, A. H. Laity, E. Lalande, S. Lalvani, M. Landry, R. N. Lang, A. Lange, R. Langgin, I. La Rosa, O. Laske, P. D. Lasky, J. Lawrence, M. Laxen, A. Lazzarini, L. Leali, Y. K. Lecoeuche, J. Lee, K. Lee, R. Lee, S. Lee, Y. Lee, I. N. Legred, J. Lehmann, L. Lehner, M. Lesovsky, Y. Levin, K. Leyde, X. Li, Y. Li, Z. Li, Q. Liang, F. Lin, C. Lindsay, S. D. Linker, A. Liu, Jian Liu, S. Liu, J. Llobera-Querol, R. K. L. Lo, S. C. G. Loggins, L. T. London, R. Rodriguez Lopez, A. Lorenzo-Medina, M. Lormand, T. P. Lott IV, J. D. Lough, H. A. Loughlin, C. O. Lousto, N. K. Y. Low, H. Lück, O. Lukina, A. P. Lundgren, A. W. Lussier, X. Ma, M. Ma'arif, S. MacBride, I. MacLaren, D. M. Macleod, I. A. O. MacMillan, S. S. Magare, R. M. Magee, E. Maggio, P. Mahapatra, M. Mahesh, S. Majhi, C. N. Makarem, E. Makelele, N. Malagon, D. Malakar, J. A. Malaquias-Reis, U. Mali, S. Maliakal, A. Malik, L. Mallick, A.-K. Malz, V. Mandic, Z. Mangi, B. Mannix, G. L. Mansell, M. Manske, J. Mark, A. S. Markosyan, J. Markus, E. Maros, I. W. Martin, R. M. Martin, B. B. Martinez, J. C. Martins, D. V. Martynov, E. J. Marx, M. Masso-Reid, T. Masters, M. Matiushechkina, A. Matte-Landry, N. Mavalvala, N. Maxwell, A. McCann, G. McCarrol, R. McCarthy, D. E. McClelland, S. McCormick, L. McCuller, L. I. McDermott, C. McElhenny, G. I. McGhee, K. B. M. McGowan, J. McIver, A. McLeod, I. McMahon, T. McRae, R. McTeague, K. McWhirter, D. Meacher, B. N. Meagher, R. Mechum, M. Mehmet, R. M. Mehta, A. Melatos, C. S. Menoni, R. A. Mercer, K. Merfeld, E. L. Merilh, J. R. Mérou, C. Messick, F. Meylahn, H. Miao, C. Michel, H. Middleton, D. P. Mihaylov, S. J. Miller, M. Millhouse, A. Mishra, C. Mishra, T. Mishra, A. Mitchell, J. G. Mitchell, O. Mitchem, S. Mitra, V. P. Mitrofanov, R. Mittleman, G. Mo, S. R. P. Mohapatra, M. Molina-Ruiz, M. Mondin, C. J. Moore, D. Moraru, A. More, S. More, C. Moreno, E. A. Moreno, G. Moreno, C. Morgan, M. Mould, C. M. Mow-Lowry, Arunava Mukherjee, D. Mukherjee, Samanwaya Mukherjee, Soma Mukherjee, Subroto Mukherjee, Suvodip Mukherjee, N. Mukund, A. Mullavey, C. L. Mungioli, P. G. Murray, S. Muusse, S. A. Vallejo-Peña, N. Nagarajan, A. Nakamura, M. Nakano, D. Nandi, S. U. Naqvi, P. Narayan, R. K. Nayak, J. Neeson, A. Nela, C. Nelle, A. Nelson, T. J. N. Nelson, A. Neunzert, M. Newell, S. Ng, A. B. Nielsen, W. Niu, J. Noller, M. Norman, C. North, A. Numic, G. Nurbek, L. K. Nuttall, J. Oberling, C. E. Ochoa, C. O'Connor, J. O'Dell, E. Oelker, J. J. Oh, T. O'Hanlon, F. Ohme, I. Oke, R. Omer, N. O'Neill, P. Ophardt, R. J. Oram, B. O'Reilly, R. O'Shaughnessy, J. Ostrovska, A. Osumi, I. Ota, G. Othman, H. Overmier, B. J. Owen, A. E. Pace, A. Pai, S. Pal, M. Pálfi, H. Pan, J. Pan, P. K. Panda, Shiksha Pandey, Swadha Pandey, B. C. Pant, F. H. Panther, A. Papadopoulos, E. E. Papalexakis, J. Park, W. Parker, G. Pascale, L. Passenger, O. Patane, A. V. Patel, L. Pathak, A. Patra, B. G. Patterson, K. Paul, S. Paul, E. Payne, T. Pearce, M. Pedraza, A. Pele, X. Peng, Y. Peng, S. Penn, S. Petracca, H. P. Pfeiffer, H. Pham, K. A. Pham, K. S. Phukon, H. Phurailatpam, A. Pied, V. Pierro, B. Pillon, I. M. Pinto, B. J. Piotrzkowski, M. Pirello, M. D. Pitkin, M. L. Planas, C. Plunkett, L. Pompili, J. Poon, A. S. Porter, C. Posnansky, J. Powell, G. S. Prabhu, A. K. Prajapati, K. Prasai, R. Prasanna, P. Prasia, A. Puecher, J. Pullin, M. Pürrer, H. Qi, M. Qiao, J. Qin, V. Quetschke, P. J. Quinonez, R. Rading, C. Rajan, B. Rajbhandari, A. Kulur Ramamohan, K. E. Ramirez, A. Ramos-Buades, S. Ranjan, M. Ranjbar, K. Ransom, B. Ratto, A. Ravichandran, A. Ray, V. Raymond, J. Read, J. Redepenning, J. Regan, T. Reichardt, S. Reid, C. Reissel, D. H. Reitze, A. I. Renzini, J. Rice, J. W. Richardson, M. L. Richardson, K. Riles, H. K. Riley, J. D. H. Rivero, M. Robinson, J. Rodriguez, J. G. Rollins, A. E. Romano, I. M. Romero-Shaw, J. H. Romie, S. Ronchini, T. J. Roocke, T. J. Rosauer, C. A. Rose, M. P. Ross, M. Rossello-Sastre, S. Rowan, K. Rowlands, P. Dutta Roy, S. K. Roy, T. RoyChowdhury, G. H. Ruiz, K. Ruiz-Rocha, V. Russ, S. M. S., S. Sachdev, T. Sadecki, S. Safi-Harb, M. R. Raj Sah, M. Sakellariadou, S. Sakon, F. Salces-Carcoba, M. Saleem, S. U. Salunkhe, A. Salvarese, P. M. Samir, A. Sanchez, E. J. Sanchez, J. Sanchez, D. Sanchez-Cid, J. R. Sanders, E. M. Sänger, J. Sanjuan, E. Sapkin, T. R. Saravanan, P. Sarkar, A. Sasli, B. S. Sathyaprakash, O. Sauter, R. L. Savage, T. Savicheva, H. L. Sawant, D. Schaetzl, M. Scheel, L. M. Scheel, A. Schiebelbein, F. Schiettekatte, M. G. Schiworski, K. Schluterman, R. Schnabel, M. Schneewind, R. M. S. Schofield, B. W. Schulte, B. F. Schutz, E. 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General Relativity and Quantum Cosmology

Constraints on ultralight bosons from merging binary and remnant black holes observed during the second and third parts of the fourth LIGO-Virgo-KAGRA observing run

The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration: A. G. Abac et al. (+1807 more)

We present constraints on ultralight bosons using binary black hole mergers observed in the second and third parts of the fourth LIGO-Virgo-KAGRA observing run. Directed searches are conducted for long-transient gravitational waves from ultralight vector boson clouds around merger remnants, using a hidden-Markov-model (HMM) tracking scheme. We target the remnant black holes formed in the binary coalescences that produced GW250114 and GW250207. We find no evidence for such signals from either target. Estimating our search sensitivity at a threshold corresponding to a 1% false alarm probability, we thus disfavor vector boson masses in the range of $[2.80, 3.95]\times 10^{-13}$ eV with greater than 90% confidence. In addition, we derive constraints on ultralight scalar and vector bosons from the inferred high spins of the constituent black holes in three binaries, using events GW240515, GW241113, and GW241225_08. The excluded mass ranges in this approach depend on the assumed black-hole ages. At $10^5$ years, corresponding to typical dynamically formed binaries, we exclude scalar and vector bosons in the ranges $[1.39, 6.94]\times 10^{-13}$ eV and $[0.32, 14.4]\times 10^{-13}$ eV at 90% confidence, respectively.

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All authors The LIGO Scientific Collaboration, the Virgo Collaboration, the KAGRA Collaboration: A. G. Abac, A. Abe, I. Abouelfettouh, F. Acernese, K. Ackley, A. Adam, S. Adhicary, D. Adhikari, R. X. Adhikari, V. K. Adkins, S. Afroz, A. Agapito, D. Agarwal, M. Agathos, N. Aggarwal, S. Aggarwal, O. D. Aguiar, I.-L. Ahrend, L. Aiello, A. Ain, P. Ajith, T. Akutsu, L. Albers, W. Ali, S. Al-Kershi, C. Allene, A. Allocca, S. Al-Shammari, J. A. Alvarez, S. Alvarez-Lopez, W. Amar, O. Amarasinghe, A. Amato, F. Amicucci, C. Amra, A. B. Anand, C. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, M. Andia, M. Ando, F. Andrade-Oliveira, M. Andrés-Carcasona, J. L. Andrey, T. Andrić, J. Anglin, J. Anna, J. M. Antelis, S. Antier, T. Aoki, M. Aoumi, E. Z. Appavuravther, E. A. Appelt, S. Appert, S. K. Apple, K. Arai, A. Araya, M. C. Araya, F. Arciprete, J. S. Areeda, N. Aritomi, F. Armato, S. Armstrong, N. Arnaud, M. Arogeti, S. M. Aronson, K. G. Arun, G. Ashton, Y. Aso, L. Asprea, M. Assiduo, S. 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Kukla, A. Kulur Ramamohan, Achal Kumar, Anil Kumar, Dhruv Kumar, Praveen Kumar, Prayush Kumar, Rahul Kumar, Rakesh Kumar, Ravi Kumar, J. Kume, K. Kuns, N. Kuntimaddi, S. Kuroyanagi, K. Kwak, K. Kwan, S. Kwon, G. Lacaille, D. Laghi, A. H. Laity, N. Lajili, A. Lakhal, E. Lalande, M. Lalleman, S. Lalvani, M. Landry, R. N. Lang, A. Lange, J. A. Lange, R. Langgin, B. Lantz, I. La Rosa, O. Laske, P. D. Lasky, L. Lavezzi, J. Lawrence, M. Laxen, A. Lazzarini, C. Lazzaro, P. Leaci, L. Leali, Y. K. Lecoeuche, H. W. Lee, J. Lee, K. Lee, R.-K. Lee, R. Lee, Sungho Lee, Sunjae Lee, W. Lee, Y. Lee, F. Legger, I. N. Legred, J. Lehmann, L. Lehner, M. Le Jean, A. Lemaître, R. Lemrani Alaoui, M. Lenti, M. Leonardi, M. Lequime, M. Lesovsky, N. Letendre, M. Lethuillier, Y. Levin, S. Lexmond, K. Leyde, A. K. Y. Li, K. L. Li, T. G. F. Li, X. Li, Y. Li, Z. Li, Q. Liang, C-Y. Lin, E. T. Lin, F. Lin, L. C.-C. Lin, Y.-C. Lin, C. Lindsay, S. D. Linker, A. Liu, F. Liu, G. C. Liu, Jian Liu, S. Liu, F. Llamas Villarreal, J. Llobera-Querol, R. K. L. Lo, J.-P. Locquet, S. C. G. Loggins, L. T. London, A. Longo, M. Lopez Portilla, M. Lorenzini, A. Lorenzo-Medina, V. Loriette, M. Lormand, M. Lorusso, G. Losurdo, T. P. Lott IV, J. D. Lough, H. A. Loughlin, C. O. Lousto, N. K. Y. Low, N. Lu, H. Lück, O. Lukina, D. Lumaca, A. P. Lundgren, L. Lunghini, A. W. Lussier, L.-T. Ma, X. Ma, M. Ma'arif, S. MacBride, K. Machida, D. M. Macleod, I. A. O. MacMillan, A. Macquet, S. S. Madekar, S. Maenaut, S. S. Magare, R. M. Magee, E. Maggio, M. Magnozzi, P. Mahapatra, M. Mahesh, S. Majhi, E. Majorana, C. N. Makarem, E. Makelele, N. Malagon, D. Malakar, J. A. Malaquias-Reis, U. Mali, S. Maliakal, A. Malik, L. Mallick, A.-K. Malz, N. Man, M. Mancarella, V. Mandic, V. Mangano, Z. Mangi, B. Mannix, G. L. Mansell, M. Manske, M. Mantovani, M. Mapelli, S. Marchetti, F. Marion, J. Mark, A. S. Markosyan, J. Markus, E. Maros, S. Marsat, F. Martelli, I. W. Martin, R. M. Martin, B. B. Martinez, M. Martinez, V. Martinez, A. Martini, Juan Carlos Martins, Julio C. Martins, D. V. Martynov, E. J. Marx, L. Massaro, A. Masserot, M. Masso-Reid, T. Masters, S. Mastrogiovanni, G. Mastropasqua, M. Matiushechkina, A. Matte-Landry, L. Maurin, N. Mavalvala, N. Maxwell, A. McCann, G. McCarrol, R. McCarthy, D. E. McClelland, S. McCormick, L. McCuller, L. I. McDermott, C. McElhenny, G. I. McGhee, K. B. M. McGowan, J. McIver, A. McLeod, I. McMahon, T. McRae, R. McTeague, K. McWhirter, D. Meacher, B. N. Meagher, R. Mechum, L. G. Medeiros, R. M. Mehta, A. Melatos, C. S. Menoni, R. A. Mercer, L. Mereni, K. Merfeld, E. L. Merilh, J. R. Mérou, C. Messick, M. Meyer-Conde, F. Meylahn, H. Miao, C. Michel, Y. Michimura, H. Middleton, D. P. Mihaylov, S. J. Miller, M. Millhouse, E. Milotti, V. Milotti, E. Minakaki, Y. Minenkov, Ll. M. Mir, L. Mirasola, C.-A. Miritescu, A. Mishra, C. Mishra, T. Mishra, A. Mitchell, J. G. Mitchell, O. Mitchem, S. Mitra, V. P. Mitrofanov, K. Mitsuhashi, R. Mittleman, O. Miyakawa, S. Miyoki, G. Mo, L. Mobilia, S. R. P. Mohapatra, M. Molina-Ruiz, M. Mondin, M. Montani, G. Montefusco, C. J. Moore, D. Moraru, A. More, S. More, C. Moreno, E. A. Moreno, G. Moreno, A. Moreso Serra, C. Morgan, S. Morisaki, S. Moriwaki, Y. Moriwaki, G. Morras, A. Moscatello, M. Mould, B. Mours, C. M. Mow-Lowry, L. Muccillo, F. Muciaccia, Arunava Mukherjee, D. Mukherjee, Samanwaya Mukherjee, Soma Mukherjee, Subroto Mukherjee, Suvodip Mukherjee, N. Mukund, A. Mullavey, C. L. Mungioli, Y. Murakami, M. Murakoshi, P. G. Murray, D. Nabari, S. Nadji, A. Nagar, N. Nagarajan, K. Nakagaki, A. Nakamura, K. Nakamura, H. Nakano, M. Nakano, D. Nanadoumgar-Lacroze, D. Nandi, V. Napolano, S. U. Naqvi, P. Narayan, A. Nardecchia, I. Nardecchia, T. Narikawa, H. Narola, L. Naticchioni, R. K. Nayak, J. Neeson, L. Negri, A. Nela, C. Nelle, A. Nelson, T. J. N. Nelson, A. Nemmani, A. Neunzert, M. Newell, S. Ng, T. C. K. Ng, L.-A. T. Nguyen, T. T. Nguyen, L. Nguyen Quynh, A. B. Nielsen, Y. Nishino, A. Nishizawa, S. Nissanke, W. Niu, F. Nocera, J. Noller, M. Norman, C. North, J. Novak, G. Nurbek, L. K. Nuttall, K. Obayashi, J. Oberling, C. E. Ochoa, C. O'Connor, J. O'Dell, E. Oelker, M. Oertel, G. Oganesyan, J. J. Oh, T. O'Hanlon, M. Ohashi, F. Ohme, Y. Okabe, I. Oke, R. Oliveira, R. Omer, N. O'Neill, M. Onishi, K. Oohara, P. Ophardt, R. J. Oram, B. O'Reilly, R. O'Shaughnessy, S. Oshino, J. Ostrovska, A. Osumi, I. Ota, G. Othman, M. Otsuka, D. J. Ottaway, A. Ouzriat, H. Overmier, B. J. Owen, A. E. Pace, M. A. Page, A. Pai, S. Pal, M. A. Palaia, M. Pálfi, C. Palomba, H. Pan, J. Pan, K.-C. Pan, P. K. Panda, Shiksha Pandey, Swadha Pandey, P. T. H. Pang, F. Pannarale, B. C. Pant, F. H. Panther, M. Panzeri, F. Paoletti, A. Paoli, A. Paolone, A. Papadopoulos, E. E. Papalexakis, L. Papalini, G. Papigkiotis, A. Paquis, A. Parisi, B.-J. Park, Jihwan Park, Junegyu Park, W. Parker, G. Pascale, D. Pascucci, A. Pasqualetti, L. Passenger, D. Passuello, O. Patane, A. V. Patel, L. Pathak, A. Patra, B. Patricelli, B. G. Patterson, K. Paul, S. Paul, E. Payne, T. Pearce, M. Pedraza, A. Pele, F. E. Peña Arellano, X. Peng, Y. Peng, S. Penn, A. Perreca, J. Perret, D. Pesios, S. Petracca, C. Petrillo, H. P. Pfeiffer, H. Pham, K. A. Pham, K. S. Phukon, H. Phurailatpam, L. Piccari, O. J. Piccinni, M. Pichot, A. Pied, M. Piendibene, F. Piergiovanni, L. Pierini, G. Pierra, V. Pierro, M. Pillas, B. Pillon, L. Pinard, I. M. Pinto, M. Pinto, B. J. Piotrzkowski, M. Pirello, A. Pisarski, M. D. Pitkin, E. Placidi, M. L. Planas, C. Plunkett, R. Poggiani, E. Polini, M. Polo, J. Pomper, L. Pompili, J. Poon, E. Porcelli, A. S. Porter, E. K. Porter, C. Posnansky, J. Powell, G. S. Prabhu, M. Pracchia, A. K. Prajapati, K. Prasai, R. Prasanna, P. Prasia, G. Pratten, G. Principe, G. A. Prodi, P. Prosperi, P. Prosposito, A. Puecher, J. Pullin, M. Punturo, P. Puppo, M. Pürrer, H. Qi, M. Qiao, J. Qin, G. Quéméner, V. Quetschke, P. J. Quinonez, R. Rading, I. Rainho, S. Raja, C. Rajan, B. Rajbhandari, M. R. Raj Sah, K. E. Ramirez, F. A. Ramis Vidal, M. Ramos Arevalo, A. Ramos-Buades, S. Ranjan, M. Ranjbar, K. Ransom, P. Rapagnani, B. Ratto, A. Ravichandran, A. Ray, V. Raymond, M. Razzano, J. Read, J. Redepenning, J. Regan, T. Regimbau, T. Reichardt, S. Reid, C. Reissel, D. H. Reitze, A. I. Renzini, B. Revenu, A. Revilla-Peña, F. Ricci, M. Ricci, A. Ricciardone, J. Rice, J. W. Richardson, M. L. Richardson, K. Riles, H. K. Riley, A. Riminucci, F. Robinet, M. Robinson, A. Rocchi, J. Rodriguez, R. Rodriguez Lopez, L. Rolland, J. G. Rollins, A. E. Romano, R. Romano, A. Romero-Rodríguez, I. M. Romero-Shaw, J. H. Romie, S. Ronchini, T. J. Roocke, T. J. Rosauer, C. A. Rose, D. Rosińska, M. P. Ross, M. Rossello-Sastre, S. Rowan, K. Rowlands, S. K. Roy, S. Roy, T. RoyChowdhury, D. Rozza, P. Ruggi, G. H. Ruiz, E. Ruiz Morales, K. Ruiz-Rocha, V. Russ, S. M. S, S. Sachdev, T. Sadecki, F. Safai Tehrani, P. Saffarieh, S. Safi-Harb, S. Saha, T. Sainrat, S. Sajith Menon, K. Sakai, Y. Sakai, M. Sakellariadou, S. Sakon, F. Salces-Carcoba, L. Salconi, M. Saleem, F. Salemi, M. Sallé, M. Salomé, S. U. Salunkhe, S. Salvador, A. Salvarese, A. Samajdar, P. M. Samir, A. Sanchez, E. J. Sanchez, J. Sanchez, D. Sanchez-Cid, N. Sanchis-Gual, J. R. Sanders, E. M. Sänger, F. Santoliquido, E. Sapkin, F. Sarandrea, T. R. Saravanan, P. Sarkar, A. Sasli, P. Sassi, B. Sassolas, B. S. Sathyaprakash, O. Sauter, R. L. Savage, T. Savicheva, T. Sawada, H. L. Sawant, D. Schaetzl, M. Scheel, A. Schiebelbein, M. G. Schiworski, K. Schluterman, P. Schmidt, R. Schnabel, M. Schneewind, R. M. S. Schofield, M. Schoor, K. Schouteden, B. W. Schulte, M. Schulz, B. F. Schutz, E. Schwartz, M. Scialpi, J. Scott, S. M. Scott, R. M. Sedas, T. C. Seetharamu, M. Seglar-Arroyo, Y. Sekiguchi, D. Sellers, N. Sembo, E. G. Seo, J. W. Seo, G. Seong, V. Sequino, M. Serra, C. K. Sethi, A. Sevrin, T. Shaffer, U. S. Shah, M. A. Shaikh, L. Shao, J. Sharkey, A. K. Sharma, Preeti Sharma, Priyanka Sharma, Sushant Sharma-Chaudhary, P. Shawhan, T. Shen, Z.-H. Shi, K. Shimode, H. Shinkai, S. Shirke, D. H. Shoemaker, D. M. Shoemaker, R. W. Short, S. ShyamSundar, H. Siegel, N. Siemonsen, V. Sierra, D. Sigg, L. Silenzi, P. J. S. Silva, L. Silvestri, M. Simmonds, L. P. Singer, A. Singh, D. Singh, M. K. Singh, N. Singh, S. Singh, M. R. Sinha, A. M. Sintes, V. Skliris, B. J. J. Slagmolen, T. J. Slaven-Blair, J. Smetana, D. A. Smith, J. R. Smith, J. Smith, L. Smith, W. J. Smith, S. Soares de Albuquerque Filho, M. Soares-Santos, K. Somiya, I. Song, S. Soni, V. Sordini, F. Sorrentino, H. Sotani, N. E. Sovitzky, F. Spada, V. Spagnuolo, A. P. Spencer, M. Spera, P. Spinicelli, A. K. Srivastava, F. Stachurski, V. V. Stanford, A. Stanton, D. A. Steer, N. Steinle, J. Steinlechner, S. Steinlechner, C. Stephens, N. Stergioulas, M. StPierre, J. Stremiz, M. D. Strong, A. Strunk, M. Suchenek, S. Sudhagar, R. Sugimoto, L. Suleiman, K. D. Sullivan, J. Sun, L. Sun, S. Sunil, J. Suresh, P. J. Sutton, K. Suzuki, M. Suzuki, A. Svizzeretto, B. L. Swinkels, A. Syx, M. J. Szczepańczyk, M. Tacca, M. Tagliazucchi, H. Tagoshi, S. C. Tait, H. Takaba, K. Takada, H. Takahashi, R. Takahashi, A. Takamori, S. Takano, H. Takeda, I. Takimoto Schmiegelow, C. Talbot, M. Tamaki, N. Tamanini, D. Tanabe, K. Tanaka, S. J. Tanaka, S. Tanioka, D. B. Tanner, W. Tanner, L. Tao, R. D. Tapia, E. N. Tapia San Martín, A. Taruya, J. D. Tasson, J. G. Tau, A. Tejera, J. G. Temple, Y. Teng, H. Themann, A. Theodoropoulos, M. P. Thirugnanasambandam, L. M. Thomas, M. Thomas, P. Thomas, J. E. Thompson, S. R. Thondapu, E. Thrane, J. Tissino, A. Tiwari, Pawan Tiwari, Praveer Tiwari, S. Tiwari, V. Tiwari, M. R. Todd, E. Tofani, M. Toffano, A. M. Toivonen, K. Toland, T. Tomaru, V. Tommasini, H. Tong, C. I. Torrie, I. Tosta e Melo, E. Tournefier, A. Trapananti, R. Travaglini, F. Travasso, G. Traylor, L. Traylor, M. Trevor, M. C. Tringali, A. Tripathee, G. Troian, A. Trovato, L. Trozzo, R. J. 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G. von Reis, J. S. A. von Wrangel, W. E. Vossius, L. Vujeva, S. P. Vyatchanin, J. Wack, L. E. Wade, M. Wade, K. J. Wagner, L. Wallace, R.-Z. Wan, H. Wang, P. Wang, W. H. Wang, Y. F. Wang, Z. Wang, R. L. Ward, J. Warner, M. Was, T. Washimi, N. Y. Washington, D. Watarai, B. Weaver, S. A. Webster, N. L. Weickhardt, M. Weinert, A. J. Weinstein, R. Weiss, L. Wen, K. Wette, C. Wheeler, J. T. Whelan, B. F. Whiting, E. G. Wickens, D. Wilken, B. M. Williams, D. Williams, M. J. Williams, N. S. Williams, J. L. Willis, B. Willke, M. Wils, L. Wimmer, C. W. Winborn, A. Wingfield, J. Winterflood, C. C. Wipf, G. Woan, N. E. Wolfe, H. T. Wong, I. C. F. Wong, T. Wouters, J. L. Wright, M. Wright, B. Wu, C. Wu, D. S. Wu, H. Wu, K. Wu, Z. Wu, E. Wuchner, D. M. Wysocki, V. A. Xu, Y. Xu, N. Yadav, H. Yamamoto, K. Yamamoto, T. S. Yamamoto, T. Yamamoto, R. Yamazaki, T. Yan, H. Yang, K. Z. Yang, Y. Yang, Z. Yarbrough, J. Yébana Carrilero, A. B. Yelikar, X. Yin, J. Yokoyama, T. Yokozawa, M. Yoshihara, S. Yuan, H. Yuzurihara, M. Zanatta, M. Zanolin, M. Zeeshan, T. Zelenova, J.-P. Zendri, M. Zeoli, M. Zerrad, M. Zevin, H. Zhang, J. Zhang, L. Zhang, N. Zhang, R. Zhang, T. Zhang, C. Zhao, J. Zhao, Yue Zhao, Yuhang Zhao, L.-M. Zheng, Y. Zheng, L. Zhizhong, H. Zhong, H. Zhou, H. O. Zhu, X.-J. Zhu, Z.-H. Zhu, Z. Zhu, D. Z. Zieba, A. B. Zimmerman, L. Zimmermann, M. E. Zucker

General Relativity and Quantum Cosmology

Pressure profile bounds from relaxing the TOV equation

Christopher Simmonds and Matt Visser

We develop several new and quite general bounds on the internal pressure profiles of general relativistic perfect fluid spheres — based on various ways of relaxing the TOV system of ODEs to obtain several distinct differential inequalities. There is, as usual, a trade-off between strength of the bound, weakness of the input assumptions, and tractability of the analysis. Specifically we shall develop several straightforward but nontrivial bounds that variously depend only on the positivity of density, the boundedness of density, the monotonicity of density, or the monotonicity of the average density. We shall carefully place these new bounds within the historical framework of previous efforts in this regard, and explore the ways in which they are inter-related.

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Tuesday 11 August

General Relativity and Quantum Cosmology

On Super-Hyperbolic Wormhole Geometries and their Deformations

Subrat Parida

In this study, we developed a unified geometric and relativistic framework for a new family of traversable wormholes constructed from a super-hyperbolic deformation of the classical catenoid, whose geometric embedding combines an explicit local curvature parameter $\kappa$, which secures a regular throat, with the Mittag-Leffler-based super-hyperboloid deformation function ${\mathfrak{S}C}_{\alpha} (v)$, where the deformation parameter $\alpha>1$ governs the radial onset and far-field growth of the embedding beyond the throat, continuously approaching the classical catenoidal geometry in the boundary limit $\alpha\rightarrow1^{+}$. Allowing a non-constant redshift $\Phi(r)$, we systematically evaluate closed analytical expressions for the shape function, curvature tensors, matter sources, and junction conditions, culminating in an exact thin-shell equation of motion and stability criterion. This work establishes a mathematically consistent and physically viable framework for the extension of wormhole theory, providing a new avenue for exploring exotic geometries within general relativity and identifying the conditions under which traversable configurations remain locally stable.

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General Relativity and Quantum Cosmology

Effects of Quantum Spin-Connection Foam in the Solar System, Galaxies, and the Universe

Igor V. Kanatchikov and Valery A. Kholodnyi

We argue that effects of the quantum spin-connection foam, which describes quantum gravity according to the precanonical quantization of General Relativity, may already be observed in the form of the small cosmological constant and a modification of Newtonian dynamics at small accelerations, manifested in the flat rotation curves of galaxies. We obtain a modification of the Newtonian potential that takes into account the existence of a fundamental small acceleration scale, $a_* = 8\pi G\hbar\varkappa$, where $\varkappa$ is a parameter with the dimensions of inverse spatial volume that appears on dimensional grounds. The connection between $\varkappa$ and the hadronic scale of the mass gap in the pure Yang-Mills sector of the Standard Model leads to an estimated value of $a_*$ compatible with the Milgromian acceleration scale in MOND. The connection between $a_*^2$ and the cosmological constant leads to a realistic value of the latter. Milgromian MOND, together with a theoretically distinct interpolating function, is derived under the assumption that classical dynamics is modified by the mean-field acceleration calculated from the simplest solution of precanonical quantum gravity in the nonrelativistic approximation. We also indicate that the effects of Newtonian dynamics modified by the spin-connection foam may be observable in the Solar System and even in laboratory experiments.

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General Relativity and Quantum Cosmology

Investigation of Circular Photon Orbits in Naked Singularity Spacetimes from a Geometric Method

Qing-Rong Xie and Chen-Kai Qiao

Circular photon orbits play a pivotal role in both gravitational theories and astronomical observations. However, the properties of circular photon orbits in naked singularity spacetimes remain insufficiently explored and deserve in-depth investigation. The present work is dedicated to a comprehensive study of the features of circular photon orbits in naked singularity spacetimes. Notably, a geometric approach is employed to investigate these orbits, in which the framework of optical geometry together with its intrinsic curvatures plays a crucial role. We analyze the existence of circular photon orbits through the intrinsic geodesic curvature, and then examine the numbers of stable and unstable circular orbits, as well as the topological invariant associated with circular photon orbits. By examining various classes of naked singularity spacetimes, we obtain a general conclusion regarding circular photon orbits that holds for the most of spherically symmetric naked singularity spacetimes: the total number of circular photon orbits is an even integer ($\textit{N} = \text{2}\textit{k}$), consisting of $\textit{k}$ stable orbits and $\textit{k}$ unstable orbits in equal proportion. A mathematical proof of this conclusion is also provided in the present work. Furthermore, a comparison with other categories of spacetimes reveals that the conclusions regarding the number of circular photon orbits in naked singularity spacetimes agree with those obtained for compact object spacetimes without naked singularities, indicating that the number of circular photon orbits is primarily governed by the presence of event horizons rather than spacetime singularities. Keywords: Circular Photon Orbit, Naked Singularity Spacetime, Optical Geometry, Geometric Curvatures

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General Relativity and Quantum Cosmology

Torsional pseudo-inflation beyond Einstein-Cartan

Fernando Izaurieta, Samuel Lepe and Cristian Quinzacara

Torsion entered early-universe cosmology twice: through the nonsingular Einstein–Cartan bounce, where the quantum spin of fermions halts the contraction, and through the proposal that the expansion following that bounce could take over the duties of cosmic inflation. We revisit the second idea in a constructive spirit. First we compute its budget: for a Weyssenhoff spin fluid with barotropic source, $w\in\left[0,1\right]$, the accelerated window that follows the bounce spans $N_e=\ln\left[4/\left(1+3w\right)\right]/3\left(1-w\right)\leq\tfrac{1}{3}\ln4\simeq0.46$ e-folds, and positive spatial curvature only shrinks it. The mechanism is sound; its torsional “fuel” dilutes as $a^{-6}$, and the engine stops two orders of magnitude short of inflationary needs. We then ask what torsion would need in order to sustain a quasi-de Sitter phase, and give a two-branch answer in Riemann–Cartan cosmology with nonminimal couplings, where torsion is fed by the couplings rather than by spin. The vectorial branch reproduces Palatini inflation, observationally alive. On the axial branch we exhibit an exact de Sitter solution sustained by a torsion condensate: constant axial torsion $f_{0}$, a linear Gauss–Bonnet coupling, and a potential fixed to $V_{0}=6f_{0}^{2}+\tfrac{5}{2}v^{2}$ by the Friedmann constraint. The solution is an attractor of the homogeneous dynamics, with eigenvalue exactly $-3H$. The phase ends when the slope $U^{\prime}$, a decreasing function of the roll speed at fixed flat potential, drifts down to the floor $5/16V_{0}$ and the condensate switches itself off; consistency of the effective theory pins the whole episode near the Planck scale, $H\gtrsim0.3$ in reduced Planck units. We studied this branch at background level; its perturbation spectrum remains open.

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General Relativity and Quantum Cosmology

Imprints of core/cusp dark matter distributions on black hole signatures in galaxies

Hassan Hassanabadi, Che-Yu Chen, Soroush Zare et al. (+1 more)

In galactic environments, a host dark matter (DM) halo can imprint weak but coherent corrections on black hole (BH) strong-field observables. We construct an exact family of static and spherically symmetric BH spacetimes sourced by a generic core/cusp DM halo, described by an anisotropic stress-energy tensor with nonvanishing radial pressure. The resulting geometry is determined self-consistently from the Einstein equations for a broad $\{\alpha,\beta,\gamma\}$ density profile, including the NFW, Moore, Hernquist, Jaffe, and core/cusp Dehnen models as special cases. We discuss the asymptotic structure, horizon location, curvature scale, and energy conditions of the corresponding geometries, emphasizing that the inner logarithmic slope $\gamma$ controls the amount of DM probed by the relativistic region. We then obtain perturbative analytic estimates for the characteristic circular geodesics, demonstrating that the leading strong-field corrections are controlled by the dimensionless compactness $q_\gamma$, rather than by the total halo mass alone. To leading order in $q_\gamma$, we derive analytic expressions for the light ring radius, angular frequency, critical impact parameter, Lyapunov exponent, innermost stable circular orbit (ISCO) radius, and ISCO frequency. For cuspy profiles, the light ring and ISCO are displaced outward, while the corresponding orbital frequencies are redshifted; for cored profiles, the light ring radius is unchanged at this order, although its frequency and capture impact parameter still carry finite environmental corrections. We also investigate the weak- and strong-deflection angles and their dependence on the halo's inner structure. We further discuss how these environmental corrections may affect ringdown physics, in particular through the perturbative imprint of the halo on quasinormal-mode redshifts and late-time wave propagation.

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All authors Hassan Hassanabadi, Che-Yu Chen, Soroush Zare, Volker Perlick

General Relativity and Quantum Cosmology · Cross-listed from astro-ph.HE

Long-duration GW Searches for Sub-solar NSs and Superkilonovae using CoCoA

Abby Tejera, Divyajyoti, Alessandra Corsi et al. (+3 more)

On 2025 August 18, the LIGO-Virgo-KAGRA collaboration reported a sub-threshold gravitational-wave (GW) candidate, S250818k, consistent with a binary neutron star (NS) merger potentially involving a sub-solar-mass compact object. Follow-up electromagnetic (EM) observations identified a Type IIb supernova, SN 2025ulz within the broad localization area of the GW signal. This potential link between a sub-solar GW event candidate and a Type IIb SN, while not confirmed given the low statistical significance of S250818k, has nonetheless sparked renewed interest in the "superkilonova" scenario, where sub-solar-mass NSs form through processes like the fragmentation of an accretion disk or core fission in a collapsing star. In this picture, the in-spiral and merger of a sub-solar NS-NS binary is followed by the merger of the NS-NS remnant with the central black hole (BH), producing chirp-like GW signals. For sub-solar NSs with masses in the (0.1-1)M_sun range and BH masses in the so-called lower mass gap range of ~(3-5) M_sun, these signals can persist in the 20 - 1024 Hz frequency band of ground-based GW detectors for (10^2-10^3)s, potentially offering an opportunity to probe the superkilonova scenario, as well as the lower mass gap between NSs and stellar-mass BHs. However, the complexity of the underlying astrophysics may yield waveforms that deviate from standard templates, limiting the use of matched filtering in real GW searches. We therefore explore the detectability of such signals using the Cross-Correlation Algorithm (CoCoA), a more robust though less sensitive cross-correlation method. We discuss general strategies for implementing CoCoA superkilonova searches via either targeted follow-up of candidate chirps identified in matched-filter searches, or EM-triggered searches of stripped-envelope core-collapse SNe.

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All authors Abby Tejera, Divyajyoti, Alessandra Corsi, Yossef Zenati, Robert Coyne, Logan Cote

General Relativity and Quantum Cosmology

Analysis of the equations of motion of fictitious matter in embedding theory

A.J. Ziyatdinov and S.A. Paston

Embedding theory is a possible modification of general relativity that provides a framework for explaining the observed effects typically attributed to dark matter. The idea of this modification is to consider our spacetime as a four-dimensional surface in a ten-dimensional flat ambient space. The equations of motion in embedding theory can be reformulated as a set of Einstein equations with the contribution of some additional fictitious matter and of equations describing this matter. We analyze static solutions of these equations, which are reduced to fictitious-matter configurations of the wall, string, and ball types. The string case is ultimately described by the Liouville equation, and the ball case is described by its three dimensional analogue. For the string case, we show that as the density contribution decreases at infinity, all solutions to the Liouville equation are rotationally symmetric. For the case of the ball, we show that under the assumption of spherical symmetry, there exists a unique one-parameter family of solutions that are smooth at the center.

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General Relativity and Quantum Cosmology · Cross-listed from astro-ph.HE

A Diverse Distribution of Black Hole Spins from Stable Mass Transfer

Linhao Ma, Jakub Klencki, Eliot Quataert et al. (+1 more)

Gravitational wave observations have found over 300 merging binary black holes, yet their origins remain uncertain. Recent work showed that many may come from isolated stellar binaries whose orbits shrink through stable mass transfer. If true, their spins may help to distinguish this channel from other formation pathways. We investigate the tidal spin up of black hole progenitor stars with detailed modeling of binaries undergoing stable mass transfer. We calculate the tidal torques by solving tidally excited oscillation modes and predict the resulting black hole spins. We find a diverse spin distribution strongly affected by the mass transfer histories of the progenitors. Binaries can form black holes with moderate spins ($0.1\lesssim\chi_\mathrm{eff}\lesssim0.3$) if they only go through case A or case B mass transfer. In the former case, they can become super-synchronized upon detachment, while in the latter case, the donor is usually only partially stripped, leaving a puffy envelope where strong tides are excited. If both case A and case AB mass transfer occur, the resulting black hole spins are almost always negligible. As the mass transfer history is jointly determined by mass ratio and initial binary period, our results predict an anti-correlation between black hole spins and mass ratio, consistent with limited evidence from data. Our results can also potentially explain the case of GW190412, a moderately-spinning binary with a high mass ratio. We discuss the limitations of our methods and additional physics (e.g., nonlinear tides, case C, and L2 mass transfer) that need to be incorporated in future work.

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All authors Linhao Ma, Jakub Klencki, Eliot Quataert, Lieke van Son

General Relativity and Quantum Cosmology · Cross-listed from astro-ph.IM

Full-Covariance Bayesian Inference of Stochastic Gravitational Wave Backgrounds with Time-Domain Simulations for Taiji-like Missions

Qingyuan Liang, Ju Chen, Minghui Du et al. (+1 more)

For Taiji-like missions, we implement a Bayesian spectral inference framework that combines second-generation time-domain (TD) simulations of time-delay interferometry (TDI) with a frequency-domain (FD) spectral likelihood for stochastic gravitational-wave background (SGWB) analyses. The $X,Y,Z$ Michelson streams generated with \trianglesim{} are divided into finite segments, Fourier transformed, and modeled with a segment-dependent complex $3\times3$ covariance matrix. For each segment we evaluate the orbit-dependent response functions and noise transfer functions, allowing unequal-arm and time-evolving effects to enter through the full $XYZ$ covariance. Controlled simulations performed with \trianglesim{} show that the calculated functions reproduce the realization-averaged spectra at the few-percent level over the retained frequency band away from TDI nulls. We then compare parameter-estimation results for static equal-arm FD, equal-arm TD, and unequal-arm TD configurations, using in each case a full $XYZ$-covariance likelihood matched to the corresponding detector configuration. All three yield consistent uncertainty trends and Bayesian-evidence diagnostics for astrophysical-background recovery after marginalizing over instrumental noise and an effective Galactic double-white-dwarf foreground. Finally, in a ten-parameter model containing instrumental noise, an effective Galactic double-white-dwarf foreground, a stochastic astrophysical background, and a sound-wave spectrum from a cosmological first-order phase transition, we recover its peak amplitude and frequency and find Bayesian evidence favoring its inclusion in all three matched configurations.

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All authors Qingyuan Liang, Ju Chen, Minghui Du, Huai-Ke Guo

General Relativity and Quantum Cosmology

All You Need is not $\Omega_\mathrm{gw}$: Beyond the Mean of the Cross-Correlation Estimator when Searching for an Astrophysical Gravitational-Wave Background

Haowen Zhong, Francesco Iacovelli, Vuk Mandic et al. (+1 more)

Searches for the stochastic gravitational-wave background (SGWB) using ground-based detectors rely heavily on the cross-correlation estimator $\bar C_f$, whose statistical properties determine the theoretical foundation for inference frameworks built on it. Past analyses usually assume Gaussianity of $\bar C_f$, but this assumption has not been systematically tested for a background of astrophysical origin like the one produced by compact binary coalescences. In this work, we decompose $\bar C_f$ into three physically motivated components: (1) the mean intensity, (2) the geometrical shot noise, and (3) the polarization leakage, and we compute 90% credible intervals for its cumulants up to fourth order for the binary black hole, binary neutron star, and neutron star-black hole populations by propagating local merger rate uncertainties. We find that for the upcoming LIGO O5 sensitivity, $\bar C_f$ remains effectively Gaussian for all three populations, validating current Gaussian likelihood frameworks. For Cosmic Explorer (CE), however, the $\bar C_f$ produced by binary black holes becomes non-Gaussian, with skewness and excess kurtosis of $0.31^{+0.04}_{-0.03}$ and $1.3^{+0.4}_{-0.3}$, respectively, in the most sensitive band over a one-year observation period. For binary neutron star and neutron star - black hole mergers, $\bar C_f$ remains largely Gaussian even at CE. These results indicate that the Edgeworth expansion provides an adequate leading-order description of the non-Gaussianity expected in the next-generation era, while also motivating the development of more sophisticated statistical methods for a more accurate treatment.

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All authors Haowen Zhong, Francesco Iacovelli, Vuk Mandic, Emanuele Berti

General Relativity and Quantum Cosmology

Quasinormal modes in effective loop quantum gravity and consequences for isospectrality

Alejandro García-Quismondo, Guillermo A. Mena Marugán and Alvaro Torres-Caballeros

We investigate the quasinormal mode spectra of axial and polar perturbations about the effective Ashtekar, Olmedo, and Singh black hole geometry within the hybrid approach to loop quantum gravity. We also compare our results with those previously obtained by del-Corral and Olmedo for the dressed metric approach. Starting from mode equations that are straightforward effective counterparts of the classical equations, we compute these spectra by means of a high-order WKB method with Padé resummation. The violation of isospectrality between axial and polar perturbations that was claimed to exist in the dressed metric approach persists with the hybrid quantization, with deviations of the same order of magnitude as in the former effective case, although slightly larger for the hybrid prescription. In both situations, the isospectrality breaking decreases with the cubic root of the squared black hole mass in Planck units, consistently recovering the classical Schwarzschild limit. In addition, we perform a careful assessment of the applicability of the WKB approximation to the present effective analysis, confirming the parameter regions where the method remains reliable and highlighting specific mode cases for which the approximation breaks down.

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General Relativity and Quantum Cosmology

Periodic orbits and gravitational wave signatures from magnetic dipoles around magnetized Kerr black holes

Shokhzod Jumaniyozov, Javlon Rayimbaev, Chengxun Yuan et al. (+3 more)

We study periodic orbits and the associated gravitational radiation of a magnetized (uncharged) test particle carrying a magnetic dipole moment with coupling constant beta, moving in the equatorial plane of a rotating, magnetized Kerr black hole immersed in an external asymptotically uniform magnetic field, starting from the effective potential derived for such particles. We compute the marginally bound orbit (MBO) and the innermost stable circular orbit (ISCO) as functions of the black hole spin a and the magnetic coupling beta, and map out the allowed region of the orbital energy-angular momentum (L, E) plane for bound motion. We then classify periodic orbits using the topological zoom-whirl scheme of Levin and Perez-Giz, characterized by three integers (z,w,v) through the rational rotation number q=w+v/z, and construct a family of closed rosette orbits at fixed angular momentum. Using the numerical-kludge, restricted-quadrupole approximation for an extreme-mass-ratio inspiral consisting of a stellar-mass magnetized secondary orbiting a supermassive magnetized Kerr black hole, we compute the time-domain gravitational waveforms h_+(t), h_\times(t) produced by these periodic orbits and their frequency-domain characteristic strain, and compare the latter with the anticipated instrumental sensitivity curves of LISA, Taiji and TianQin. We find that the magnetic coupling \beta systematically shifts the MBO and ISCO outward and lowers their orbital energy and angular momentum, that the zoom-whirl structure of the periodic orbits is imprinted directly on the burst-like morphology of the emitted waveform, and that the resulting gravitational-wave signals fall within the sensitivity band of upcoming space-based detectors for suitably close and massive sources.

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All authors Shokhzod Jumaniyozov, Javlon Rayimbaev, Chengxun Yuan, Satimbay Palvanov, Khurshida Khaknazarova, Faisal Javed

General Relativity and Quantum Cosmology

Ultracompact anisotropic stars and gravastars in general relativity

Prajwal Hassan Puttasiddappa, Nora Bretón and Santiago Esteban Perez Bergliaffa

We study static, spherically symmetric ultracompact objects in General Relativity with anisotropic stress. Using the covariant anisotropic equation of state and assuming homogeneous density, we construct a mostly analytical model admitting configurations beyond the Buchdahl limit and with compactness arbitrarily close to the black hole value. The solutions exhibit two regimes separated by a critical curve in the parameter space of compactness and anisotropy, associated with the divergence of the central pressure: regular anisotropic configurations with positive central pressure, and singular configurations with negative central pressure for arbitrary anisotropy. In the latter case, we show that introducing a thick shell removes the pressure divergence, yielding regular ultracompact gravastar configurations. We further construct both anisotropic and isotropic gravastar models using this thick-shell construction.

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General Relativity and Quantum Cosmology

Radiation-reaction driven dynamics at the third-and-a-half post-Newtonian order in different gauges

Donato Bini, Andrea Geralico and Sara Rufrano Aliberti

We consider the coordinate-dependent definition of the radiation-reaction force at the third-and-a-half post-Newtonian order for general orbits. In order to (partially) determine its expression we refer to the balance method, involving the energy and angular momentum lost by the system, the Schott terms, and the energy and angular momentum fluxes at infinity. Only the latter are gauge-invariant quantities when passing from a coordinate system to another. The gauge dependence of both radiation-reaction force and Schott terms is encoded in a set of gauge parameters entering their definitions. We show how to relate the harmonic-coordinate losses of mechanical energy and angular momentum by the system with the radial and azimuthal components of the radiation-reaction force in a different coordinate system expressed in terms of phase-space variables in a Hamiltonian framework. The advantage of this approach is that only the coordinate transformation between harmonic coordinates and coordinates and momenta in the new coordinate system is needed, without solving again the balance equations. We derive such a transformation for both Arnowitt-Deser-Misner and Effective-One-Body coordinates. In the latter case we also discuss some simplifying choices of the gauge parameters adopted in current waveform models. Finally, we show how to obtain the solution for the radiation-reaction correction to the orbit in the new coordinate system simply by transforming the harmonic-coordinate solution known in the literature. This is a remarkable simplification, since one can avoid to solve again for the radiation-reacted dynamics.

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General Relativity and Quantum Cosmology · Cross-listed from hep-th

Gravitational Faraday rotation, gravitational spin Hall effect, and spin-refined causality analysis from Magnusian matrix in effective field theories of gravity

Kibok Jeong, Jung-Wook Kim and Soochang Lee

The effects of black hole's spin in effective field theories (EFTs) of gravity are explored through observables of wave scattering on black hole backgrounds in the geometric optics approximation. The considered observables are polarisation rotation angle, wavenumber kick (or deflection angle), and (Shapiro/Wigner–Smith) time delay, each of which are related to gravitational Faraday rotation, gravitational spin Hall effect, and infrared causality. The observables are computed from scattering amplitudes through the Magnusian formalism, where the Magnusian is promoted to a matrix to account for helicity information. It is found that (1) the gravitational spin Hall effect in EFTs of gravity are qualitatively different from that of general relativity due to "noncommutative" wavenumber kicks, and (2) black hole's spin slightly enhances the causality constraints on EFT coefficients.

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General Relativity and Quantum Cosmology

Constraining ModMax Black Holes with EHT and GRAVITY Observations: Optical Signatures and Accretion Disk Properties

Tursunali Xamidov, Mirjavoxir Mirkhaydarov, Sanjar Shaymatov et al. (+2 more)

In this work, we study photon propagation and the radiative properties of a thin accretion disk around a ModMax black hole and examine the effects of the charge $Q$ (i.e. $Q^2 = Q^2_e +Q^2_m$ is the total dyonic charge, with $Q_e$ and $Q_m$ denoting the electric and magnetic charges, respectively) and the nonlinearity parameter $v$. We determine the event-horizon, photon-sphere, and shadow radii and find that increasing $Q$ decreases these radii, whereas increasing $v$ shifts them toward their Schwarzschild values. Using the EHT shadow measurements of M87$^\star$ and Sgr~A$^\star$, together with the available mass and distance measurements, we perform an MCMC analysis to constrain the ModMax parameters. The strongest upper limits are found to be $Q<0.391$ and $v<4.153$ at the 95% credible level. We also investigate a Novikov-Thorne thin accretion disk and generate simulated disk images using backward ray tracing. The observed flux increases with $Q$, while increasing $v$ produces a slight decrease in the disk brightness. These results show how the ModMax parameters affect the black-hole shadow and thin-disk emission and provide observational constraints on $Q$ and $v$.

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All authors Tursunali Xamidov, Mirjavoxir Mirkhaydarov, Sanjar Shaymatov, Pankaj Sheoran, Chengxun Yuan

General Relativity and Quantum Cosmology

Conductors and superconductors in stationary spacetimes: generalized Schiff-Barnhill and Meissner effects

F. Masghatian, M.Nouri-Zonoz and H. Sadegh

Previous studies on conductors and superconductors in curved spacetimes, and the gravitationally-induced electric and magnetic fields in them, are mostly restricted to the limit of weak fields and low velocities. Also the observer-dependence of these phenomena are not discussed in the literature. In this article, following London's phenomenological approach to superconductivity, we consider the electrodynamics of superconductors in stationary spacetimes without employing any weak field or low velocity limit. To this end, first we define the 3-force acting on charged particles in gravitational and electromagnetic fields, and derive its explicit form in a general spacetime decomposition formalism. Then, to highlight the role of observers, we apply the force equation to the free charges in superconductors in stationary spacetimes in the two well known threading and slicing decomposition formalisms. Applying the stationary condition in the superconducting state, we arrive at the generalized Schiff-Barnhill and Meissner effects, which compared to the low velocity and weak field limit include extra terms originating from the recently introduced gravitationally-induced constitutive equations. To show the consistency of our approach, we also derive the generalized Meissner effect from the second London equation in stationary spacetimes.

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General Relativity and Quantum Cosmology

Radiative Signatures from Warp Drives Traveling Through the Earth's Atmosphere

Shaun David Brocus Fell and Abraham Loeb

We investigate the observable signatures of zero ADM mass warp drive spacetimes traversing Earth's atmosphere. Numerical simulations indicate that an aircraft-scale spacetime bubble moving at relativistic velocities would have a pronounced observational signature, where interaction with the atmosphere can produce luminosities exceeding one terawatt. The signature of a spacetime bubble at rest or moving at low velocity relative to the Earth would not generate such extreme luminosities. These results establish observational constraints on spacetime-based propulsion operating within the terrestrial environment and provide a framework for identifying potential high-velocity signatures. In particular, a warp drive traveling through the atmosphere at speeds exceeding approximately 10% of the speed of light would produce a unique brilliant glow.

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General Relativity and Quantum Cosmology · Cross-listed from hep-ph

Baryogenesis and CMB spectral distortion from Axions

Zhenhao Zhang, Mingqiu Li and Sichun Sun

We discuss a mechanism for generating the baryon asymmetry in the early universe. We show that an axion-like particle can modify the related gauge field configurations in the Standard Model, thereby altering their dispersion relations. This change in the Chern-Simons number can source a violation of baryon number. We derive the relationship between the resulting baryon number and the evolution of the axion background. We estimate the baryon asymmetry produced via this mechanism and show that the observed value can be naturally achieved. We also show that axion photon coupling produces Cosmic Microwave Background spectral distortion. Our results show that the resulting distortion approaches a constant at low frequencies, unlike the conventional y-type and $\mu$-type distortions.

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General Relativity and Quantum Cosmology · Cross-listed from astro-ph.HE

Transmutation Timescales for Dark Matter Induced Collapse of Compact Stars into Black Holes

H. A. Adarsha, Chandrachur Chakraborty and Sudip Bhattacharyya

Ultra-heavy asymmetric dark matter (DM) particles captured by compact stars can thermalize, self-gravitate, and collapse to form an endoparasitic black hole (EBH), whose subsequent growth may transmute the host star into a black hole. The continued existence of old millisecond pulsars (MSPs) and white dwarfs (WDs) thus places powerful constraints on the DM particle mass $m_\chi$ and the DM-nucleon scattering cross-section $\sigma_{\rm n\chi}$. We derive an analytical expression for the transmutation timescale by solving the EBH growth equation, consistently accounting for Bondi accretion of stellar matter, Hawking evaporation, and sustained DM feeding of the EBH in a steady-state capture regime. We also incorporate quantum effects in baryonic accretion when the hydrodynamic description breaks down, providing a unified treatment of EBH growth across both particle and fluid regimes. Adopting a physically transparent collapse criterion for fermionic and bosonic asymmetric DM, we compute EBH transmutation timescales for representative MSPs and WDs in environments with different DM densities. Although the physical ingredients are broadly similar to previous studies, this work derives updated constraints through a closed-form analytical treatment of EBH growth and an adopted prescription for the EBH formation timescale, yielding a lower critical EBH mass for sustained growth and revised transmutation timescales. Requiring the transmutation time to exceed $\sim 1$ Gyr for MSPs and $\sim 10$ Gyr for WDs, we derive revised constraints on $\sigma_{\rm n\chi}$ over $m_\chi \sim 10^{6}$–$10^{14}$ GeV, and show that EBHs with initial masses as small as $\sim 4\times10^{4}$ kg can undergo sustained growth, extending the region of DM parameter space probed by compact stars.

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General Relativity and Quantum Cosmology

Octupolar Gravitational Radiation in de Sitter Spacetime

Harsh, Omkar Shetye and Amitabh Virmani

We derive the gravitational radiation generated by a localised matter source in de Sitter spacetime at octupolar order in the multipolar expansion, working in generalised harmonic gauge in the future Poincaré patch. The scalar, vector, and tensor perturbation equations are solved explicitly, taking into account the cosmological tail. This constitutes the first extension of the de Sitter multipolar expansion beyond quadrupolar order. A key technical ingredient is a universal multipole moment differentiation identity, which unifies the relations between multipole moments into a single recursive formula and enables a controlled extension to higher multipoles. Using the symmetric trace-free tensor formalism of Blanchet, Damour, and Iyer, we further develop a systematic translation of the radiative solution into a spherical harmonic basis, and apply it to both the quadrupolar and octupolar metric perturbations. This representation renders the angular structure of the radiation manifest, simplifies the verification of the linearised field equations, and facilitates direct comparison with Bondi-gauge and other perturbative treatments of de Sitter spacetime.

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Papers

Physics › General Relativity and Quantum Cosmology

Wednesday 12 August

Static multipolar Einstein-vector-Gauss-Bonnet black holes

Taiji Resolving Power for the Transverse Scalar Mode of Gravitational Waves

A Nonsingular Logarithmic Bouncing Cosmology in $f(R,T)$ Gravity with Thermodynamic Viability

Vishveshwara's waveform revisited: insights from a Keldysh quasinormal mode expansion

Trapped surface formation via radial boosts

On-Shell Amplitudes and Black-Hole Perturbations: Exact Reissner-Nordström Mixing

LIGO A$^\sharp$: Detector Design and Science Prospects Beyond A+

Constraints on ultralight bosons from merging binary and remnant black holes observed during the second and third parts of the fourth LIGO-Virgo-KAGRA observing run

Pressure profile bounds from relaxing the TOV equation

Tuesday 11 August

On Super-Hyperbolic Wormhole Geometries and their Deformations

Effects of Quantum Spin-Connection Foam in the Solar System, Galaxies, and the Universe

Investigation of Circular Photon Orbits in Naked Singularity Spacetimes from a Geometric Method

Torsional pseudo-inflation beyond Einstein-Cartan

Imprints of core/cusp dark matter distributions on black hole signatures in galaxies

Long-duration GW Searches for Sub-solar NSs and Superkilonovae using CoCoA

Analysis of the equations of motion of fictitious matter in embedding theory

A Diverse Distribution of Black Hole Spins from Stable Mass Transfer

Full-Covariance Bayesian Inference of Stochastic Gravitational Wave Backgrounds with Time-Domain Simulations for Taiji-like Missions

All You Need is not $\Omega_\mathrm{gw}$: Beyond the Mean of the Cross-Correlation Estimator when Searching for an Astrophysical Gravitational-Wave Background

Quasinormal modes in effective loop quantum gravity and consequences for isospectrality

Periodic orbits and gravitational wave signatures from magnetic dipoles around magnetized Kerr black holes

Ultracompact anisotropic stars and gravastars in general relativity

Radiation-reaction driven dynamics at the third-and-a-half post-Newtonian order in different gauges

Gravitational Faraday rotation, gravitational spin Hall effect, and spin-refined causality analysis from Magnusian matrix in effective field theories of gravity

Constraining ModMax Black Holes with EHT and GRAVITY Observations: Optical Signatures and Accretion Disk Properties

Conductors and superconductors in stationary spacetimes: generalized Schiff-Barnhill and Meissner effects

Radiative Signatures from Warp Drives Traveling Through the Earth's Atmosphere

Baryogenesis and CMB spectral distortion from Axions

Transmutation Timescales for Dark Matter Induced Collapse of Compact Stars into Black Holes

Octupolar Gravitational Radiation in de Sitter Spacetime

Physics General Relativity and Quantum Cosmology