Astrophysics papers — 2026-10-16

The Morning Preprint — this day as one edition: the day's papers, the five things worth knowing, and the episodes behind them.

Today we are diving into the high-energy astrophysics of black holes because understanding where neutrinos come from is key to probing extreme environments. The work on identifying supernovae in active galactic nuclei accretion disks, AKMPC, is central to this effort as it seeks to detect these transient events. This detection builds upon the broader context of high-energy observations from missions like the Dark Matter Particle Explorer (DAMPE), Dark Matter Particle Explorer: Ten-Year On-Orbit Performance and Scientific Outcomes, which is designed to look for cosmic rays and gamma rays up to ten TeV.

We also have research into the physics around supermassive black holes, specifically concerning neutrino production near NGC 1068. This study uses updated IceCube data to constrain where neutrinos might originate. It finds that the emission region is quite tightly limited, excluding certain radii based on statistical constraints. Furthermore, the identification of this source helps us understand particle acceleration mechanisms. They suggest stochastic acceleration is the most natural fit for producing these neutrinos.

In parallel, we are looking at how planetary systems maintain stability through orbital mechanics. The work on orbital stability of apsidally aligned planetary systems investigates how a systematic component in eccentricity affects long-term stability. It shows that coherent apsidal precession provides a protective mechanism against chaos. This dynamical insight contrasts with the work on gas tracers in galaxies, where ALMA observations toward M83 show that N2H+ is more sensitive to dense gas than previously thought.

The characterization of dust activity evolution in interstellar comets is crucial because it helps us understand the physical processes that govern how these icy bodies interact with their environment before and after they pass close to the sun. This work by AKMPC shows that before perihelion, the effective scattering cross section brightened across a region of two times ten four kilometers because it was proportional to r H-gamma. Gamma increased from one point six three plus or minus zero point one four to one point eight eight plus or minus zero point three four as the aperture size changed.

This implies that the implied dust mass-loss rates are about one hundred twenty-three to two hundred three kilograms per second before perihelion. After perihelion, these rates are about five hundred ninety-six to one thousand four hundred twelve kilograms per second. The morphology derived from this study suggests a sunward ejection speed scale of approximately one nine zero plus or minus three a micrometers per square meter per second. It also suggests an effective perpendicular velocity of seventy nine plus or minus six a micrometers per square meter per second.

This is followed by the analysis in Post-perihelion dust activity and a candidate icy-grain halo in long-period comet C/2023 A3 (Tsuchinshan--ATLAS. This examines the post-perihelion coma of the Great Comet of two thousand twenty four to assess the contribution of sublimating icy grains to a candidate near-nucleus halo. This analysis found that the effective dust cross section decreased by a factor of two point four, following C e proportional to r h minus three point one.

The dust mass production rate scaled as d proportional to r h minus three point four one, which is consistent with activity driven by water ice. The thermophysical sublimation calculations suggest that this scale of fading, combined with the order of magnitude of water production near the main imaging epoch, is consistent with zero about five to ten micrometers icy grains containing a small absorbing carbonaceous fraction of f C about zero point one percent. This finding links to the results in AKMPC by suggesting that the early post-perihelion coma likely contained a short-lived, volatile-bearing icy-grain component whose fading contributed to the outer-coma brightness and color evolution.

Furthermore, observations of supernova candidates with the ILMT in Optical observations of supernova candidates with the ILMT report the discovery of six supernova candidates using this telescope. These results provide light curves for these transients in the gri spectral bands. These results are distinct from the dynamical studies presented in Model-independent parameters from DESI DR1 LRG2 with an explicitly varying power-spectrum shape, which used an emulator to constrain dark energy and modified gravity parameters using measurements of cosmic distances and structure growth.

The work concerning polarization properties of Thomson-scattering triaxial ellipsoids is particularly important because it offers a simple physical understanding of how polarization depends on photospheric geometry. This study found that strongly deformed spheroids show a non-monotonic dependence on viewing angle, a behavior not seen in previous work.

The research into molecular gas flows in Abell 1795's central galaxy is also significant because it provides new constraints on the molecular gas mass and conditions within extended filaments near active galactic nucleus jets. Using the low-opacity tracer 13 CO(2-1), this study determined a filament molecular gas mass of one to two times ten to the ninth solar masses. This implies a much lower CO-to-H 2 conversion factor than standard assumptions suggest. This finding suggests that direct entrainment by radio bubbles is plausible because it provides enough mechanical energy for the molecular gas flow.

The survey of brown dwarfs and planetary-mass objects in Taurus is relevant because it settles the binary frequency for planetary-mass objects at young ages. This suggests that wide-orbit binaries are inefficient and are likely disrupted very early in a low density environment. This work shows that companion candidates down to one million Jupiter masses can be found, with a binary frequency less than six point five percent in the relevant mass ratio range.

The analysis of GRB 251222A connects prompt emission and afterglow features by considering a multiple-shell scenario where faster ejecta catch up to slower ones. This investigation yielded an energy release estimate and a dynamical dissipation efficiency, allowing for testing a prompt-afterglow connection through shell collisions.

The ALMA observations of neutron stars are crucial because they offer the first systematic exploration of the millimeter-wavelength spectral window for pulsars and fast radio transients. This opens avenues to discover new phenomena and test fundamental physics near supermassive black holes. This work seeks to unveil the neutron-star population in the Galactic Centre and probe dark matter existence there.

The clump population framework for star formation across galactic scales is important because it establishes an observationally grounded connection between star formation in the Milky Way and external galaxies. It shows a consistent molecular gas mass to star formation rate relation across many orders of magnitude. This framework suggests that star formation occurs within dense clumps embedded in molecular clouds, explaining the nearly universal relation observed across different environments.

The most significant work here is exploring how modified gravity and inertia theories can reconcile with MOND phenomenology, as this touches on fundamental physics beyond Newtonian limits. The paper by Mixed modified-gravity--modified-inertia MOND theories investigates families of nonrelativistic MOND theories that modify both kinetic and gravitational actions. It shows how their combination can reproduce key MOND predictions like asymptotic flatness and the mass-asymptotic-speed relation.

This is important because it shows that different theoretical structures can lead to the same observable outcomes in astrophysics. Less central but still relevant is the work by Extracting the Central Sound Speed of Neutron Stars through Intrinsic Stellar Structure Scaling with Reduced Equation-of-State Model Dependence. This uses intrinsic stellar structure scaling to constrain neutron star core properties by finding an EOS-independent estimator for the central squared sound speed.

Another piece that provides context on probing astrophysical structures is Minkowski Functionals of CII Line Intensity Maps: Probing Astrophysics and Primordial Features. This uses Minkowski functionals on mock intensity maps to constrain astrophysical model parameters while also looking for potential primordial features in the power spectrum. This work connects observational morphology to underlying cosmological structure.

Finally, the work by From Scaling Relations to Physical Laws: Constraining the Physics of Star Formation Across Local Galaxies addresses the fundamental problem of how cold gas converts into stars. It suggests that future facilities like ALMA2040 will allow us to move beyond empirical relations toward a predictive theory of this process.

The most significant piece of work addresses how to accurately measure interstellar features in binary star spectra. Traditional template matching methods often fail when dealing with complex stellar line contamination. The MCMC-RVSD algorithm allows researchers to separate stellar lines from diffuse interstellar bands by exploiting the fact that stellar lines shift with radial velocity while DIBs stay fixed in their rest frame. This method proved highly effective, recovering parameters for DIB lambda six sixty one four and performing reliably across various spectral resolutions and noise levels when applied to real binary sources.

This precise separation technique is complemented by studies looking at how different numerical methods affect simulations of solar coronal heating. Investigations using the MAGEC code showed that domain height, vertical grid design, and boundary conditions critically dictate the relaxed thermal structure and energetic balance of these 2D simulations.

Another area where computational methods are being refined is in simulating chaotic planetary system evolution. Researchers developed an almost exactly time-reversible direct N-body integrator called MTR. This integrator allows individual pairs of planets to use their own variable timesteps, which helps resolve close encounters without violating desirable properties like symplecticity or reversibility.

In the realm of astrophysics observations, analysis of nascent planetary nebulae provides important clues about stellar evolution pathways. Intermediate- and high-resolution optical spectroscopy on Vy 2-2 revealed chemical abundances and a new value for the abundance discrepancy factor, suggesting this nebula belongs to a group with unusually high ADFs. This analysis also pointed toward a post-common-envelope binary system, linking its structure to the formation process of stars like the progenitor of Vy 2-2.

Finally, work on Active Galactic Nuclei catalogs is refining how we categorize these objects based on their mass and star formation activity. A comprehensive AGN inventory cataloged Active Galactic Nuclei in RESOLVE and ECO surveys. This shows that the occupation fraction of AGN shifts significantly as baryonic mass increases, indicating a continuum of classifications from star-forming to conventional AGN.

The work on constraining the gravitational constant at recombination is particularly important because it directly tests fundamental physics during the early universe. This investigation uses a modified version of CLASS to see how a variation in G affects acoustic scales and dark ages ionization. It finds that while the equality scale and acoustic scale are nearly independent of G, non-equilibrium recombination shows a damping proportional to lambda g minus zero point three zero four.

This dependence only appears above a critical value set by fundamental parameters, which is about forty-nine times below the laboratory value of G N. This result isolates the effect of gravity at recombination by comparing the damping scale to the acoustic scale, up to lensing and screening effects. This comparison allows researchers to directly compare G at that epoch with its modern laboratory value.

The mission market concept is also relevant as it addresses the practical challenges in funding science. It suggests that an advance market commitment can fly lower cost missions without competing for federal appropriations, primarily fueled by capital flowing into artificial intelligence companies. This funding mechanism complements traditional sources like philanthropy and patron-scientists.

Solar observations provide detailed insights into solar activity. The investigation of an X class flare and quasi periodic pulsations in NOAA AR 13842 using SDO, Aditya-L1 and Solar Orbiter reveals intricate magnetic configurations including a flux rope and sheared arcade. The presence of recurrent magnetic reconnection inside the arcade and at the hyperbolic flux tube is speculated to be what causes these quasi periodic pulsations.

Stellar mass census of S 4G local bars offers a physically motivated way to assess how bar growth depends on galaxy mass and internal structure by decomposing mid-infrared data from 344 barred galaxies. The study found that more massive galaxies with prominent bulges host more massive bars and higher median bar to total stellar mass ratios. This suggests different evolutionary pathways across various galaxy mass regimes.

Dark matter in the Galaxy insights from the dynamics of stellar streams examine how stream morphology and kinematics can constrain the Milky Way's dark matter halo structure using tracers like Sagittarius, GD-1, Palomar 5, Orphan-Chenab, and Cetus Polar. These studies utilize analytical, statistical, and Bayesian methods to infer dark matter properties while confronting challenges like parameter degeneracies.

A sample of thick disk stars hosting hot Jupiters provides a catalog of confirmed and candidate transiting hot Jupiter host stars by combining high-resolution TRES spectra with Gaia astrometry. The analysis classifies these stars based on their alpha/Fe and Fe/H ratios, finding potential differences in giant planet formation across galactic environments.

A new method for constraining 3D exoplanet atmospheres applies to WASP-94A b's panchromatic spectrum by using the temporal signature of limb asymmetry instead of fitting transit depths. This framework reduces the mean squared error on retrieved molecular abundances by factors of about thirty to fifty compared to alternative approaches.

The work concerning the identification of deformed exoplanets with JWST and Ariel is particularly important because it provides a new way to probe the deep interiors of planets by measuring their Love numbers. This measurement relies on quantifying how much a planet deforms under stellar tidal forces. This research introduces a new deformation metric called the deformation metric D to select the most promising targets for this science case.

This study first applied this metric to the Ariel target list and highlighted WASP-33 b, WASP-76 b, and HAT-P-32 b as the top three candidates that currently lack Love number measurements. Using WASP-76 b as a reference point, end to end retrieval simulations demonstrated that a single continuous JWST phase curve observation could constrain the Love number h 2f to a precision of about 0.09. A single Ariel visit could achieve about 0.18 for the same parameter. This level of precision is thought to be sufficient for meaningful constraints on planetary interior models and can help distinguish between different internal structure scenarios, opening up a new observational avenue for probing exoplanet interiors.

The characterization of comet P/2026 N2 provides insight into sustained activity in the outer Main Belt. Observations from the Legacy Survey of Space and Time at the Vera C. Rubin Observatory and Keck/LRIS imaging are consistent regarding its active morphology over a period spanning July nine to October seven. This sustained activity suggests prolonged or recurrent dust production near perihelion, which researchers hypothesize is driven by volatile sublimation, possibly of water ice.

The analysis of the Parsec-scale Circumstellar Shell Around VX Sgr reveals that the arc-shaped shell surrounding this red supergiant exhibits a mass-loss rate estimated at about four times ten to the fifth solar masses per year. The slow peculiar velocity and lack of far infrared emission suggest this material is steady RSG wind or ejecta photoionized by a nearby O or B type star, rather than being produced by a bow shock.

The JWST observations of RR Lyrae in Leo P offer an opportunity to explore metal-poor RR Lyrae studies using well understood relationships from past HST work. By fitting the Period-Wesenheit-Metallicity function to the HST population and simultaneously fitting a JWST-based PWZ, the study found that this combined approach decreases the mean fractional uncertainty on both the slope and intercept by thirty one percent and eleven percent, respectively.

The impact of high mass clusters on binary black hole merger rates shows that local cluster mergers are dominated by low mass mergers originating from recently formed, high metallicity clusters. While high mass clusters drive hierarchical mergers, their contribution to the overall rate is suppressed by an exponential cutoff in the cluster initial mass function. This suggests that gravitational wave constraints can independently constrain the high mass end of this initial mass function.

The most important finding relates to how dark matter and baryonic gas interact in galaxy evolution because it directly informs models of structure formation. The NSphere-IDM code allows researchers to numerically evolve systems including dark matter-baryon scattering and radiative gas cooling. This work shows that the added complexity of scattering and cooling only incrementally increases the simulation time needed, meaning complex physics can be explored on standard laptops.

This capability builds upon the work by Efficient numerical evolution of self-gravitating systems with dark-matter-baryon scattering, which demonstrates how to incorporate these interactions into a fast N-body code. Furthermore, the study in HI rotation curves and mass-size relation for 568 galaxies from the Apertif Wide-area Extragalactic Survey provides vital kinematic models of HI disks, showing that these disks have a very tight mass-size relation with an inferred intrinsic scatter of only 0.067 dex.

The implications for galaxy growth are further explored by Wandering intermediate-mass black holes and off-nuclear tidal disruption events from early star clusters. This uses merger trees from the IllustrisTNG TNG50 simulation to predict off-nuclear tidal disruption events resulting from runaway stellar collisions in dense star clusters. This connects to the study of galaxy assembly by The Pristine survey XXIX. Data Release 2: Photometric metallicities for 15 millions stars down to G about 20.5, which provides photometric metallicities for faint stars in the Milky Way halo, offering constraints on stellar populations that feed into larger galaxy models.

Finally, the cosmological context is shaped by work such as The unified Bound Dark Energy--Bound Dark Matter model: theory and constraints from DESI DR2. This fits the BDE-BDM model to various cosmological data, suggesting that current datasets constrain nonlocal gravity close to the standard Lambda CDM limit.

Today's papers

The papers

Important terms

Supermassive Black Hole Neutrino Production
Research uses IceCube data to constrain where neutrinos come from near supermassive black holes like NGC 1068, suggesting stochastic acceleration is the natural mechanism for producing these particles.
Dust Activity Evolution in Comets
Studies show how dust production rates change in comets, linking activity before and after perihelion to water ice sublimation. This helps determine the physical processes governing icy body interaction with their environment.
Orbital Stability and Apsidal Precession
Investigating planetary systems, this work shows that coherent apsidal precession acts as a protective mechanism against chaotic instability, maintaining long-term orbital stability in aligned systems.
Modified Gravity and MOND Theories
This research explores how modified gravity theories can reconcile with MOND phenomenology by modifying kinetic and gravitational actions. This tests fundamental physics beyond standard Newtonian limits.