Peer Revenue Fully funded

Papers

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

Physics Astrophysics

astro-ph Watch Astrophysics

Monday 6 April

Earth and Planetary Astrophysics

Super-Solar Metallicity and Tentative Evidence for Photochemistry on WASP-96b from JWST and Ground-Based VLT Transmission Spectroscopy

Michael Radica, Jake Taylor, Yoav Rotman et al. (+13 more)

With its expanded wavelength coverage and increased precision compared to previous space-based observatories, JWST provides the opportunity to revisit benchmark planets and view them in a new light. Here, we conduct an in-depth study of the atmosphere of the hot-Saturn WASP-96b combining a new JWST NIRSpec/G395H transit with archival NIRISS/SOSS and VLT/FORS2 transmission spectra. The combined spectrum shows clearly-visible features from H2O, CO2, and Na. CO, though, remains unconstrained, precluding a firm metallicity derivation from free retrievals alone. However, self-consistent grids yield a broadly super-stellar atmospheric metallicity of 2-6x stellar. When combined with a roughly stellar C/O ratio ($0.41^{+0.10}_{-0.09}$ from self-consistent grids), we find that WASP-96b potentially formed via core-accretion beyond the H2O snowline and subsequently accreted volatile-rich material. Free retrievals also find a moderate preference (ln B=2.69) for models with SO2 versus without. WASP-96b falls directly on the proposed "SO2 shoreline" and the retrieved SO2 abundance is well-matched to predictions from photochemical models. Our combined spectrum displays an optical slope, which our models fit with opacity from scattering aerosols – either small-particle condensate clouds or photochemical hazes – though we cannot completely rule out the broad wings of Na or the effects of stellar contamination. Future observations are necessary to disentangle these effects. Finally, we explore the possibility for limb asymmetry in WASP-96b's transmission spectrum and provide several tests to identify asymmetries in our data. We encourage the community to prioritize the development of a robust pathway to quantify the presence of limb asymmetry – particularly for low signal-to-noise cases.
Read the full abstract

All authors Michael Radica, Jake Taylor, Yoav Rotman, Jasmina Blecic, Luis Welbanks, Eva-Maria Ahrer, Duncan Christie, Louis-Philippe Coulombe, Gillis Lowry, Matthew M. Murphy, Adina D. Feinstein, David Lafreniere, Ryan J. MacDonald, Nathan J. Mayne, Shang-Min Tsai, Maria Zamyatina

High Energy Astrophysical Phenomena

Wide Jets or Low Rates: Reconciling Short GRB and Gravitational-Wave Neutron Star Merger Rates

Keerthi Kunnumkai, Antonella Palmese, Brendan O'Connor et al. (+2 more)

Gravitational wave (GW) and short Gamma Ray Burst (sGRB) observations provide us with complementary views of compact object mergers. The paucity of binary neutron star merger (BNS) detections in the latest LIGO/Virgo/KAGRA (LVK) observing run raises the question of whether the GW merger rates are sufficient to explain the observed sGRB rate with compact object mergers alone. We investigate this connection using the latest merger rate constraints from the fourth LVK observing run (O4) and published estimates of the local sGRB rate density. For an observed sGRB rate density of $ \sim 1-7~\mathrm{Gpc^{-3}\,yr^{-1}}$, if $>55\%$ of BNS mergers can successfully launch a jet, we find that the current LVK BNS merger rate can be reconciled with a sGRB merger population containing a significant fraction of relatively wide jets with core half-opening angles $\theta_j \geq 10^\circ$. Meanwhile, a narrow jet population ($\theta_j \sim 6^\circ$) can only be matched with the O4 neutron star merger rate estimates for an observed sGRB rate density of $\lesssim 1~\mathrm{Gpc^{-3}\,yr^{-1}}$, which is broadly consistent with several of the latest available estimates. We also find that neutron star-black hole mergers (NSBH) are expected to be a subdominant component of the sGRB population compared to BNS mergers, and they cannot help reconcile some of the highest available sGRB rate ($ >7~\mathrm{Gpc^{-3}\,yr^{-1}}$) with the GW rate estimates. However, they can still substantially contribute to the sGRB population, comprising $\sim 6-16\%$ of it for an observed sGRB rate density of $\sim 1-3~\mathrm{Gpc^{-3}\,yr^{-1}}$. Overall, our results indicate that present GW and sGRB observations remain broadly consistent with BNS mergers as the main progenitors of sGRBs.
Read the full abstract

All authors Keerthi Kunnumkai, Antonella Palmese, Brendan O'Connor, Amanda Farah, Ignacio Magana Hernandez

Solar and Stellar Astrophysics

Lithium and the evolution of intermediate-mass T Tauri and Herbig stars. Rotation, accretion, and planets

I. Mendigutía, J. Campbell-White, B. Montesinos et al. (+9 more)

(Abridged) We contribute to our understanding of the evolution of young intermediate-mass stars by providing a comprehensive analysis of their lithium (Li) content. A sample of 71 intermediate-mass T Tauri (IMTT) and Herbig stars within the mass range 1.5 – 3.5 M$_{\odot}$ was carefully selected for the analysis. Metallicities, rotational velocities, and accretion rates were obtained from spectra. The curves of growth for stars hotter than 8000 K were built to infer the Li abundances, which were interpreted considering standard models of stellar interiors and non-standard processes affecting Li depletion. Li is generally less strongly depleted in intermediate-mass stars than in their lower-mass counterparts, as expected from standard evolution models. However, Li abundances significantly below the cosmic value are observed in 25 – 30$\%$ of intermediate-mass stars. It is also unexpected that the results show no significant difference between the 1.5 –2.5 M$_{\odot}$ and 2.5 – 3.5 M$_{\odot}$ subsamples. Evidence is provided showing that disk-locking works in young intermediate-mass stars. This constitutes independent support for the hypothesis that magnetospheric accretion scenario operates in these sources. We found that disk-locking is effective for a timescale that is about twice shorter than for lower-mass stars, before magnetospheres reduce their sizes during the transition from the IMTT to the Herbig regime. This contraction of the magnetosphere can explain the increase in rotation by a factor of about 3 and in accretion by a factor of about 4 that is observed during this transition. We propose a complex scenario linking rotation, accretion, and the surface Li abundance. Finally, we tentatively suggest that the known relation between the presence of planets and Li depletion might also be present in intermediate-mass main sequence (MS) stars and might originate in the pre-MS.
Read the full abstract

All authors I. Mendigutía, J. Campbell-White, B. Montesinos, J. Maldonado, L. Fullana-García, G.M. Mirouh, G. Meeus, M. Vioque, A. Sicilia-Aguilar, M.R. Zapatero-Osorio, E. Villaver, R. Kahar

Earth and Planetary Astrophysics

Two-stage disruption of resonant chains

Nick Choksi, Yoram Lithwick, Eugene Chiang et al. (+1 more)

TESS is enabling the discovery of transiting planets around young stars. These observations suggest that most close-in planets were born in chains of mean-motion resonances that break on a characteristic timescale of order 100 Myr. This observation is surprising because the same dissipative forces that capture planets into resonance render their orbits long-term stable. We explore a two-stage disruption scenario for resonant chains of super-Earths. First, the chains have their (free) eccentricities excited by some mechanism. We show that any such mechanism that seeds eccentricities of a few percent sets in motion a second stage of dynamical instability on a $\sim$100 Myr timescale. A possible stage-one mechanism is the accretion of a handful of Mercury-sized bodies totaling a few percent of the planetary system mass, which excites the requisite eccentricities and triggers a stage two that reproduces the observed decline in the incidence of resonance. Impacts from such bodies can also explain why some young systems have period ratios narrow of commensurability. We sketch how these impactors may have grown out of debris left over from an earlier epoch of planet formation. We also identify two new trends in the observational data: a decline in multiplicity on the same timescale as the decline in the incidence of resonance, and an increase in the occupation of resonances with multiplicity.
Read the full abstract

All authors Nick Choksi, Yoram Lithwick, Eugene Chiang, Rixin Li

Cosmology and Nongalactic Astrophysics

Universal Dark-matter Density Profiles of Cosmic Filaments

Peng Xu, Fangzhou Jiang, Farhanul Hasan et al. (+5 more)

We present a comprehensive analysis of the radial dark-matter (DM) density profiles of cosmic filaments in the hydrodynamical simulation TNG50. The cosmic web is extracted from high-resolution density grids at redshifts $z =$ 0, 0.5, 1, 2 and 3 using the DisPerSE algorithm. We show that the filament spine locations returned directly by DisPerSE do not accurately reflect the true density ridges. To address this issue, we introduce a "shrinking-cylinder" re-centering algorithm, which significantly increases the inferred central densities and restores the inner power-law behavior of the profiles. When the radial coordinate is scaled by the virial radii of the terminal nodes, the filament density profiles exhibit a nearly universal form that depends only weakly on redshift, node mass, and filament length. This result suggests that cosmic filaments, much like dark-matter halos, obey a form of structural self-similarity once an appropriate characteristic scale is introduced. By repeating the measurement using only smoothly distributed, unbound DM particles, we find that the apparent central cusp of the full profile is primarily produced by low-mass halos embedded along the filament spines, while the smooth component develops a flat core within $R/R_{\rm vir}\lesssim0.1$. The redshift evolution of this smooth component further suggests a transition from predominantly smooth filamentary accretion at high redshift to increasingly clumpy accretion at late times. Finally, we show that the universal filament profile is accurately described by a generalized triple-power-law model.
Read the full abstract

All authors Peng Xu, Fangzhou Jiang, Farhanul Hasan, Joanna Woo, Douglas Hellinger, Joel R. Primack, Sandra M. Faber, David Koo

Solar and Stellar Astrophysics

Toward Early-type Eclipsing Binaries as Extragalactic Milestones: First Calibration of the SBCR from O- and B-type Stars in Detached Eclipsing Binaries

Mónica Taormina, G. Pietrzyński, B. Pilecki et al. (+4 more)

To measure precise distances beyond the Magellanic Clouds and determine an accurate value of the Hubble constant, eclipsing binary systems composed of early-type stars can play a crucial role. However, it is fundamental to first obtain a reliable empirical surface brightness-color relation (SBCR) for the hottest possible stars. Based on our previous study of six detached eclipsing binaries composed of O- and B-type stars in the Large Magellanic Cloud, we calibrated the SBCR using 12 stars with $V-K_{s} < -0.6$ mag. We found a significant difference between O-type and B-type stars in SBCRs, which are clearly separated in mass. The relation based on B-type stars is consistent with the relation for redder stars from the literature. This allowed us to provide a combined relation valid for stars less massive than $\sim 16\,M_\odot$ in the wide color range $-0.9 < V-K_{s} < 2.1$ mag, with $\sigma = 0.025$ mag. Such a relation can provide extragalactic distances precise to as high as $\sim$1.2% given the sufficient quality and number of target objects. The relation for O-type stars ($\sigma = 0.055$ mag) remains uncertain due to its strong dependence on the method used to determine reddening and requires further study. However, we tested it on the only known eclipsing system in M33, and obtained distance modulus DM=$24.90 \pm 0.17 $ mag, which perfectly agrees with the published distance to the system.
Read the full abstract

All authors Mónica Taormina, G. Pietrzyński, B. Pilecki, R.-P. Kudritzki, D. Graczyk, J. Puls, M. Górski

High Energy Astrophysical Phenomena

Characterizing the Gamma-ray Emission from Low-Luminosity AGN

Chris Karwin, Nikita Khatiya, Margot Boughelilba et al. (+3 more)

A majority of the active galactic nuclei (AGN) in the local Universe are classified as low-luminosity AGN (LLAGN), having bolometric luminosities $\lesssim 10^{42} \ \mathrm{erg \ s^{-1}}$. Although high-energy gamma-ray emission is predicted from both the jets and disks of LLAGN, to date only four have been detected by the Fermi Large Area Telescope (Fermi-LAT). In this work, we therefore conduct a comprehensive study of all the LLAGN from the Palomar spectroscopic survey of bright, northern galaxies, including both subthreshold and detected gamma-ray sources, using 14.4 years of LAT data. Our analysis results in a new detection of one LLAGN, as well as a detection of the subthreshold population using a stacking technique. We find that the signal from the subthreshold sample is consistent with being dominated by star-formation activity, although a contribution from compact jets or a mixed contribution from jetted and non-jetted systems is also feasible. On the other hand, the individually detected LLAGN are likely dominated by jet emission. We perform detailed spectral modeling for a subset of these sources and find that the gamma-ray signal can be explained by synchrotron self-Compton radiation, if the inner jet emission region is weakly magnetized with its total energy density being strongly particle dominated, and only slowly moving. With this work we also publicly release our Python-based stacking library for analyzing subthreshold source populations with the LAT, based on a proven technique used in numerous studies.
Read the full abstract

All authors Chris Karwin, Nikita Khatiya, Margot Boughelilba, Xiurui Zhao, Anita Reimer, Marco Ajello

Astrophysics of Galaxies

Winding Back the Clock: Recent Star Formation Histories of Massive Quiescent Galaxies Are Consistent With Their Rapid Number Density Evolution Since $\mathbf{z\sim7}$

Yunchong Zhang, Zhiyuan Ji, Rachel Bezanson et al. (+17 more)

Massive quiescent galaxies have been identified out to $z\sim7$ in early JWST data in a substantial excess ($\rm \gtrsim 1\,dex$ at $z>4$) of number densities from most theoretical predictions. We investigate whether the number densities implied by the star formation histories of quiescent galaxies at $2<z<5$ are consistent with the observed number density evolution of that population since $z>7$. For this work, we rely on stellar population synthesis modeling of JWST NIRCam photometry (from CEERS and PRIMER) and NIRSpec/PRISM spectra of massive ($\rm M_{*} > 10^{10.5}M_{\odot}$) quiescent galaxies in the RUBIES survey. We infer their star-formation histories through Bayesian spectro-photometric fitting with Prospector, exploring the sensitivity of our results to stellar libraries and SFH priors. For each source, we compute a timescale over which it would be identified as quiescent – leveraging the recent and most robust SFH timescale – and deduce the number density of the quiescent population at previous epochs. These reconstructed number densities are then compared to existing observational constraints, including a new measurement from the PANORAMIC pure parallel survey, whose wide-area and independent sightlines reduce sensitivity to cosmic variance. We find striking agreement between reconstructed and observed number densities up to $z\sim7$, a self-consistency that lends credence to stellar population synthesis modeling of distant quiescent galaxies. Furthermore, by connecting the recent ($\rm \sim 1\,Gyr$) star-formation histories and number densities of quiescent galaxies and their implied progenitors, we reinforce the known tension between observations and model predictions at $3<z<7$.
Read the full abstract

All authors Yunchong Zhang, Zhiyuan Ji, Rachel Bezanson, Christina C. Williams, Gabriel Brammer, Aidan P. Cloonan, Anna de Graaff, Jenny E. Greene, Michaela Hirschmann, Christian Kragh Jespersen, Gourav Khullar, Claudia del P. Lagos, Joel Leja, Michael V. Maseda, Ian McConachie, Pascal A. Oesch, Sedona H. Price, David J. Setton, Katherine A. Suess, Katherine E. Whitaker

Astrophysics of Galaxies

PANORAMIC: The Dawn of Massive Quiescent Galaxies I. Number Density and Cosmic Variance from 1000 arcmin$^2$ NIRCam Imaging

Zhiyuan Ji, Christina C. Williams, Peter Behroozi et al. (+13 more)

We measure the number density and field-to-field variance of massive quiescent galaxies at $z\sim3$ - 8 using the JWST/NIRCam pure-parallel imaging survey PANORAMIC together with archival observations, covering an area of 0.28 deg$^2$ ($\sim1000$ arcmin$^2$) in at least six filters. We identify quiescent galaxy candidates at $z\gtrsim3$ with $M_\ast \gtrsim 10^{10}\,M_\odot$, comprising 101 galaxies in a gold sample of high-confidence candidates and 137 in a more inclusive silver sample. We measure their evolving comoving number density, finding $(1.5$ vs. $3.1)\times10^{-5}\,\mathrm{Mpc}^{-3}$ at $z=3$ - 4 for the gold and silver samples, respectively, and a decline by more than a factor of 20 by $z\sim6$. Comparisons with empirical models and cosmological simulations show that widely used frameworks underpredict the abundance of massive quiescent galaxies at $z\gtrsim4$ by $\gtrsim1$ dex, indicating that current implementations of early star formation, feedback, and quenching do not produce enough early quenched systems. With 34 independent sightlines, we present the first direct empirical measurement of field-to-field variance for quiescent galaxies at $z>3$, finding a high cosmic variance of $\sigma_{\rm CV}\approx0.7\pm0.3$. This exceeds predictions from abundance-matched mock catalogs, suggesting that early quiescent galaxies are more strongly clustered, and more likely to be found near one another or in more biased regions, than expected in current galaxy-formation models. Any successful model for the emergence of early massive quiescent galaxies must reproduce both their abundance evolution and their imprint on the large-scale distribution.
Read the full abstract

All authors Zhiyuan Ji, Christina C. Williams, Peter Behroozi, Andrea Weibel, Christian Kragh Jespersen, Pascal A. Oesch, Rachel Bezanson, Katherine E. Whitaker, Jenny E. Greene, Gabriel Brammer, Pratika Dayal, Ivo Labbé, Sinclaire M. Manning, Pierluigi Rinaldi, Mengyuan Xiao, Yunchong Zhang

High Energy Astrophysical Phenomena · Cross-listed from physics.plasm-ph

Ion Weibel Instability in the hybrid framework: the optimal resolution

Luca Orusa and Taiki Jikei

The study of collisionless shocks and their role in cosmic-ray acceleration has gained increasing importance through both observations and simulations. Accurately modeling the shock transition region, where particle injection occurs, requires a proper description of the microinstabilities governing its structure. In high-Mach-number shocks, such as those associated with supernova remnants, the ion Weibel instability is believed to provide the dominant dissipation mechanism. In this work, we investigate the ion Weibel instability driven by counterstreaming beams in the presence of an external perpendicular magnetic field. We employ hybrid simulations, in which ions are treated kinetically while electrons are modeled as a charge-neutralizing fluid. Although hybrid models are widely employed to study collisionless shocks, the resolution requirements needed to accurately capture ion-scale instabilities remain poorly understood. We address this issue by developing a linear theory of the ion Weibel instability tailored to the massless electron assumption of hybrid models and validating it with one- and two-dimensional simulations over a wide range of Alfvénic Mach numbers. We show that hybrid simulations can reliably reproduce the growth, saturation, and polarization of Weibel-generated magnetic fields in weakly magnetized regimes, provided that the relevant ion-scale modes are properly resolved. From the scaling of the dominant mode, we derive a minimum spatial resolution required as a function of Alfvénic Mach number. We also demonstrate that excessive resolution introduces unphysical small-scale whistler modes inherent to the massless-electron approximation. We validate the analysis by comparing the results with full particle-in-cell simulations. Together, these results provide practical guidance for hybrid simulations of collisionless shocks and beam-driven plasma systems.
Read the full abstract

High Energy Astrophysical Phenomena

Electromagnetic Flares from Compact-Object Mergers in AGN Disks: Signatures and Predictions

Hiromichi Tagawa, Zoltán Haiman, Shigeo S. Kimura et al. (+2 more)

Accretion disks in active galactic nuclei (AGN) are promising sites for mergers of stellar-mass black holes (BHs) detectable via gravitational waves (GWs). These environments facilitate both in-situ formation and dynamical capture of compact objects, and their subsequent mergers. The uncertain origin of GW events detected by LIGO, Virgo and KAGRA motivates searching for accompanying electromagnetic (EM) signatures. Here we investigate post-merger EM flares associated with jets launched from merger remnants, as well as from the shocked ambient gas as the jet breaks out of the disk. We find that jet breakout produces luminous gamma-ray emission, detectable with MeV-band telescopes. Cooling emission from a shocked circum-BH minidisk, winds and background AGN-disk peaks in the UV and optical, with durations ranging from about an hour to a month, and can be identified through year-long monitoring of $\sim10^3$ AGNs with luminosities ranging from $\sim 10^{44}$ to $\sim 10^{45}~{\rm erg~s^{-1}}$. With a single set of parameters, this post-merger jet model produces gamma-ray, hard X-ray and optical flares similar to those claimed to be associated with GW events. Furthermore, by incorporating a transition from a high- to low-angular-momentum accretion state after the merger, the model avoids excessive BH growth, alleviating tensions with hyper-Eddington accretion scenarios.
Read the full abstract

All authors Hiromichi Tagawa, Zoltán Haiman, Shigeo S. Kimura, Hassen M. Yesuf, Hengxiao Guo

Solar and Stellar Astrophysics

The neighboring stars of N6946-BH1 and the observational characteristics of failed supernovae

R. Forés-Toribio and C. S. Kochanek

Stellar collapse models predict that some stars more massive than $\sim$15$M_\odot$ may collapse directly to a black hole, sometimes with a weak optical transient, a phenomenon known as a failed supernova. Detecting such events is challenging, but searches of vanishing stars have found two promising candidates, N6946-BH1 and M31-2014-DS1. We re-analyze the JWST NIRCam and MIRI images of N6946-BH1 to characterize the remnant emission of the object and its surrounding sources. We found four near-infrared stellar neighbors within approximately 0$.\!\!^{\prime\prime}$1 that are not related to the mid-infrared emission of the candidate. The SED of N6946-BH1 is well modeled by a $\log(L/L_\odot)$=$4.727_{-0.025}^{+0.026}$ (at 95% confidence) source obscured by a silicate dust shell with a maximum grain size of $\sim$3 $\mu$m and producing negligible emission at $\lesssim$2 $\mu$m. Given proposals that failed SN candidates are actually stellar mergers, we model the progenitor and remnant emission of four Galactic and seven extragalactic stellar mergers and compare their properties with those of the failed supernova candidates. We found that the merger remnants are 10-100 times more luminous than their progenitors at these late phases while the remnants of failed supernovae are $\sim$10 times dimmer than their progenitors. Axisymmetric, disky dust distributions cannot explain the factor of $\sim$100 or more difference in the ratios of the progenitor and remnant luminosities.
Read the full abstract

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

Electroweak Doublet Dark Matter for a Galactic Halo Gamma-Ray Excess

Yasunori Nomura and Tomonori Totani

Weakly interacting massive particles provide a well-motivated framework for dark matter, naturally reproducing the observed relic abundance through thermal freeze-out. A recent claim of an indirect-detection signal from the Galactic halo, consistent with dark matter annihilation in the mass range 400–800 GeV, motivates a reexamination of minimal models that can account for such a signal while remaining consistent with existing constraints. In this paper, we analyze the simplest extensions of the Standard Model capable of explaining the signal. We show that electroweak doublet dark matter with Higgs-portal interactions provides a natural and economical explanation. The model predicts annihilation predominantly into gauge bosons with characteristic branching fractions and allows for inelastic dark matter with a mass splitting of order 100 keV, intriguingly consistent with a recent direct-detection anomaly. Possible enhancements of the present-day annihilation rate relative to the thermal value are also discussed, including a simple extension with a light scalar field that induces Sommerfeld enhancement.
Read the full abstract

Astrophysics of Galaxies · Cross-listed from gr-qc

Revisiting The Gravitational Mirroring In Presence of Compact Objects

Bikramarka S Choudhury, Aritra Sanyal, Md Khalid Hossain et al. (+1 more)

We propose a novel concept of astrophysical mirroring in the schwarzschild framework, which emerges as a direct consequence of gravitational lensing effects occurring in the immediate vicinity of extremely dense massive objects within spacetime. Through rigorous theoretical calculations and numerical ray-tracing analysis, we demonstrate that sufficiently compact astrophysical objects possess the capability to induce such extreme curvature in spacetime that the resulting gravitational field can bend light rays to extraordinary degrees, creating what we term a "reflection image" or mirror-like appearance of the source in distant regions of space. We discuss the theoretical framework as well as the observational consequences of this phenomenon.
Read the full abstract

All authors Bikramarka S Choudhury, Aritra Sanyal, Md Khalid Hossain, Farook Rahaman

Cosmology and Nongalactic Astrophysics

Fast Radio Burst Dispersion Measure–Timing Cross-Correlations: Bias Self-Calibration and Primordial Non-Gaussianity Constraints

Simthembile Dlamini

Fast Radio Bursts (FRBs) carry fossil information about non-Gaussianity generated during inflation. This primordial signal is most accessible on the largest scales, where the scale-dependent bias correction $\propto f_\mathrm{NL}\,H_0^2/k^2$ dominates, but where systematic effects are also strongest. A central challenge is the degeneracy between the intergalactic-medium electron bias $b_e$ and the primordial non-Gaussianity (PNG) signal, which can degrade $\sigma(f_\mathrm{NL})$ by orders of magnitude when $b_e$ is marginalised. We show this degeneracy can be broken internally by exploiting the cross-power spectrum $C_\ell^{D\Delta t}$ between the FRB dispersion measure (DM) field and Shapiro timing delays along multiple interferometric sightlines. The DM field traces the biased electron density, while the Shapiro timing signal probes the Newtonian gravitational potential independently of astrophysical bias. Their cross-correlation is directly proportional to $b_e$, independently of the matter power spectrum, providing a self-calibration of the electron bias. We derive $C_\ell^{D\Delta t}$ analytically in the Limber approximation and find a correlation coefficient $|\rho(\ell)|\approx 0.51$–$0.79$ across $\ell = 2$–$100$. A joint Fisher matrix analysis over $\{f_\mathrm{NL},\,b_e^0,\,z_\mathrm{fb}\}$ shows that including the cross-spectrum reduces $\sigma(b_e^0)$ by a factor of $2.1$–$5.1$ relative to a DM-only analysis. After full marginalisation, the joint analysis recovers $\sigma(f_\mathrm{NL})$ within a factor of $1.0$–$1.9$ of the fixed-bias benchmark, compared with $1.7$–$3.3$ degradation without the cross-spectrum. For a shallow survey with a 500\,AU baseline and $10^4$ FRBs, the joint constraint achieves $\sigma(f_\mathrm{NL})\approx 790$, within 4% of the fixed-bias result and a factor $3.3$ better than the marginalised DM-only case.
Read the full abstract

High Energy Astrophysical Phenomena · Cross-listed from hep-ph

Light neutrinos, Dark matter and leptogenesis near electroweak scale and $Z_4$ symmetry

Kunal Pandey and Rathin Adhikari

Considering $Z_4$ symmetry in Type I seesaw scenario, one could obtain mass-squared differences of light neutrinos, mixings and $CP$ violating phase within $3 \sigma$ confidence level based on neutrino oscillation data. This is possible with only three independent complex parameters for allowed Yukawa couplings and one real mass parameter for heavy right handed neutrino fields around electroweak scale. After considering only three more real parameters as coming from small soft-symmetry breaking terms, the lightest right handed neutrino could be considered as dark matter candidate via freeze-in mechanism and the other two heavier right handed neutrinos through their decays, could generate the baryonic asymmetry of the universe naturally via resonant leptogenesis.
Read the full abstract

Earth and Planetary Astrophysics

The Zhamanshin Impact Event: Potential Implications for Environmental Responses and Biological Linkages on Earth and Beyond

James B. Garvin, Connor J. Anderson, Katherine A. Melocik et al. (+4 more)

At least one large-body (diameter > 1.1 km) hypervelocity cratering event occurred during ~ 0.8-0.90 Ma (Zhamanshin, Kazakhstan) in the Middle Pleistocene Transition period. Analysis designed to reduce uncertainty in the dimensions of the Zhamanshin structure employing high resolution topography demonstrated that it likely generated a ~ 26.5 km diameter multi-ring crater. This is at least two times larger than the current best estimates. Using a range of accepted impactor sizes, velocities, compositions, and angles of impact, such impacts typically yield kinetic energies of impact over 240,000 Megatons (TNT). Explosive energetic events of this magnitude (e.g., Yellowstone Caldera) at other times (K-Pg) have created global environmental effects. The factor of two discrepancy in the dimensions of Zhamanshin increases the kinetic energy yield by factors of 7-10, with significantly larger environmental consequences. This justifies examination of rapid climate transitions linked to biological consequences, including those related to environmental perturbations, at ~0.9 Ma.
Read the full abstract

All authors James B. Garvin, Connor J. Anderson, Katherine A. Melocik, Devin R. McClain, Scott S. Sinno, Myoung-Jong Noh, Compton J. Tucker

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

Probing Unification Scenarios with Big Bang Nucleosynthesis

I. M. Dreyer and C. J. A. P. Martins

We extend a recently developed Big Bang Nucleosynthesis (BBN) code, PRyMordial, to constrain a broad class of Grand Unified Theories to which BBN is sensitive, since these lead to varying fundamental couplings. A previously developed self-consistent perturbative analysis of the effects of these variations has been implemented in PRyMordial, leading to robust constraints of the value of the fine-structure constant, $\alpha$, at the BBN epoch using current observations of Helium-4 and Deuterium abundances. We explored two different viable scenarios, relying on alternative assumptions on the gravitational sector: the variation of the gravitational coupling can be implemented by varying either particle masses, or Newton's gravitational constant. For the variation of masses, we obtained at $68\%$ confidence level a constraint on the relative variation of $\alpha$, between the BBN epoch and the present-day laboratory value, of $\Delta\alpha/\alpha=2\pm51$ ppm (parts per million), while for the variation of Newton's constant the analogous constraint is $\Delta\alpha/\alpha=2\pm22$ ppm. We also show that, given these constraints, these models do not provide a solution to the cosmological Lithium problem.
Read the full abstract

Cosmology and Nongalactic Astrophysics

Measurement of the galaxy-velocity power spectrum of DESI tracers with the kinematic Sunyaev-Zeldovich effect using DESI DR2 and ACT DR6

Edmond Chaussidon, Selim C. Hotinli, Simone Ferraro et al. (+49 more)

Joint analyses of high-resolution CMB temperature maps with galaxy surveys provide a unique way to reconstruct the radial velocity field of the underlying matter distribution via the kinematic Sunyaev-Zeldovich (kSZ) effect. Using data from the Atacama Cosmology Telescope (ACT) DR6 and the Dark Energy Spectroscopic Instrument (DESI) DR2, we present radial velocity reconstructions for luminous red galaxies (LRGs), emission-line galaxies (ELGs), and quasars (QSOs). Leveraging the spectroscopic data, we are able to reliably model the foreground contamination and report a negligible impact on our main observables. We detect the velocity-galaxy cross-correlation at $17.0\sigma$ for LRGs, and for the first time, at $8.3\sigma$ for ELGs and $6.8\sigma$ for QSOs. We further report the first detection of the velocity-velocity correlation using LRGs at $3.1\sigma$, as well as the highest cumulative detection of the kSZ effect to date at $20.8 \sigma$. Similarly to previous results, we find a lower amplitude of the kSZ signal compared to our fiducial halo model prediction and electron profile assuming a Battaglia profile. Combining these new observables, we obtain constraints on local-type primordial non-Gaussianity (PNG): $f_{\rm NL}^{\rm loc} = 15.9_{-34.4}^{+34.6}$ at 68% confidence, which represents the tightest constraint to date derived from the velocity field. The measurements presented here already exhibit lower noise on a per-mode basis than the galaxy auto-correlation on the largest scales, $k<0.004~\rm{Mpc^{-1}}$, highlighting the key role these observables will play in the context of future CMB experiments such as the Simons Observatory.
Read the full abstract

All authors Edmond Chaussidon, Selim C. Hotinli, Simone Ferraro, Kendrick Smith, Xinyi Chen, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, A. Cuceu, A. de la Macorra, B. Dey, P. Doel, A. Font-Ribera, J. E. Forero-Romero, E. Gaztañaga, S. Gontcho A Gontcho, G. Gutierrez, J. Guy, H. K. Herrera-Alcantar, K. Honscheid, C. Howlett, D. Huterer, M. Ishak, R. Joyce, D. Kirkby, A. Kremin, O. Lahav, M. Landriau, L. Le Guillou, M. Manera, A. Meisner, R. Miquel, S. Nadathur, J. A. Newman, N. Palanque-Delabrouille, W. J. Percival, F. Prada, I. Pérez-Ràfols, G. Rossi, L. Samushia, E. Sanchez, D. Schlegel, M. Schubnell, H. Seo, J. Silber, D. Sprayberry, G. Tarlé, B. A. Weaver, C. Yèche, R. Zhou

Astrophysics of Galaxies

The Delay Time Distribution of Tidal Disruption Events

Margaret Shepherd, K. Decker French, Nicholas C. Stone et al. (+6 more)

Tidal disruption events (TDEs) can be observed when stars get too close to supermassive black holes and are torn apart and accreted. The delay time distribution of TDEs, or rate of TDEs as a function of time since a burst of star formation, can be used to determine what mechanisms influence the TDE rate. We compile a catalog of 41 TDE host galaxies with optical spectra, model the stellar populations with Bagpipes, and retrieve the age of the most recent burst of star formation to construct the delay time distribution of TDEs. TDEs occur more frequently in post-starburst galaxies than in other types of galaxies, though the mechanism causing this rate enhancement is unknown. We find that the TDE rate increases with post-burst age to reach a peak at ~1 Gyr relative to a control sample. We compare the observational TDE delay time distribution to theoretical models, which propose overdense stellar nuclei, radial anisotropies in stellar orbits, supermassive black hole binaries, and AGN disks as potential mechanisms that may enhance the TDE rate in post-starburst galaxies. Most models predict a TDE rate that declines with post-burst age, in contrast to our observational results, though some models are still feasible at certain ages (e.g., the black hole binary model matches at old burst ages and the stellar overdensity model matches at intermediate burst ages).
Read the full abstract

All authors Margaret Shepherd, K. Decker French, Nicholas C. Stone, Nicholas Earl, Denyz Melchor, Teddy R. Smith, Jean Somalwar, Odelia Teboul, Margaret E. Verrico

Astrophysics of Galaxies

Nexae in caverna: the secular evolution of disks via collectively excited, transient spiral structure

Sharon E. Meidt and Arjen van der Wel

Using the hydrodynamical (fluid) approximation, we present a self-consistent theoretical framework that couples the origin, evolution and decay of spiral structures to the secular dynamical evolution of their host galactic disks. Our approach highlights non-resonant spiral excitation through azimuthal forcing that leverages mild, pervasive gradients in the disk's mass and angular momentum distributions, structural features we term cavernae. These cavernae are weaker but more widespread than the sharp features behind groove mode excitation and commonplace in exponential disks. We discuss how non-resonant features combine with other responses – resonant dressing, steady waves, groove modes – to produce a global, evolving spiral nexum that transports angular momentum and reshapes the disk. Using expressions for torques, angular momentum transport and heating, we demonstrate that global spirals are intrinsically self-limiting; the angular momentum changes and heating they generate quenches their own growth, dictating a finite lifetime for any single spiral episode. A succession of transient episodes, each with properties adjusted to the changed disk conditions, lays the pathway to long-lived spiral activity. This behavior suggests that the character of secular evolution shifts over time. We find that the short-lived, high-multiplicity (high-m) spirals that dominate in dynamically cold disks induce widespread, impulse-like non-resonant heating, yet with a low ratio of heating to radial migration. As the disk warms, high-m features are suppressed, leading to steadier, lower-m spirals that heat progressively more efficiently near resonances. In this light, the dynamical coldness of disk galaxies today requires a past dominated by high-m transient perturbations, whereas warmer, more compact systems reflect an advanced stage of evolution regulated by transient, low-m spirals.
Read the full abstract

Earth and Planetary Astrophysics

Assessment of PLATO Science Performance

Juan Cabrera, Heike Rauer, Reza Samadi et al. (+121 more)

The PLATO mission is scheduled for launch early 2027. In this paper we present an overview of the performance drivers for the mission at the time where all flight models of the cameras have been tested and integrated on the optical bench. The PLATO consortium needs an estimate of the planet detection yield to dimension the ground-based radial velocity follow-up resources. We provide updated estimates on the yield of planet detections that can be expected from the mission under certain assumptions. As of today, large uncertainties remain on the planet occurrence rates, especially for small planets in long-period orbits, and on our ability to detect these planets in the presence of stellar variability and instrumental noise. To partially overcome these limitations, we compare results using different planet occurrence rates, detectability rates, and we include an estimate on the expected contribution of stellar variability to the noise budget. The final detection yield of PLATO will provide constraints to planet occurrence rates which in turn will help constraining planet formation models.
Read the full abstract

All authors Juan Cabrera, Heike Rauer, Reza Samadi, Valerio Nascimbeni, Anko Boerner, Denis Grießbach, Carsten Paproth, Martin Pertena{\i}s, Sami-M. Niemi, Szilard Csizmadia, Asier Abreu, Conny Aerts, Suzanne Aigrain, Matthias Ammler-von Eiff, Beatriz Aparicio del Moral, Thierry Appourchaux, David J. Armstrong, Ann Baeke, Gabor G. Balazs, Kevin Belkacem, Aaron Birch, Paz Bluhm, Tobias Boenke, Fabrice Boquet, Sam Bowling, David J. A. Brown, Claude Catala, William J. Chaplin, Margarida S. Cunha, Cilia Daminani, Guy R. Davies, Jeanne Davoult, Francesca De Angeli, Joris De Ridder, Magali Deleuil, Jean-Michel Desert, Jose Javier Diaz Garcia, Anna M. Di Giorgio, Lauren Doyle, Billy Edwards, Philipp Eigmueller, Johannes Eising, Anders Erikson, Yoshi Emilia Nike Eschen, Lorenza Ferrari, Dominic C. Ford, Hugo García-Vázquez, Laurent Gizon, Juan Manuel Gomez Lopez, Nicolas Gorius, Marie-jo Goupil, Valentina Granata, John Lee Grenfell, Emmanuel Grolleau, Sascha Grziwa, Tristan Guillot, Diana L. Harrison, Rene Heller, Ana M. Heras, Simon T. Hodgkin, Rik Huygen, Nicholas Jannsen, David Kappel, Peter Klagyivik, Alexander Koncz, Diana Kossakowska, Alvaro Labiano, Kristine Lam, Antonino Francesco Lanza, Monika Lendl, Yves Levillain, Francisco A. Lobon Villanueva, Demetrio Magrin, Luca Malavolta, Silvia Marinoni, Paola Marrese, Cesar Martin Garcia, Miguel Mas Hesse, Pierre Maxted, James McCormac, Andrea Miglio, Marco Montalto, Thierry Morel, Alvaro Morena, Andres Moya, Matteo Munari, Martin B. Nielsen, Rhita-Maria Ouazzani, Isabella Pagano, Carmen Pastor Morales, Gisbert Peter, Jordan Philidet, Giampaolo Piotto, Philippe Plasson, Don Pollacco, Elena Puga, Roberto Ragazzoni, Gonzalo Ramos Zapata, Sara Regibo, Guy T. Rixon, Nicolas Robles Muñoz, Julio Rodriguez Gomez, Pierre Royer, Miguel Andres Sanchez Carrasco, Rosario Sanz Mesa, Gabriel Schwarzkopf, Dries Seynaeve, Alan Smith, Alexis M. S. Smith, Leigh C. Smith, Sophia Sulis, Geert Jan J. Talens, Ruth Titz-Weider, Stephane Udry, Bart Vandenbussche, Ivan Valtchanov, Peter Verhoeve, Dave Walton, Nicholas A. Walton, Thomas G. Wilson, Ulrike Witteck, David Wolter, Claas Ziemke, Konstanze Zwintz

High Energy Astrophysical Phenomena

Diffusion of PeV Cosmic Rays in the Turbulent and Multiphase Interstellar Medium

Yue Hu

Galactic cosmic rays (CRs) are a fundamental non-thermal component of the interstellar medium (ISM). Understanding the transport of super-high-energy particles is essential for interpreting observations of Galactic PeVatrons. Classical diffusion models assuming a homogeneous and isothermal medium oversimplify the multiphase ISM. We utilize high-resolution 3D MHD simulations to self-consistently generate a multiphase ISM, comprising the warm (WNM), unstable (UNM), and cold neutral medium (CNM), and investigate 1.5-15 PeV particle transport using a test-particle approach. We find that thermal phase transitions induce steep magnetic field strength gradients at phase boundaries, creating localized magnetic fluctuations that act as efficient sites for adiabatic mirror reflections and non-adiabatic pitch-angle scattering, strongly enhancing cross-field transport at these interfaces. However, because phase boundaries occupy only a small volume fraction and particles spend most of their trajectory in the weakly scattering WNM and UNM, the global pitch-angle scattering coefficient in the multiphase ISM is smaller than in an equivalent isothermal medium. This locally strong scattering nevertheless drives both parallel and perpendicular spatial diffusion coefficients to $\sim10^{30} {\rm cm^2 s^{-1}$ at 1.5~PeV, with the perpendicular component exceeding its isothermal counterpart ($\sim 10^{28}{\rm cm^2 s^{-1}$) by two orders of magnitude. Using a phase–phase diffusion matrix decomposition, we show that global CR transport is governed by the volume-filling, trans-Alfvénic WNM and UNM, where particles stream along stochastically wandering field lines. Cross-phase displacement correlations are universally positive, indicating cooperative transport between thermal phases. In contrast, the super-Alfvénic CNM acts as an efficient confinement that substantially suppresses local diffusion.
Read the full abstract

Instrumentation and Methods for Astrophysics

Independent Recovery of Vanishing Sources on POSS-I Photographic Plates Using Automated Source Detection and Cross-Epoch Matching

Zachary Hayes

We present an independent pipeline for detecting candidate vanished sources on digitized first-epoch Palomar Observatory Sky Survey (POSS-I) photographic plates. The pipeline detects and PSF-filters sources on POSS-I Red DSS cutouts, applies local astrometric registration refinement, and identifies candidates by cross-epoch matching against POSS-I Blue and POSS-II Red with Pan-STARRS DR1 rejection. On a 20-case benchmark harness, the pipeline recovers 8/9 sources in the April 1950 field and 3/3 in the July 1952 field, with a false positive rate of about 0.2 per 10 arcmin field on random non-crowded controls. A full-footprint sweep over the POSS-I coverage using 30 arcmin patches yields a filtered catalog of 2.85 million candidate vanished sources after post-processing PSF cuts, deduplication, and Pan-STARRS DR1 rejection. Cross-matching against the published 5,399-source Solano et al. (2022) catalog yields 3,450 matches (63.9%) with median separation 0.94 arcsec; among unrecovered catalog entries within our footprint, we find no Pan-STARRS DR1 counterpart within 3 arcsec. Applying Bruehl and Villarroel (2025)-style temporal windows to this catalog over the 368 POSS-I observation nights in the 1949-1957 interval gives a post-test calendar-day relative risk of 1.35 for the +1 day window, but the effect is not statistically significant (95% CI 0.91-2.00; two-sided Fisher p = 0.17) and is sensitive to coding unobserved days as zero-transient days. A negative binomial model of nightly candidate counts with nightly patch coverage as exposure is likewise null (IRR = 1.03, 95% CI 0.89-1.18, p = 0.71). The catalog-level replication is strong; the temporal association remains inconclusive.
Read the full abstract

Solar and Stellar Astrophysics

Flare Impulsive-phase Durations

Brian R. Dennis, Hugh Hudson and Joel Allred

This Research Note is in response to the recent paper by S. M. Perriyil et al. (2026). They provide measurements of the time delay (delta t) between the hard X-ray and soft X-ray peak times for 96 flares observed with RHESSI and GOES. These delays are found to be dependent on the length of 9 the magnetic loop(s) joining the HXR footpoints seen in RHESSI images. We offer a possible explanation for this coincidence in terms of the duration of the electron beam heating, commonly inferred from the duration of the HXR emission, and the time taken for heated plasma to rise to the loop top as inferred in this paper from delta t. We suggest that the particle acceleration occurs at or near the top of the loop(s) and that it is quenched by the increase in density as the heated plasma reaches the acceleration site.
Read the full abstract

Astrophysics of Galaxies

Galaxy populations in groups and clusters-II. Conditional luminosity functions at redshifts from z~1 to z~0

Ce Gao, Cheng Li, Houjun Mo et al. (+5 more)

Using DESI SV3 spectroscopic group centrals and HSC photometric data, we measure conditional luminosity functions (CLFs) of central and satellite galaxies for red and blue populations in dark matter haloes spanning $M_h\sim10^{12}- 10^{15}M_{\odot}$ and $0<z<1$. HSC depth permits measurements to $M_r \approx -15$ at $0.2 \leqslant z < 0.5$ and $M_r \approx -17$ at $0.5 \leqslant z < 1.0$. We find satellite CLFs evolve weakly over $0<z<1$. Blue satellite CLFs are well described by a single Schechter function across halo masses and redshifts, with a nearly constant slope of $-1.25\lesssim \alpha\lesssim -1.2$. In contrast, red satellite CLFs exhibit a pronounced faint-end upturn in all halo mass and redshift bins, with little evolution in the faint-end slope ($-1.8\lesssim \alpha_f\lesssim -1.7$). The low-mass red sequence was therefore already established in clusters/groups by $z\sim1$. The lack of faint-end-slope evolution favors models where the steep upturn originates from early formation processes at $z\gtrsim2$, rather than environmental quenching after infall. Satellite characteristic magnitudes and central galaxy luminosities fade with time. Red central galaxies are consistent with passive evolution, whereas blue-central luminosity evolution is dominated by ongoing star formation. Satellites evolve more rapidly than predicted by simple stellar population models, highlighting environmental effects. Satellite quenched fractions as a function of stellar mass exhibit a minimum at $M_{*} \sim 10^9M_{\odot}$ that is consistent across halo masses and redshifts. We discuss possible interpretations of these results and their implications for galaxy formation and evolution.
Read the full abstract

All authors Ce Gao, Cheng Li, Houjun Mo, Jiacheng Meng, Qinglin Ma, Xiaohu Yang, Yizhou Gu, Qingyang Li

High Energy Astrophysical Phenomena

Constraining the PeV gamma-ray emission zone of Cygnus X-3 with contemporaneous GeV timing and spectral observations

Xing-Fu Zhang, Ruo-Yu Liu, Dmitriy Khangulyan et al. (+2 more)

Cygnus X-3 has recently been established as a variable ultra-high-energy(UHE) gamma-ray source with photons detected up to 3.7~PeV. The temporal correlation between its PeV activity and GeV flares, together with the possible orbital modulation, suggests that the emission is produced within or close to the binary system. In this work, we test whether the contemporaneous GeV emission zone can also host the acceleration of the parent protons responsible for the multi-PeV photons. We jointly model the contemporaneous Fermi-LAT spectrum and orbital light curve with a one-zone leptonic scenario dominated by anisotropic external inverse-Compton scattering. The fit places the GeV emission region at $H\sim2.8\times10^{11}\,$cm and constrains the magnetic field–size product to $BH\lesssim10^{13.3}\,$G\,cm at the $3\sigma$ level. This implies a maximum proton energy of only $\sim0.3$~PeV from the Hillas criterion, far below that required by the observed PeV emission. We therefore conclude that the GeV zone cannot be the main PeV acceleration site. Instead, the PeV emission should originate from a more compact inner region, and the jet magnetic field must dissipate rapidly between the PeV and GeV emitting zones.
Read the full abstract

All authors Xing-Fu Zhang, Ruo-Yu Liu, Dmitriy Khangulyan, Cui-Yuan Dai, Xiang-Yu Wang

Instrumentation and Methods for Astrophysics

Enhancing astrometric registration of Chinese historical Astronomical Digital Plates with deep learning

Quanfeng Xu, Zhengjun Shang, Shiyin Shen et al. (+6 more)

China has systematically collected nighttime astronomical plates since 1900, creating a large historical dataset that has been digitized with optical scanners. For astrometric registration of these digitized plates, sources were first extracted using SExtractor, and then matched astrometrically with Astrometry.net and the Gaia catalog. However, suboptimal early storage conditions and subsequent environmental deterioration have impeded accurate source matching, resulting in processing failures for several thousand digitized plates. In this work, we introduce a Transformer-based classification model that takes cutouts of SExtractor-detected sources as input and leverages multi-scale feature fusion to identify trustworthy stellar sources on the plates. Trained on plates with successful astrometric calibration, our AI-based classifier was then applied to SExtractor detected sources of 1883 digitized plates, enabling us to complete the astrometric registration for 1353 of them. This AI-augmented pipeline streamlines the processing of historical plate archives and enhances their scientific value for long-term time-domain astronomical studies.
Read the full abstract

All authors Quanfeng Xu, Zhengjun Shang, Shiyin Shen, Yong Yu, Meiting Yang, Hao Luo, Zhenghong Tang, Jing Yang, Jianhai Zhao

High Energy Astrophysical Phenomena

On the transformation of the Maxwell-Boltzmann Distribution to a Power-Law

Ari Laor and Igor Gitelman

Power-law (PL) distribution functions (DF) are prevalent in highly diverse systems. The systems range in size from nanometer to mega light years, in complexity from dust grains to living organisms, and characterize the distribution of various events in nature and in various human activities. To gain some insight on why PL DF are so prevalent, we explore the conditions leading to the formation of a PL DF in a simple system of colliding hard sphere. We follow the time evolution of the energy DF through direct Monte Carlo simulations. In statistical equilibrium, the DF evolves into the Maxwell-Boltzmann (MB) DF. A transition to a PL DF occurs when: 1. The system is initially far from equilibrium. For example, a mix of light and heavy particles with the same velocity. 2. The system dynamics is scale-free, which holds in the intermediate asymptotic regime, far from the initial and the final equilibrium states. The scale-free dynamics leads to a DF which evolves in a self-similar form. 3. The system is open with a scale-free boundary condition. For example, a constant injection of particles far from equilibrium. The DF PL index is set by the time dependence of the self-similar DF and by the boundary condition. The PL index is independent of the self-similar DF form. Conditions 1-3 are common in a great variety of systems, which may explain why PL DF are so prevalent in nature.
Read the full abstract

Solar and Stellar Astrophysics · Cross-listed from gr-qc

Preliminary study on the impact of stress-energy tensor compared to scalar field in Nonminimal Derivative model

Ilham Prasetyo, Bobby Eka Gunara and Agus Suroso

In this article, we report the results of comparing the effect of using trace of stress-energy tensor versus real-valued scalar field in Nonminimal Derivative Coupling gravitation model, respectively denoted as NMDC-T and NMDC-phi. We employ the model into an incompressible star and see the effect of both models NMDC-T and NMDC-phi on the compactness and mass-radius relation. We find that coupling parameters of NMDC-T is less sensitive than NMDC-phi.
Read the full abstract

2604.04617 · 6 Apr · 13 pages, 5 figures. This is a preprint, prior to copyediting, of an article accepted in Modern Physics Letters A, copyright World Scientific Publishing Company, on March 31, 2026. This is a part of papers related to IP's presentation in Southeast Asian Workshop on Nuclear and Hadron Physics (SEA-NHP), UGM, Indonesia https://indico.global/event/13949/page/4743-proceeding

Abstract PDF $STAR ×1