Peer Revenue Impact factor: volatile

Papers

Fresh from arXiv, typeset properly. Highlighted words trade on the market.

Physics Astrophysics

astro-ph Watch Astrophysics

Saturday 1 November

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ex

Single-Point Search for eV-scale Axion-like particles with Variable-Angle Three-Beam Stimulated Resonant Photon Collider

Takumi Hasada, Kensuke Homma, Airi Kodama et al. (+5 more)

We report a laboratory search for axion-like particles (ALPs) in the eV-mass range using a variable-angle three-beam stimulated resonant photon collider. The scheme independently focuses and collides three laser beams, providing a cosmology- and astrophysics-independent test. By varying the angles of incidence, the center-of-mass energy can be scanned continuously across the eV range. In this work, we operated the collider in a vacuum chamber at a large-angle configuration, verified the spacetime overlap of the three short pulses, and performed a first search centered at $m_a\simeq 2.27~\mathrm{eV}$. No excess was observed. We thus set a $95\%$ C.L.\ upper limit on the pseudoscalar two-photon coupling, with a minimum sensitivity of $g/M\simeq 4.2\times 10^{-10}~\mathrm{GeV}^{-1}$ at $m_a=2.27~\mathrm{eV}$. This provides the first model-independent upper limit on the coupling that reaches the KSVZ benchmark in the eV regime and demonstrates the feasibility of eV-scale mass scans in the near future.
Read the full abstract

All authors Takumi Hasada, Kensuke Homma, Airi Kodama, Haruhiko Nishizaki, Yuri Kirita, Shin-ichiro Masuno, Shigeki Tokita, Masaki Hashida

Solar and Stellar Astrophysics

Properties of Carbon-rich Asymptotic Giant Branch Stars in the LMC and the Milky Way

Kyung-Won Suh

We present a comparative study of carbon-rich asymptotic giant branch (CAGB) stars in the Large Magellanic Cloud (LMC; 7347 stars) and the Milky Way (7163 stars) using infrared color-magnitude diagrams, spectral energy distributions (SEDs), two-color diagrams, and variability data. Observed SEDs are compared with theoretical models to characterize the central stars and their circumstellar dust envelopes and to estimate distances. For the LMC, a set of best-fitting CAGB models is derived by fitting observed SEDs with radiative transfer models, utilizing the galaxy's well-established distance. For Galactic CAGB stars, where Gaia DR3 parallaxes are uncertain, we estimate distances by fitting observed SEDs with the CAGB models validated against LMC stars, and for Mira variables, from the period-magnitude relation calibrated with LMC Miras. A comparison of these approaches demonstrates that the SED-based distances are both reliable and practical for a large sample of Galactic CAGB stars. We find that CAGB stars in both galaxies show broadly similar infrared properties, although the LMC sample lacks stars with extremely thick dust envelopes.
Read the full abstract

High Energy Astrophysical Phenomena

Neutrino and Cascade Gamma-Ray Emission from Magnetized Turbulent Coronae in Seyfert Galaxies

Xing-Jian Wang, Jing-Fu Hu, Hao-Ning He et al. (+1 more)

Recent neutrino observations from the IceCube Collaboration suggest that Seyfert galaxies are promising candidate sources of neutrinos. Within the standard disk-corona model, we assume that protons are accelerated by a non-resonant acceleration mechanism driven by magnetized turbulence in the corona. These accelerated protons interact with ambient radiation or matter, producing high-energy neutrinos and gamma rays. In this scenario, gamma rays are largely absorbed within the corona. The neutrino luminosity depends primarily on the properties of the corona (such as the X-ray luminosity and radius) and the spectral energy distribution of the target photons. This study demonstrates the relation between the neutrino luminosity and the X-ray luminosity, and further discusses the contribution of cascade gamma rays to coronal radiation. Notably, MeV gamma rays can effectively escape the source, together with neutrinos, and serve as key observational probes for testing this model. Future MeV gamma-ray telescopes, such as AMEGO-X and e-ASTROGAM, are expected to detect such gamma-ray signatures, providing a critical multi-messenger test of the hadronic corona model.
Read the full abstract

All authors Xing-Jian Wang, Jing-Fu Hu, Hao-Ning He, Cheng-Qun Pang

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

The thermal view of $f(R)$ cosmology

Valerio Faraoni and Santiago Novoa Cattivelli

A new thermal view of scalar-tensor gravity, in which general relativity is the zero-temperature state of gravity, is applied to the specific subclass of $f(R)$ gravity theories and, specifically, to spatially homogeneous and isotropic universes. Within the limits of application of the new thermal formalism, results on the convergence to Einstein cosmology (or lack thereof) are first obtained for general $f(R)$ theories, and then illustrated with power-law and Starobinsky $f(R)$ gravity.
Read the full abstract

Friday 31 October

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Symmetry-Protected $\alpha$-Attractor Hybrid Inflation in Supergravity and Constraints from ACT DR6 and DESI DR2

Swapnil Kumar Singh

We present a symmetry-protected supergravity effective realization of hybrid $\alpha$-attractor inflation with a sequestered Stückelberg uplift. The model contains four chiral multiplets, an inflaton modulus $T$, a stabilizer field $S$, and a pair of oppositely charged waterfall multiplets $(\Psi,\bar\Psi)$, together with a hidden Stückelberg $U(1)_D$ sector that generates an approximately constant positive contribution to the scalar potential. Along the real inflationary trajectory, the F-term potential realizes the E-model plateau \[ U(\phi)=V_0\left(1-e^{-\sqrt{2/(3\alpha)}\,\phi}\right)^2 , \] while the sequestered uplift shifts the total energy density without directly modifying the tree-level inflaton slope. We derive the background evolution, the analytic $N$–$\phi$ relation, the waterfall stability condition, and the leading predictions for the scalar spectral index and tensor-to-scalar ratio. The model retains the characteristic red-tilted $\alpha$-attractor behavior, with $n_s\simeq1-2/N_*$ and tensor amplitudes controlled primarily by the curvature parameter $\alpha$, while the uplift and the hybrid end point generate only subleading corrections at fixed $N_*$. We also discuss the assumptions required for an effectively single-field trajectory, including the treatment of the light angular component of $T$, and examine the sensitivity of the sequestered uplift to Planck-suppressed cross-couplings. The resulting construction provides a controlled supergravity embedding of hybrid $\alpha$-attractor inflation compatible with current CMB constraints, including Planck, ACT DR6, and DESI DR2, while remaining testable by future $B$-mode searches such as LiteBIRD and CMB-S4.
Read the full abstract

High Energy Astrophysical Phenomena · Cross-listed from gr-qc

Spin-up and mass-gain in hyperbolic encounters of spinning black holes

Healey Kogan, Frederick C.L. Pardoe and Helvi Witek

Scattering black holes spin up and gain mass through the re-absorption of orbital angular momentum and energy radiated in gravitational waves during their encounter. In this work, we perform a series of numerical relativity simulations to investigate the spin-up and mass-gain for equal-mass black holes with a wide range of equal initial spins, $\chi_{\rm i}\in[-0.7,0.7]$, aligned (or anti-aligned) to the orbital angular momentum. We also consider a variety of initial momenta. Furthermore, we explore a range of incident angles and identify the threshold between scattering and merging configurations. The spin-up and mass-gain are typically largest in systems with incident angles close to the threshold value, large momenta, and negative (i.e. anti-aligned) initial spins. When evaluated at the threshold angle, we find that the spin-up decreases linearly with initial spin. Intriguingly, systems with initial spin $\chi_{\rm i}=0.7$ sometimes experience a spin-down, in spite of an increase in the black-hole angular momentum, due to a corresponding gain in the black-hole mass. Across the simulation suite, we find a maximum spin-up of $0.3$ and a maximum increase in the black-hole mass of $15\%$.
Read the full abstract

Earth and Planetary Astrophysics

Sharp dynamic points in Earth-Sun physics

José A. Rueda, Sergio Ramírez, Miguel A. Sánchez et al. (+2 more)

The subsolar point, the closest location on Earth's surface to the Sun, marks the Sun-Earth line of gravity that governs Earth's coupled orbital-rotational cycle. We examined the dynamic interactions among the Sun meridian declination (SMD), the Equation of Time (EoT), Earth's rotational speed (ER$_\omega$) – equatorial and with respect to the Sun – and the path of the subsolar point (NBI) across longitude, including time derivatives up to the fourth order (snap). A central finding was that the function NBI$_\alpha$(SMD) traces a lemniscate whose temporal structure mirrors the analemma, EoT(SMD), and whose symmetry converges to the obliquity component of the EoT. The EoT velocity ($\omega^*$) peaks at solstices, troughs near the equinoxes, and crosses zero every mid-season. ER$_\omega$ decreases monotonically along trans-equinoctial phases where the net drives of EoT and SMD coincide, and increases along trans-solstitial phases, where their net drives oppose. Eight sharp kinematic periods were identified for the cycle SMD-EoT-ER$_\omega$: two equinoctial, two solstitial, and one within each season. The non-solstitial sharp terms, defined by ZCPs and troughs of $\omega^*$, display a consistent 3$^\circ$ northward offset from the function NBI$_\alpha$(SMD). These results reveal a direct dynamical link between SMD, EoT, and Earth's rotational speed, providing a novel framework for understanding Earth's rotation.
Read the full abstract

All authors José A. Rueda, Sergio Ramírez, Miguel A. Sánchez, Cecilio U. Aguilar, Sandra Rueda B

High Energy Astrophysical Phenomena

The Advanced X-ray Imaging Satellite (AXIS) Community Science Book

Michael Koss, Nafisa Aftab, Steven W. Allen et al. (+395 more)

The AXIS Community Science Book represents the collective effort of 592 scientists worldwide to define the transformative science enabled by the Advanced X-ray Imaging Satellite (AXIS), a next-generation X-ray mission selected by NASA's Astrophysics Probe Program for Phase A study. AXIS will advance the legacy of high-angular-resolution X-ray astronomy with ~1.5” imaging over a wide 24' field of view and an order of magnitude greater collecting area than Chandra in the 0.3-12 keV band. Combining sharp imaging, high throughput, and rapid response capabilities, AXIS will open new windows on virtually every aspect of modern astrophysics, exploring the birth and growth of supermassive black holes, the feedback processes that shape galaxies, the life cycles of stars and exoplanet environments, and the nature of compact stellar remnants, supernova remnants, and explosive transients. This book compiles 138 community-contributed science cases developed by five Science Working Groups focused on AGN and supermassive black holes, galaxy evolution and feedback, compact objects and supernova remnants, stellar physics and exoplanets, and time-domain and multi-messenger astrophysics. Together, these studies establish the scientific foundation for next-generation X-ray exploration in the 2030s and highlight strong synergies with facilities of the 2030s, such as JWST, Roman, Rubin/LSST, SKA, ALMA, ngVLA, and next-generation gravitational-wave and neutrino networks.
Read the full abstract

All authors Michael Koss, Nafisa Aftab, Steven W. Allen, Roberta Amato, Hongjun An, Igor Andreoni, Timo Anguita, Riccardo Arcodia, Thomas Ayres, Matteo Bachetti, Maria Cristina Baglio, Arash Bahramian, Marco Balboni, Ranieri D. Baldi, Solen Balman, Aya Bamba, Eduardo Banados, Tong Bao, Iacopo Bartalucci, Antara Basu-Zych, Rebeca Batalha, Lorenzo Battistini, Franz Erik Bauer, Andy Beardmore, Werner Becker, Ehud Behar, Andrea Belfiore, Paz Beniamini, Elena Bertola, Vinicius Bessa, Henry Best, Stefano Bianchi, N. Biava, Breanna A. Binder, Elizabeth L. Blanton, Arash Bodaghee, Tamara Bogdanovic, David Bogensberger, A. Bonafede, Matteo Bonetti, Pol Bordas, Alice Borghese, Andrea Botteon, Stella Boula, Enrico Bozzo, Marica Branchesi, William Nielsen Brandt, Joel Bregman, Fabrizio Brighenti, Ettore Bronzini, Giulia Brunelli, Marcella Brusa, Esra Bulbul, Kevin Burdge, Alessandro Caccianiga, Michael Calzadilla, Sergio Campana, Milvia Capalbi, Fiamma Capitanio, Nico Cappelluti, Jonathan Carney, Sabrina Casanova, Daniel Castro, S. Bradley Cenko, Joheen Chakraborty, Priyanka Chakraborty, George Chartas, Arka Chatterjee, Prakriti Pal Choudhury, Raven Cilley, Francesca Civano, Andrea Comastri, Thomas Connor, Michael F. Corcoran, Lia Corrales, Francesco Coti Zelati, Weiguang Cui, Filippo D'Ammando, Kristen Dage, Tansu Daylan, Sabrina De Grandi, Alessandra De Rosa, Roberto Decarli, Anne Decourchelle, Nathalie Degenaar, Antonino Del Popolo, Alessandro Di Marco, Tiziana Di Salvo, Simone Dichiara, Stephen DiKerby, Steven Dillmann, Neil Doerksen, Paul Draghis, Jeremy J. Drake, Lorenzo Ducci, Renato Dupke, Joseph Durbak, Girish M. Duvvuri, Hannah Dykaar, Dominique Eckert, Martin Elvis, Catherine Espaillat, Paolo Esposito, Felix Furst, Giuseppina Fabbiano, Joshua Fagin, Abraham Falcone, Elena Fedorova, Adina Feinstein, Jorge Fernandez Fernandez, Gilles Ferrand, Anthony M. Flores, N. Foo, Nicholas Foo, Adi Foord, Alessia Franchini, Federico Fraschetti, Brenda L. Frye, James D. Lowenthal, Chris Fryer, Shin-ichiro Fujimoto, Seth Gagnon, Luigi Gallo, Carlos Garcia Diaz, Massimo Gaspari, Fabio Gastaldello, Joseph D. Gelfand, Suvi Gezari, Simona Ghizzardi, Simona Giacintucci, A. Gill, Roberto Gilli, Myriam Gitti, Margherita Giustini, Andrea Gnarini, Paola Grandi, Arran Gross, Liyi Gu, Sean Gunderson, Hans Moritz Gunther, Daryl Haggard, Kenji Hamaguchi, Jeremy Hare, Kevin C. Harrington, Craig Heinke, Sebastian Heinz, Julie Hlavacek-Larrondo, Wynn C. G. Ho, Edmund Hodges-Kluck, Jeroen Homan, R. Huang, Luca Ighina, Alessandro Ignesti, Matteo Imbrogno, Christopher Irwin, Jimmy Irwin, Nazma Islam, Gian Luca Israel, Wynn Jacobson-Galan, Chetana Jain, Arghajit Jana, Amruta Jaodand, Fred Jennings, Jiachen Jiang, Eric F. Jimenez-Andrade, Y. Jimenez-Teja, S. Johnson, Peter Jonker, Patrick S. Kamieneski, Elias Kammoun, Erin Kara, Oleg Kargaltsev, George W. King, Demet Kirmizibayrak, Noel Klingler, Albert K.H. Kong, Marina Kounkel, Manish Kumar, Alexander Kutyrev, Rebecca Kyer, Fabio La Monaca, Erini Lambrides, Giorgio Lanzuisi, Wonki Lee, Bret Lehmer, Elisa Lentini, Marika Lepore, Jiangtao Li, Carey M. Lisse, Daizhong Liu, Tingting Liu, Monica Isla Llave, Nicola Locatelli, Laura A. Lopez, Sebastian Lopez, Lorenzo Lovisari, Elisabeta Lusso, Brydyn Mac Intyre, Austin MacMaster, Roberto Maiolino, Jaya Maithil, Chandreyee Maitra, Walid Majid, Daniele Bjorn Malesani, Julie Malewicz, Labani Mallick, Shifra Mandel, Antonios Manousakis, Adam Mantz, Stefano Marchesi, Maxim Markevitch, Tatsuya Matsumoto, James Matthews, Martin G. F. Mayer, Giovanni Mazzolari, Chiara Mazzucchelli, Michael McDonald, Eileen T. Meyer, Riccardo Middei, Giulia Migliori, Martin Millon, Giovanni Miniutti, Mohammad Mirakhor, Silvano Molendi, Erik B. Monson, Alberto Moretti, Christopher Morgan, Kaya Mori, R. Glenn Morris, Sachindra Naik, Preethi Nair, Emanuele Nardini, Yael Naze, Michela Negro, Favio Neira, Chi Yung Ng, Mason Ng, Thong T. Q. Nguyen, Scott C. Noble, Brendan O'Connor, Ewan O'Sullivan, Matthew O'Dowd, Kwangmin Oh, Laura Olivera-Nieto, Marina Orio, Lidia M. Oskinova, Rachel Osten, Fabio Pacucci, Dany Page, Eric Paic, Belen Alcalde Pampliega, Abby Pan, Francesca Panessa, Manali Parvatikar, Massimo Pascale, Dheeraj Pasham, Biswajit Paul, Aaron B. Pearlman, Alessandro Peca, Eric S. Perlman, Maria Petropoulou, Pierre-Olivier Petrucci, Ryan W. Pfeifle, Enrico Piconcelli, Annalisa Pillepich, Ciro Pinto, Tsvi Piran, Andrealuna Pizzetti, Gabriele Ponti, Bettina Posselt, Pragati Pradhan, David A. Principe, Marine Prunier, Andrew Ptak, Giovanna Pugliese, Jonathan Quirola-Vasquez, Kamlesh Rajpurohit, Scott W. Randall, Chris Reynolds, Mark T. Reynolds, Lauren Rhodes, Angelo Ricarte, Claudio Ricci, Roberto Ricci, Fabio Rigamonti, Ketan Rikame, Guido Risaliti, Giacomo Riva, Liliana Rivera Sandoval, Guillermo Andres Rodriguez-Castillo, Daniele Rogantini, Patrizia Romano, Piero Rosati, Mariachiara Rossetti, Barry Rothberg, Alicia Rouco Escorial, Helen Russell, Geoffrey Ryan, Andrea Sacchi, Samar Safi-Harb, Takanori Sakamoto, Chiara Salvaggio, Ruben Salvaterra, Francesco Salvestrini, Isabel Sander, Arnab Sarkar, Manami Sasaki, Gerrit Schellenberger, Eric Schlegel, Jeremy D. Schnittman, Emma Schwartzman, Roberto Serafinelli, Alberto Sesana, Paola Severgnini, Rahul Sharma, Yue Shen, Timothy Shimwell, Avi Shporer, Matilde Signorini, Jasbir Singh, Julia Sisk-Reynes, Dominique Sluse, Taweewat Somboonpanyakul, Roberto Soria, Navin Sridhar, Keivan G. Stassun, Robert Stein, Nathan Steinle, Daniel Stern, Ceaser Stringfield, Haley Stueber, Yuanyuan Su, Janette Suherli, Nial Tanvir, Antonella Tarana, Yukikatsu Terada, Ira Thorpe, Andrea Tiengo, Francesco Tombesi, Nuria Torres-Alba, Eleonora Torresi, Alessia Tortosa, Lee Townsend, Paolo Tozzi, Cole Treyturik, Anna Trindade Falcao, Eleonora Troja, Naomi Tsuji, Aysegul Tumer, Francesco Ubertosi, Hendrik van Eerten, Reinout van Weeren, Georgios Vasilopoulos, Susanna D. Vergani, Georgios Vernardos, Benjamin Vigneron, Amit Vishwas, Fabio Vito, Zorawar Wadiasingh, Stephen Walker, Dominic J. Walton, F. Wang, Q. Daniel Wang, Kimberly Weaver, Peter J. Wheatley, Rudy Wijnands, Dan Wilkins, Brian J. Williams, Scott Wolk, Anna Wolter, Ka-Wah Wong, Jooyun Woo, Tyrone Woods, Kinwah Wu, Yerong Xu, Muskan Yadav, Hui Yang, J. Yang, Yuhan Yao, Michael Yeung, George Younes, Andrew Young, Mihoko Yukita, Min S. Yun, Silvia Zane, Luca Zappacosta, Stephen Zepf, Bing Zhang, Congyao Zhang, Shuo Zhang, Xiying Zhang, Yuexin Zhang, Xiurui Zhao, Xueying Zheng, Dazhi Zhou, Mingyang Zhuang, Fan Zou, John ZuHone

High Energy Astrophysical Phenomena

Deep Chandra X-ray Observations of Abell 2029: the Merger History of a Relaxed, Strong Cool Core Cluster

Courtney B. Watson, Elizabeth L. Blanton, Scott W. Randall et al. (+2 more)

We present results from very deep (485 ks) Chandra X-ray observations of the relaxed, cool core cluster Abell 2029 (z = 0.0767). A2029 hosts one of the longest, most continuous sloshing spirals ever observed, which we find extends nearly 600 kpc from the cluster core. In addition to providing detailed views of the sloshing spiral, imaging and spectroscopic analysis reveals ICM substructure related to the merger history including a broad “splash” of cooler gas and a potential merger shock. The radio lobes of the central WAT source show evidence of alignment with the sloshing motions, consistent with ICM bulk flow, rather than host-galaxy motion, being the primary driver of lobe bending. Comparison to a 1:10 mass-ratio off-axis merger simulation indicates that the observed ICM structures are relics of a second core passage of a subcluster ~4 Gyr after the start of the merger, where the “splash” feature is revealed to be a wake of cool gas trailing behind the subcluster. Overall, our results suggest that A2029 is still settling from past interactions – showing that even the initially most relaxed-looking clusters can be hiding a rich history of dynamical activity.
Read the full abstract

All authors Courtney B. Watson, Elizabeth L. Blanton, Scott W. Randall, Tracy E. Clarke, John A. ZuHone

Astrophysics of Galaxies

The Universality of Dark Matter Density Profiles for Milky Way Analog Galaxies

Maria Clara Cavalcante-Siviero, K. Menéndez-Delmestre, P. P. B. Beaklini et al. (+4 more)

The structure, extent, and mass of the Milky Way's (MW) dark matter (DM) halo are observationally challenging to determine due to our position within the Galaxy. To overcome this limitation, we study a combined sample of 127 MW analogs from the IllustrisTNG-50 cosmological simulation with observations of 11 nearby galaxies. Using both spatial and spectral high-resolution data from VLA and GMRT telescopes, we employ the 3D-Barolo algorithm to derive precise kinematic maps and rotation curves (RCs). To perform a careful analysis of the stellar component, we use Spitzer mid-IR imaging at 3.6 and 4.5um. We decompose the RCs into their different mass components, enabling the construction of a DM radial profile for each galaxy. By using a MCMC-based routine, we account for the DM contribution for the observed RCs. For our simulated sample, we obtain DM radial profiles directly from the TNG50 database. We probe for the universality of the DM profiles by deriving and comparing the equivalent local DM density (LDMD), a critical parameter linked to DM direct detection experiments on Earth. We calculate the DM density at the corresponding location of the Sun in each of the analogs. Our analysis yields a final LDMD range of 0.17-0.46 GeV cm^-3. Finally, by leveraging our mass estimates (M200}, Mgas and Mstar), we contextualize our findings with the efficiency of star formation in MW analogs and with the diversity of galaxies inhabiting similar halo masses.
Read the full abstract

All authors Maria Clara Cavalcante-Siviero, K. Menéndez-Delmestre, P. P. B. Beaklini, T. S. Gonçalves, D. C. Rodrigues, N. G. de Isídio, A. E. Araújo-Carvalho

Astrophysics of Galaxies

A Milky Way mass model for isolated simulations

J A Sellwood

This paper presents an equilibrium model of a Milky Way-like spiral galaxy that supports open, mostly 2- and 3-arm spiral patterns but does not form a bar. It is suggested as a more realistic alternative model to that employed by the Agora collaboration; their model has a much lower disk mass and therefore forms only multi-arm spiral patterns. This improved model should enable simulations that test star-formation and feedback models in a more realistic isolated galaxy. Three versions of the same model having $2.1\times 10^5$, $2.1\times 10^6$, and $2.1\times 10^7$ particles are available for download.
Read the full abstract

Earth and Planetary Astrophysics

Watching a Comet Turn On: High Spectral Resolving Power Observations of Comet C/2017 K2 (PanSTARRS)

Anita L. Cochran, Adam J. McKay and Youssef Moulane

We report high spectral resolving power optical observations of comet C/2017\,K2 (PanSTARRS) as it approached the Sun. This comet was discovered when it was 16\,au from the Sun. At discovery, the comet had a large and relatively bright coma. However, the spectrum at discovery showed only signatures of dust. We used the coudé spectrograph on the McDonald Observatory 2.7\,m telescope to obtain spectra, starting when the comet was at a heliocentric distance of 5.06\,au and following it until 2.47\,au, to determine what spectral features would appear at each heliocentric distance. The first heliocentric distance for which we detected any emission from the gas was 3.39\,au, when we first detected CN. As the comet continued inward towards the Sun, various other species were detected. We discuss the implications of the early turn-on of CN and of species first appearing at different heliocentric distances in the context of control of the activity by water.
Read the full abstract

Cosmology and Nongalactic Astrophysics · Cross-listed from gr-qc

Conserved Quantities in Expanding Gödel Cosmology

Alexander Leithes

At linear order we study perturbations to a Gödel background spacetime which includes expansion in addition to rotation. We investigate the transformation behaviour of these perturbations under gauge transformations and construct gauge invariant quantities. Using the perturbed energy conservation equation we find that there are conserved quantities in Expanding Gödel (EG) Cosmology, in particular a spatial metric trace perturbation, {\zeta} SMTP , which is conserved on large scales for pressureless dust. We finally extend our discussion to a perfect fluid matter content to also obtain conserved quantities in this context.
Read the full abstract

Astrophysics of Galaxies

Chemodynamic evidence of pristine gas accretion in the void galaxy VGS 12

Evgeniya Egorova, Kathryn Kreckel, Oleg Egorov et al. (+5 more)

Accretion of metal-poor gas is expected to be an important channel of gas replenishment in galaxy evolution studies. However, observational evidence of this process is still relatively scarce. The unusual polar disk galaxy VGS 12 was found in the Void Galaxy Survey. It appears to be isolated and resides in the cosmological wall between two large voids. The suggested formation scenario for this peculiar system is accretion of metal-poor gas from the void interior. We present the data on the gas-phase chemical abundance of VGS 12 obtained with the Russian 6m telescope BTA. We complement our analysis with HI data obtained with VLA and the data on the kinematics of the ionized gas. VGS 12 appears to be a strong outlier from the "metallicity - luminosity" relation, with gas oxygen abundance ~0.7dex lower than expected for its luminosity. The nitrogen abundance, on the other hand, is higher than what is typically observed in galaxies with similar metallicity, but is consistent with the metallicity expected given its luminosity. Such behavior is what is expected in the case of metal-poor gas accretion. The HI reveals clear morphological and kinematical asymmetry between the northern and southern parts of the disk, which are likely related to its unsettled state due to the recent accretion event. The kinematics of the ionized gas seen in Halpha reveal prolate rotation and follow closely the rotation of the HI disk, so we suggest this is accreted HI gas ionized by the stars in the central region of the galaxy. Together, our findings provide strong, multiwavelength evidence of ongoing cold gas accretion in a galaxy caught in the act of growing from the cosmic web. This is one of the very few individual galaxies where a convincing case can be made for such a process, and demonstrates the potential for cold accretion to contribute to galaxy growth even in the low-redshift universe.
Read the full abstract

All authors Evgeniya Egorova, Kathryn Kreckel, Oleg Egorov, Alexei Moiseev, Miguel A. Aragon-Calvo, Rien van de Weygaert, Sergey Kotov, Jacqueline van Gorkom

Astrophysics of Galaxies

Multiphase gas in Circumgalactic cloud complexes: Insights from kiloparsec-scale Magnetohydrodynamic Turbulence Simulations

Rajsekhar Mohapatra, Alankar Dutta and Prateek Sharma

The circumgalactic medium (CGM) is the diffuse gas surrounding a galaxy's halo, and it plays a vital role in the galactic baryon cycle. However, its mass distribution across the virial phase and the cooler, denser atomic phase, remains uncertain. To investigate this, we perform high-resolution magnetohydrodynamic simulations of 0.125–8 kpc-scale representative patches of the CGM, with parameters informed by quasar absorption line observations. Our simulations resolve the cooling length (the minimum across all temperatures of $c_s t_{\rm cool}$, where $c_s$ is the sound speed and $t_{\rm cool}$ is the cooling time in isobaric conditions), allowing us to track the evolution of cold gas more accurately. We find that low-density CGM gas ($3\times10^{-4}$ cm$^{-3}$) cannot sustain cold gas below $10^4$ K for long, due to a large value of the ratio between the cooling to mixing time ($t_{\rm cool}/t_{\rm mix}$). In contrast, higher-density environments ($3\times10^{-3}~{\rm cm}^{-3}$) reach a turbulent multiphase steady state, with up to $50\%$ of the mass in the cold phase, occupying only about $1\%$ of the volume. To connect with large-volume cosmological simulations and small ${\rm pc}$-scale idealized simulations, we explore different box sizes (0.125–8 kpc) and identify a key scaling relation: simulations with similar $t_{\rm cool}/t_{\rm mix}$ exhibit comparable cold gas mass fractions and lifetimes. Importantly, we find that simply sub-sampling (reducing box-size) a small region from a large-volume simulation while maintaining a constant turbulent energy density injection rate from larger to smaller scales artificially shortens $t_\mathrm{mix}$, leading to inaccurate predictions for cold gas survival. This means that cold gas at small $\lesssim 10$ kpc scales arises in relatively dense, quiescent regions of the CGM rather than the turbulent ones undergoing cascade from large scales.
Read the full abstract

Solar and Stellar Astrophysics

A Complete Analysis of Subgiant Stellar Systems III: Hip70868

Hoda E. Elgendy, Mashhoor A. Al-Wardat, Hassan B. Haboubi et al. (+3 more)

This study utilizes "Al-Wardat's method for analysing binary and multiple stellar systems" to estimate a set of parameters for the triple system Hip70868. The method compares the system's observational magnitudes, color indices, and spectral energy distribution (SED) and synthetic SEDs generated through atmospheric modeling of each component. Feedback-adjusted parameters and an iterative approach were employed to achieve the best fit between observational (including the latest measurements of Gaia, release DR3) and synthetic spectral energy distributions. The findings were completed using the distance of 71.89 pc given by Hipparcos 2007's new reduction. The individual components' parameters for the system were derived afterward. The parameters obtained for the individual components are as follows: Component A has an effective temperature (Teff) of 6000 +- 50 K, a surface gravity (log ga) of 4.50 +- 0.05, and a radius (Ra) of 1.43 +- 0.07 R_sun. Component B has a (Teff) of 5910 +- 50 K, a (log gb) of 4.40 +- 0.05, and a radius (Rb) of 1.35 +- 0.07 R_sun. The spectral types of the components were found to be F9 IV and G1 IV, respectively. The findings from this analysis were utilized to accurately position the two system components on the Hertzsprung-Russell (H-R) diagram and the evolutionary tracks. The analysis shows that the components have transitioned from the main sequence to the sub-giant stage of their evolution.
Read the full abstract

All authors Hoda E. Elgendy, Mashhoor A. Al-Wardat, Hassan B. Haboubi, Lin R. Benchi, Abdallah M. Hussein, Hussein M. Elmehdi

Astrophysics of Galaxies

Seeds to success: growing heavy black holes in dense star clusters

Lavinia Paiella, Manuel Arca Sedda, Benedetta Mestichelli et al. (+1 more)

The observational dearth of black holes (BHs) with masses between $\sim$100 and 100,000 $M_\odot$ raises questions about the nature of intermediate-mass black holes (IMBHs). Proposed formation channels for IMBHs include runaway stellar collisions and repeated binary BH (BBH) mergers driven by dynamical interactions in stellar clusters, but the formation efficiency of these processes and the associated IMBH occupation fraction are largely unconstrained. In this work, we study IMBH formation via both mechanisms in young, globular, and nuclear star clusters. We carry out a comprehensive investigation of IMBH formation efficiency by exploring the impact of different seeding models and star cluster formation histories. We employ a new version of the B-POP population synthesis code, able to model several seeding mechanisms as well as hierarchical BBH mergers. We quantify the efficiency of IMBH production across different cluster families, and estimate the fraction of BBH mergers involving an IMBH primary. Comparison with low-redshift IMBH candidates suggests that, depending on the seeding mechanism, stellar collisions can play a pivotal role in explaining potential IMBHs in local globular clusters. Our simulations highlight stellar collisions as the primary IMBH formation channel across a wide range of cluster types. They further suggest that wandering IMBHs may populate Milky Way-like galaxies and that correlations between cluster and IMBH masses can help distinguish the origins of Galactic globular clusters.
Read the full abstract

All authors Lavinia Paiella, Manuel Arca Sedda, Benedetta Mestichelli, Cristiano Ugolini

High Energy Astrophysical Phenomena

Black Holes at high and low metallicity

Jorick S. Vink, Gautham N. Sabhahit and Ethan R.J. Winch

At the end of their lives the most massive stars collapse into black holes (BHs). The detection of an 85 $M_{\odot}$ BH from GW 190521 appeared to challenge the upper-mass limit imposed by pair-instability (PI). Using systematic MESA calculations with new mass-loss implementations, we show that 100 $M_{\odot}$ stars at metallicities below 0.1 $Z_{\odot}$ can evolve into blue supergiant progenitors with cores small enough to avoid PI, yet with limited envelope loss, yielding remnants within the second mass gap. The key ingredients involve (i) a proper consideration of internal mixing and (ii) physically motivated stellar winds. Our modelling provides a robust pathway that roughly doubles the maximum BH mass permitted by PI theory and establish a physically-consistent framework to explore the upper BH mass limit versus metallicity. For rapid rotation ($\ge$50% of critical), the upper BH mass comes down to $\simeq$35 $M_{\odot}$, matching the LIGO/Virgo BH mass pile-up.
Read the full abstract

Instrumentation and Methods for Astrophysics

StarDICE IV: correcting visible photometry from atmospheric gray extinction using thermal infrared observations

Kélian Sommer, Bertrand Plez, Johann Cohen-Tanugi et al. (+11 more)

Ground-based surveys such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time require photometric calibration that is both long-term stable and spatially uniform at the sub-per cent level, even during non-photometric conditions. Achieving this precision motivates new approaches to characterize atmospheric transmission, particularly to mitigate grey extinction from clouds. The StarDICE experiment aims to establish a metrology chain linking laboratory standards to astrophysical fluxes with 1 mmag accuracy in the $\textit{griz}$ bands, a goal for which controlling variable atmospheric effects is essential. We present a method that corrects photometric measurements using simultaneous radiometric information from an infrared thermal camera. The grey-extinction model is fit on an image-by-image basis using thermal radiance excess and the difference between synthetic and instrumental fluxes of calibration stars, without requiring assumptions about the spatial structure of extinction. The method relies on a forward model that incorporates environmental monitoring, radiative-transfer simulations, and Gaia DR3 stellar catalogues. Using data from a remote observing system that repeatedly monitored two fields under diverse atmospheric conditions, we show that the corrections reduce residuals between corrected and reference magnitudes and produce extinction maps with 2-arcmin resolution and ~0.01 mag accuracy. Using this technique, we can recover data acquired under non-photometric conditions with a precision comparable to data obtained under photometric conditions. For the most affected exposures, the mean absolute error improves from 0.64 to 0.11 mag, and temporal extinction variations can be reduced to 0.025 mag per source. We discuss the implications of this technique for future surveys and outline directions for further refinement.
Read the full abstract

All authors Kélian Sommer, Bertrand Plez, Johann Cohen-Tanugi, Marc Betoule, Sébastien Bongard, Thierry Souverin, Sylvie Dagoret-Campagne, Marc Moniez, Jérémy Neveu, Fabrice Feinstein, Claire Juramy, Laurent Le Guillou, Eduardo Sepulveda, Eric Nuss

Instrumentation and Methods for Astrophysics

BOOM and Babamul: a real-time, multi-survey, optical alert broker system operating at scale

Theophile Jegou du Laz, Michael W. Coughlin, Peter Bachant et al. (+17 more)

With the arrival of ever higher throughput wide-field surveys and a multitude of multi-messenger and multi-wavelength instruments to complement them, software capable of harnessing these associated data streams is urgently required. To meet these needs, a number of community supported alert brokers have been built, currently focused on processing of Zwicky Transient Facility (ZTF; $\sim 10^5$-$10^6$ alerts per night) with an eye towards Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST; $\sim 2 \times 10^7$ alerts per night). Building upon the system that successfully ran in production for ZTF's first seven years of operation, we introduce BOOM (Burst & Outburst Observations Monitor), an analysis framework focused on real-time, joint brokering of these alert streams. BOOM harnesses the performance of a Rust-based software stack relying on a non-relational MongoDB database combined with a Valkey in-memory processing queue and a Kafka cluster for message sharing. With this system, we demonstrate feature parity with the existing ZTF system with a throughput $\sim 7 \times$ higher. We describe the workflow that enables the real-time processing as well as the results with custom filters we have built to demonstrate the system's capabilities. In conclusion, we present the development roadmap for both BOOM and Babamul - the public-facing LSST alert broker built atop BOOM - as we begin the Rubin era.
Read the full abstract

All authors Theophile Jegou du Laz, Michael W. Coughlin, Peter Bachant, Jacob E. Simones, Thomas Culino, Antoine Le Calloch, Sushant Sharma Chaudhary, Xander J. Hall, Tyler Barna, Daniel Warshofsky, Matthew Graham, Mansi M. Kasliwal, Ashish Mahabal, Joshua S. Bloom, Antonella Palmese, Frank J. Masci, Steven L. Groom, Richard Dekany, Reed L. Riddle, George Helou

Earth and Planetary Astrophysics

The Coupled Tidal Evolution of the Moons and Spins of Warm Exoplanets

Yubo Su and Melaine Saillenfest

Context: The Solar System giant planets harbour a wide variety of moons. Moons around exoplanets are plausibly similarly abundant, even though most of them are likely too small to be easily detectable with modern instruments. Moons are known to affect the long-term dynamics of the spin of their host planets; however, their influence on warm exoplanets (i.e.\ with moderately short periods of about $10$ to $200$~days), which undergo significant star-planet tidal dissipation, is still unclear. Aims: Here, we study the coupled dynamical evolution of exomoons and the spin dynamics of their host planets, focusing on warm exoplanets. Methods: Analytical criteria give the relevant dynamical regimes at play as a function of the system's parameters. Possible evolution tracks mostly depend on the hierarchy of timescales between the star-planet and the moon-planet tidal dissipations. We illustrate the variety of possible trajectories using self-consistent numerical simulations. Results: We find two principal results: i) Due to star-planet tidal dissipation, a substantial fraction of warm exoplanets naturally evolve through a phase of instability for the moon's orbit (the `Laplace plane' instability). Many warm exoplanets may have lost their moon(s) through this process. ii) Surviving moons slowly migrate inwards due to the moon-planet tidal dissipation until they are disrupted below the Roche limit. During their last migration stage, moons – even small ones – eject planets from their tidal spin equilibrium. Conclusions: The loss of moons through the Laplace plane instability may contribute to disfavour the detection of moons around close-in exoplanets. Moreover, moons (even those that have been lost) play a critical role in the final obliquities of warm exoplanets. Hence, the existence of exomoons poses a serious challenge in predicting the present-day obliquities of observed exoplanets.
Read the full abstract

Astrophysics of Galaxies

Figuring Out Gas & Galaxies In Enzo (FOGGIE). XIII. On the Observability of Extended HI Disks and Warps

Cameron W. Trapp, Molly S. Peeples, Jason Tumlinson et al. (+6 more)

Atomic Hydrogen (HI) is a useful tracer of gas in and around galaxies, and can be found in extended disk-like structures well beyond a system's optical extent. Here, we investigate the properties of extended HI disks that emerge in six Milky Way-mass galaxies using cosmological zoom-in simulations from the Figuring Out Gas & Galaxies in Enzo (FOGGIE) suite. This paper focuses on the observability of the extended HI in these systems. We find overall agreement with observational constraints on the HI size-mass relation. To facilitate direct comparisons with observations, we present synthetic HI 21 cm emission cubes. By spatially filtering our synthetic cubes to characterize the absence of short baselines in interferometric maps, we find that such observations at 20 Mpc retain ~96%-99%$ of total HI emission on average, but can miss up to ~15% of HI signal outside the central disk due to missing short spacings. This effect is small for more isolated systems, but more significant for more strongly interacting systems, as there is more diffuse signal. This preferentially removes low column density, low velocity dispersion gas in the circumgalactic medium (CGM). The amount of observable material depends strongly on its distribution, distance, and the system's observed orientation, preventing the formulation of a simple correction factor. Therefore, to fully characterize extended disks, their CGMs, and the interfaces between them, including data from large single-dish radio telescopes is likely necessary.
Read the full abstract

All authors Cameron W. Trapp, Molly S. Peeples, Jason Tumlinson, Brian W. O'Shea, Anna C. Wright, Ayan Acharyya, Britton D. Smith, Vida Saeedzadeh, Ramona Augustin

Astrophysics of Galaxies

FOGGIE: Figuring Out Gas & Galaxies In Enzo XII. The Formation and Evolution of Extended HI Galactic Disks and Warps with a Dynamic Circumgalactic medium

Cameron W. Trapp, Molly S. Peeples, Jason Tumlinson et al. (+8 more)

Atomic hydrogen (HI) is an important component of gas in and around galaxies and forms extended disk-like structures well beyond the extent of starlight. Here we investigate the properties and evolution of extended HI disks that emerge in six Milky Way-mass galaxies using cosmological zoom-in simulations from the Figuring Out Gas & Galaxies in Enzo (FOGGIE) suite. We focus on the formation, evolution, and morphology of extended gaseous disks that emerge in all six systems. We find that median HI column densities drop sharply at the disk edge, with mean column densities outside the disk dominated by dense (N_HI~10^{19} cm^{-2}), clumpy structures. All systems have significant misaligned features (warps or polar rings) at some point in their evolution; however, their frequencies, lifetimes, and origins vary significantly. We find that the morphologies of the FOGGIE disks are correlated with properties of their Circumgalactic Medium (CGM). We place these systems along a continuum based on how populated their CGMs are with HI relative to their central disk. All systems kinematically settle similarly by z=0. The less populated systems tend to form coherently rotating, thin, extended disks while the more populated systems do not. Location on this continuum is independent of disk and halo mass, implying a relation to local environmental factors.
Read the full abstract

All authors Cameron W. Trapp, Molly S. Peeples, Jason Tumlinson, Brian W. O'Shea, Cassandra Lochhaas, Anna C. Wright, Britton D. Smith, Vida Saeedzadeh, Ayan Acharyya, Ramona Augustin, Raymond C. Simons

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Nucleosynthesis and CMB bounds on photophilic ALPs: a fresh look

Miguel Escudero, Clara Garcia-Perez and Maksym Ovchynnikov

We provide a fresh look at the cosmological constraints on axion-like particles (ALPs) that couple predominantly to photons, focusing on lifetimes $\tau_{a} \lesssim 10^{4}\, {\rm s}$ and masses $m_a\lesssim 10\,{\rm GeV}$. We consider Big Bang Nucleosynthesis (BBN) and Cosmic Microwave Background (CMB) bounds and explore how these limits depend upon the unknown reheating temperature of the Universe, $T_{\rm reh}$. Compared with some previous studies, we account for the rare decays of these ALPs into light hadrons and show that this leads to extended constraints for several reheating temperatures. Our limits are cast in a model-independent way, and we identify regions of parameter space where these ALPs could alleviate small tensions in the determinations of $N_{\rm eff}$ and the deuterium abundance.
Read the full abstract

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-th

Every Wrinkle Carries A Memory: An Integro-differential Bootstrap for Features in Cosmological Correlators

Sadra Jazayeri, Xi Tong and Yuhang Zhu

Motivated by cosmological observations, we push the cosmological bootstrap program beyond the de Sitter invariance lamppost by considering correlators that explicitly break scale invariance, thereby exhibiting primordial features. For exchange processes involving heavy fields with time-dependent masses and sound speeds, we demonstrate that locality in the bulk implies a set of integro-differential equations for correlators on the boundary. These scale-breaking boundary equations come with a built-in memory kernel in momentum-kinematic space encapsulating the universe's evolution during inflation. Specialising to heavy fields with sinusoidal masses such as those found in axion monodromy scenarios, we show that a powerful synthesis of microcausality and analyticity allows an analytical solution of these equations at leading order in the amplitude of mass oscillations. Meanwhile, we also unveil non-perturbative information in the integro-differential equations by resumming apparent infrared divergences as parametric resonances. In addition, we provide a first-of-its-kind example of numerical bootstrap that directly maps out the solution space of such boundary equations. Finally, we compute the bispectrum and uncover, in the squeezed limit, a scale-breaking cosmological collider signal, whose amplitude can be exponentially enhanced (with respect to the Boltzmann suppression) due to particle production triggered by high-frequency mass oscillations.
Read the full abstract

Solar and Stellar Astrophysics

Re-evaluating Lyman $\alpha$ wing opacities and the low mass-problem in cool white dwarfs

Snehalata Sahu, Pier-Emmanuel Tremblay, Detlev Koester et al. (+4 more)

Gaia observations have reignited interest in the optical and ultraviolet (UV) opacity problems of cool white dwarfs ($T_{\rm eff} \leq 6000$ K), which were thought to be resolved nearly two decades ago through the inclusion of Lyman $\alpha$ red wing opacity arising from H-H$_2$ collisions in atmospheric models. Recent studies have revealed that their masses derived from Gaia optical photometry are 0.1$-$0.2 M$_{\odot}$ lower than expected from single-star evolution. Since the Ly $\alpha$ H-H$_2$ wing opacity significantly affects the blue end of their optical spectra, it may contribute to the mass discrepancy. To investigate this hypothesis, we revisited the Ly $\alpha$ opacity calculations in the quasi-static single and multi-perturber approximations by explicitly using the ab initio potential energy data of H$_3$ while fully accounting for the H-H$_2$ collision angle. We find that the opacity is slightly smaller than the standard models at the shortest wavelengths ($\leq5000$ angstrom), but larger at longer wavelengths. Comparing synthetic magnitudes (GALEX, Gaia, WISE) to the observations of the 40 pc white dwarf sample, we note that the revised models tentatively reproduce the observed $NUV-G$ colours for stars cooler than 6000 K, but still fail to match $G_{\rm BP} - G_{\rm RP}$ colours, resulting in similarly low inferred masses ($\leq 0.5$ M$_{\odot}$) as obtained with the standard Ly $\alpha$ opacity. Exploring other dominant opacity sources, we discover that decreasing the strength of the bound-free H$^-$ opacity in existing models better reproduces the optical and infrared colours, while collision-induced absorption (CIA) opacity is ineffective in resolving the low-mass problem. We highlight the need for improved opacities and multi-wavelength observations in future studies.
Read the full abstract

All authors Snehalata Sahu, Pier-Emmanuel Tremblay, Detlev Koester, Mairi W. O'Brien, Simon Blouin, Boris T. Gänsicke, Vince Fairchild

Instrumentation and Methods for Astrophysics

Deconvolution for Large Astronomical Surveys: A Study of the Scaled Gradient Projection Method on Zwicky Transient Facility Data

Yash Gondhalekar, Richard M. Feder, Matthew J. Graham et al. (+4 more)

Ground-based astronomical observations will continue to produce resolution-limited images due to atmospheric seeing. Deconvolution reverses such effects and thus can benefit extracted science in multifaceted ways. We apply the Scaled Gradient Projection (SGP) algorithm for the single-band deconvolution of several observed images from the Zwicky Transient Facility and mainly discuss the performance on stellar sources. The method shows good photometric flux preservation, which deteriorates for fainter sources but significantly reduces flux uncertainties even for the faintest sources. Deconvolved sources have a well-defined Full-Width-at-Half-Maximum (FWHM) of roughly one pixel (one arcsecond for ZTF) regardless of the observed seeing. Detection after deconvolution results in catalogs with $\gtrsim$99.6% completeness relative to detections in the observed images. A few observed sources that could not be detected in the deconvolved image are found near saturated sources, whereas for others, the deconvolved counterparts are detected when slightly different detection parameters are used. The deconvolution reveals new faint sources previously undetectable, which are confirmed by crossmatching with the deeper DESI Legacy DR10 and with Pan-STARRS1 through forced photometry. The method could identify examples of serendipitous potential deblends that exceeded SExtractor's deblending capabilities, with as extreme as $\Delta m \approx 3$ and separations as small as one arcsecond between the deblended components. Our survey-agnostic approach is better and eight times faster than Richardson-Lucy deconvolution and could be a reliable method for incorporation into survey pipelines.
Read the full abstract

All authors Yash Gondhalekar, Richard M. Feder, Matthew J. Graham, Ajit K. Kembhavi, Margarita Safonova, Snehanshu Saha, Ashish A. Mahabal

Instrumentation and Methods for Astrophysics

The Variable Universe with the Gaia mission and AI methods

L. Eyer, P. Huijse, N. Chornay et al. (+5 more)

The Gaia mission has observed over 2 billion stars repeatedly across the entire sky over 10 years, revealing the many astronomical objects that vary on human timescales from seconds to years. Its repeated astrometric, photometric, spectrophotometric and spectroscopic measurements create an unprecedented dataset to probe the variable celestial sources down to G ~ 21 mag. To extract meaningful results from these many time series for so many sources, we have used machine learning techniques for crossmatching, variability detection, and variability classification. This approach has now led to the largest catalogue of classified variable sources ever produced over the entire celestial sphere.
Read the full abstract

All authors L. Eyer, P. Huijse, N. Chornay, J. De Ridder, B. Holl, L. Rimoldini, K. Nienartowicz, G. Jevardat de Fombelle

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

Rydberg Single Photon Detection for Probing 0.1-10 meV Dark Matter with BREAD

Abhishek Banerjee, Reza Ebadi and Surjeet Rajendran

We introduce a Rydberg-based single photon detector (SPD) for probing dark matter in the 0.1-10 meV mass range (20 GHz-2 THz). The Rydberg SPD absorbs photons produced and focused by the BREAD dish antenna and trades them for free, detectable electrons. At the lower end of the mass range, photons drive Rydberg-Rydberg transitions, which are read out via state-selective ionization. At higher masses, they directly ionize the Rydberg atoms.
Read the full abstract

Cosmology and Nongalactic Astrophysics · Cross-listed from hep-ph

WallGo investigates: Theoretical uncertainties in the bubble wall velocity

Jorinde van de Vis, Philipp Schicho, Lauri Niemi et al. (+3 more)

We examine theoretical uncertainties in state-of-the-art calculations of the bubble wall velocity during first-order cosmological phase transitions. By utilising the software WallGo for two extensions of the Standard Model, we find several $O(1)$ uncertainties arising from the number of particles taken out of equilibrium, the logarithmically and power enhanced collision integrals, the treatment of thermal masses, the nucleation temperature, the $\tanh$ ansatz, and the perturbative order of the effective potential. However, we show that the linearisation of the Boltzmann equations is generally a good approximation with much smaller associated errors. We further clarify the limitations of the quasiparticle approximation in regions with negative mass squared. This study provides a detailed uncertainty budget and highlights where future efforts should be directed to improve the reliability of wall velocity and hence gravitational wave predictions.
Read the full abstract

All authors Jorinde van de Vis, Philipp Schicho, Lauri Niemi, Benoit Laurent, Joonas Hirvonen, Oliver Gould