Cosmology and Nongalactic Astrophysics
Probing Cosmology through Higher-Order CMB Lensing Statistics
Shu-Fan Chen, J. Colin Hill and Zoltán Haiman
We investigate the cosmological information in higher-order statistics of the
cosmic microwave background (CMB)
lensing convergence field for a near-term experiment with noise properties similar to the Simons Observatory (SO). Using a fully field-level forward-modeling pipeline based on ray-traced simulations from the MassiveNuS suite and realistic SO-like CMB
lensing reconstruction, we naturally include nonlinear structure formation, post-Born effects, and higher-order reconstruction noise. We measure several non-Gaussian statistics, including Minkowski functionals, peak and minima counts, moments, and wavelet-scattering coefficients. We train Gaussian-process emulators to model each statistic's dependence on the matter density fraction $\Omega_m$, the scalar power spectrum amplitude $A_s$, and the
neutrino mass sum $M_\nu$. We quantify the relative information gain these statistics provide beyond the
lensing power spectrum and identify which are most robust to reconstruction noise. We find that morphology-based statistics, particularly Minkowski functionals and peak/minima counts, offer significant complementary constraining power: combining all non-Gaussian statistics with the power spectrum yields reductions of 40% and 38% in the marginalized uncertainties on $\Omega_m$ and $A_s$, respectively, and a 70% reduction in the one-sided uncertainty on $M_\nu$. These gains remain non-negligible even when the power spectrum is extended to larger scales and combined with primary CMB and BAO data, with Minkowski functionals providing an additional 11% improvement in $\sigma(M_\nu)$ and 35% in $\sigma(\Omega_m)$ beyond the extended power spectrum. By contrast, moments and wavelet-scattering coefficients provide more limited gains at SO noise levels. Our results highlight the potential of non-Gaussian statistics to enhance cosmological constraints from SO and future CMB surveys.
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Cosmology and Nongalactic Astrophysics
Fast Fourier Transform evaluation of the Fresnel integral for gravitational-wave lensing
Nino Ephremidze, Marc Kamionkowski and Cora Dvorkin
Gravitational waves (GWs) exhibit wave-optics effects when their wavelength is comparable to the scale of the gravitational lens. This may occur in
lensing from
galactic subhalos in GWs emitted by binary black-hole mergers, and is gaining interest as a novel probe of dark matter. Predictions for observables in these cases ultimately rely on evaluating a Fresnel integral that quantifies the effect of
lensing on the amplitude of a GW at a given frequency. However, numerical evaluation of this Fresnel integral is tricky, and several
algorithms and publicly available codes that implement it have been developed. Here, we show that the dependence of this integral on the lens position can be written as a two-dimensional
Fourier transform. Modern FFT techniques then enable rapid evaluation at all-sky positions simultaneously for general lenses without
symmetry. Vectorization of FFT routines allows for derivatives with respect to model parameters to be obtained with only incremental additional computational cost. If the lens is axisymmetric, further speedups can be achieved with recently developed techniques for non-uniform fast Hankel transforms. To demonstrate, we make available Fresnel Integral Optimization with Non-uniform trAnsforms (FIONA), an efficient and accurate code that is significantly faster than current methods for dense source grids, reaching 2-3 orders of magnitude speedups for $\sim 10^6$ GW-emitting points. As part of FIONA, we developed code that provides vectorized non-uniform fast Hankel transforms that may have other uses (e.g., calculation of cosmological two-point correlation functions) beyond those considered here.
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Astrophysics of Galaxies
A Hot DOG Forged in FIRE: Nuclear and Starburst Spectral Decomposition of a Luminous Infrared Galaxy Simulation with a Resolved Dust Torus
Jaeden Bardati, Philip F. Hopkins and Claude-André Faucher-Giguère
Ultraluminous infrared
galaxies are powered by a combination of rapid
star formation and active
galactic nucleus (AGN) emission, but their relative importance is not always observationally clear. We study the
galactic continuum spectrum of a cosmologically simulated $\sim 4 \times 10^{10} M_\odot$
stellar mass starburst
galaxy at
redshift $z\sim 4.4$ that refines down to resolve beyond the
dust sublimation boundary of its super-Eddington-accreting $\sim 10^7 M_\odot$ supermassive black hole. We find that this system resembles the rare class of hot
dust-obscured
galaxy (Hot DOG), with a roughly flat (in $\nu F_\nu$) IR emission spectrum that sharply drops off at wavelengths $\lesssim 5~\mu\mathrm{m}$. Our system also matches with the observational properties of many Hot DOGs, including undergoing multiple
galaxy mergers and being the most massive
galaxy within a dense cosmological environment. The distinctive Hot DOG spectral shape in our system is caused by AGN-heated mid-IR warm
dust, predominately starburst-heated far-IR cold
dust, and a steep near- to mid-IR cutoff caused by strong absorption in the dense ISM of the
galactic nucleus, rather than the
dust torus itself. This system is lower luminosity ($L_\mathrm{IR} \sim 2 \times 10^{12} L_\odot$) than those detected by the WISE survey at similar
redshifts, but will be a
prime target for future far-IR surveys such as PRIMA. Our results show that Hot DOGs can naturally result as a transitional phase during rapid AGN
accretion, but before significant AGN-driven
outflows clear optically thin paths.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
All-electron dark matter-electron scattering with random-phase approximation dielectric screening and local field effects
Cyrus Dreyer, Rouven Essig, Marivi Fernandez-Serra et al. (+2 more)
Accurate predictions for dark matter-electron scattering in solids require an all-electron treatment together with a faithful description of dielectric screening beyond simple approximations. In particular, local field effects, arising from microscopic inhomogeneities of the electronic response, can significantly modify scattering rates across relevant momentum and energy scales. We present an all-electron framework for computing dark matter-electron scattering rates that incorporates dielectric screening at the random-phase approximation (RPA) level, including local field effects. Using crystalline silicon as a
benchmark, we show that local field effects play an important role both at large momentum transfers, spanning multiple Brillouin zones, and at low momentum near the plasmon resonance. We compute electron
recoil spectra and projected sensitivities for non-relativistic
halo dark matter and for boosted dark matter or other dark-sector particles, which are sensitive to the impact of local field effects in these high and low momentum regimes, respectively. We further present RPA dielectric functions including local field effects for Ge, GaAs, SiC, and diamond, enabling a systematic comparison across target materials. These developments are implemented in the open source code QCDark2.
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All authors Cyrus Dreyer, Rouven Essig, Marivi Fernandez-Serra, Megan Hott, Aman Singal
Astrophysics of Galaxies
Simulating AGN wind feedback with variable feedback efficiencies in idealised disc galaxies
Jinning Liang, Cedric G. Lacey, Filip Huško et al. (+2 more)
Active
Galactic Nucleus (AGN) feedback plays a critical role in
galaxy formation and
evolution. AGN-driven winds can significantly influence their host
galaxies, although the details of their impact remain unclear. In this study, we investigate the feedback effects of AGN winds on idealized disc
galaxies using the SWIFT hydrodynamical code with COLIBRE subgrid physics. We implement a new thermal AGN feedback model in which the energy injection coupling efficiency has a power-law dependence on the Eddington ratio of the black hole (BH)
accretion rate, motivated by scaling relations for AGN winds from numerical models and observations. We simulate idealised Milky Way-mass
galaxies, incorporating a BH, cold gas disc,
stellar disc, and hot circumgalactic medium, within a static dark matter
halo. We vary the BH mass and the slope and normalisation of the new coupling efficiency model. For a fixed BH mass, we find that while systematic trends with coupling efficiency exist, most
galaxy and BH properties show only modest variations. This likely reflects BH self-regulation in the COLIBRE model, which modulates the effects of changes in the feedback efficiency, provided the BH mass is sufficiently high. Key exceptions are the BH
accretion rate and mass growth history, and
outflow behaviour, where lower coupling efficiencies lead to faster BH growth and weaker
outflows, potentially helping to explain the presence of overmassive BHs at high
redshifts. Varying the BH mass, however, has a much larger impact, confirming that BH mass remains the primary factor shaping
galaxy and BH
evolution in our simulations.
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All authors Jinning Liang, Cedric G. Lacey, Filip Huško, Evgenii Chaikin, Sownak Bose
Cosmology and Nongalactic Astrophysics
Phenomenology of an Open Effective Field Theory of Dark Energy
Santiago Agüí Salcedo, Thomas Colas, Lennard Dufner et al. (+1 more)
All observational evidence for dark matter and dark energy is so far exclusively gravitational. Hence, the dark sector may be equivalently described by a theory of the spacetime metric whose dynamics is affected by interactions with an unknown environment. Adapting open-system techniques, we have recently constructed such a general theory of open gravitational dynamics. Here we study a minimal and concrete realization of this theory that describes the late-time acceleration of the Universe. Our model provides a good fit to recent
baryon acoustic oscillation measurements by construction, while avoiding violations of the null energy condition. Moreover, it leads to a set of correlated and observationally testable predictions. Studying the modified cosmological perturbation theory and compared to the $\Lambda$CDM model we find: a dissipative suppression of the gravitational-wave luminosity distance relative to the electromagnetic one; a modification in the
evolution of the Bardeen potentials with a clear signal in the gravitational slip; and an enhancement of structure formation at low
redshift. We present semi-analytical estimates of the magnitude of these effects and show that they lie within the reach of current constraints while providing clear targets for upcoming cosmological surveys.
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All authors Santiago Agüí Salcedo, Thomas Colas, Lennard Dufner, Enrico Pajer
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Number Theory in Quantum Physics: Minicharged Particles and the Prouhet-Tarry-Escott Problem
Junseok Lee, Fuminobu Takahashi and Yu-Dai Tsai
In
quantum gauge theories, anomaly cancellation severely restricts the allowed patterns of
chiral charges. Here we show that, in a phenomenologically motivated framework for light minicharged particles, the anomaly cancellation conditions are equivalent to the degree $k=3$ Prouhet-Tarry-Escott problem in number theory. This correspondence immediately implies that the hidden sector must contain at least four minicharged states. For constructions based on minimal ideal solutions, the mass spectrum generically exhibits a near-degenerate doublet structure, so that the discovery of one minicharged particle would point to a partner state with the same minicharge and a nearby mass. Our results uncover an unexpected link between
quantum consistency and number theory, with direct implications for model building and future searches.
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Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th
Quantum Signatures of Cosmic Topology: How Casimir Backreaction Transmits Isotropy Violation
Anna Negro, Kurt Hinterbichler, Glenn D. Starkman et al. (+17 more)
A finite, scheme-independent Casimir contribution to the stress-energy tensor arises naturally for
quantum fields in universes with non-trivial spatial
topology. We compute this Casimir stress-energy tensor contribution for a conformally coupled scalar field and for a minimally coupled scalar field. We show that, for the conformally coupled case, the backreaction of this contribution to the Einstein equations during an expanding de Sitter phase drives anisotropic expansion even when the Universe begins in a locally homogeneous and isotropic state. We conclude that
quantum imprints of the underlying non-trivial
topology inevitably give rise to local departures from homogeneity and isotropy.
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All authors Anna Negro, Kurt Hinterbichler, Glenn D. Starkman, Yashar Akrami, Stefano Anselmi, Javier Carrón Duque, Mikel Martin Barandiaran, Thiago S. Pereira, George Alestas, Craig J. Copi, Fernando Cornet-Gomez, Linn Htat Lu, Andrew H. Jaffe, Arthur Kosowsky, Deyan P. Mihaylov, Joline Noltmann, José Javier Ortega Gómez, Catherine Petretti, Amirhossein Samandar, Andrius Tamosiunas
Astrophysics of Galaxies
A simulation-based inference of the Milky Way merger history
Andrea Sante, Andreea S. Font, Daisuke Kawata et al. (+2 more)
Accreted
stars in the Milky Way (MW) preserve information about the progenitor
galaxies where they formed in their chemical and kinematic properties. In this study, we use the chemo-dynamical signatures in the merger debris to approximate the posterior distribution of disrupted satellite properties at the time of infall. Adopting a simulation-based inference framework, we train an ensemble of normalizing flows using samples of merger debris from the Auriga suite of simulations of MW-like
galaxies. Applying this methodology to a local sample of accreted
stars in the MW, we infer the lookback times,
stellar and
halo masses, and
halo mass merger ratios of several known
accretion events in the
Galaxy:
Gaia Enceladus-Sausage (GES), Helmi streams, Heracles, I'itoi, LMS-1/Wukong, Sagittarius (Sgr), Sequoia and Thamnos. Our predictions align with the
accretion time and mass estimates from the literature, and the expected relation between the progenitor
stellar masses and debris
metallicities across
redshifts. The total
stellar mass accreted from these events is predicted to be $2.2^{+1.1}_{-0.6}\times10^{9}~\rm{M_{\odot}}$, with GES and Sgr being the largest contributors. The predicted
stellar mass accreted from fully disrupted progenitors in the
stellar halo is $1.3^{+1.0}_{-0.5}\times10^{9}~\rm{M_{\odot}}$, which is consistent with previous mass measurements of this component. We provide a prediction for the
evolution of the MW
halo mass until the
accretion of Sgr ($z\approx1$): specifically, we find that the mass growth of the
Galaxy from the time of its first merger ($z\approx5$) to $z\approx2$ exceeds the total mass of the known progenitors accreted during that interval, suggesting the presence of unidentified substructures. Our estimate of the
Galaxy halo mass after the Sgr merger, but prior to the
accretion of the Magellanic Clouds, is $5.9^{+1.4}_{-1.1}\times10^{11}~\rm{M_{\odot}}$.
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All authors Andrea Sante, Andreea S. Font, Daisuke Kawata, T. Lucas Makinen, Robert J. J. Grand
Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph
Dark Matter, Baryon Number, and Cosmic-Ray Antinuclei
Caleb Gemmell, Dan Hooper, Seth Koren et al. (+1 more)
Antideuterons and antihelium
nuclei in the
cosmic-ray spectrum have long been considered a smoking gun signature of dark matter annihilation, making the tentative observation of several such events by AMS highly intriguing. Conventional dark matter models, however, can produce only up to O(1) antideuteron events at AMS and are not capable of generating observable fluxes of antihelium. In this Letter, we propose a class of models in which dark matter annihilates into particles carrying
baryon and
lepton number, whose subsequent decays produce enhanced fluxes of antinucleons and antinuclei. Such scenarios are motivated by Grand Unified Theories and can lead to an order-of-magnitude or larger enhancement in the resulting antideuteron and antihelium-3 fluxes, providing a means by which to potentially explain the events reported by the AMS Collaboration.
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All authors Caleb Gemmell, Dan Hooper, Seth Koren, Fabrizio Vassallo
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Looking for non-gaussianity in Pulsar Timing Arrays through the four point correlator
Adrien Kuntz, Clemente Smarra and Massimo Vaglio
Pulsar Timing Arrays have recently reported strong evidence for a
stochastic gravitational wave background. In standard analyses, it is modeled through
pulsar-dependent
Fourier coefficients assumed to follow gaussian statistics, so that the signal is fully characterized by its two-point function. However, if the background arises from a finite population of inspiralling supermassive black hole binaries, non-gaussian features may emerge, making the determination of higher-order correlators essential. In this work, we compute the complete four-point correlator of the
stochastic gravitational wave background
Fourier coefficients for four arbitrary
pulsar positions, identifying it as the leading probe of non-gaussianity. The result separates into a gaussian contribution, proportional to the square of the two-point function, and a genuinely non-gaussian connected component, whose non-trivial angular dependence generalizes the Hellings and Downs correlation to four
pulsars. This angular structure depends only on averages of products of
antenna pattern functions, and is therefore expected to be independent of the specific physical origin of the background. We further propose to incorporate the four-point correlator into the parameter-estimation pipeline by deriving a marginalized likelihood that perturbatively accounts for non-gaussian effects. Our results provide the theoretical framework to search for non-gaussian features in
pulsar timing array data, opening the way to a more complete characterization of gravitational-wave backgrounds.
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Astrophysics of Galaxies
An Updated SynthPop Model for Microlensing Simulations I: Model Description & Evaluation
Macy J. Huston, Alison L. Crisp, Marz Newman et al. (+21 more)
The optimization and interpretation of microlensing surveys depends on having an accurate model of the Milky Way. However, existing population synthesis
Galactic modeling tools often perform poorly in replicating the
stellar contents of the inner
Galactic bulge region and reproducing microlensing survey results. We present an updated
Galactic model implementation within the \synthpop framework that has been tuned for simulating the upcoming Nancy Grace Roman Space
Telescope's
Galactic Bulge Time Domain Survey (RGBTDS). We evaluate the model against
stellar catalogs and kinematics from optical and infrared surveys toward the
Galactic bulge, finding good agreement in much of the bulge, including the RGBTDS' contiguous lower bulge fields. However, within
Galactic latitudes of $b\lesssim0.5^\circ$ of the
Galactic plane, some inconsistencies arise which may impact projections for the RGBTDS'
Galactic center field. The model over-predicts optical microlensing event rate per
star measurements by a $\sim20$%, but detailed comparisons to near-infrared measurements are hampered by their lack of detection efficiencies. Roman's GBTDS and
Galactic Plane Survey will be instrumental in resolving the remaining model inconsistencies and improving our understanding of the structure of the central few degrees of our
Galaxy.
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All authors Macy J. Huston, Alison L. Crisp, Marz Newman, Riley Patlak, Matthew T. Penny, Jonas Kluter, Samson A. Johnson, Peter McGill, Leigh C. Smith, Victor Karkour, Natasha S. Abrams, Tabetha S. Boyajian, Rachel B. Fernandes, B. Scott Gaudi, Eamonn Kerins, Casey Y. Lam, Jessica R. Lu, Carissma McGee, Sebastiano Calchi Novati, Keivan G. Stassun, Sean K. Terry, Emelly D. Tiburcio, Himanshu Verma, Farzaneh Zohrabi
Cosmology and Nongalactic Astrophysics
Scale-Dependent Loop Corrections to the Inflationary Power Spectrum
Matteo Braglia, Sebastián Céspedes and Lucas Pinol
Loop corrections to
primordial correlation functions are unavoidable due to the non-linear nature of
gravity. Previous works have established a robust framework for computing the renormalised one-loop power spectra of scalar and tensor modes, but primarily in (near) de Sitter backgrounds. In this work, we develop a consistent renormalisation procedure applicable to inflationary backgrounds that strongly break de Sitter
symmetries and generate scale-dependent features in the
primordial spectra. Our analysis is performed within the Effective Field Theory (EFT) of inflationary fluctuations, allowing for arbitrary time dependence of the Wilson coefficients. We show that both ultraviolet divergences and tadpoles of the theory, despite their strong time and scale dependence, can be cancelled by a finite set of local counter-terms compatible with the EFT
symmetries. Importantly, this result only relies on the existence of an initial phase of adiabatic
evolution continuously related to the Bunch-Davies
vacuum and holds independently of the precise time dependence of the background and of the free-field mode functions. We then study two concrete realisations, corresponding to resonant and sharp features. In both cases, all calculations are carried out exactly in the limit of small feature amplitude. We analyse perturbativity and provide the first explicit demonstration that the renormalised one-loop power spectrum generated by a localised feature along the inflationary trajectory vanishes both at large and small scales. Our scale-dependent renormalisation framework implies that models of
primordial features used to fit CMB residuals are consistent with perturbativity bounds, and opens the door to systematic studies of loop corrections in more complicated scenarios relevant for scalar-induced gravitational waves and
primordial black holes.
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Solar and Stellar Astrophysics
Magnetoacoustic Shocks and Spectropolarimetric Signals in He I 10830 Å
Hirdesh Kumar, Tobias Felipe, Christoph Kuckein et al. (+2 more)
Umbral flashes are manifestations of magnetoacoustic shocks in the
solar chromosphere. These phenomena are thought to influence the
evolution of chromospheric umbral
magnetic fields. However, the impact of these shocks on inferred chromospheric
magnetic field oscillations remains unclear. We examined five different sunspots located near the
solar disk center, observed with the GRIS instrument installed at the GREGOR
telescope. The HAZEL2 Spectropolarimetric inversion code is used to obtain the photospheric and chromospheric line-of-sight velocities and
magnetic fields in Si 10827 Å and He 10830 Å spectral lines, respectively, using various inversion strategies. In the inversions with one chromospheric component, three of the sunspots exhibit remarkably stronger
magnetic fields accompanying the shocks, while the other two sunspots show striking reductions in the
magnetic field. Alternatively, the Stokes profiles can be reproduced by models with two chromospheric slabs, one on top of the other, through two-component inversions. These inversions provide excellent fits even when
magnetic field fluctuations are discarded by imposing a constant
magnetic field during the whole temporal series. In this scenario, the observed Stokes profiles are interpreted as the result of strong velocity gradients, where the He 10830 Å line is sensitive to both sides of the shock front. Both competing models explaining the spectral profiles during the shocks, either large
magnetic field fluctuations or velocity gradients, are critically discussed.
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All authors Hirdesh Kumar, Tobias Felipe, Christoph Kuckein, S. J. González Manrique, A. Asensio Ramos
Astrophysics of Galaxies
Comparing the $M_{gas}-N_{yso}$ Relation inside a Giant Molecular Cloud
Carlos G. Román-Zúñiga, Aina Palau, Javier Ballesteros-Paredes et al. (+3 more)
In this paper we present a simple analysis around scaling relations derived from the Schmidt
conjecture for
star-forming molecular clouds, at the intra-cloud scale. Using a hierarchical tree (dendrograms) above a constant threshold ($A_V$ = 7 mag), we separate individual gas structures in a column density map of the nearby
Giant Molecular Cloud Orion A, constructed from Herschel far-infrared maps. These structures define regions of dense molecular gas that can actively form
stars. We also estimate their current embedded population using a list of known young
stars. From the combined analysis of the column density map and the young
star catalog, we construct a series of plots that show the intra-cloud level behavior of three well-known scaling relations: $N_{yso}$ vs. $M_{gas}$, $\Sigma_{SFR}$ vs. $\Sigma_{gas}$ and $R_{eq}$ vs. $M_{gas}$. Our
dataset, along with other sets from literature, show the validity of a linear relation for $N_{yso}$ vs. $M_{gas}$, from intra-cloud to inter-cloud scales, over three orders of magnitude. We also especulate on the possibility that the relation could be valid over an even larger scale range. Additionally, our data are consistent with the $R_{eq}$ vs. $M_{gas}$ discussed in previous studies. However, our data is not quite in agreement with previously proposed fits for the $\Sigma_{SFR}$ vs. $\Sigma_{gas}$ relation, and we discuss the implications of using the free-fall timescale as the main parameter defining the
star-forming efficiency in dense gas regions.
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All authors Carlos G. Román-Zúñiga, Aina Palau, Javier Ballesteros-Paredes, Manuel Zamora-Avilés, Joshua Peltonen, Karla Gutiérrez-Davila
High Energy Astrophysical Phenomena
X-ray evidence from NuSTAR for a Mach 3 shock in Merging Galaxy Cluster ZWCL 1856.8
Ayşegül Tümer, Christian T. Norseth and Daniel R. Wik
We present spectral analysis results of deeper (270 ks) NuSTAR observations of the merging
galaxy cluster system, ZWCL1856.8+6616, at
redshift z=0.304, following a pilot study using shallower (30 ks) NuSTAR data (Tumer et al. 2024). The cluster hosts a double
radio relic, pointing to a similar mass head-on collision at/near the plane of sky. We aim to find the relation between
radio and X-ray shock features. Using data from both focal plane modules of NuSTAR, we study the temperature structure across the field of view and report on the X-ray detected shock strength at the relic sites. We generate nominal and cross-ARFs with nucrossarf to disentangle
photon cross-contamination within regions of interest due to the moderate point spread function of NuSTAR. Here we report one of the strongest X-ray detected shocks in a
galaxy cluster merger with M=3.90(+1.64,-0.85) at the Northern relic site, that is unprecedentedly larger than the
radio counterpart; M=2.5+/-0.2 (Jones et al. 2021a), and we report Southern shock strength as M=2.36(+0.58,-0.46). We argue that since the Northern relic (or
radio shock), is confined in a very small region in the sky, particle acceleration is more efficient and is likely to grow in the post-shock regions. In addition, we search for inverse Compton (IC) emission at the
radio relic sites; however, an IC component was not detected.
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Astrophysics of Galaxies
GATOS XIV: The first direct kinematic evidence of dusty outflows from AGN via PAH kinematics of local Seyfert galaxies with JWST
Fergus R. Donnan, Ismael García-Bernete, Dimitra Rigopoulou et al. (+30 more)
We present the first spatially resolved kinematic evidence for
dust in the
outflows of Active
Galactic Nuclei (AGN). We utilise observations from JWST with NIRSpec IFU and MIRI MRS data of 10 local Seyferts and use Principal Component Analysis (PCA)
tomography to extract the kinematics of Polycyclic Aromatic Hydrocarbon (PAH) features. PAHs comprise the smallest carbonaceous
dust molecules in the Interstellar Medium (ISM), and produce emission features in the infrared providing the potential to measure kinematics. This is however challenging due to their broad shapes and variations in their intrinsic profile, prompting the need for techniques such as PCA
tomography. We find that the velocity of the PAHs is similar to the molecular gas as traced by the rotational transitions of H$_2$, where for NGC 5728 and NGC 7582, both disk and
outflow are present. We detect the
outflow in the kinematics of large and neutral PAHs, namely the 11.3 $\mu$m and 17 $\mu$m PAH features, where after subtracting the disk, the velocity field matches that of high-ionisation potential lines such as [NeVI] (7.65 $\mu$m, IP = 158 eV). Finally, we fail to detect kinematics of the 6.2 $\mu$m PAH due to an altered intrinsic profile while the the 3.3 $\mu$m PAH kinematics purely trace the circumnuclear disk. This suggests the PAHs in the
outflow are more neutral and larger than in
star-forming regions, consistent with PAH band ratios in previous studies of AGN.
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All authors Fergus R. Donnan, Ismael García-Bernete, Dimitra Rigopoulou, Almudena Alonso-Herrero, Anelise Audibert, Enrica Bellocchi, Andrew Bunker, Steph Campbell, Françoise Combes, Richard Davies, Tanio Díaz-Santos, Juan A. Fernández-Ontiveros, Poshak Gandhi, Santiago García-Burillo, Omaria González-Martín, Erin K. S. Hicks, Laura Hermosa Muñoz, Sebastian F. Hoenig, Masatoshi Imanishi, Alvaro Labiano, Nancy A. Levenson, Miguel Pereira-Santaella, Cristina Ramos Almeida, Claudio Ricci, Rogemar A. Riffel, Daniel Rouan, David Rosario, Karin Sandstrom, Taro T. Shimizu, Marko Stalevski, Niranjan Thatte, Oscar Veenema, Lulu Zhang
High Energy Astrophysical Phenomena · Cross-listed from hep-th
Hawking Radiation from Tunneling in Black Hole Quantum Mechanics
Chong-Sun Chu
It was proposed in \cite{Chu:2024qil} that a
quantum black hole can be described by a
quantum space configuration of a fuzzy sphere together with a half-filled
Fermi sea. In this paper we propose that the tunneling of the fuzzy sphere system to a small one describes the
quantum decay of black hole by Hawking radiation. Since the
Fermi sea shrinks and the
quantum mechanical
Hamiltonian conserves
fermion number, the amplitude of transition naively vanishes unless the tunneling path provides exact number of zero modes to soak up the excess
fermi states. We show that a monopole on fuzzy sphere does exactly that. This fixes the tunneling path. The resulting tunneling rate reproduces Page's result for the semi-classical decay rate of black hole. The
quantum states released by the monopole corresponds to gravitational Hawking radiation. At the level of probability, the Hawking radiation is found to be given by a Boltzmann distribution at the Hawking temperature. One can go beyond the probabilistic description by determining the full wave function of the multi-partite Hawking quanta. This is possible with a real time formulation of the tunneling process. Unitarity is manifest in our
quantum mechanics.
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High Energy Astrophysical Phenomena · Cross-listed from gr-qc
Shifted-geodesic approximation for spinning-body gravitational wave fluxes
Lisa V. Drummond, Scott A. Hughes, Viktor Skoupý et al. (+2 more)
We present a shifted-geodesic framework for computing gravitational-wave fluxes from spinning test bodies moving on bound orbits of Kerr black holes. The method provides a simple and efficient means of evaluating energy and angular momentum fluxes incorporating the leading effect of the smaller body's
spin. Because post-adiabatic corrections, including secondary
spin contributions, are subdominant to the leading adiabatic terms, this approximation is well justified. In particular, we find that oscillatory
spin terms typically contribute very little to fluxes, but their contribution to the description of orbits is computationally expensive, making such terms a natural target for approximation. In our framework, orbital frequencies and integrals of the motion are perturbed to include
spin effects, while the trajectory retains the global structure of geodesic motion. This simplifies the computation of gravitational radiation. The shifted-geodesic approximation is most reliable for orbits with lower eccentricity, lower inclination, and larger semi-latus recta. The approximation becomes less reliable as we approach the separatrix between stable and unstable orbits; fortunately, many inspirals spend less time in this region of parameter space. A diagnostic inspiral
evolution shows very small dephasing due to use of the shifted-geodesic approximation ($\approx10^{-2}$ radians over 1 year), confirming that
spin-induced flux corrections can be accurately included using this simple modification to a geodesic trajectory. This approximation provides a rapid and convenient way to compute spinning-body orbits, but is not intended to replace more accurate treatments. We propose it as a pragmatic alternative when speed and simplicity are prioritized, enabling efficient EMRI/IMRI flux calculations and supporting parameter-space studies for LISA. (Abridged)
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All authors Lisa V. Drummond, Scott A. Hughes, Viktor Skoupý, Philip Lynch, Gabriel Andres Piovano
Solar and Stellar Astrophysics
Small-Scale and Transient EUV Kernels in Solar Flare Ribbons
Hannah Collier, Säm Krucker, Laura A. Hayes et al. (+3 more)
Flare ribbons form when energy released by coronal
magnetic reconnection is deposited in the low
solar atmosphere, so by studying the dynamics of
flare ribbons, one obtains an indirect measurement of reconnection. Our aim is to quantify the spatial and temporal scales of substructures in the Extreme Ultraviolet (EUV)
flare ribbons, known as kernels, as a probe of the spatial extent and duration of energy injection during the impulsive phase of
solar flares. Unprecedented observations of an M2.5 GOES-class
flare from the March 2024 major
flare campaign of
Solar Orbiter were used. These data were obtained at high-cadence in short-exposure mode with the Extreme Ultraviolet Imager's high-resolution
telescope, HRI_EUV. Individual kernels were automatically identified using a classical computer
vision algorithm. Size distributions of ribbon kernels were derived, and an average light curve of individual kernels was extracted. The EUV
flare kernels were small ($\lesssim 60~\text{pixels} \approx 1~\text{Mm}^2$) and a significant fraction were unresolved at a plate scale of 135 km/pix. Furthermore, we derived surprisingly short EUV kernel heating times of less than a few seconds. The average profile exhibits a sharp rise of $1.7\pm0.3$ s from half-maximum, requiring an additional $2.3^{+0.7}_{-0.4}$ s to return to its reference value. Our findings indicate that approximately half of the kernels were unresolved in this
flare, despite the enhanced angular resolution offered by
Solar Orbiter's proximity to the Sun at 0.38 AU here. Furthermore, we show that energy was only injected in a localised region ($\lesssim 1~\text{Mm}^2$) of
flare ribbons for less than a few seconds. These results necessitate an in-depth investigation into the implications of such small-scale and transient injections on the energy flux deposited in
solar flares, and the resulting response of the
solar atmosphere.
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All authors Hannah Collier, Säm Krucker, Laura A. Hayes, Emil Kraaikamp, David Berghmans, Daniel F. Ryan
Astrophysics of Galaxies
AstroSat-UVIT observations of a possibly interacting pair of galaxies in HCG 77
Anshul Srivastava, Harvinder K. Jassal, Mamta Gulati et al. (+1 more)
We aim to study
star-forming regions and the spectral energy distribution of two possibly interacting
galaxies, PGC 56121 and PGC 56125, in the Hickson Compact Group 77. We utilized the far-ultraviolet (FUV) channel of the Ultra Violet Imaging
Telescope (UVIT) on board AstroSat to observe and produce FUV images of the
galaxies. Our FUV images are at a much higher resolution in comparison to those obtained from previous
galaxy surveys by GALEX in the near-UV and those from PS-1, DSS. We have identified several
star-forming regions in the two possibly interacting
galaxies, PGC 56121 and PGC 56125. These two
galaxies form a pair widely separated in
redshift and are seen in projection. We also report the presence of a candidate
tidal dwarf galaxy at the end of one of the
tidal tails located to the east of the pair, and we identified three major
star-forming regions in the
tidal dwarf. The spectral energy distribution of three
galaxies in the system is presented and analyzed to investigate the key physical properties, such as
stellar mass,
dust mass, total luminosity, and
star formation history, of the three
galaxies. Based on these observations and on a comparison with observations in
radio, these three
galaxies are probably part of a small group of interacting
galaxies.
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All authors Anshul Srivastava, Harvinder K. Jassal, Mamta Gulati, Kulinder P. Singh
Cosmology and Nongalactic Astrophysics
The Targeted Standard Siren Cosmology with Pulsar Timing Arrays
Shubhit Sardana, Boris Goncharov and Jacob Cardinal Tremblay
The sky localisation of about $10$ to $100~\text{deg}^2$, which is expected to be achieved in all-sky blind searches for gravitational waves from supermassive black hole binaries (SMBHBs) with
Pulsar Timing Array (PTA) experiments, has long been posed as a prohibitive factor in utilising these sources as standard sirens for precision cosmology. We propose a solution to this problem, which makes use of targeted searches rather than all-sky blind searches for SMBHBs. Using our simulated data informed by current PTA observations, we show that the Chinese
Pulsar Timing Array (CPTA) alone could infer the Hubble constant with a precision of 2~km/s/Mpc. Such precision in an independent cosmological probe could provide decisive support in the resolution of the Hubble tension. We demonstrate the application of our method to several simultaneously observed SMBHBs, as well as the method's robustness against confusion between the host
galaxies of SMBHB sources in realistic observing scenarios.
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Solar and Stellar Astrophysics
Rediscussion of eclipsing binaries. Paper XXIX. The F-type twin system BS Draconis
John Southworth
We present an analysis of BS Dra, a detached eclipsing binary containing two almost-identical F3 V
stars in a 3.36-d circular orbit, based on 40 sectors of observations from the Transiting
Exoplanet Survey Satellite (TESS) and published spectroscopic results. We measure masses of 1.305 +/- 0.015 Msun and 1.284 +/- 0.017 Msun, and radii of 1.409 +/- 0.006 Rsun and 1.400 +/- 0.006 Rsun, for the two components. The high quality of the TESS data allow – for the first time – a definitive identification of the primary eclipse, which is 0.007 mag deeper than the secondary. The primary
star is the hotter, larger and more massive of the two: the ratios of the radii and surface brightnesses are both slightly but significantly below unity. We find a distance concordant with the
Gaia DR3 parallax and, by comparison to theoretical models, an age of 1600 +/- 300 Myr and a slightly sub-
solar chemical composition. Our mean times of primary eclipse, each representing all eclipses in one sector, have a scatter of only 0.37 s around a linear ephemeris: BS Dra may be useful as a celestial clock.
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Astrophysics of Galaxies
Comparison of Bar Formation Mechanisms. IIIA. The role of classical bulges in spontaneous bar formation
Yirui Zheng, Juntai Shen and Bin-Hui Chen
We run a suite of $N$-body simulations to investigate how classical bulges affect bar formation and properties under the internal formation mechanism. We incorporate bulges of varying mass and compactness into disk
galaxy models and evolve them in isolation to examine the resulting bar pattern speeds and growth timescales. A more massive/compact bulge increases the Toomre $Q$ stability parameter and the circular velocity in the central region, while decreasing the disk mass fraction. It therefore delays the onset of bar formation and increases the bar growth timescale; sufficiently strong bulges can suppress bar formation entirely. During the formation stage, bars exhibit higher initial pattern speeds and faster deceleration rates when the bulges become more massive or compact. This faster deceleration persists after the bar buckling phase, leading to slower-rotating bars in the secular growth stage. However, when the bulge's "diluting" effect on the measured bar strength is removed or reduced, all bars within the same disk share similar distributions in the pattern speed-bar strength ($\Omega_p$-$A_2$) space during the secular growth stage. They also show comparable ratios of the co-rotation radius to the bar length ($\mathcal{R}=R_{\mathrm{CR}}/R_{\mathrm {bar}}$) in this stage. These results suggest that the bulge's influence on the pattern speed is more significant during the bar formation stage, while in the secular growth stage, the bulge's effect may be less important, and the disk component dominates the pattern speed
evolution.
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Astrophysics of Galaxies
The shocking features in the closest rich galaxy cluster Norma
Chong Ge, Ming Sun, Mpati Ramatsoku et al. (+2 more)
The merger shocks generated by the collision of
galaxy clusters elevate the pressure within the intracluster medium, significantly influencing the
evolution of embedded cluster
galaxies. We detect a merger shock (Mach number $\sim 1.3$) on the northwest side of the closest rich
galaxy cluster Norma (A3627), using XMM-Newton and Chandra data. The textbook ram pressure stripping (RPS)
galaxy ESO 137-001 appears to be located in the post-shock region. The shock boosts RPS and may induce the formation of the brightest known X-ray tail behind a cluster late-type
galaxy. Another prominent head-tail
radio galaxy ESO 137-007, with one of the longest
radio continuum tails ($> 500$ kpc), is also likely in the post-shock region. The shock may have reversed the upstream jet to a one-sided
radio head-tail morphology. Moreover, the shock can strip and roll the jet cocoon into a
vortex ring structure like a `smoke ring' behind the end of the jet as observed by the ASKAP data. Therefore, the cluster merger shock can remarkably change cluster
galaxies. Furthermore, Norma is the second brightest non-cool-core cluster following the Coma cluster, with a cool core remnant on its southeast side. Its original cool core may be disrupted by cluster mergers and/or active
galactic nuclei.
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All authors Chong Ge, Ming Sun, Mpati Ramatsoku, Chris Nolting, Bärbel S. Koribalski
Astrophysics of Galaxies
Chemical radial gradients for the bulge-bar stellar populations from the APOGEE survey
J. V. Sales-Silva, K. Cunha, V. V. Smith et al. (+20 more)
The Milky Way bulge-bar is composed of multiple populations. Using chemical and kinematical planes, we segregate six populations in a bulge-bar sample observed by the APOGEE survey: two with bar-driven orbits, two with eccentric orbits, and two with low-eccentricity orbits, each composed of low- and high-[Mg/Fe]
stars. Our sample spans $-2.0\lesssim$[Fe/H]$\lesssim+0.5$ and Galactocentric distance $R_{Gal}$ $<6$ kpc. We use chemical abundances from APOGEE DR17 for the elements Mg, Si, Ca, Al, K, Mn, Co, Ni, and Fe, and from the BAWLAS catalog for Ce and Nd. We find that the low- and high-[Mg/Fe]
stars with low-eccentricity orbits, which exhibit chemical and orbital characteristics similar to those of the low- and high-[$\alpha$/Fe] disks, display slightly negative and positive
metallicity gradients, respectively. This result for the low-[Mg/Fe] low-eccentricity
stars indicates a break in the global thin disk
metallicity gradient. The high eccentricity populations with both low- and high-[Mg/Fe] show approximately flat
metallicity gradients. In general, the [X/H] gradients of all elements for all populations follow Fe, except for the
neutron-capture elements Ce and Nd. For all elements, the high-[Mg/Fe] bar population shows a much steeper positive [X/H] gradient than the nearly flat gradient for the low-[Mg/Fe] bar
stars. The positive [X/H] gradients observed among our high-[Mg/Fe] bar
stars probably reflect an age variation along the peanut structure. This interpretation agrees with the N-body simulations. Such steep positive gradients have also been reported in some high-
redshift (z$\sim$4–10)
galaxies.
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All authors J. V. Sales-Silva, K. Cunha, V. V. Smith, S. Daflon, D. Souto, R. Guerço, V. Loaiza-Tacuri, A. Queiroz, C. Chiappini, I. Minchev, S. R. Majewski, B. Barbuy, D. Bizyaev, J. G. Fernández-Trincado, P. M. Frinchaboy, S. Hasselquist, D. Horta, H. Jönsson, T. Masseron, N. Prantzos, R. P. Schiavon, M. Schultheis, M. Zoccali
Solar and Stellar Astrophysics
Detection of a weak magnetic field in the Balmer emission line white dwarf WDJ1653-1001
Abbigail Elms, Stefano Bagnulo, Pier-Emmanuel Tremblay et al. (+8 more)
The small DAHe and DAe spectral classes comprise isolated, hydrogen-dominated atmosphere white
dwarfs that exhibit variable photometric flux and Balmer line emission. These mysterious systems offer unique insight into the complex interplay between
magnetic fields,
stellar rotation and atmospheric activity in single white
dwarfs. DAHe
stars have detectable
magnetic fields through Zeeman-split spectral lines, whereas DAe
stars lack such splitting. We report the first discovery and characterisation of magnetism in the DAe white
dwarf WDJ165335.21-100116.33 with new time-resolved spectropolarimetry from FORS2. We detect a weak but variable longitudinal
magnetic field with values $\langle B_z \rangle > -9.2 \pm 2.4$ kG and $\langle B_z \rangle < -2.2 \pm 1.0$ kG. Independent ZTF and ATLAS photometry reveal a consistent period of P = 80.3070 $\pm$ 0.0007 h. Time-resolved optical spectroscopy obtained with six ground-based instruments demonstrates strong modulation in the strength of the H$\alpha$ and H$\beta$ Balmer line emission with P = 80.2922 $\pm$ 0.0108 h. The photometric flux and Balmer emission strength vary in antiphase, with the strongest
magnetic detections coinciding with phases of low photometric flux and strong line emission. These characteristics support the theory that a magnetically active, temperature-inverted spot/region is producing an optically thin chromospheric emission region. Comparison with other DAe and DAHe white
dwarfs reveals all systems have a strikingly similar antiphase phenomenology, reinforcing the theory that they are subject to a unified physical mechanism. With the detection of a weak
magnetic field, we reclassify WDJ165335.21-100116.33 as a low-field DAHe white
dwarf.
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All authors Abbigail Elms, Stefano Bagnulo, Pier-Emmanuel Tremblay, Tim Cunningham, James Munday, John Landstreet, Kareem El-Badry, Ilaria Caiazzo, Carl Melis, Viktoria Pinter, Alycia Weinberger
Earth and Planetary Astrophysics
A Cloudy Fit to the Atmosphere of WASP-107 b
Helong Huang, Michiel Min, Chris W. Ormel et al. (+2 more)
Context. WASP-107 b has been observed comprehensively by JWST in the near- and mid-IR bands, making it an ideal
planet to probe the composition and internal dynamics. Recent analysis reveals a 8-10 um silicate feature, but it still remains uncertain how silicate clouds form on this
planet. Aims. We aim at fitting the complete JWST spectrum of WASP-107 b, from 0.9 um to 12 um with a physically motivated cloud model and self-consistent temperature profile. Methods. Two-stream radiative transfer is coupled to a cloud formation model until convergence between cloud and temperature profiles is reached. We search a model grid spanning
metallicity, turbulent diffusivity, internal heat flux and nucleation parameters to find the best fit model. Results. The silicate cloud feature at 10 um and the near-IR molecular band strength can be simultaneously and naturally explained without assuming a parametrized temperature profile. A moderate vertical diffusivity of Kzz = 10^9 cm^2 s^-1 is needed to bring the cloud particles to the upper atmosphere of WASP-107 b. This Kzz is favored by the joint fitting of the near-IR water feature and mid-IR silicate feature – both sensitive to clouds. From the strength of H2O and CO2 bands, our model suggests a
metallicity 17 times
solar. Conclusions. Even in warm
planets such as WASP-107 b, silicate clouds can form in the relatively cool upper atmosphere because
turbulence uplifts vapor and cloud particles. Despite having considerably fewer degrees of freedom, the self-consistent modeling approach successfully fits WASP-107 b's multi-wavelength data, instilling confidence in the derived physical parameters.
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All authors Helong Huang, Michiel Min, Chris W. Ormel, Achrène Dyrek, Nicolas Crouzet
Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc
Assessing the robustness of amortized simulation-based inference to transient noise in gravitational-wave ringdowns
Song-Tao Liu, Tian-Yang Sun, Yu-Xin Wang et al. (+4 more)
Gravitational waves (GW) emitted by binary systems allow us to perform precision tests of general relativity in the strong field regime. Ringdown signals allow for probing black hole mass and
spin with high precision in GW astronomy. With improvements in current and next-generation GW detectors, developing likelihood-free parameter inference methods is crucial. This is especially important when facing challenges such as non-standard noise, partial data, or incomplete signal models that prevent the use of analytical likelihood functions. In this work, we propose an amortized simulation-based inference strategy to estimate ringdown parameters directly. Specifically, our method is based on amortized neural posterior estimation, which trains a neural density
estimator of the posterior for all data segments within the prior range. The results show that our trained amortized network achieves valid confidence coverage and yields posteriors in agreement with established Markov-chain methods at moderate signal-to-noise ratios. At higher signal-to-noise ratios, the recovered posteriors agree with the Markov-chain results in location, although the amplitude posterior is broader. The network provides inference speeds that are orders of magnitude faster. Furthermore, we evaluate the robustness of the method against transient noise contamination. Our results indicate that the timing of glitch injection significantly affects estimation bias, in particular when the glitch contaminates the early, high-amplitude portion of the signal. This study not only provides an efficient and statistically validated inference framework under the tested conditions for ringdown analysis but also lays a foundation for developing robust data-processing pipelines for future GW astronomy in realistic noise environments.
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All authors Song-Tao Liu, Tian-Yang Sun, Yu-Xin Wang, Yong-Xin Zhang, Shang-Jie Jin, Jing-Fei Zhang, Xin Zhang
High Energy Astrophysical Phenomena
Sensitivity to Axion-like Particle dark matter with very-high-energy gamma-ray observations of Active Galactic Nuclei located behind Galaxy Clusters
Cervane Grimaud, Denys Malyshev and Emmanuel Moulin
Axion-Like-Particles (ALPs) are hypothetical pseudo-scalar particles actively searched as light dark matter candidates. The coupling of ALPs to
photons can give rise to distinctive spectral features in the observed gamma-ray spectrum of astrophysical sources. We perform a forecast study on the sensitivity to ALP-
photon interactions using stacked mock observations of selected active
galactic nuclei (AGNs) located behind
galaxy clusters (GC). The ALP-
photon conversion in the
magnetic fields of
galaxy clusters give rise to absorption-like features in AGN spectra that are subject to large variance in their prediction for individual sources. We consider here a stacking analysis of multiple AGN-cluster pairs, which yields a more controlled prediction of the expected ALP-induced spectral patterns in the observed gamma-ray spectra. Using realistic mock observations of selected
Fermi-LAT AGNs by ongoing Imaging Atmospheric Cherenkov
Telescopes such as H.E.S.S., MAGIC and VERITAS, we provide a careful assessment of the expected sensitivity of a combined statistical analysis of many AGN-GC pairs, together with the impact of modelling and instrumental uncertainties. The sensitivity reaches ALP-
photon couplings down to 6$\times$10$^{-13}$ GeV$^{-1}$ for an ALP mass of 3$\times$10$^{-8}$ eV, and is currently statistically dominated indicating further improvements from more observations. Such a stacking analysis approach enables exploration of the yet-uncharted ALP dark matter parameter space in the 10$^{-8}$ - 10$^{-7}$ eV mass range.
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