You are browsing the site archives for May 2025.
How Likely Are Habitable Exo-Moons? Of the roughly 6,000 exoplanets we’ve discovered, a significant number are in the apparent habitable zones of their stars. Most are giant planets; either gas giants like Jupiter and Saturn, or ice giants like Uranus and Neptune. Could some of those have habitable exomoons? Universe Today Go to SourceRead More →
Water ice detected in a debris disk around young nearby star Using the James Webb Space Telescope (JWST), astronomers from Johns Hopkins University (JHU) and elsewhere have detected water ice in a debris disk around HD 181327—a young star located within 160 light years away from the Earth. The finding was reported in a paper published May 14 in the journal Nature. phys.org Go to SourceRead More →
On the Broadening of the Characteristic Frequency Range towards Higher Photon Energies in the X-ray Variability of the Black Hole Transient MAXI J1820+070 Chenxu Gao (Shanghai Astronomical Observatory), Wenfei Yu (Shanghai Astronomical Observatory), Zhen Yan (Shanghai Astronomical Observatory) arXiv:2409.06414v2 Announce Type: replace Abstract: Energy-dependent X-ray power spectral states and Band-Limited Noise (BLN) components have been seen in the low-hard state and intermediate states of black hole X-ray binaries. Here we report our analysis of Insight-HXMT observations of the black hole transient MAXI J1820$+$070 during its 2018 outburst when the source was brightest. We found opposite trends of low-frequency ($$ 10 Hz) BLN components, i.e., decreasingRead More →
Projections of Earth’s Technosphere: Luminosity and Mass as Limits to Growth Jacob Haqq-Misra, Cl’ement Vidal, George Profitiliotis arXiv:2410.23420v4 Announce Type: replace Abstract: Earth remains the only known example of a planet with technology, and future projections of Earth’s trajectory provide a basis and motivation for approaching the search for extraterrestrial technospheres. Conventional approaches toward projecting Earth’s technosphere include applications of the Kardashev scale, which suggest the possibility that energy-intensive civilizations may expand to harness the entire energy output available to their planet, host star, or even the entire galaxy. In this study, we argue that the Kardashev scale is better understood as a “luminosity limit”Read More →
Searching for extreme mass ratio inspirals in LISA: from identification to parameter estimation Stefan H. Strub, Lorenzo Speri, Domenico Giardini arXiv:2505.17814v1 Announce Type: cross Abstract: The Laser Interferometer Space Antenna (LISA) is a planned space-based observatory designed to detect gravitational waves (GWs) within the millihertz frequency range. LISA is anticipated to observe the inspiral of compact objects into black holes at the centers of galaxies, so called extreme-mass-ratio inspirals (EMRIs). However, the extraction of these long-lived complex signals is challenging due to the large size and multimodality of the search space. In this study, we introduce a new search strategy that allows us to findRead More →
Thermodynamics of magnetized BPS baryonic layers Sergio Luigi Cacciatori, Fabrizio Canfora, Evangelo Delgado, Federica Muscolino, Luigi Rosa arXiv:2505.18007v1 Announce Type: cross Abstract: Through the Hamilton-Jacobi equation of classical mechanics, BPS magnetized Baryonic layers (possessing both baryonic charge and magnetic flux) have been constructed in the gauged non-linear sigma model (G-NLSM), which is one of the most relevant effective theories for Quantum Chromodynamics (QCD) in the strongly interacting low-energy limit. Since the topological charge that naturally appears on the right hand side of the BPS bound is a non-linear function of the baryonic charge, the thermodynamics of these magnetized Baryonic layers is highly non-trivial. In thisRead More →
The polarimetric response of the Nanc{c}ay Radio Telescope and its impact on precision pulsar timing Lucas Guillemot, Willem van Straten, Isma"el Cognard, Aur’elien Chalumeau, Gilles Theureau, ‘Eric G’erard arXiv:2505.04990v2 Announce Type: replace Abstract: In citet{Guillemot2023} we presented a new method for calibrating pulsar observations conducted with the Nanc{c}ay decimetric Radio Telescope (NRT), which significantly improved NRT polarimetric measurements and pulsar timing quality for data taken after this method was developed, in November 2019. Results hinted at a dependence of the polarimetric response of the NRT on the observed direction. We investigated this potential dependence, since unaccounted variations of the instrumental response could degrade polarimetric measurements.Read More →
New estimates of the spin and accretion rate of the black hole M87* Michael Drew, Joshua S. Stanway, Brett A. Patterson, Timothy J. Walton, Derek Ward-Thompson arXiv:2505.17035v1 Announce Type: new Abstract: In this paper we use the imaging results of M87* from the EHT to calculate the rotational velocity of the inner edge of the accretion disk and find a value of $sim$0.14c. We then calculate the dimensionless spin parameter, $a$, of the black hole, obtaining a value of $a sim 0.8$. We deduce that this is probably a lower limit. We go on to use the results of the EHT polarization study of theRead More →
The Lyman-$alpha$ emitter bispectrum as a probe of reionization morphology Soumak Maitra (TIFR), Girish Kulkarni, Shikhar Asthana, James S. Bolton, Martin G. Haehnelt, Laura Keating arXiv:2505.17188v1 Announce Type: new Abstract: Ly$alpha$ emitters (LAEs) have now been discovered out to redshift $z=13$, and are valuable probes of the reionization history at redshifts beyond the reach of other currently available tracers. Most inferences of the neutral hydrogen fraction from LAE observations rely on one-point and two-point statistics like the luminosity function and the power spectrum. We present here an analysis of the bispectrum of high-redshift LAEs and demonstrate its sensitivity to the Epoch of Reionization. We useRead More →
Serial MultiView: an efficient approach to mitigating atmospheric spatial-structure errors for VLBI astrometry Jingdong Zhang, Bo Zhang, Shuangjing Xu, Maria J. Rioja, Richard Dodson, Xiaofeng Mai, Oleg Titov arXiv:2501.10978v3 Announce Type: replace Abstract: Atmospheric propagation errors are a main constraint on the accuracy of Very Long Baseline Interferometry (VLBI) astrometry. For relative astrometry, differential techniques can mitigate these errors, but their effectiveness diminishes with decreasing elevation and increasing angular separations between target and calibrator, among others. The MultiView technique addresses atmospheric spatial-structure errors by observing multiple calibrators around the target and interpolating at the target position, thereby reducing atmospheric errors more effectively than phase-referencing withRead More →
Luminosity function of Type II GRBs:differences from long GRBs Yan-Kun Qu, Zhong-Xiao Man, Yu-Peng Yang, Shuang-Xi Yi, Fa-Yin Wang arXiv:2505.17180v1 Announce Type: new Abstract: Gamma-ray bursts (GRBs) are generally categorized into long and short bursts based on their duration ($T_{90}$). Recently, it has been proposed that GRBs can also be classified into type I (merger) and type II (collapsar) bursts based on the different origin. From a sample of textit{Swift} long GRBs~(LGRBs) with a redshift completeness of 60% and $P geq 2.6 , text{ph} , text{cm}^{-2} , text{s}^{-1}$, collected through the end of 2023, we identify a pure sample of 146 Type II GRBs. WithRead More →
Caught in the act: detections of recoiling supermassive black holes from simulations Alexander Rawlings, Peter H. Johansson, Thorsten Naab, Antti Rantala, Jens Thomas, Bianca Neureiter arXiv:2505.17183v1 Announce Type: new Abstract: We study the detectability of supermassive black holes (SMBHs) with masses of $M_{bullet}gtrsim 10^{9},mathrm{M}_odot$ displaced by gravitational wave recoil kicks $(v_{rm kick}=0mathrm{-}2000,mathrm{km,s}^{-1})$ in simulations of merging massive $(M_{star}>10^{11},mathrm{M}_odot)$ early-type galaxies. The used KETJU code combines the GADGET-4 fast multiple gravity solver with accurate regularised integration and post-Newtonian corrections (up to PN3.5) around SMBHs. The ejected SMBHs carry clusters of bound stellar material (black hole recoil clusters, BRCs) with masses in the range of $10^6 lesssimRead More →
Asteroseismology of WD J004917.14-252556.81, the Most Massive Pulsating White Dwarf O. Caliskan, M. Uzundag, M. Kilic, F. C. Geronimo, A. Moss, A. H. Corsico, S. G. Parsons, I. Pelisoli, G. Jewett, A. Rebassa-Mansergas, A. J. Brown, V. K. Dhillon, P. Bergeron arXiv:2505.17177v1 Announce Type: new Abstract: We present extensive follow-up time-series photometry of WD J0049$-$2525, the most massive pulsating white dwarf currently known with $T_{rm eff} = 13, 020,{rm K}$ and $log{it g} = 9.34$ cm s$^{-2}$. The discovery observations detected only two significant pulsation modes. Here, we report the detection of 13 significant pulsation modes ranging from 170 to 258 s based on 11Read More →
A Morphological Model to Separate Resolved–unresolved Sources in the DESI Legacy Surveys: Application in the LS4 Alert Stream Chang Liu, Adam A. Miller, Joshua S. Bloom, Robert A. Knop, Peter E. Nugent arXiv:2505.17174v1 Announce Type: new Abstract: Separating resolved and unresolved sources in large imaging surveys is a fundamental step to enable downstream science, such as searching for extragalactic transients in wide-field time-domain surveys. Here we present our method to effectively separate point sources from the resolved, extended sources in the Dark Energy Spectroscopic Instrument (DESI) Legacy Surveys (LS). We develop a supervised machine-learning model based on the Gradient Boosting algorithm texttt{XGBoost}. The features inputRead More →
Probing the origins. II. Unravelling lithium depletion and stellar motion: Intrinsic stellar properties drive depletion, not kinematics M. L. L. Dantas, R. Smiljanic, D. Romano, G. Guiglion, L. Magrini, P. B. Tissera, R. S. de Souza arXiv:2505.17173v1 Announce Type: new Abstract: In Paper I, we classified a stellar sample from the thin disc with a broad range in metallicity as being churned outward or inward, or blurred/undisturbed. In this paper (Paper II), we delve deeper by analysing our entire metallicity-stratified sample along with their dynamic properties, focusing on the connection between radial migration and Li depletion. We analyse the chemo-dynamics of a set of 1188Read More →
The mass distribution of stars stripped in binaries: The effect of metallicity B. Hovis-Afflerbach, Y. G"otberg, A. Schootemeijer, J. Klencki, A. L. Strom, B. A. Ludwig, M. R. Drout arXiv:2412.05356v2 Announce Type: replace Abstract: Stars stripped of their hydrogen-rich envelopes through binary interaction are thought to be responsible for both hydrogen-poor supernovae and the hard ionizing radiation observed in low-$Z$ galaxies. A population of these stars was recently observed for the first time, but their prevalence remains unknown. In preparation for such measurements, we estimate the mass distribution of hot, stripped stars using a population synthesis code that interpolates over detailed single and binary stellarRead More →
Far-ultraviolet flares and variability of the young M dwarf AU Mic: a non-detection of planet c in transit at Lyman-alpha Keighley E. Rockcliffe, Elisabeth R. Newton, Allison Youngblood, Girish M. Duvvuri, Emily A. Gilbert, Peter Plavchan, Peter Gao, Hans-R. M"uller, Adina D. Feinstein, Thomas Barclay, Eric D. Lopez arXiv:2505.17197v1 Announce Type: new Abstract: Atmospheric escape’s potential to shape the exoplanet population motivates detailed observations of systems actively undergoing escape. AU Mic is a young and active M dwarf hosting two close-in transiting sub- to Neptune-sized planets. Atmospheric escape was previously detected on the inner planet b, with radially-blown neutral hydrogen producing ~30% blue-shifted absorption inRead More →
Introducing a multiscale feature integration network for inpainting with applications to enhanced CMB map reconstruction Reyhan D. Lambaga, Vipin Sudevan, Pisin Chen arXiv:2501.06139v3 Announce Type: replace Abstract: We introduce a novel neural network, SkyReconNet, which combines the expanded receptive fields of dilated convolutional layers along with standard convolutions, to capture both the global and local features for reconstructing the missing information in an image. We implement our network to inpaint the masked regions in a full-sky Cosmic Microwave Background (CMB) map. Inpainting CMB maps is a particularly formidable challenge when dealing with extensive and irregular masks, such as galactic masks which can obscure substantial fractionsRead More →
Reconstructing Cosmic History with Machine Learning: A Study Using CART, MLPR, and SVR Agripino Sousa-Neto, Maria Aldinez Dantas arXiv:2505.17205v1 Announce Type: new Abstract: In this work, we reconstruct cosmic history via supervised learning through three methods: Classification and Regression Trees (CART), Multi-layer Perceptron Regressor (MLPR), and Support Vector Regression (SVR). For this purpose, we use ages of simulated galaxies based on 32 massive, early-time, passively evolving galaxies in the range $0.12 arXiv:2505.17205v1 Announce Type: new Abstract: In this work, we reconstruct cosmic history via supervised learning through three methods: Classification and Regression Trees (CART), Multi-layer Perceptron Regressor (MLPR), and Support Vector Regression (SVR). For thisRead More →
The very high X-ray polarisation of accreting black hole IGRJ17091-3624 in the hard state Melissa Ewing, Maxime Parra, Guglielmo Mastroserio, Alexandra Veledina, Adam Ingram, Michal Dovv{c}iak, Javier A. Garc’ia, Thomas D. Russell, Maria C. Baglio, Juri Poutanen, Oluwashina Adegoke, Stefano Bianchi, Fiamma Capitanio, Riley Connors, Melania Del Santo, Barbara De Marco, Mar’ia D’iaz Trigo, Poshak Gandhi, Maitrayee Gupta, Chulsoo Kang, Elias Kammoun, Vladislav Loktev, Lorenzo Marra, Giorgio Matt, Edward Nathan, Pierre-Olivier Petrucci, Megumi Shidatsu, James F. Steiner, Francesco Tombesi arXiv:2503.22665v2 Announce Type: replace Abstract: We report the first detection of the X-ray polarisation of the transient black hole X-ray binary IGRJ17091-3624 taken with the ImagingRead More →
