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Physics Astrophysics

astro-ph Watch Astrophysics

Thursday 12 February

Astrophysics of Galaxies

Subaru High-$z$ Exploration of Low-Luminosity Quasars (SHELLQs). XXV. Large-scale environments of low-luminosity quasars at $z\sim6$ traced by Ly$\alpha$ emitters

Junya Arita, Nobunari Kashikawa, Yoshiki Matsuoka et al. (+18 more)

High-$z$ quasars are believed to reside in massive dark matter haloes (DMHs), suggesting that they reside in galaxy overdense regions. However, previous observations have shown a range of environments around them. These fields have been limited to luminous quasars ($M_{1450}\lesssim-25$), for which photoevaporation may hinder galaxy formation in their vicinity. Here, we present Subaru/Hyper-Suprime Cam observations of the environments of four low-luminosity quasars ($-24<M_{1450}<-22$) at $z\sim6.18$, which are expected to have a smaller photoevaporation effect. We detect Lyman $\alpha$ emitters (LAEs) with narrowband NB872 imaging, and measure the local LAE overdensity. One quasar (J0844$-$0132) resides in an overdense region ($\delta_\mathrm{LAE}=1.97\pm0.40$), whereas the other three fields are consistent with no overdensity. These results hold over the proximity zone of each quasar, suggesting that the diverse environment around quasars is independent of photoevaporation. We find no significant correlation between the LAE overdensities and the characteristics of host galaxies and supermassive black holes. Our quasars have host stellar mass measurements from JWST, allowing us to compare them with the LAE overdensity around galaxies without quasar activity with comparable stellar masses. We find that the LAE overdensity in the J0844$-$0132 field is stronger than that of galaxies with similar stellar mass at $z\sim6$.
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All authors Junya Arita, Nobunari Kashikawa, Yoshiki Matsuoka, Masafusa Onoue, Michael A. Strauss, Kentaro Koretomo, Yoshihiro Takeda, Ryo Emori, Wanqiu He, Hiroki Hoshi, Masatoshi Imanishi, Rikako Ishimoto, Kei Ito, Kazushi Iwasawa, Satoshi Kikuta, Yongming Liang, Camryn L. Phillips, Shunta Shimizu, John D. Silverman, Yoshiki Toba, Takehiro Yoshioka

Instrumentation and Methods for Astrophysics

Beyond One-Thousandth Energy Resolution with an AlMn TES Detector

Liangpeng Xie, Yifei Zhang, Zhengwei Li et al. (+10 more)

The superconducting Transition-Edge Sensor (TES) is a critical technology for next-generation X-ray spectrometers, known for its exceptional energy resolution. In the last decade, TESs based on AlMn alloy films have been extensively used in several cosmic microwave background (CMB) experiments. The advantages of simple fabrication process and easily tunable critical temperature make them an alternative to bilayer TESs. However, they have rarely been applied to X-ray detection until now. We developed an annular AlMn TES for X-ray detection and tested it in a dilution refrigerator with a Superconducting Quantum Interference Device (SQUID) amplifier, achieving an Full Width at Half Maximum (FWHM) of 12.1 +- 0.3 eV at 17.48 keV. To the best of our knowledge, this is the first demonstration of an AlMn TES achieving an energy resolution below 0.1%, highlighting its potential for high-resolution X-ray detection.
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All authors Liangpeng Xie, Yifei Zhang, Zhengwei Li, Zhouhui Liu, Shibo Shu, Junjie Zhou, Xufang Li, Haoyu Li, He Gao, Yudong Gu, Xuefeng Lu, Yong Zhao, Congzhan Liu

Astrophysics of Galaxies

The faint end of the UV luminosity function at $0.4 < z < 0.7$ from the Hubble Frontier Fields

Lei Sun, Xiao-Lei Meng, Xin Wang et al. (+7 more)

By extending the Hubble Frontier Fields (HFF) observations to the F225W band using HST WFC3/UVIS, we measure the rest-frame UV luminosity function (LF) of galaxies at $0.4 < z < 0.7$, pushing into the low-luminosity galaxy regime. In this first paper of a series, we describe the HST Cycle-27 GO-15940 F225W observations and data reduction, and present a corresponding catalog for the Abell 2744 field, which is the most data-rich HFF cluster field. Combining deep Near-UV imaging and the high magnification from strong gravitational lensing of the foreground cluster, we identify 152 faint galaxies with $-19.5 < M_{UV} < -12.1$ at $0.4 < z < 0.7$ through hybrid photometric-spectroscopic redshift selection from the Abell 2744 F225W catalog. Using a sample defined by a $50\%$ completeness cut and applying the maximum likelihood estimation, we derive the best-fit Schechter parameters for the UV LF at $z \sim 0.55$ down to $M_\text{UV} < -13.5$ mag, including a faint-end slope of $\alpha = -1.324^{+0.072}_{-0.074}$. We incorporate a curvature parameter $\delta$ in parameter estimation to account for a possible turn-over at the faint end of the UV LF, leveraging the exceedingly low luminosities probed by our sample. Our results rule out a turn-over brighter than $M_{UV} = -15.5$ at the $3\sigma$ confidence level.
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All authors Lei Sun, Xiao-Lei Meng, Xin Wang, Hu Zhan, Anahita Alavi, Nicha Leethochawalit, Brian Siana, Hang Zhou, Shengzhe Wang, Shamuhawu Hailanhazi

Cosmology and Nongalactic Astrophysics

Numerical simulation of the stochastic formalism including non-Markovianity

Masahiro Kawasaki and Tomotaka Kuroda

We numerically investigate stochastic dynamics in cosmology by solving Langevin equations for Infrared (IR) modes with stochastic noises generated by Ultraviolet (UV) modes at the coarse-graining scale. By construction, the stochastic formalism relies on the separation of scales, which requires solving the equations for UV modes on top of the evolving IR modes for all modes at every time step, leading to a non-Markovian system in general. In this paper, working on a de Sitter background, we analyze several representative models by simultaneously solving the Langevin equations for IR modes and the equations for UV modes at each time step. We demonstrate that once the effects of effective masses are treated consistently by our simulation, the flat direction in the minimal supersymmtric model (MSSM) does not saturate but instead evolves as an exactly flat direction. Furthermore, we investigate memory effects in simple two models; $V=\lambda\phi^4$ and $V=\mu\phi\chi + \lambda\phi^4$, and non-Markovian contributions can lead to quantitative differences, even in stationary configurations, when compared with Markovian approximations, particularly in the strong-coupling regime.
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Solar and Stellar Astrophysics

Dynamic modeling of coronal abundances during flares on M-dwarf stars

David H. Brooks, Jeffrey W. Reep, Andy S.H. To et al. (+2 more)

Solar atmospheric elemental abundances are now known to vary both in space and time. Dynamic modeling of these changes is therefore necessary to improve the accuracy of radiative hydrodynamic simulations. Recent studies have shown that including spatio-temporal variations in coronal abundances during solar flares leads to the formation of coronal condensations (rain), which are otherwise difficult to create in impulsively heated field aligned hydrodynamic flare models. These simulations start with a solar corona dominated by the first ionization potential (FIP) effect, and evaporate photospheric material into the post-flare loops. We here explore perhaps the most extreme non-solar starting condition for the coronal composition in these simulations: an initial corona dominated by the inverse FIP (iFIP) effect, such as is observed on active M-dwarf stars. We show that a flaring event in a corona enriched with high FIP elements leads to a solution similar to the solar case. Coronal rain is harder to form by this method during flares on M-dwarfs, however, if the corona is depleted of low FIP elements.
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All authors David H. Brooks, Jeffrey W. Reep, Andy S.H. To, Luke Fushimi Benavitz, Lucas A. Tarr

Astrophysics of Galaxies

A Multiwavelength Evaluation of AGN in the Post-Starburst Phase

Yuanze Luo, Kate Rowlands, Katherine Alatalo et al. (+14 more)

The quenching of star formation is a crucial phase in galaxy evolution. Although active galactic nuclei (AGN) feedback has been proposed as a key driver of this transition, the lack of strong AGN in nearby quenching galaxies raises questions about its effectiveness. In this study, we investigate AGN activity in post-starburst galaxies (PSBs), star-forming galaxies (SFGs), and quiescent galaxies (QGs) at $z<$ 0.2, using multiwavelength data from eROSITA/eFEDS (X-ray), WISE (mid-infrared), and FIRST (radio). We assess AGN incidence and strength across different stages and apply stacking techniques to undetected galaxies to recover average AGN properties. Comparisons between observed luminosity and that expected from star formation (L$_{\rm obs}$/L$_{\rm SF}$) show that PSBs are consistent with star formation dominating their radio and X-ray emission. Although PSBs exhibit a MIR AGN incidence rate twice that of SFGs, their estimated AGN luminosities are small compared to those of MIR AGN in the literature. PSBs overall do not display significantly enhanced AGN emission relative to mass- and redshift-matched SFGs and QGs. While the presence of obscured, low-luminosity AGN in PSBs cannot be excluded, such AGN, if present, could be fueled by residual gas from the preceding starburst and may not play a dominant role in quenching. Our findings suggest that AGN's role in quenching at low redshift is more subtle than violently removing the gas – the feedback is likely more "preventive" than "ejective".
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All authors Yuanze Luo, Kate Rowlands, Katherine Alatalo, Lauranne Lanz, Timothy Heckman, Elizaveta Sazonova, Pallavi Patil, Omar Almaini, Vincenzo R. D'Onofrio, K. Decker French, Justin Otter, Andreea O. Petric, Namrata Roy, Maya Skarbinski, Justin S. Spilker, Margaret E. Verrico, Vivienne Wild

High Energy Astrophysical Phenomena

Understanding coronal geometry in NGC 4593 using Fourier frequency-resolved covariance and time-lag spectral analysis

Shree Suman, Mayukh Pahari, Gulab Dewangan et al. (+1 more)

Understanding disc-corona geometry through X-ray reverberation variability studies in Seyfert galaxies is crucial, yet our knowledge mostly relies on flux-averaged mean spectral analysis. In this study, we investigate the origin of the large X-ray variability of the Seyfert 1 galaxy NGC 4593 using two \xmm{} observations, which are at least 65 ksec long and have a 0.3-10 keV X-ray flux difference by a factor of $\sim$2.5. We extracted mean spectra, Fourier-frequency resolved covariance, and time-lag spectra and performed modelling of all spectra in a self-consistent manner. From the best-fit covariance spectra, we have shown that energy-dependent covariance during low flux shows dominances of direct powerlaw continuum over reflection continuum at all Fourier frequencies (2.1 $-$ 390 $\times$ 10$^{-5}$ Hz). However, during high flux, the variabilities are dominated by the reflection components most of the time. Our results are further supported by the Fourier frequency-dependent time-lag (between soft: 0.3-1 keV and hard: 1-5 keV bands) spectral modeling during high and low fluxes. A significant change is observed in the X-ray reverberation delay timescale from 483 $\pm$ 135 sec (during high flux) to $<$96 sec (during low flux), indicating a change in coronal size at least by a factor of $\sim$2 (from $<$3.3 R$_g$ to $>$7.2 R$_g$) during low to high flux transitions.
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All authors Shree Suman, Mayukh Pahari, Gulab Dewangan, Ian M McHardy

Instrumentation and Methods for Astrophysics

Design and characterization of W-band and D-band calibration sources for the AliCPT-1 experiment

Xu-Fang Li, Cong-Zhan Liu, Ai-Mei Zhang et al. (+11 more)

Ali Cosmic Microwave Background Polarization Telescope (AliCPT-1) is the first Chinese cosmic microwave background experiment aiming to make sensitive polarization maps of the potential B-mode signal from inflationary gravitational waves. The telescope was deployed on the Tibet Ali site at 5250 m above sea level in early 2025. Before and after each observation season, the instrument performance must be carefully calibrated, including the far field beam performance, far sidelobe, spectral response, polarization angle, and cross-polar beam response. To characterize these optical performances, several calibrators have been developed. We developed a W-band source and a D-band source for the AliCPT-1 telescope's beam characterizations. We present the design and performance of the two calibration sources.
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All authors Xu-Fang Li, Cong-Zhan Liu, Ai-Mei Zhang, Zheng-Wei Li, Xue-Feng Lu, Zhong-Xue Xin, Guo-Feng Wang, Yong-Ping Li, Yong-Jie Zhang, Shi-Bo Shu, Yi-Fei Zhang, Ya-Qiong Li, Zhi Chang, Dai-Kang Yan

Astrophysics of Galaxies

The ALMA-QUARKS Survey: Discovery of Superfine Dusty Fibrils inside Massive Star-forming Clumps

Yan-Kun Zhang, Tie Liu, Wenyu Jiao et al. (+35 more)

We report the discovery of more than 320 superfine dusty filamentary structures (fibrils) inside 121 massive star forming clumps that are located in widely different Galactic environments (Galactocentric distances of ~1.2 - 12.9 kpc). These fibrils are identified from the 1.3-mm continuum emission in the ALMA-QUARKS survey, which has a linear resolution of ~900 AU for a source at ~3 kpc. The typical width of these fibrils identified in clumps is found to be ~0.01 pc, which is about ten times narrower than that of dusty filaments in nearby clouds identified by the Herschel Space Observatory. The mass (M) versus length (l) relation for these fibrils follows M ~ l^2, similar to that of Galactic filaments identified in space (e.g., Herschel) and ground-based single-dish (e.g., APEX) surveys. However, these fibrils in the ALMA-QUARKS survey are significantly denser (N_{H_2} = 10^{23} - 10^{24} cm^{-2}) than the filaments found in previous Herschel surveys (N_{H_2} = 10^{20} - 10^{23} cm^{-2}). This work contributes a large sample of newly found superfine fibrils in massive clumps, following the identification of large 0.1 pc-wide filaments and associated internal velocity coherent molecular fibers in nearby molecular clouds, further emphasizing the crucial role played by filamentary structures in star formation at various physical scales.
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All authors Yan-Kun Zhang, Tie Liu, Wenyu Jiao, Pak-Shing Li, Jia Zeng, Chao Zhang, Pablo García, Mika Juvela, Guido Garay, Amelia M. Stutz, Sami Dib, Dezhao Meng, Jian-Cheng Feng, Dongting Yang, Fengwei Xu, Anandmayee Tej, Enrique Vázquez-Semadeni, Gilberto C. Gómez, Yong Zhang, Xindi Tang, Paul F. Goldsmith, Kee-Tae Kim, James O. Chibueze, Zhiyuan Ren, Patricio Sanhueza, Aiyuan Yang, Jihye Hwang, Shanghuo Li, Tapas Baug, Shivani Gupta, Swagat R. Das, Gang Wu, Jianjun Zhou, Chang Won Lee, Lokesh Dewangan, Prasanta Gorai, Tianning Lyu, Lei Zhu

Earth and Planetary Astrophysics

An optical transient candidate of $\lesssim$ 2-second duration captured by wide-field video observations

Noriaki Arima, Mamoru Doi, Shigeyuki Sako et al. (+14 more)

Recent time-domain surveys have revealed rapid transients that evolve on timescales of $\lesssim 10$ days, expanding the transient population into the short-duration regime. The transient search on even shorter timescales, particularly those lasting only seconds or less, remains a largely unexplored frontier. Very short-duration optical transients could serve as potential counterparts to millisecond-duration fast radio bursts (FRBs), providing clues to their origins. However, the optical search for transients on such short timescales has been limited primarily by instrumental constraints. Here we report the discovery of an optical transient candidate (TMG20200322) with a duration of $\lesssim 2$~s by wide-field video observations in the direction of the Earth's shadow. TMG20200322 was detected in just two consecutive images of 1-second exposure time, with its shape becoming elongated in the second frame. PSF shape variability analysis of field stars reveals that such an elongated PSF cannot be explained by atmospheric fluctuations. We investigate the potential origins of TMG20200322 in two scenarios: meteoroid impact flashes on near-Earth asteroids (NEAs) and head-on meteors in the Earth's atmosphere. None of the scenarios provides a satisfactory explanation for this transient. We derive a sky-projected rate of the TMG20200322 event of $R_{\mathrm{trans}} = (3.4 \times 10^{-2})^{+0.13}_{-0.028}$~deg$^{-2}$~day$^{-1}$ and an upper limit on second-timescale transients with durations of $1~\mathrm{s} \leq \tau \lesssim 15~\mathrm{s}$ of $R_{\mathrm{trans}} \lesssim 0.10$~deg$^{-2}$~day$^{-1}$ for the non-detection case. We highlight that continuous monitoring observations in the direction of the Earth's shadow could be a key strategy to unveil a new population of optical transients on timescales of seconds or less.
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All authors Noriaki Arima, Mamoru Doi, Shigeyuki Sako, Yuu Niino, Ryou Ohsawa, Nozomu Tominaga, Masaomi Tanaka, Michael Richmond, Shinsuke Abe, Naoto Kobayashi, Sohei Kondo, Yuki Mori, Ko Arimatsu, Toshihiro Kasuga, Shin-ichiro Okumura, Jun-ichi Watanabe, Takuya Yamashita

Earth and Planetary Astrophysics

Analysis of Karin and Koronis2 asteroid families: new findings and challenges

David Vokrouhlický, David Nesvorný and William F. Bottke

We use our home catalog of the asteroid proper elements to study the Karin family. The hierarchical clustering method provides formal identification with 3,863 members, but this set also includes objects from the neighboring Koronis2 and Kuitaisi families, as well as interlopers originating from the much older Koronis family. By tracking the trajectories of cluster objects backward in time, we identified 2,161 asteroids whose orbits converged with that of their parent body (832) Karin at $5.72\pm 0.09$ My ago ($95$% C.L.). This method of calculating the family's age is based on a novel convergence metric that is directly related to the velocities at which fragments were ejected from (832) Karin. We analyze the extent to which members $\leq 1.5$ km in diameter had drifted in semimajor axis due to Yarkovsky thermal forces and find it reflects the tilt of their rotation poles away from the ecliptic, recording the influence of the YORP torque. Karin's size frequency distribution in the $\simeq(0.8-3)$ km range follows a power-law with a cumulative slope index $-3.20\pm 0.01$. Removing members of the Karin family from the original group, we examine the Koronis2 family, whose members are associated with (158) Koronis. We find it difficult for large members of the Koronis2 family to converge with the orbit of (158) Koronis within its previously estimated age of $7.6$ My. Achieving such convergence would require the Koronis2 family to be older than $10$ My, but our result must be verified with a direct numerical approach in the future.
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Earth and Planetary Astrophysics

Eccentricity Evolution of Warm Jupiters: The Role of Distant Perturbers and Nearby Companions

Ying He, Dong-Hong Wu and Sheng Jin

Warm Jupiters-giant exoplanets with orbital periods between 10 and 200 days-exhibit a broad range of eccentricities and are often accompanied by nearby low-mass planets. Understanding the origins of their orbital architectures requires examining both their migration histories and subsequent dynamical interactions. In this study, we perform extensive N-body simulations to explore how distant giant planet perturbers affect the eccentricity evolution of warm Jupiters and the role of nearby super-Earth companions in mediating these interactions. We find that while distant perturbers can induce large-amplitude eccentricity oscillations in warm Jupiters via the von Zeipel-Lidov-Kozai mechanism, the presence of nearby super-Earth companions often suppresses these variations via strong dynamical coupling. This mechanism naturally leads to a bimodal eccentricity distribution: warm Jupiters with nearby companions tend to maintain low eccentricities, whereas those without exhibit significantly broader eccentricity distributions. We show that reproducing the observed eccentricity distribution of warm Jupiters lacking nearby companions is most naturally explained if a substantial fraction of distant perturbers occupy dynamically extreme orbits, either with large mutual inclinations or high orbital eccentricities. These results support a scenario in which warm Jupiters experience substantial post-disk dynamical evolution, shaped jointly by distant perturbers and nearby companions.
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High Energy Astrophysical Phenomena

Searching for Anisotropy in the Gravitational Wave Background Using the Parkes Pulsar Timing Array

Yiqin Chen, Shi-Yi Zhao, Zhi-Zhang Peng et al. (+17 more)

In recent years, several pulsar timing array collaborations have reported evidence for a nanohertz gravitational wave background (GWB). Such a background signal could be produced by supermassive binary black holes, early-Universe processes such as inflation and phase transitions, or a mixture of both. One way to disentangle different contributions to the GWB is to search for anisotropic signatures. In this work, we search for anisotropy in the GWB using the third data release of the Parkes Pulsar Timing Array. Our analysis employs both the radiometer method and the spherical harmonic basis to characterize the distribution of GWB power across the sky. We calculate the angular power in the lowest five frequency bins and compare it with detection thresholds determined under the null hypothesis of isotropy. In the 5.26 nHz frequency bin, we identify a hotspot in the reconstructed sky map with a $p$-value of $0.016$ (the lowest in our analysis), which we attribute to noise fluctuations. While our search reveals no statistically significant anisotropy, we expect that the precise measurement of angular power spectrum of the GWB will become instrumental in determining the origin of the nanohertz GWB signal.
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All authors Yiqin Chen, Shi-Yi Zhao, Zhi-Zhang Peng, Xingjiang Zhu, N. D. Ramesh Bhat, Zu-Cheng Chen, Małgorzata Curyło, Valentina Di Marco, George Hobbs, Agastya Kapur, Wenhua Ling, Rami Mandow, Saurav Mishra, Daniel J. Reardon, Christopher J. Russell, Ryan M. Shannon, Jacob Cardinal Tremblay, Jingbo Wang, Lei Zhang, Andrew Zic

Cosmology and Nongalactic Astrophysics

Stone Skipping Black Holes in Ultralight Dark Matter Solitons

Alan Zhang, Yourong Wang, J. Luna Zagorac et al. (+1 more)

The orbit of a black hole moving within an ultralight dark matter (ULDM) soliton is naively expected to decay due to dynamical friction. However, in isolated near-circular soliton–black-hole systems, single black holes can undergo “stone skipping”, with their orbital radius varying quasi-periodically. We show that, within this controlled setting, stone skipping is driven by a dipole excitation of the soliton. We model the effect as a resonance in a forced, damped harmonic oscillator, demonstrating that the coherent response of the soliton can significantly modify the dynamics of objects orbiting within it. In this regime, a dipole perturbation of a soliton can modify inspiral timescales when the black hole masses are significantly smaller than the soliton mass, with implications for supermassive black hole dynamics, the final parsec problem and gravitational wave observations in a ULDM cosmology.
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All authors Alan Zhang, Yourong Wang, J. Luna Zagorac, Richard Easther

High Energy Astrophysical Phenomena

Unification Model of Active Galactic Nuclei by Photoionization Equilibrium Calculation Based on Radiative Hydrodynamic Simulations

Atsushi Tanimoto, Keiichi Wada, Yuki Kudoh et al. (+3 more)

To investigate the origin of the dependence of the covering factor on the Eddington ratio suggested by X-ray observations, we examined the angular distribution of HI and HII based on two-dimensional radiative hydrodynamic simulations. To calculate the Compton-thin covering factor $C_{22}$ and Compton-thick covering factor $C_{24}$ of HI alone, we performed one-dimensional photoionization equilibrium calculations with the XSTAR code based on radiative hydrodynamic simulations. The results obtained are as follows. (1) The Compton-thin covering factor $C_{22}$ of HI and HII is independent of the Eddington ratio and is approximately $70\%$, while $C_{22}$ of HI alone is also independent of the Eddington ratio and is approximately $30\%$. (2) The Compton-thick covering factor $C_{24}$ of HI has the same value as $C_{22}$ of HI. (3) Our $C_{24}$ is consistent with that obtained from X-ray observations. (4) Our $C_{22}$ agrees with that obtained from X-ray observations in a high Eddington ratio, while our $C_{22}$ is smaller than that from X-ray observations in a low Eddington ratio. (5) To explain the difference between $C_{22}$ obtained from theoretical calculations and that inferred from X-ray observations, a Compton-thin gas is required in regions extending at least $10~\mathrm{pc}$ beyond the current computational regions.
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All authors Atsushi Tanimoto, Keiichi Wada, Yuki Kudoh, Nozomu Kawakatu, Mariko Nomura, Hirokazu Odaka

Wednesday 11 February

Earth and Planetary Astrophysics

Distinguishing life from non-life via molecular frontier orbital energy gaps

José L. Ramírez-Colón, Ziqin Ni and Christopher E. Carr

Amino acids (AAs) are a key target in the search for life beyond Earth due to their extensive role in the machinery of all known life, persistence over geologic timescales, and analytical detectability. However, AAs can also arise from abiotic processes on planets and in space. For example, material from asteroid Bennu contained 33 AAs, including 15 of the 20 proteinogenic AAs that are fundamental to life's functions. Distinguishing life from non-life based on AAs in a sample remains an unsolved problem, particularly when their isotopic and structural signatures (e.g., chirality) could be altered via physicochemical processes. Here we introduce LUMOS (Life Unveiled via Molecular Orbital Signatures), a statistical framework that distinguishes life from non-life by analyzing the distribution of abundance-weighted HOMO-LUMO gap (HLG) values of AAs within a sample. Compilation of AAs datasets from diverse environments and provenances revealed that abiotic samples display highly uniform distributions of AAs HLGs. In contrast, biotic samples show greater variance and preference towards AAs with lower HLG, likely reflecting the need for life to control when, where, and how chemical reactions occur. LUMOS achieves >95% accuracy in distinguishing biotic versus abiotic provenance across diverse environmental and extraterrestrial conditions. These results suggest that varied molecular reactivity within biochemical systems may be a universal feature of life, representing an agnostic biosignature unlinked to the specific set of AAs used by life as we know it. LUMOS is compatible with existing analytical instrumentation, applicable to returned samples or in situ analyses. Broader characterization of abiotic and biotic environments will further refine the chemical boundaries separating biotic from abiotic chemical systems.
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Earth and Planetary Astrophysics · Cross-listed from physics.ao-ph

Blackening Cryosphere: Revealing Hotspot Shifts and HGB-Based Forecasting of Absorbing Aerosol Threats over the Himalayan Frozen Frontiers

Abira Sengupta, Ayoti Banerjee, Sarbani Palit et al. (+1 more)

Black carbon and mineral dust are key absorbing aerosols that influence atmospheric radiation and increasingly threaten global cryospheric stability. This study examines the long-range transport and seasonal variability of these aerosols over Pakistan and their movement toward the western Himalayas. Using satellite-derived Absorption Aerosol Optical Depth (AAOD) data from 2019 to mid-2025, we analyse their spatiotemporal behaviour across Pakistan's urban lowlands and high-altitude regions. Fifteen-day aggregated AAOD fields are used to track seasonal transport into glaciated terrain, where deposited aerosols can darken snow and ice and accelerate melt. For high-AAOD events, a probabilistic forecasting approach based on machine learning (ML) was developed. Using geographical, seasonal, and lagged indicators, a histogram-based gradient boosting classifier was trained to predict AAOD exceedance one step in advance. ROC-AUC, PR-AUC, and the Brier score were used to assess the model's performance. The results show high predictive capacity and good probability calibration, with values of 0.791, 0.269, and 0.028, respectively. Forecasts indicate that areas adjacent to Himalayan glaciers consistently exhibit the highest probability of increasing AAOD, signalling an elevated risk of aerosol-induced snowmelt.
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All authors Abira Sengupta, Ayoti Banerjee, Sarbani Palit, Brendon Woodford

Instrumentation and Methods for Astrophysics

Astrophysics Wrapped 2025: Year-in-Review of Every Astrophysics arXiv Paper from 2025

Rommulus Francis Lewis, Hetansh Shah and Amruth Alfred

Astrophysics has experienced an overwhelming increase in research output, as is evident from the year-over-year increase in the number of research papers submitted to the online repository arXiv. As a result, keeping up with progress happening outside our respective sub-fields can be exhausting. While it is impossible to be informed on every single aspect of every sub-field, this paper aims to be the next best thing. We present a summary of statistics for every paper uploaded onto the Astrophysics arXiv over the past year - 2025. We analyse a host of metrics like the most used keywords, subfields and telescopes, the distribution of journals, the most studied astrophysical objects like GW, GRB, FRB events, exoplanets and much more. We also indexed the authors' affiliations to put into context the global distribution of research and collaboration. Combining this data with the citation information of each paper allows us to understand how influential different papers have been on the progress of the field this year. We also present a first of its kind Astrophysical Spectral Fingerprint showing the distribution of research across the electromagnetic spectrum as well as the distribution of research by redshift. Overall, these statistics highlight the general current state of the field, the hot topics people are working on and the different research communities across the globe and how they function. We hope that this is helpful for both students and professionals alike to adapt their current trajectories to better benefit the field.
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Astrophysics of Galaxies

The "bubbly" interstellar medium as origin for the inhomogeneous internal metallicity distributions in large disk galaxies

Benjamin Metha, Michele Trenti and Colin Norman

Resolved metallicity studies of local disk galaxies have revealed that their interstellar media (ISMs) are far from chemically homogeneous, displaying significant ($\sim 0.05$ dex) variations in the metallicity on characteristic scales of a few hundred parsecs. Such data is at odds with most analytical models, where the ISM is predicted to be more well-mixed. Here, we suggest that the observed small-scale features seen in galaxies may be superbubbles of metal-enriched gas created by a collection of core collapse supernovae with tight spatial (and temporal) correlation. In this scenario, the size of the metallicity fluctuations (superbubble radius, $\phi$) is set by the disk scale height of the galaxy in question (after which point shock breakout favours preferential expansion along directions perpendicular to the dense disc), and the amount of additional metals contained within a fluctuation is proportional to the star formation efficiency in superbubble regions ($\epsilon$). To test this theory, we analysed metallicity maps from the PHANGS-MUSE sample of galaxies using a geostatistical forward-modelling approach. We find $\phi \simeq 300$ pc and $\epsilon = 0.1-0.2$, in good agreement with our theoretical model. Further, these small-scale parameters are found to be related to the global galaxy properties, suggesting that the local structure of the interstellar medium of galaxies is not universal. Such a model of star formation paints a new picture of galaxy evolution in the modern universe: in large local galaxies, star formation appears steady and regular when averaged over large scales. However, on small scales, these large galaxies remain intrinsically bursty like their smaller, high-redshift counterparts.
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Astrophysics of Galaxies

Evidence for Shallow Nebular Attenuation Curves and Patchy Dust Geometry at z~2 with Pa-beta/H-alpha Measurements from JWST-MegaScience Medium Band Photometry

Brian Lorenz, Katherine A. Suess, Mariska Kriek et al. (+25 more)

We constrain the nebular attenuation curve and investigate dust geometry in star-forming galaxies at cosmic noon using photometric medium-band emission line measurements. We measure H-alpha emission line fluxes for a sample of 209 star-forming galaxies at 1.2<z<2.4 in MegaScience/UNCOVER with stellar masses spanning $7.85<\log_{10}(M_*/M_\odot)<11.0$. For 66 of these galaxies, we also measure a Pa-beta flux. We find that the Pa-beta/H-alpha line ratio increases strongly with stellar mass and star-formation rate (SFR) across our full mass range, indicating that more massive galaxies are dustier. We compare our results with a mass-, SFR-, and redshift-matched sample of galaxies from the MOSDEF survey with spectroscopic measurements of H-alpha/H-beta, finding that a shallow Reddy et al. (2025) nebular attenuation curve is more consistent with our observations than the typically assumed Cardelli et al. (1989) attenuation curve, especially for massive galaxies. This shallow attenuation curve could be explained by low dust covering fractions in star-forming regions. Through comparison to other studies, we show that assuming this shallower attenuation curve can increase the inferred A_Halpha,neb by up to 1 magnitude at high masses. We observe no trend between A_Halpha,neb and axis ratio, indicating that nebular attenuation is likely localized to small clumps. Altogether, our results strongly suggest that dust geometry is patchy and non-uniform, especially in massive galaxies. Our results highlight the ability of JWST medium bands to probe emission lines for large samples of galaxies, and statistically constrain dust properties in upcoming large programs.
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All authors Brian Lorenz, Katherine A. Suess, Mariska Kriek, Sedona H. Price, Joel Leja, Hakim Atek, Abhiyan Barailee, Rachel Bezanson, Gabriel Brammer, Sam E. Cutler, Pratika Dayal, Anna de Graaf, Jenny E. Greene, Lukas J. Furtak, Ivo Labbe, Danilo Marchesini, Michael V. Maseda, Tim B. Miller, Abby Mintz, Ikki Mitsuhashi, Themiya Nanayakkara, Erica Nelson, Richard Pan, Natalia Porraz Barrera, Bingjie Wang, John R. Weaver, Christina C. Williams, Katherine E. Whitaker

Astrophysics of Galaxies

ALMA Band1 observations of the rhoOphW filament I. Enhanced power from excess microwave emission at high spatial frequencies

Simon Casassus, Matias Vidal, Miguel Carcamo et al. (+3 more)

The rhoOphW photo-dissociation region (PDR) is an example source of bright excess microwave emission (EME), over synchrotron, free-free, and the Rayleigh-Jeans tail of the sub-millimetre (sub-mm) dust continuum. Its filamentary morphology follows roughly that of the IR poly-cyclic aromatic hydrocarbon (PAHs) bands. The EME signal in rhoOphW drops abruptly above ~30GHz and its spectrum can be interpreted in terms of electric-dipole radiation from spinning dust grains, or “spinning dust”. Deep and high-fidelity imaging and spectroscopy of rhoOphW may reveal the detailed morphology of the EME signal, free from imaging priors, while also enabling a search for fine structure in its spectrum. The same observations may constrain the spectral index of the high-frequency drop. An ALMA Band1 mosaic yields a deep deconvolved image of the filament at 36-44GHz, which we use as template for the extraction of a spectrum via cross-correlation in the uv-plane. Simulations and cross-correlations on near-infrared ancillary data yield estimates of flux-loss and biases. The spectrum is a power law, with no detectable fine structure. It follows a spectral index alpha=-0.78+-0.05, in frequency, with some variations along the filament. Interestingly, the Band1 power at high spatial frequencies increases relative to that of the IR signal, with a factor of two more power in Band1 at ~20” than at ~100” (relative to IRAC3.6um). An extreme of such radio-only structures is a compact EME source, without IR counterpart. It is embedded in strong and filamentary Band1 signal, while the IRAC maps are smooth in the same region. We provide multi-frequency intensity estimates for spectral modelling.
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All authors Simon Casassus, Matias Vidal, Miguel Carcamo, Laurent Verstraete, Nathalie Ysard, Emilie Habart

Astrophysics of Galaxies

Using astrochemical models to simulate reactivity experiments on cold surfaces

Valeriia Sokolova, Basile Husquinet, Stephan Diana et al. (+7 more)

The development of molecular complexity during stellar and planetary formation owes much to the interaction of gas and dust. When the first astrochemical models including solid-state chemistry were developed more than forty years ago, data from dedicated laboratory experiments were limited. Since then, many groups have developed specific experimental setups to address this issue, but astrochemical models have rarely been directly confronted with these new results. We want to demonstrate whether it is possible to use rate-equation-type astrochemical models developed in the context of the Interstellar Medium to compare them with laboratory astrophysics experiments. In this work, we use the case of low-temperature hydrogenation of CO, which is known to lead to methanol, among other molecules. We carried out 9 experiments, varying the experimental parameters such as temperature and dose. We give quantitative results and take care of detailing the vocabulary used in the experiments. We use astrochemical codes, NAUTILUS, pyRate and MONACO, to reproduce our experimental conditions, which requires good control of the change of vocabulary and scales, especially for fluxes and time scales. This work demonstrates that it is possible to use different astrochemical codes to compare modelling results directly with the output of experiments. There are discrepancies between models and experiments, as well as between models, but a fair agreement is achieved. We discuss the possible origin of the differences, which could originate from the chemical network or the difference in the description of physical processes.
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All authors Valeriia Sokolova, Basile Husquinet, Stephan Diana, Paola Caselli, Emanuele Congiu, Wiebke Riedel, Olli Sipila, Anton Vasyunin, Valentine Wakelam, Francois Dulieu

Solar and Stellar Astrophysics

Filling The Pockets: The Spherical Nature of 3D Deflagration in Thermonuclear Supernovae

S. Shiber, P. Hoeflich, T. Mera et al. (+9 more)

We investigate thermonuclear explosions within the delayed detonation framework. While spherical delayed detonation models generally reproduce key observational features, a fundamental inconsistency emerges in three dimensions: 3D hydrodynamic simulations exhibit insufficient white dwarf expansion during the deflagration phase. We identify the early deflagration stage, when the burning is dominated by the laminar speed, as a critical phase and explore potential solutions using three-dimensional magnetohydrodynamic simulations performed with the FLASH code. In absence of preexisting small-scale velocity fields, hydrodynamical simulations of the early deflagration phase produce large pockets of unburned C/O, leading to inefficient burning. Much of the released energy is deposited into buoyantly rising plumes rather than into the global preexpansion of the white dwarf, which is required to produce the partially burned layers characteristic of SNe Ia. In contrast, when preexisting turbulent velocity fields on scales expected from the smoldering phase are included, the entrainment of burned material into unburned pockets enables the conductive ignition of the surrounding unburned fuel. The effective burning approaches that in spherical models, addressing a long-standing problem in multidimensional deflagration models. For magnetic fields considered here, < 1% of the saturation strength, we find that the effective burning rate is dominated by the turbulence. Magnetic fields only marginally suppress the rising of burned plumes and the formation of small structures, leading to a slightly more confined burning region and a reduced burning rate.
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All authors S. Shiber, P. Hoeflich, T. Mera, E. Fereidouni, Z. Levy, D. Maci, C. Ashall, E. Baron, M. Shahbandeh, K. Medler, W. B. Hoogendam, C. M. Pfeffer

Earth and Planetary Astrophysics

Revealing Exotic Nanophase Iron in Lunar Samples Through Impact-Driven Spatial Fingerprints

Ziyu Huang and Masatoshi Hirabayashi

Nanophase iron (npFe) plays a crucial role in controlling the optical, chemical, and physical evolution of lunar regolith grains. While in-situ formation of npFe via reduction of native Fe-bearing minerals has long been considered a dominant pathway, recent mineralogical evidence from X.Zeng et al. (2025) reveals that the source of a significant fraction of npFe may be delivered directly by exotic micrometeoroid impacts (exotic npFe). Yet the atomic-scale processes governing how exotic np-Fe forms and survives during hypervelocity impacts remain largely unknown. To quantitatively compare in-situ and exotic delivery and formation of npFe, we perform a series of innovative atomistic modeling of micrometeoroid impacts with distinct projectile target compositions: (1) SiO$_2$ projectiles on Fe$_2$SiO$_4$ targets (in-situ formation), (2) Fe$_2$SiO$_4$ projectiles on SiO$_2$ targets (exotic delivery). Our results reveal distinct mechanistic fingerprints: in-situ np-Fe forms diffusely and radially around the impact site, whereas exotic np-Fe is efficiently retained and concentrated in asymmetric, momentum-aligned clusters. These contrasting spatial signatures provide a potential diagnostic criterion for distinguishing exotic versus in-situ np-Fe in returned lunar soils. In agreement with Chang'e-5 observations, our simulations demonstrate that exotic np-Fe production can be substantial, particularly in Fe-poor terrains such as highland regions. These findings highlight the need to account for exotic np-Fe when interpreting space weathering processes and remote-sensing data for the Moon and other airless bodies.
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Cosmology and Nongalactic Astrophysics

Linear Growth of Matter Perturbations Probed by Redshift-Space Distortions in Interacting $\Lambda(t)$CDM Cosmologies

A. A. Escobal, H. A. P. Macedo, J. F. Jesus et al. (+2 more)

In the context of a spatially flat $\Lambda(t)$CDM cosmology, we investigate interacting dark energy (IDE) scenarios characterized by phenomenological interaction terms proportional to the Hubble expansion rate and the dark energy density. Our analysis is performed at both the background and linear perturbation levels, with particular emphasis on the evolution of dark matter density fluctuations. Cosmological constraints are derived from a joint analysis of CMB distance priors, Baryon Acoustic Oscillations (BAO), Type Ia supernovae (SNe Ia) from Pantheon+, Redshift-Space Distortions (RSD), and $H(z)$ data from Cosmic Chronometers (CC). Using the linear growth of matter perturbations, we estimate the clustering parameter $S_8$ within IDE extensions of the flat $\Lambda(t)$CDM framework. At the perturbative level, we consider interaction terms of the form $Q_{\text{I}}=\varepsilon a H\bar{\rho}_{\Lambda(t)}$ (Model I) and $Q_{\text{II}}=\varepsilon H\bar{\rho}_{\Lambda(t)}$ (Model II). From the combined dataset, we obtain the constraints $S_8 = 0.870 \pm 0.026$ for Model I and $S_8 = 0.872 \pm 0.026$ for Model II. Finally, we discuss the implications for the coupling parameter $\varepsilon$, taking into account the semi-analytical approximations and observational data employed in this study.
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All authors A. A. Escobal, H. A. P. Macedo, J. F. Jesus, R. C. Nunes, J. A. S. Lima

High Energy Astrophysical Phenomena

Measurement prospects for the pair-instability mass cutoff with gravitational waves

Matthew Mould, Jack Heinzel, Sofia Alvarez-Lopez et al. (+3 more)

Pair-instability supernovae leave behind no compact remnants, resulting in a predicted gap in the distribution of stellar black-hole masses. Gravitational waves from binary black-hole mergers probe the relevant mass range and analyses of the LIGO-Virgo-KAGRA catalog (GWTC-4) indicate a possible mass cutoff at $40$-$50\,M_\odot$. However, the robustness of this result remains unclear. To this end, using full Bayesian parameter estimation, we simulate gravitational-wave catalogs with and without such a mass cutoff, then test whether its presence or absence is correctly inferred with parametric population models. For catalogs similar to GWTC-4, confident identification of a cutoff is not guaranteed, but the best constraints among our simulations are compatible with results from GWTC-4 when the model includes a cutoff. Conversely, spurious identification of a cutoff is unlikely. For catalogs expected by the end of the O4 observing run, uncertainty in the cutoff mass is reduced by $\gtrsim20\,\%$, but a cutoff at 40-50$M_\odot$ yields only a lower bound on the $^{12}\mathrm{C}(\alpha,\gamma)^{16}\mathrm{O}$ reaction rate, our most stringent constraints on the S-factor at $300\,\mathrm{keV}$ being $S_{300}\gtrsim125\,\mathrm{keV}\,\mathrm{b}$ at $90\,\%$ credibility. Relative uncertainties on the Hubble parameter $H_0$ from gravitational-wave data alone can still be up to $100\,\%$. We also analyze GWTC-4 with the nonparametric PixelPop population model, finding that some mass features are more prominent than in parametric models but a sharp cutoff is not required. However, the parametric model passes a likelihood-based predictive test in GWTC-4 and the PixelPop results are consistent with those from our simulated catalogs with a cutoff. Such tests are necessary to make astrophysical claims from gravitational-wave catalogs.
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All authors Matthew Mould, Jack Heinzel, Sofia Alvarez-Lopez, Cailin Plunkett, Noah E. Wolfe, Salvatore Vitale

Instrumentation and Methods for Astrophysics

DeepRed: an architecture for redshift estimation

Alessandro Meroni, Nicolò Oreste Pinciroli Vago and Piero Fraternali

Estimating redshift is a central task in astrophysics, but its measurement is costly and time-consuming. In addition, current image-based methods are often validated on homogeneous datasets. The development and comparison of networks able generalize across different morphologies, ranging from galaxies to gravitationally-lensed transients, and observational conditions, remain an open challenge. This work proposes DeepRed, a deep learning pipeline that demonstrates how modern computer vision architectures, including ResNet, EfficientNet, Swin Transformer, and MLP-Mixer, can estimate redshifts from images of galaxies, gravitational lenses, and gravitationally-lensed supernovae. We compare these architectures and their ensemble to both neural networks (A1, A3, NetZ, and PhotoZ) and a feature-based method (HOG+SVR) on simulated (DeepGraviLens) and real (KiDS, SDSS) datasets. Our approach achieves state-of-the-art results on all datasets. On DeepGraviLens, DeepRed achieves a significant improvement in the Normalized Mean Absolute Deviation compared to the best baseline (PhotoZ): 55% on DES-deep (using EfficientNet), 51% on DES-wide (Ensemble), 52% on DESI-DOT (Ensemble), and 46% on LSST-wide (Ensemble). On real observations from the KiDS survey, the pipeline outperforms the best baseline (NetZ), improving NMAD by 16% on a general test set without high-probability lenses (Ensemble) and 27% on high-probability lenses (Ensemble). For non-lensed galaxies in the SDSS dataset, the MLP-Mixer architecture achieves a 5% improvement over the best baselines (A3 and NetZ). SHAP shows that the models correctly focus on the objects of interest with over 95% localization accuracy on high-quality images, validating the reliability of the predictions. These findings suggest that deep learning is a scalable, robust, and interpretable solution for redshift estimation in large-scale surveys.
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Astrophysics of Galaxies

First statistical constraints on galactic scale outflows properties traced by their extended Mg II emission with MUSE

Ismael Pessa, Lutz Wisotzki, Tanya Urrutia et al. (+7 more)

Galaxies evolve within vast gaseous halos that fuel star formation and carry signatures of feedback-driven outflows. Deep integral field data have enabled the study of MgII halos, which trace galaxy-scale outflows in emission, but their faintness has limited studies to single-object analyses. Here, we present the first statistical study of MgII-emitting halos using deep MUSE observations of 47 star-forming galaxies at $0.7<z<2.0$. Building on our previous work, where we developed and applied an outflow modeling framework for a single MgII halo, we now extend this approach to a larger sample, enabling robust population-level insights on the properties of circumgalactic outflows traced by their extended MgII emission. We detect extended emission out to tens of kiloparsecs and model the outflows as an ensemble of radially accelerating shells. Galaxies with MgII outflows tend to have higher SFRs, sSFRs, and younger stellar populations, consistent with star-formation-driven winds. The observations are consistent with winds that accelerate linearly with radius, from launching velocities of ~60 km/s up to maximum velocities that correlate with stellar mass and reach ~490 km/s. Their inner regions are highly opaque, and we find a tentative trend between stellar mass and central optical depth. The opening angle of the outflow shows some dependency on the host-galaxy stellar mass, with less massive galaxies showing primarily wide opening angles, and more massive galaxies showing a broader range of values, with both wide and narrow opening angles. The distribution of the spatial extent of MgII halos exhibits a clear peak at half-light radius (HLR) of ~5 kpc, with an extended tail of larger HLR values, up to ~20 kpc. Compact halo sizes (HLR $< 8$ kpc) correlate with stellar mass, but extended halos do not, which could suggest a difference in the powering mechanism between compact and extended halos.
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All authors Ismael Pessa, Lutz Wisotzki, Tanya Urrutia, Nicolas F. Bouché, Floriane Leclercq, Ramona Augustin, Yucheng Guo, Daria Kozlova, Haruka Kusakabe, John Pharo

Cosmology and Nongalactic Astrophysics

SPT-3G D1: Compton-$y$ maps using data from the SPT-3G and Planck surveys

A. S. Maniyar, F. Bianchini, W. L. K. Wu et al. (+105 more)

We present thermal Sunyaev-Zel'dovich (tSZ) Compton-$y$ parameter maps constructed from two years (2019-2020) of observations with the South Pole Telescope (SPT) third-generation camera, SPT-3G, combined with data from the Planck satellite. Using a linear combination (LC) pipeline, we obtain a suite of reconstructions that explore different trade-offs between statistical sensitivity and suppression of astrophysical contaminants, including minimum-variance, CMB-deprojected, and CIB-deprojected $y$-maps. We validate these maps through different statistical techniques such as auto- and cross-power spectra with large-scale structure tracers as well as stacking on cluster locations. These tests are used to understand the balance between noise and astrophysical foreground residuals (such as the CIB) in combination with the recovery of the tSZ signal for different maps. For example, results from stacking at the location of clusters confirm the robustness of the recovered tSZ signal over the $\sim 1500\: {\rm deg}^2$ SPT-3G survey field used in this analysis. The high-resolution and low-noise maps produced here provide an important cosmological tool for future studies, including measurements of the Compton-$y$ map power spectrum, cross-correlations with other tracers of the large-scale structure, detailed modeling of cluster pressure profiles, and study of the thermodynamic state of the baryons in the Universe.
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All authors A. S. Maniyar, F. Bianchini, W. L. K. Wu, S. Raghunathan, A. J. Anderson, B. Ansarinejad, M. Archipley, L. Balkenhol, D. R. Barron, P. S. Barry, K. Benabed, A. N. Bender, B. A. Benson, L. E. Bleem, S. Bocquet, F. R. Bouchet, L. Bryant, E. Camphuis, M. G. Campitiello, J. E. Carlstrom, J. Carron, C. L. Chang, P. Chaubal, P. M. Chichura, A. Chokshi, T.-L. Chou, A. Coerver, T. M. Crawford, C. Daley, T. de Haan, K. R. Dibert, M. A. Dobbs, M. Doohan, A. Doussot, D. Dutcher, W. Everett, C. Feng, K. R. Ferguson, N. C. Ferree, K. Fichman, A. Foster, S. Galli, A. E. Gambrel, A. K. Gao, R. W. Gardner, F. Ge, N. Goeckner-Wald, R. Gualtieri, F. Guidi, S. Guns, N. W. Halverson, E. Hivon, A. Y. Q. Ho, G. P. Holder, W. L. Holzapfel, J. C. Hood, A. Hryciuk, N. Huang, T. Jhaveri, F. Kéruzoré, A. R. Khalife, L. Knox, M. Korman, K. Kornoelje, C.-L. Kuo, K. Levy, Y. Li, A. E. Lowitz, C. Lu, G. P. Lynch, T. J. Maccarone, E. S. Martsen, F. Menanteau, M. Millea, J. Montgomery, Y. Nakato, T. Natoli, G. I. Noble, Y. Omori, A. Ouellette, Z. Pan, P. Paschos, K. A. Phadke, A. W. Pollak, K. Prabhu, W. Quan, M. Rahimi, A. Rahlin, C. L. Reichardt, M. Rouble, J. E. Ruhl, E. Schiappucci, A. C. Silva Oliveira, A. Simpson, J. A. Sobrin, A. A. Stark, J. Stephen, C. Tandoi, B. Thorne, C. Trendafilova, C. Umilta, J. D. Vieira, A. G. Vieregg, A. Vitrier, Y. Wan, N. Whitehorn, M. R. Young, J. A. Zebrowski

High Energy Astrophysical Phenomena

Evolution of the transitional millisecond pulsar PSR J1023+0038 from Aqueye+ and NICER observations

Silvia Conforti, Luca Zampieri, Michele Fiori et al. (+3 more)

Transitional millisecond pulsars (tMSPs) are old neutron stars spun up by accretion from a low-mass companion. These objects can switch between two emission regimes: rotation-powered radio pulsar and accreting X-ray pulsar. The origin of their optical and X-ray pulsations is still debated, although one model attributes them to synchrotron emission produced in a shock between the pulsar wind and the accretion flow. The small phase lag observed between optical and X-ray pulses in PSR J1023+0038 supports a common origin. We present a new measurement of the phase lag between optical and X-ray pulse profiles of PSR J1023+0038 and investigate the evolution of the time of passage at the ascending node ($T_{\rm{asc}}$) up to 2023. We performed a timing analysis of optical observations obtained with Aqueye+ between 2021 and 2023 and of X-ray data from NICER in 2023. We derive updated values of $T_{\rm{asc}}$ and measure the optical - X-ray phase lag from simultaneous observations. We find that $T_{\rm{asc}}$ increases by about 20 s per year. In January 2023, we measure a phase lag of $0.067 \pm 0.018$, corresponding to $112.3 \pm 30.7\,\mu$s. Since 2017, the evolution of $T_{\rm{asc}}$ follows a parabolic trend, indicating an increase in the orbital period and orbital separation of the system. This behaviour is consistent with non-conservative Roche-lobe overflow, with the donor losing mass at a rate much higher than the accretion rate. The phase lag measurement further supports a common origin of the optical and X-ray pulsations.
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All authors Silvia Conforti, Luca Zampieri, Michele Fiori, Alessia Spolon, Giampiero Naletto, Aleksandr Burtovoi