Astronomy & Astrophysics最新文献

{"title":"Estimating redshift distributions of Fermi blazars with multiple machine-learning models","authors":"Kerui. Zhu,Jiaming. Chen,Yonggang. Zheng,Ruixin. Zhou,Shan. Chang,Li. Zhang,Niansheng. Tang","doi":"10.1051/0004-6361/202659451","DOIUrl":"https://doi.org/10.1051/0004-6361/202659451","url":null,"abstract":"Approximately half of the Fermi-LAT-detected blazars lack spectroscopic redshift measurements, which limits population studies and investigations of the cosmological evolution of the gamma-ray blazar population. We aim to develop a multi-model ensemble framework to systematically evaluate the performance of machine-learning models for blazar redshift estimation and provide predictive redshift probability distributions with quantified uncertainties for all blazars with unknown redshifts. We constructed an ensemble of 35 machine-learning regression models in the space. We combined predictions from the individual models to build nonparametric redshift probability density functions (PDFs) for each source, thereby explicitly characterizing the predictive uncertainty. We then stacked the source-level PDFs to derive population-level redshift distributions. We find comparable predictive performance across the diverse models within our framework, indicating a feature-limited performance plateau. We compiled a catalog of predictive redshift distributions for 1590 blazars without measured redshifts. The stacked PDFs recover the characteristic double-peaked redshift structure of blazars without using source-class labels. For blazar candidates of uncertain type, the predicted redshift distribution exhibits a bimodal structure, suggesting a slightly larger contribution from FSRQ-like sources. Our multi-model statistical framework achieves competitive predictive performance while retaining faint sources. We provide predicted redshift distributions with quantified uncertainties for 1590 blazars without measured redshifts, offering improved support for population and evolutionary studies. More broadly, this approach highlights the practical value of uncertainty-aware multi-model regression ensembles in astronomical data analysis.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"18 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D simulations of magnetospheric accretion in T Tauri stars I. Disk truncation, stellar torques, and application to observations","authors":"G. Pantolmos,C. Zanni,J. Bouvier","doi":"10.1051/0004-6361/202659929","DOIUrl":"https://doi.org/10.1051/0004-6361/202659929","url":null,"abstract":"Young stars accrete material from their circumstellar disk through their magnetosphere and undergo contraction, these two processes impact their rotational evolution. We investigate stable and unstable magnetospheric accretion regimes attributed to the development of an interchange instability in the disk truncation region. We examine the associated stellar torques to assess the spin evolution of young stars. We performed 3D magnetohydrodynamic (MHD) simulations of disk accretion onto an inclined stellar dipole. We ran 21 simulations with varying stellar rotation rates, dipole field strengths and obliquities, and mass accretion rates. For each simulation, we estimated the disk truncation radius, a critical quantity to determine the accretion regime and the star-disk angular momentum transfer. We also computed the torques that dictate the stellar spin evolution. We find that stars with a ratio of truncation-to-corotation radius of R_t/R_ co accrete through a stable regime, whereas accretion becomes unstable otherwise. In addition, our R_t/R_⋆ parametrization weakly depends on the mass accretion rate and the dipolar intensity, while strongly depending on the stellar rotation rate. We derived torque formulae for each flow component affecting the stellar rotation; namely, accretion, magnetospheric ejections, and stellar winds. Finally, we applied our results to a sample of young stars with measured magnetic fields, mass accretion rates, and rotational periods. We find that most of them should currently accrete in an unstable regime and undergo spin-up torques. Our study confirms and expands upon previous results. Unstable accretion should lead to a net spin-up torque on the central star, while stable accretion can lead to stellar spin-down. When applying our truncation radius and torque prescriptions to observational data, we find that most young stars in our sample should be in a spin-up state. Thus, for young stars, which are slow rotators in spite of accretion and contraction, the angular momentum problem remains.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"JWST detection of methane emission from a young brown dwarf","authors":"K. L. Luhman,C. Alves de Oliveira,J. K. Faherty,B. C. Smith","doi":"10.1051/0004-6361/202662704","DOIUrl":"https://doi.org/10.1051/0004-6361/202662704","url":null,"abstract":"In recent studies, we used low-resolution spectroscopy (R∼100) with the James Webb Space Telescope (JWST) to uncover low-mass brown dwarfs (2--10 M_ Jup) in the young cluster IC 348 that exhibit the so-called 3.4 μm absorption band from aliphatic hydrocarbons. Atmospheric models have not predicted the presence of that band in brown dwarfs at any age. Instead, methane absorption is expected in the coolest newborn brown dwarfs, but it was not detected. We have performed JWST spectroscopy at a higher resolution (R on one of the brown dwarfs in IC 348, LRL 11001 (sim6 M_̊m Jup). The new measurement of the 3.4 μm band is fit well with four Gaussians that represent the CH stretching modes of CH_2 and CH_3 groups, indicating that the carrier is a large alkane (C_nH_2n+2). In addition, the spectrum contains emission lines at 3.324 and 3.333 μm, which we attribute to Q branches of CH_4 hot bands between the octad and dyad regions (primarily ν_3+ν_4̊ightarrowν_4) and the tetradecad and pentad regions. This is the first detection of 3.33 μm CH_4 emission from a young brown dwarf. The emission probably arises from the photosphere rather than a circumstellar disk given that no disks around stars or brown dwarfs are known to exhibit emission in these transitions. Modeling of the emission is needed to constrain the excitation mechanism, which could be either thermal (e.g., an accretion shock) or pumping by external radiation (e.g., neighboring cluster members). We speculate that vertical mixing has suppressed CH_4 and enhanced large alkanes in the photosphere, but CH_4 survives in the upper atmosphere, where it is available to experience the observed emission.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"8 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A three-dimensional exploration of magnetic fields, rotation, and shock revival in a 39 M⊙ core-collapse supernova progenitor","authors":"Liubov Kovalenko,Evan O'Connor,Haakon Andresen,Sean M. Couch","doi":"10.1051/0004-6361/202660993","DOIUrl":"https://doi.org/10.1051/0004-6361/202660993","url":null,"abstract":"We present three-dimensional hydrodynamic and magnetohydrodynamic core-collapse supernova simulations of a rapidly rotating, high-compactness 39,M_⊙ progenitor to investigate the roles of rotation and magnetic fields in shock revival and outflow morphology. This study is designed to separate neutrino-driven expansion, rotation-induced deformation, and magnetically aided polar outflow within the same progenitor. We evolved three models: a non-rotating hydrodynamic baseline, a rotating hydrodynamic model, and a rotating magnetised model. All three models reach runaway shock expansion within the simulated interval, but with markedly different morphologies and timescales. The magnetised model revives first and develops the clearest bipolar outflow. The rotating non-magnetised model undergoes the latest shock revival and remains comparatively compact at the end of the simulation. The non-rotating model also undergoes shock revival but subsequently collapses to a black hole about one second after core bounce. In the magnetised model, Maxwell stresses redistribute angular momentum and extract energy from the differential rotation of the proto-neutron star, reducing the inner-core spin and helping channel rotational free energy into the emerging polar outflow. Neutrino emission provides an additional, though smaller, angular-momentum sink in both rotating models. We find that rapid rotation and strong magnetic fields can launch an early magnetically aided polar outflow in 3D, while the resulting dynamics remain intrinsically non-axisymmetric. In this extreme progenitor, rotation also provides significant support against prompt black hole formation, although the longer-term remnant stability remains uncertain beyond the simulated interval.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"89 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of cosmic-ray acceleration on the early evolution of bow shocks around massive runaway stars","authors":"K. Watanabe,S. Walch,T.-E. Rathjen,J. Mackey,P. C. Nürnberger,P. Girichidis","doi":"10.1051/0004-6361/202557689","DOIUrl":"https://doi.org/10.1051/0004-6361/202557689","url":null,"abstract":"Bow shocks generated from the interaction of winds from massive runaway stars with the interstellar medium have been shown to be prominent particle accelerators through recent γ-ray and radio synchrotron observations. They are ideal candidates for exploring the space- and time-dependence of particle acceleration due to their axisymmetric morphology and short dynamical timescales (∼ 100 kyr). Current studies on the particle acceleration from bow shocks investigate the cosmic-ray (CR) transport only in the test-particle limit. We aim to bridge this gap by conducting ideal cosmic-ray magnetohydrodynamic simulations in the advection-diffusion limit that accelerate CRs at spatially resolved shocks at each timestep. We qualitatively compared with current observations through the expected γ-ray and synchrotron emission. We performed 3D ideal cosmic-ray magnetohydrodynamic simulations with the Eulerian grid-based code FLASH, where stellar winds are injected through tabulated wind velocities and mass-loss rates. We implemented a gradient-based shock-detection algorithm to resolve the shocked regions where the CRs are injected dynamically. Simulations were performed for different values of the CR diffusion coefficient and star velocities within an ISM-like environment up to 500 kyr to show the impact of dynamical CR injection on the early evolution of the wind-driven bow shock. With a simplified spectral model in post-processing, we calculated the expected upper limits of γ-ray and synchrotron emission and compared the results with those from current observations. Variations of CR diffusion rates can strongly dictate the morphology of the bow shock and the overall γ-ray and radio synchrotron luminosity due to the balance between the CR injection efficiency and diffusion. Our results are underestimated compared to those from current observations, even with an overestimated particle acceleration, primarily due to the weaker wind kinematic luminosities we used and the lack of a stellar magnetic field in our model. The morphology of wind-driven bow shocks and their non-thermal emission can be substantially affected by CR acceleration and diffusion, if there is efficient particle acceleration at shocks.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"183 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution of the morphology-density and morphology-mass relations of quiescent galaxies at 0.5 {2}lt;z<$ 2.5 in the COSMOS-Web survey","authors":"Guanwen Fang,Yuguo Su,Shiying Lu,Zesen Lin,Xu Kong","doi":"10.1051/0004-6361/202661025","DOIUrl":"https://doi.org/10.1051/0004-6361/202661025","url":null,"abstract":"Within the lambda cold dark matter (ΛCDM) cosmological framework, the interplay between galaxy morphology, stellar mass, and environment remains uncertain at z&gt;1. To clarify their relative roles, we analysed quiescent galaxies (QGs) selected via near-ultraviolet (NUV)-r-J colour criteria from a mass-complete parent sample of 0.5 &lt; z &lt; 2.5 galaxies in the COSMOS2025 catalogue. Galaxy morphologies were determined using a machine learning-based classification that combines unsupervised and supervised learning methods applied to JWST/NIRCam imaging. Local environmental densities were estimated using an improved Bayesian method to examine how the fraction of early-type galaxies (ETGs) among QGs varies with stellar mass, environment, and redshift. We find a strong dependence on stellar mass: at all redshifts, the ETG fraction increases with stellar mass, exhibits a pronounced morphological transition in the mass range 10^ 9.0 M_⊙ to 10^ 10.3 M_⊙, and then approaches a plateau around M_* ∼ 10^ 10.3 M_⊙. Environmental effects show a clear redshift evolution. At z łesssim 1.5, low-mass QGs exhibit a significantly higher ETG fraction in dense regions, indicating a stronger environmental dependence of their morphological mix at the population level. At z &gt; 1.5, this dependence becomes weak or absent, suggesting that internal mechanisms dominate morphological evolution in the early Universe. High-mass systems remain largely early-type regardless of environment. These results indicate that stellar mass primarily governs the morphological composition of the quiescent galaxy population, while environmental influence emerges later and mainly affects low-mass QGs.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"146 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149955","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water-rich sub-Neptunes and rocky super-Earths around different stars: Radii shaped by volatile partitioning, formation, and evolution","authors":"Remo Burn,Komal Bali,Caroline Dorn,Rafael Luque,Simon L. Grimm","doi":"10.1051/0004-6361/202452905","DOIUrl":"https://doi.org/10.1051/0004-6361/202452905","url":null,"abstract":"Despite precise characterization measurements, the nature of planets with radii between 2 and 4 Earth radii -- sub-Neptunes -- remains unknown due to degeneracies in interior models. Nevertheless, the field has compiled an impressive ensemble of small planets with measured masses and radii orbiting different stars. This dataset can be used to test the prediction of large water reservoirs on sub-Neptunes, as proposed by planet formation theory with orbital migration. We aim to determine whether this water reservoir is included in photoevaporative winds and how much of it can partition into the rocky and metallic interior. We coupled the results of a planetary formation model with planetesimal and gas accretion as well as orbital migration with evolution models that assume either perfect mixing of water with H/He in the envelope or complete segregation. For the mixed envelopes, we also included an analytic treatment of fractionation during photoevaporative mass loss. Furthermore, we studied the effect of equilibrium dissolution of water into an assumed magma ocean and metallic core for the first time in coupled formation-evolution models. Out of the tested scenarios, the mass-radius relation of exoplanets is relatively well matched by all scenarios where the atmosphere is of mixed composition. The agreement depends on mass, with better consistency for the model without dissolution below 3 Earth masses and hints of the opposite at higher masses. Fractionation is not found to significantly alter the properties of the planets for our initial conditions due to initially massive envelopes on all planets. For all scenarios, we quantified the radius valley location and its scaling with stellar mass. The mass--radius relations for water-rich sub-Neptunes are broadly consistent with observations. However, statistical surveys in both mass and radius are required to distinguish between the scenarios. The mixed-composition loss of different volatiles, their dissolution into the planetary interior, and the solidification of the magma ocean are natural next steps toward a comprehensive atmosphere-interior evolution model.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149150022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Astrometric planet search around southern ultracool dwarfs. V. Discovery of the exoplanet candidate PALTA-1 b","authors":"J. Sahlmann,P. F. Lazorenko,E. L. Martín,D. Ségransan,M. Mayor,S. Udry","doi":"10.1051/0004-6361/202660121","DOIUrl":"https://doi.org/10.1051/0004-6361/202660121","url":null,"abstract":"We report the discovery of ,M_̊m Jup, depending on the uncertain mass of the ultracool dwarf host. The system's mass ratio is about 0.010, and the relative separation is estimated at 1.6--3.4 au. This discovery finalises a larger astrometric planet search survey that targeted 20 nearby ultracool dwarfs and previously discovered three new ultracool binary systems. a sub-Jupiter mass exoplanet candidate orbiting the nearby early-L dwarf DENIS-P J1253108-570924 ( over more than eight years and characterising the deviations from the expected single-source motion. The estimated planet mass is between 0.54,M_̊m Jup and located at a distance of ∼17 pc. The exoplanet was discovered by monitoring the L dwarf's astrometric motion with FORS2 at the Very Large Telescope 0.77 If confirmed, would be one of the very few known examples of a giant planet orbiting a nearby ultracool dwarf.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"9 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"GA-NIFS: The interplay between feedback and star formation at 3 < z < 9 probed by JWST/NIRSpec IFU","authors":"L. Ulivi,M. Perna,S. Arribas,B. Rodríguez Del Pino,P. G. Pérez-González,I. Lamperti,C. Marconcini,H. Übler,F. D'Eugenio,T. Böker,A. J. Bunker,S. Carniani,S. Charlot,R Maiolino,P. Alvarez,E. Bertola,G. Cresci,M. Curti,M. Hamed,L. R. Ivey,G. C. Jones,E. Parlanti,R. Pascalau,C. Prieto Jimenez,B. Trefoloni,G. Venturi,S. Zamora","doi":"10.1051/0004-6361/202661424","DOIUrl":"https://doi.org/10.1051/0004-6361/202661424","url":null,"abstract":"The study of starburst- and active galactic nucleus (AGN)-driven feedback is fundamental for understanding the processes that shape galaxy growth, quench star formation, and drive the co-evolution of galaxies and their central black holes. We present a spatially resolved study of six galaxies at 3 &lt; z &lt; 9, including starburst- and AGN-dominated systems, observed with the /NIRSpec Integral Field Unit in low- (R ∼ 100) and high-resolution (R ∼ 2700) mode. Previous analyses of R ∼ 2700 data revealed ionized outflows in all these galaxies. We explored possible links between outflows and stellar population properties to assess the mechanisms driving galaxy evolution at early epochs. We derived stellar masses and star formation histories (SFHs) using the spectral energy distribution fitting code , applied to both single spaxels and spatially integrated spectra, exploring parametric and non-parametric SFHs. We find that unresolved stellar mass measurements are systematically underestimated, with discrepancies increasing towards higher sSFRs (up to ∼ 0.75 dex), consistent with the so-called outshining effect. Combining the spatially resolved stellar population analysis with the outflow properties, we find that the most massive galaxies $(M_⋆&gt;5 M_⊙)$ with strong AGN-driven ionized outflows show evidence of past quenching episodes occurring within the last ∼ 100–300 Myr, mainly in the nuclear regions (r &lt; 3 kpc). In contrast, higher-redshift (z&gt;5) and less massive $(M_⋆&lt;10^ JWST Prospector 10 10 M_⊙)$ starburst galaxies with powerful (starburst-driven) outflows appear to have experienced continuous growth, with no clear sign of quenching. Massive galaxies with weaker outflows do not show evidence of quenching in their history. One massive AGN host (GS20936) shows evidence of a recent (10--30 Myr) rejuvenation phase, likely fuelled by a recent major merger. This interpretation is supported by TNG300 cosmological simulations, which indicate that ∼ 5% of galaxies with M_⋆ &gt; 5 , _⊙ undergo similar rejuvenation events driven by merging at z∼ 3. These results suggest that (AGN-driven) outflows can already play a key role in shaping the SFHs of massive galaxies at early cosmic epochs, while also highlighting the importance of spatially resolved analyses for accurately reconstructing their evolutionary pathways. 10^ 10 M","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"28 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"To collapse or not to collapse: Halo evolution with self-interacting dark matter mass segregation","authors":"Yashraj Patil,Moritz S. Fischer","doi":"10.1051/0004-6361/202556178","DOIUrl":"https://doi.org/10.1051/0004-6361/202556178","url":null,"abstract":"Surprisingly compact substructures in galaxies and galaxy clusters, as well as field halos, observed by gravitational lensing could be challenging to explain solely on the basis of collisionless dark matter (DM). To investigate such objects, recent studies have focussed on the gravothermal collapse that occurs in halos consisting of self-interacting dark matter (SIDM). However, simple models of elastic scattering could face issues when attempting to explain the nature of these compact objects during very late stages of the collapse and the post-collapse phase, where a black hole may have formed from DM. We aim to explain compact halos, while avoiding the gravothermal catastrophe that conventional SIDM models are subject to. We investigate the evolution of a DM halo for a model consisting of two species with unequal masses, which features only non-gravitational interactions among the different species, but not within their own structures. By employing N-body simulations, we studied the effect of unequal-mass scattering on the evolution of an isolated DM halo. In particular, we simulated the late stage of its evolution with a high central density. We find that our two-species models can produce density cores with sizes that are dependent on the mass ratio between the two species. Moreover, mass segregation caused by the unequal particle masses leads to an enhanced finite final central density, or at least a slowly growing state, which depends on the mass ratio and the mass fraction of the two DM species. We find that SIDM models consisting of two DM species have the capacity to simultaneously explain DM halos with density cores and systems that are denser in their centre than would otherwise be expected from collisionless DM, while avoiding the gravothermal catastrophe scenario. This approach offers a compelling alternative to single-species models, along with a rich phenomenology.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"36 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2026-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149149954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}