Through the analysis of representative samples of field galaxies,both local(z~0.027)and distant(z~0.7),we explore the barred galaxy fraction and its dependence on stellar mass,color,and morphology,aiming to understand...Through the analysis of representative samples of field galaxies,both local(z~0.027)and distant(z~0.7),we explore the barred galaxy fraction and its dependence on stellar mass,color,and morphology,aiming to understand the evolution of these structural components through cosmic time.To this end,two complementary bar detection techniques were employed:elliptical isophote fitting and two-dimensional Fourier analysis,both applied to deep optical images.The observational samples were drawn from previously established and calibrated catalogs to ensure a homogeneous selection in stellar mass,enabling a robust comparison between local galaxies(z~0.027)and those in the distant Universe(z~0.7).This study systematically applies both isophotal fitting and Fourier decomposition across a wide redshift range,offering a comprehensive view of the evolution of bar incidence as a function of stellar mass and morphology.The results indicate that the fraction of barred galaxies is significantly higher in the local Universe than at earlier epochs,particularly among spiral galaxies.Furthermore,a clear correlation is observed between the presence of bars and stellar mass,especially in the high-mass regime(log(M_*/M☉)>10.5).In distant galaxies,this fraction is lower across all mass ranges,which may be related to more active dynamical processes.Overall,the findings reinforce the idea that stellar bars emerge as a consequence of dynamical cooling and the progressive stabilization of galactic disks,playing a key role in gas transport and the internal structural evolution of galaxies from z~1 to the present day.展开更多
Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis...Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis reveals a strong correlation between halo spin and the H I-to-stellar mass ratio in both low-mass and massive galaxy samples.This finding suggests a universal formation scenario:higher halo spin reduces angular momentum loss and gas condensation,leading to lower star formation rates and weaker feedback,which in turn help retain gas within dark matter halos.展开更多
Leveraging the semi-analytic method,we compute halo spins for a substantial sample of H I-bearing galaxies observed in the Arecibo Legacy Fast ALFA Survey.Our statistical analysis reveals a correlation between halo sp...Leveraging the semi-analytic method,we compute halo spins for a substantial sample of H I-bearing galaxies observed in the Arecibo Legacy Fast ALFA Survey.Our statistical analysis reveals a correlation between halo spin and environment,although the trend is subtle.On average,galaxies exhibit a decreasing halo spin tendency in denser environments.This observation contrasts with previous results from N-body simulations in the Lambda Cold Dark Matter framework.The discrepancy may be attributed to environmental gas stripping,leading to an underestimation of halo spins in galaxies in denser environments,or to baryonic processes that significantly alter the original dark matter halo spins,deviating from previous N-body simulation findings.展开更多
We investigate the small-scale clustering of star-forming galaxies(SFGs) in the local universe, using both observational samples from the final data release of the Sloan Digital Sky Survey and IllustrisTNG300, one of ...We investigate the small-scale clustering of star-forming galaxies(SFGs) in the local universe, using both observational samples from the final data release of the Sloan Digital Sky Survey and IllustrisTNG300, one of the state-of-the-art hydrodynamic simulations of galaxy formation. We measure the projected two-point crosscorrelation function, wp(rp), for subsamples of SFGs with different specific star formation rates(sSFRs) and stellar masses(M*), with respect to reference samples of galaxies with early-type or late-type morphology. On scales smaller than ~100 kpc and at fixed M*, SFGs with higher sSFR are more strongly clustered, reflecting the interaction-induced central star formation found in previous studies. More importantly, the small-scale clusteringsSFR correlation is stronger when the reference sample is limited to late-type galaxies only. This confirms the previous finding that the enhancement of star formation in close pairs depends on the morphology of companion galaxies. These observational trends are broadly reproduced by IllustrisTNG300, indicating that current hydrodynamic simulations are capable of capturing the main recipes governing star formation in interacting/merging galaxies, although further work is needed to identify the exact physical processes involved.展开更多
This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE...This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE THINGS in 3D catalogs.Utilizing the Markov Chain Monte Carlo(MCMC)method for model fitting and Bayesian Information Criterion for model comparison,we find that compared to CDM,both FDM and SIDM haloes generally provide better fits to the observed rotation curves.Our findings reveal that the concentration–mass relation derived from the dark matter-only simulations is not followed by concentrations or masses obtained from the rotation curve data.Our analysis highlights a positive correlation between the core sizes of FDM and SIDM haloes and the effective radius of the galaxy,attributable to gravitational couplings between baryonic and dark matter components.Moreover,our exploration of dark matter fractions at characteristic radii indicates considerable diversity in dark matter distributions across dwarf galaxies.Notably,FDM and SIDM exhibit greater diversity than CDM in this respect.展开更多
We present the morphological study of 18,572 massive quiescent galaxies at z~1.2, selected by i-y colors in the Hyper Suprime-Cam(HSC) Deep and UltraDeep fields. The majority of our sample(94.3%) fall in the quiescent...We present the morphological study of 18,572 massive quiescent galaxies at z~1.2, selected by i-y colors in the Hyper Suprime-Cam(HSC) Deep and UltraDeep fields. The majority of our sample(94.3%) fall in the quiescent region in the rest-frame UVJ diagram. Comparing the five HSC bands and the subsample with HST F160W images, consistent with the decreasing effective radius re, Sérsic index n shows an increasing trend indicating a more bulge-dominant morphology towards the infrared. Even for our massive, quiescent galaxies,which are dominated by typical elliptical galaxies with bulges, the reand n values still vary with the wavelengths.For instance, there is a systematic drop in n of ~0.4 going from y band to F160W, making 20% of the HSC “disklike” galaxies appear “bulge-like” in the HST images. We suggest to use caution when comparing galaxy morphological types based on images at different resolutions or at different wavelengths, and whenever possible,to apply a reor n correction. More massive quiescent galaxies are systematically larger than the less massive ones,though no mass dependence is found for n measurements. The size–mass relation based on our sample and lowerz control samples show a monotonic increase of rewith M*, with a power-law of 0.61 ± 0.01, lower than previously found in similar samples of smaller sizes. Future high-resolution space-based surveys like NGRST will help confirm the possible n evolution, and if the flattening at the low-mass end is a genuine physical trend or limited by the image resolutions.展开更多
We determined HI parameters for eleven nearby late-type dwarf galaxies using FASHI data cubes,despite the fact that the first version of the FAS HI catalog does not list any radio sources that could correspond to thes...We determined HI parameters for eleven nearby late-type dwarf galaxies using FASHI data cubes,despite the fact that the first version of the FAS HI catalog does not list any radio sources that could correspond to these galaxies.Four of them are probable peripheral satellites of the bright spiral galaxies:NGC 3556,NGC 4258,NGC 4274 and NGC 4490,while others are isolated objects.The considered sample has the following median parameters:a heliocentric velocity of V_(h)=542 km s^(-1),an HI-line width of W_(50)=28 km s^(-1),a hydrogen mass of log(M_(HI)/M_(⊙))=6.83,a stellar mass of log(M_(*)/M_(⊙))=7.19,and a specific star formation rate of sSFR=-10.17 yr^(-1).展开更多
Slitless spectroscopy onboard space telescopes is a powerful tool to detect emission-line objects such as emissionline galaxies(ELGs)and quasars.In this work,we present a study of ELGs observed with slitless spectrosc...Slitless spectroscopy onboard space telescopes is a powerful tool to detect emission-line objects such as emissionline galaxies(ELGs)and quasars.In this work,we present a study of ELGs observed with slitless spectroscopy by the Hubble Space Telescope(HST)in a deep field of~44 arcmin^(2).This is one of the deepest HST fields with a wealth of imaging and spectral data.In particular,previous VLT/MUSE observations have covered this field and identified a large number of ELGs.We reduce the HST spectra using the latest pipeline with a forward modeling algorithm and construct a sample of ELGs.By comparing with the MUSE spectra,we characterize our ELG detection in the HST spectra,including the impact of the line flux,line width,signal-to-noise ratio,etc.We find that the morphological broadening may affect the detection of ELGs,such that more compact sources are easier to be detected in slitless spectra.We discuss its implications to future slitless spectroscopic surveys that will be carried out by the China Space Station Telescope(CSST)and find that the CSST slitless spectroscopy has a capability comparable to that of HST in terms of the detection of emission lines.展开更多
According to the standard“inside-out”galaxy formation scenario,galaxies first form a dense core and then gradually assemble their outskirts.This implies that galaxies with similar central stellar mass densities migh...According to the standard“inside-out”galaxy formation scenario,galaxies first form a dense core and then gradually assemble their outskirts.This implies that galaxies with similar central stellar mass densities might have evolutionary links.We use the UVJ color-color diagram to select quiescent galaxies in the redshift interval from 0.5 to 2.5 and classify them into different subsamples based on their central stellar mass densities,stellar mass,morphological type and redshift.We then infer the intrinsic axis ratiosμ_(B/A) andμC/A of different subsamples based on the apparent axis ratio q distributions,where A,B,and C refer to,respectively,the major,intermediate and minor axis of a triaxial ellipsoidal model.We find that(1)massive quiescent galaxies have typical intrinsic shapes similarly close to thick oblate structures,withμ_(B/A)0.9,regardless of stellar mass,redshift,or central stellar mass densities,and(2)galaxies at higher redshift are systematically thinner than their lower-redshift counterparts,and(3)when splitting the sample into early type and late type with Sérsic indices,ETGs at higher redshift are slightly more prolate(smaller averageμ_(B/A))than those at lower redshift.Minor mergers of galaxies may have played important roles in the structural evolution of quiescent galaxies found in this work.展开更多
Hydrodynamical cosmological simulations of galaxy formation such as IllustrisTNG or Auriga have shown considerable success in approximately matching many galaxy properties,but their treatment of the star-forming inter...Hydrodynamical cosmological simulations of galaxy formation such as IllustrisTNG or Auriga have shown considerable success in approximately matching many galaxy properties,but their treatment of the star-forming interstellar medium(ISM)has relied on heuristic sub-grid models.However,recent high-resolution simulations of the ISM that directly resolve the regulation of star formation suggest different mean relations for the dependences of pressure and star formation rate on the average gas density.In this study,we adopt such a modern,physically grounded parameterization inspired by the TIGRESS small-scale simulations.We dub this model TEQS and use it for a detailed comparative analysis of the formation and evolution of a Milky Way-sized galaxy when compared with the widely used TNG model.By employing high-resolution simulations in tall box setups,we first investigate the structural differences expected for these two models when applied to different self-gravitating gas surface densities.Our results indicate that TEQS produces considerably thinner gaseous layers and can be expected to form stellar distributions with smaller scale-height than TNG,especially at higher surface density.To test whether this induces systematic structural differences in cosmological galaxy formation simulations,we carry out zoom-in simulations of 12 galaxies taken from the set of Milky Way-sized galaxies that have been studied in the Auriga project.Comparing results for these galaxies shows that disk galaxies formed with the TEQS model have on average very similar stellar mass but are more concentrated in their central regions and exhibit smaller stellar radii compared to those formed with the TNG model.The differences in the scale-heights of the formed stellar disks are only marginal,however,suggesting that other factors for setting the thickness of the disk are more important than the applied ISM equation-of-state model.Overall,the predicted galaxy structure is quite similar for TNG and TEQS despite significant differences in the employed star formation law,demonstrating that feedback processes are more important in regulating the stellar mass than the precise star formation law itself.展开更多
Recent JWST observations have revealed that dwarf galaxies start to cease star formation at redshifts z>1,yet the quenching process remains unclear.In this study,we selected a large sample of 3405 dwarf galaxies wi...Recent JWST observations have revealed that dwarf galaxies start to cease star formation at redshifts z>1,yet the quenching process remains unclear.In this study,we selected a large sample of 3405 dwarf galaxies with stellar masses below 109.5Me and redshifts ranging from 1.0 to 1.5 across all five CANDELS fields.By utilizing multi-wavelength imaging data from both JWST and HST,we examined the growth patterns and modes of star formation quenching in dwarf galaxies during the cosmic noon era.Based on their specific star formation rates (sS FR),we categorized the sample into three subgroups:star-forming dwarf galaxies below and above the star formation main sequence (SFMS),and quiescent dwarf galaxies.To analyze the UVJ color profiles of these three subgroups of dwarf galaxies,we applied the image stacking technique.This method improves the signal-to-noise ratio and extends the color profiles to the outer regions of the galaxies.Our results show that these galaxies generally exhibit nearly flat stacked color profiles,suggesting that,on average,their growth and star formation quenching patterns are self-similar,differing from those previously observed in dwarf galaxies at lower redshifts.We further discuss the potential roles of internal and external physical processes in the star formation quenching of dwarf galaxies during the cosmic noon period.展开更多
This paper presents a statistical study of the division of the[CⅡ]158μm line into ionized and neutral components,using a new carbon-to-nitrogen abundance ratio,log(C/N)=0.75,for a sample of 108 local galaxies.We inv...This paper presents a statistical study of the division of the[CⅡ]158μm line into ionized and neutral components,using a new carbon-to-nitrogen abundance ratio,log(C/N)=0.75,for a sample of 108 local galaxies.We investigate the correlation between the ionized-to-total[CⅡ]ratio([CⅡ]_(ionized)/[CⅡ]_(total))and the farinfrared color f60/f100,finding a moderate negative correlation.Additionally,we explore the dependence of[CⅡ]_(ionized)/[CⅡ]_(total)on various physical properties.We find that[CⅡ]_(ionized)/[CⅡ]_(total)exhibits a weak negative correlation with the offset from the main sequence and a moderate negative correlation with the[OⅢ]88μm/[NⅡ]122μm.Furthermore,no significant correlation with molecular gas mass is found.It shows a positive correlation with metallicity.Our results suggest that[CⅡ]_(ionized)/[CⅡ]_(total)is influenced by the ionization parameter,star formation efficiency and metallicity.展开更多
We examine the consequences of the dark matter halo presence on the alignment of angular momenta of the luminous astronomical objects like galaxies and their clusters.For that we calculate the distribution function of...We examine the consequences of the dark matter halo presence on the alignment of angular momenta of the luminous astronomical objects like galaxies and their clusters.For that we calculate the distribution function of their gravitational fields within the statistical method,generalized to the the presence of dark matter halos.The generalization deals both with direct account for halo component in the form of Navarro,Frenk and White(NFW)profile and indirect influence of dark matter on the tidal interaction between luminous objects.The NFW profile s gravitational field distribution isolates luminous objects within the halo,suppressing mutual interactions,which contradicts observational data and simulations.To address this,we propose a hypothetical short-range interaction,which can be a well of Newtonian(gravitational)nature.Namely,we derive this short-range interaction on the basis of a multipole expansion of the initial Newtonian interaction.Introducing the short-range part in the initial interaction,we arrive at modified quadrupolar intergalaxy interaction,which permits the luminous objects,which are closer than interaction range rc,to effectively interact with each other inside the dark matter halo.This permits us to show that the more clumpy the luminous objects are,the more probably their orbital moments will be aligned.Our theoretical analysis,supported by observational and simulation data(Illustris Project 2013),indicates that dark matter halos significantly alter the gravitational field distribution,affecting angular momenta alignment.We find that while angular momenta alignment increases with cluster richness in galaxy clusters,it does not in superclusters,likely due to the abundant dark matter in superclusters.Our theoretical predictions align well with both observational data and numerical simulations.展开更多
In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and...In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and the disk region by the well established exponential profile.In order to understand the distribution of dark matter in the halo region,we consider three different dark matter profiles in the framework of the standardΛCDM model namely,Navarro-Frenk-White(NFW),Hernquist and Einasto profiles.We use recent data sets of rotation curves of the Milky Way and Andromeda galaxy.The data consist of rotation velocities of the stars and gas in the galaxy as a function of the radial distance from the center.Using Bayesian statistics,we perform an overall fit including all the components,i.e.,bulge,disk and halo with the data.Our results indicate that the NFW and Hernquist profiles are in concordance with the observational data points.However,the Einasto profile poorly explains the behavior of dark matter in both the galaxies.展开更多
In the study of spiral galaxy morphology,spiral arm structures are valuable for intuitively reflecting active physical and chemical processes within galaxies.However,long-term scarcity of high-quality one-,three-,and ...In the study of spiral galaxy morphology,spiral arm structures are valuable for intuitively reflecting active physical and chemical processes within galaxies.However,long-term scarcity of high-quality one-,three-,and four-armed galaxy samples has limited deep learning model performance.To address this,this study developed a spiral galaxy data simulation program with a three-stage workflow:first,screening highly reliable training samples;second,selecting the best-performing Imagen architecture as the generative model after comparing nine mainstream ones;finally,training Imagen to generate an open data set of 9402 one-/three-armed galaxies,expanding the original sample size by 6 times.Multi-dimensional evaluations verified reliability and usability:Fréchet Inception Distance scores for N=1 and N=3 tasks were 6.05 and 9.13;the t-distributed Stochastic Neighbor Embedding showed generated data covered and expanded real data distribution;the Structural Similarity Index Measure confirmed no sample duplication.In downstream validation,data augmentation improved seven classification models'average accuracy by 8.7%(DenseNet peaked at 97%),and SHapley Additive exPlanations analysis showed model decisions focused on spiral arm topology.In conclusion,the program and data set support spiral galaxy morphology deep learning research and are publicly available at https://github.com/TuAstroAILab/AstroGS.展开更多
We determined the relative stellar ages and metallicities of about 80 elliptical galaxies in both low and high density environments using the latest binary stellar population （BSP） synthesis model and tested the pre...We determined the relative stellar ages and metallicities of about 80 elliptical galaxies in both low and high density environments using the latest binary stellar population （BSP） synthesis model and tested the predictions of a recent hierarchical formation model that adopted the new ACDM cosmology. The stellar ages and metallicities were estimated from two high-quality published spectra line indices, the Hβ and [MgFe] indices. The results show that the stellar populations of elliptical galaxies are older than 3.9 Gyr and more metal rich than 0.02. Most of our results are in agreement with the model predictions; （1） elliptical galaxies in denser environment are redder and have older populations than field galaxies; （2） elliptical galaxies with more massive stellar components are redder and have older and more metal rich populations than less massive ones; （3） the most massive galaxies have the oldest and most metal rich stars. However, some of our results differ from the model predictions on the metallicity distributions of low- and high-density elliptical galaxies and the dependence on the distance to the cluster center.展开更多
Chandra observations of the Seyfert-2 galaxies NGC 2110 and NGC 7582 arepresented. With the superb spatial resolution of Chandra we found that in NGC 7582 the soft (≤2keV) and hard (2-10 keV) X-rays are emitted in di...Chandra observations of the Seyfert-2 galaxies NGC 2110 and NGC 7582 arepresented. With the superb spatial resolution of Chandra we found that in NGC 7582 the soft (≤2keV) and hard (2-10 keV) X-rays are emitted in different regions, consistent with the report by Xueet al. By comparing the present X-ray data with the previous infrared data, we determined that thesoft X-ray region is the site of starburst activities. We found no significant temporal variationsduring our observations. We confirm the previous finding that NGC 2110 and NGC 7582 areflat-spectrum sources. We argue that the flat spectra may result from a cold absorbing material suchas envisaged in the 'dual absorbed' model. Strong FeK_α emission feature is detected in 6～7keV.Its equivalent width is so large that it cannot be reproduced by using the Galactic column densityof ～ 10^(22) cm^(-2).展开更多
Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sampl...Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sample. Fitting the rotation curves, we obtain the root-mean-square (rms) velocity and density of dark matter in the core of the galaxies. We then calculate the rms velocity vhrms (1) that dark matter particles would have if expanded adiabatically from the core of the galaxies to the present mean density of dark matter in the universe. We obtain this “adiabatic invariant” vhrms (1) for 40 spiral galaxies. The distribution of vhrms (1) has a mean 0.87 km/s and a standard deviation of 0.27 km/s. This low relative dispersion is noteworthy given the wide range of the properties of these galaxies. The adiabatic invariant vhrms (1) may, therefore, have a cosmological origin. In this case, the rms velocity of non-relativistic dark matter particles in the early universe when density perturbations are still linear is vhrms (a)=vhrms (1)/a, where a is the expansion parameter. The adiabatic invariant obtains the ratio of dark matter temperature Th (a) to mass mh in the early universe.展开更多
The distribution of abundance for iron-peak elements in dwarf spheroidal galaxies （dSphs） is important for galaxy evolution and supernova （SN） nucleosynthesis. Nowadays, manganese （Mn） is one of the most observe...The distribution of abundance for iron-peak elements in dwarf spheroidal galaxies （dSphs） is important for galaxy evolution and supernova （SN） nucleosynthesis. Nowadays, manganese （Mn） is one of the most observed iron-peak elements in local dSphs. Studies of its distributions allow us to derive and understand the evolution history of these dSphs. We improve a phenomenological model by a two-curve model including a new initial condition, that includes detailed calculations of SN explosion rates and yields. We compare the results with the observed Mn distribution data for three dSphs： Fornax, Sculpture and Sextans. We find that the model can describe the observed Fe and Mn distributions well simultaneously for the three dSphs. The results also indicate that the initial conditions should be determined by the low metallicity sam- ples in the beginning time of the galaxies and the previous assumption of metellicity-dependant Mn yield of SNIa is not needed when a wide mass range of core-collapse SNe is included. Our method is applicable to the chemical evolution of other iron-peak elements in dSphs and can be modified to provide more detailed processes for the evolution of dSphs.展开更多
We compile a sample of spectral energy distributions （SEDs） of 12 GeV radio galaxies （RGs）, including eight FR I RGs and four FR II RGs. These SEDs can be represented with the one-zone leptonic model. No significa...We compile a sample of spectral energy distributions （SEDs） of 12 GeV radio galaxies （RGs）, including eight FR I RGs and four FR II RGs. These SEDs can be represented with the one-zone leptonic model. No significant unification, as expected in the unification model, is found for the derived jet parameters between FR I RGs and BL Lacertae objects （BL Lacs） and between FR II RGs and flat spectrum radio quasars （FSRQs）. However, on average FR I RGs have a larger ＇Tb （break Lorentz factor of electrons） and lower B （magnetic field strength） than FR II RGs, analogous to the differences be- tween BL Lacs and FSRQs. The derived Doppler factors （~） of RGs are on average smaller than those of blazars, which is consistent with the unification model such that RGs are the misaligned parent pop- ulations of blazars with smaller tS. On the basis of jet parameters from SED fits, we calculate their jet powers and the powers carded by each component, and compare their jet compositions and radiation efficiencies with blazars. Most of the RG jets may be dominated by particles, like BL Lacs, not FSRQs. However, the jets of RGs with higher radiation efficiencies tend to have higher jet magnetization. A strong anticorrelation between synchrotron peak frequency and jet power is observed for GeV RGs and blazars in both the observer and co-moving frames, indicating that the ＂sequence＂ behavior among blazars, together with the GeV RGs, may be intrinsically dominated by jet power.展开更多
基金financial support from the Secretaría Nacional de Ciencia,Tecnologia e Innovacion(SENACYT),through the Departamento de Fortalecimiento a los Posgrados Nacionalesthe coordination of the program"MOVILIDAD DE INVESTIGACION."+3 种基金the financial support provided by PAPIIT projects IN108323 and IN111825 from DGAPA-UNAMsupport from the Agencia Nacional de Investigación y Desarrollo(ANID)through Basal project FB210003FONDECYT Regular projects 1241426 and 123044Millennium Science Initiative Program NCN2024_112。
文摘Through the analysis of representative samples of field galaxies,both local(z~0.027)and distant(z~0.7),we explore the barred galaxy fraction and its dependence on stellar mass,color,and morphology,aiming to understand the evolution of these structural components through cosmic time.To this end,two complementary bar detection techniques were employed:elliptical isophote fitting and two-dimensional Fourier analysis,both applied to deep optical images.The observational samples were drawn from previously established and calibrated catalogs to ensure a homogeneous selection in stellar mass,enabling a robust comparison between local galaxies(z~0.027)and those in the distant Universe(z~0.7).This study systematically applies both isophotal fitting and Fourier decomposition across a wide redshift range,offering a comprehensive view of the evolution of bar incidence as a function of stellar mass and morphology.The results indicate that the fraction of barred galaxies is significantly higher in the local Universe than at earlier epochs,particularly among spiral galaxies.Furthermore,a clear correlation is observed between the presence of bars and stellar mass,especially in the high-mass regime(log(M_*/M☉)>10.5).In distant galaxies,this fraction is lower across all mass ranges,which may be related to more active dynamical processes.Overall,the findings reinforce the idea that stellar bars emerge as a consequence of dynamical cooling and the progressive stabilization of galactic disks,playing a key role in gas transport and the internal structural evolution of galaxies from z~1 to the present day.
基金support from the National Natural Science Foundation of China(NSFC)grant 12273037the CAS Pioneer Hundred Talents Program(Category B)+1 种基金the USTC Research Funds of the Double First-Class Initiativesupported by the China Manned Space Program with grant No.CMS-CSST-2025-A06 and CMS-CSST-2025-A08.
文摘Using a semi-analytic approach,we estimate halo spins for a large sample of H I-rich galaxies from the Arecibo Legacy Fast ALFA Survey and examine the correlation between H I mass fractions and halo spins.Our analysis reveals a strong correlation between halo spin and the H I-to-stellar mass ratio in both low-mass and massive galaxy samples.This finding suggests a universal formation scenario:higher halo spin reduces angular momentum loss and gas condensation,leading to lower star formation rates and weaker feedback,which in turn help retain gas within dark matter halos.
基金supports from the CAS Pioneer Hundred Talents Program(Category B)the National Natural Science Foundation of China(NSFC,grant No.12273037)the USTC Research Funds of the Double First-Class Initiative。
文摘Leveraging the semi-analytic method,we compute halo spins for a substantial sample of H I-bearing galaxies observed in the Arecibo Legacy Fast ALFA Survey.Our statistical analysis reveals a correlation between halo spin and environment,although the trend is subtle.On average,galaxies exhibit a decreasing halo spin tendency in denser environments.This observation contrasts with previous results from N-body simulations in the Lambda Cold Dark Matter framework.The discrepancy may be attributed to environmental gas stripping,leading to an underestimation of halo spins in galaxies in denser environments,or to baryonic processes that significantly alter the original dark matter halo spins,deviating from previous N-body simulation findings.
基金supported by the National Key R&D Program of China through grant 2020YFC2201400the NSFC Key Program through grants 11733010 and 11333008.
文摘We investigate the small-scale clustering of star-forming galaxies(SFGs) in the local universe, using both observational samples from the final data release of the Sloan Digital Sky Survey and IllustrisTNG300, one of the state-of-the-art hydrodynamic simulations of galaxy formation. We measure the projected two-point crosscorrelation function, wp(rp), for subsamples of SFGs with different specific star formation rates(sSFRs) and stellar masses(M*), with respect to reference samples of galaxies with early-type or late-type morphology. On scales smaller than ~100 kpc and at fixed M*, SFGs with higher sSFR are more strongly clustered, reflecting the interaction-induced central star formation found in previous studies. More importantly, the small-scale clusteringsSFR correlation is stronger when the reference sample is limited to late-type galaxies only. This confirms the previous finding that the enhancement of star formation in close pairs depends on the morphology of companion galaxies. These observational trends are broadly reproduced by IllustrisTNG300, indicating that current hydrodynamic simulations are capable of capturing the main recipes governing star formation in interacting/merging galaxies, although further work is needed to identify the exact physical processes involved.
基金financially supporting this research through PPMI KK 2024 Program,contract number 616BO/IT1.C02/KU/2024。
文摘This study examines the properties of standard cold dark matter(CDM),fuzzy dark matter(FDM),and selfinteracting dark matter(SIDM)haloes by analyzing the rotation curves of selected dwarf galaxies from SPARC and LITTLE THINGS in 3D catalogs.Utilizing the Markov Chain Monte Carlo(MCMC)method for model fitting and Bayesian Information Criterion for model comparison,we find that compared to CDM,both FDM and SIDM haloes generally provide better fits to the observed rotation curves.Our findings reveal that the concentration–mass relation derived from the dark matter-only simulations is not followed by concentrations or masses obtained from the rotation curve data.Our analysis highlights a positive correlation between the core sizes of FDM and SIDM haloes and the effective radius of the galaxy,attributable to gravitational couplings between baryonic and dark matter components.Moreover,our exploration of dark matter fractions at characteristic radii indicates considerable diversity in dark matter distributions across dwarf galaxies.Notably,FDM and SIDM exhibit greater diversity than CDM in this respect.
基金sponsored by the National Key R&D Program of China(MOST)with grant No.2022YFA1605300the National Natural Science Foundation of China(NSFC,grant Nos.12273051 and 11933003)Support for this work is also partly provided by the Chinese Academy of Sciences(CAS)through a grant to the South America Center for Astronomy(CASSACA)。
文摘We present the morphological study of 18,572 massive quiescent galaxies at z~1.2, selected by i-y colors in the Hyper Suprime-Cam(HSC) Deep and UltraDeep fields. The majority of our sample(94.3%) fall in the quiescent region in the rest-frame UVJ diagram. Comparing the five HSC bands and the subsample with HST F160W images, consistent with the decreasing effective radius re, Sérsic index n shows an increasing trend indicating a more bulge-dominant morphology towards the infrared. Even for our massive, quiescent galaxies,which are dominated by typical elliptical galaxies with bulges, the reand n values still vary with the wavelengths.For instance, there is a systematic drop in n of ~0.4 going from y band to F160W, making 20% of the HSC “disklike” galaxies appear “bulge-like” in the HST images. We suggest to use caution when comparing galaxy morphological types based on images at different resolutions or at different wavelengths, and whenever possible,to apply a reor n correction. More massive quiescent galaxies are systematically larger than the less massive ones,though no mass dependence is found for n measurements. The size–mass relation based on our sample and lowerz control samples show a monotonic increase of rewith M*, with a power-law of 0.61 ± 0.01, lower than previously found in similar samples of smaller sizes. Future high-resolution space-based surveys like NGRST will help confirm the possible n evolution, and if the flattening at the low-mass end is a genuine physical trend or limited by the image resolutions.
基金supported by the Russian Science Foundation grant No 24-12-00277。
文摘We determined HI parameters for eleven nearby late-type dwarf galaxies using FASHI data cubes,despite the fact that the first version of the FAS HI catalog does not list any radio sources that could correspond to these galaxies.Four of them are probable peripheral satellites of the bright spiral galaxies:NGC 3556,NGC 4258,NGC 4274 and NGC 4490,while others are isolated objects.The considered sample has the following median parameters:a heliocentric velocity of V_(h)=542 km s^(-1),an HI-line width of W_(50)=28 km s^(-1),a hydrogen mass of log(M_(HI)/M_(⊙))=6.83,a stellar mass of log(M_(*)/M_(⊙))=7.19,and a specific star formation rate of sSFR=-10.17 yr^(-1).
基金support from the National Key R&D Program of China(2022YFF0503401)the China Manned Space Project with No.CMS-CSST-2021-A05the National Natural Science Foundation of China(12225301)。
文摘Slitless spectroscopy onboard space telescopes is a powerful tool to detect emission-line objects such as emissionline galaxies(ELGs)and quasars.In this work,we present a study of ELGs observed with slitless spectroscopy by the Hubble Space Telescope(HST)in a deep field of~44 arcmin^(2).This is one of the deepest HST fields with a wealth of imaging and spectral data.In particular,previous VLT/MUSE observations have covered this field and identified a large number of ELGs.We reduce the HST spectra using the latest pipeline with a forward modeling algorithm and construct a sample of ELGs.By comparing with the MUSE spectra,we characterize our ELG detection in the HST spectra,including the impact of the line flux,line width,signal-to-noise ratio,etc.We find that the morphological broadening may affect the detection of ELGs,such that more compact sources are easier to be detected in slitless spectra.We discuss its implications to future slitless spectroscopic surveys that will be carried out by the China Space Station Telescope(CSST)and find that the CSST slitless spectroscopy has a capability comparable to that of HST in terms of the detection of emission lines.
基金support from the National Key Research and Development Program of China (grant No.2023YFA1608100)from the National Natural Science Foundation of China(NSFC,grant Nos.12122303 and 11973039)+2 种基金supported by the China Manned Space Project (grant Nos.CMSCSST-2021-B02 and CMS-CSST-2021-A07)support from the CAS Pioneer Hundred Talents Programthe Cyrus Chun Ying Tang Foundations
文摘According to the standard“inside-out”galaxy formation scenario,galaxies first form a dense core and then gradually assemble their outskirts.This implies that galaxies with similar central stellar mass densities might have evolutionary links.We use the UVJ color-color diagram to select quiescent galaxies in the redshift interval from 0.5 to 2.5 and classify them into different subsamples based on their central stellar mass densities,stellar mass,morphological type and redshift.We then infer the intrinsic axis ratiosμ_(B/A) andμC/A of different subsamples based on the apparent axis ratio q distributions,where A,B,and C refer to,respectively,the major,intermediate and minor axis of a triaxial ellipsoidal model.We find that(1)massive quiescent galaxies have typical intrinsic shapes similarly close to thick oblate structures,withμ_(B/A)0.9,regardless of stellar mass,redshift,or central stellar mass densities,and(2)galaxies at higher redshift are systematically thinner than their lower-redshift counterparts,and(3)when splitting the sample into early type and late type with Sérsic indices,ETGs at higher redshift are slightly more prolate(smaller averageμ_(B/A))than those at lower redshift.Minor mergers of galaxies may have played important roles in the structural evolution of quiescent galaxies found in this work.
基金supported by the National SKA Program of China(grant No.2020SKA0110100)the CAS Project for Young Scientists in Basic Research (No.YSBR-092)the science research grants from the China Manned Space Project with Nos.CMS-CSST-2021-A02 and GHfund C(202407031909)
文摘Hydrodynamical cosmological simulations of galaxy formation such as IllustrisTNG or Auriga have shown considerable success in approximately matching many galaxy properties,but their treatment of the star-forming interstellar medium(ISM)has relied on heuristic sub-grid models.However,recent high-resolution simulations of the ISM that directly resolve the regulation of star formation suggest different mean relations for the dependences of pressure and star formation rate on the average gas density.In this study,we adopt such a modern,physically grounded parameterization inspired by the TIGRESS small-scale simulations.We dub this model TEQS and use it for a detailed comparative analysis of the formation and evolution of a Milky Way-sized galaxy when compared with the widely used TNG model.By employing high-resolution simulations in tall box setups,we first investigate the structural differences expected for these two models when applied to different self-gravitating gas surface densities.Our results indicate that TEQS produces considerably thinner gaseous layers and can be expected to form stellar distributions with smaller scale-height than TNG,especially at higher surface density.To test whether this induces systematic structural differences in cosmological galaxy formation simulations,we carry out zoom-in simulations of 12 galaxies taken from the set of Milky Way-sized galaxies that have been studied in the Auriga project.Comparing results for these galaxies shows that disk galaxies formed with the TEQS model have on average very similar stellar mass but are more concentrated in their central regions and exhibit smaller stellar radii compared to those formed with the TNG model.The differences in the scale-heights of the formed stellar disks are only marginal,however,suggesting that other factors for setting the thickness of the disk are more important than the applied ISM equation-of-state model.Overall,the predicted galaxy structure is quite similar for TNG and TEQS despite significant differences in the employed star formation law,demonstrating that feedback processes are more important in regulating the stellar mass than the precise star formation law itself.
基金supported by the National Natural Science Foundation of China (NSFC,grant Nos.12273052,11733006,12090040,12090041 and 12073051)the science research grants from the China Manned Space Project (No.CMS-CSST-2021-A04)+6 种基金the support from the Ministry of Science and Technology of China (No.2020SKA0110100)the science research grants from the China Manned Space Project (No.CMS-CSST-2021-A01)the CAS Project for Young Scientists in Basic Research (No.YSBR-062)supported by the National Key R&D Program(2023YFE0101200)the China Manned Space Project (No.CMS-CSST-2025-A07)the NSFC (grant No.12393813)the Yunnan Revitalization Talent Support Program (YunLing Scholar Project)。
文摘Recent JWST observations have revealed that dwarf galaxies start to cease star formation at redshifts z>1,yet the quenching process remains unclear.In this study,we selected a large sample of 3405 dwarf galaxies with stellar masses below 109.5Me and redshifts ranging from 1.0 to 1.5 across all five CANDELS fields.By utilizing multi-wavelength imaging data from both JWST and HST,we examined the growth patterns and modes of star formation quenching in dwarf galaxies during the cosmic noon era.Based on their specific star formation rates (sS FR),we categorized the sample into three subgroups:star-forming dwarf galaxies below and above the star formation main sequence (SFMS),and quiescent dwarf galaxies.To analyze the UVJ color profiles of these three subgroups of dwarf galaxies,we applied the image stacking technique.This method improves the signal-to-noise ratio and extends the color profiles to the outer regions of the galaxies.Our results show that these galaxies generally exhibit nearly flat stacked color profiles,suggesting that,on average,their growth and star formation quenching patterns are self-similar,differing from those previously observed in dwarf galaxies at lower redshifts.We further discuss the potential roles of internal and external physical processes in the star formation quenching of dwarf galaxies during the cosmic noon period.
基金supported by the National Natural Science Foundation of China(NSFC,grant No.12173079)。
文摘This paper presents a statistical study of the division of the[CⅡ]158μm line into ionized and neutral components,using a new carbon-to-nitrogen abundance ratio,log(C/N)=0.75,for a sample of 108 local galaxies.We investigate the correlation between the ionized-to-total[CⅡ]ratio([CⅡ]_(ionized)/[CⅡ]_(total))and the farinfrared color f60/f100,finding a moderate negative correlation.Additionally,we explore the dependence of[CⅡ]_(ionized)/[CⅡ]_(total)on various physical properties.We find that[CⅡ]_(ionized)/[CⅡ]_(total)exhibits a weak negative correlation with the offset from the main sequence and a moderate negative correlation with the[OⅢ]88μm/[NⅡ]122μm.Furthermore,no significant correlation with molecular gas mass is found.It shows a positive correlation with metallicity.Our results suggest that[CⅡ]_(ionized)/[CⅡ]_(total)is influenced by the ionization parameter,star formation efficiency and metallicity.
文摘We examine the consequences of the dark matter halo presence on the alignment of angular momenta of the luminous astronomical objects like galaxies and their clusters.For that we calculate the distribution function of their gravitational fields within the statistical method,generalized to the the presence of dark matter halos.The generalization deals both with direct account for halo component in the form of Navarro,Frenk and White(NFW)profile and indirect influence of dark matter on the tidal interaction between luminous objects.The NFW profile s gravitational field distribution isolates luminous objects within the halo,suppressing mutual interactions,which contradicts observational data and simulations.To address this,we propose a hypothetical short-range interaction,which can be a well of Newtonian(gravitational)nature.Namely,we derive this short-range interaction on the basis of a multipole expansion of the initial Newtonian interaction.Introducing the short-range part in the initial interaction,we arrive at modified quadrupolar intergalaxy interaction,which permits the luminous objects,which are closer than interaction range rc,to effectively interact with each other inside the dark matter halo.This permits us to show that the more clumpy the luminous objects are,the more probably their orbital moments will be aligned.Our theoretical analysis,supported by observational and simulation data(Illustris Project 2013),indicates that dark matter halos significantly alter the gravitational field distribution,affecting angular momenta alignment.We find that while angular momenta alignment increases with cluster richness in galaxy clusters,it does not in superclusters,likely due to the abundant dark matter in superclusters.Our theoretical predictions align well with both observational data and numerical simulations.
基金supported by the Startup Research Fund of the Henan Academy of Sciences under grant No.241841219。
文摘In this paper,we study the rotation curves of the Milky Way galaxy and Andromeda galaxy(M31)by considering their bulge,disk,and halo components.We model the bulge region by the widely accepted de Vaucouleur’s law and the disk region by the well established exponential profile.In order to understand the distribution of dark matter in the halo region,we consider three different dark matter profiles in the framework of the standardΛCDM model namely,Navarro-Frenk-White(NFW),Hernquist and Einasto profiles.We use recent data sets of rotation curves of the Milky Way and Andromeda galaxy.The data consist of rotation velocities of the stars and gas in the galaxy as a function of the radial distance from the center.Using Bayesian statistics,we perform an overall fit including all the components,i.e.,bulge,disk and halo with the data.Our results indicate that the NFW and Hernquist profiles are in concordance with the observational data points.However,the Einasto profile poorly explains the behavior of dark matter in both the galaxies.
基金supported by the National Natural Science Foundation of China(NSFC,grant No.U1731128)the support of the Association for Astronomy X A.I.(A3),funded by the Science and Education Integration Funding of the University of Chinese Academy of Sciences。
文摘In the study of spiral galaxy morphology,spiral arm structures are valuable for intuitively reflecting active physical and chemical processes within galaxies.However,long-term scarcity of high-quality one-,three-,and four-armed galaxy samples has limited deep learning model performance.To address this,this study developed a spiral galaxy data simulation program with a three-stage workflow:first,screening highly reliable training samples;second,selecting the best-performing Imagen architecture as the generative model after comparing nine mainstream ones;finally,training Imagen to generate an open data set of 9402 one-/three-armed galaxies,expanding the original sample size by 6 times.Multi-dimensional evaluations verified reliability and usability:Fréchet Inception Distance scores for N=1 and N=3 tasks were 6.05 and 9.13;the t-distributed Stochastic Neighbor Embedding showed generated data covered and expanded real data distribution;the Structural Similarity Index Measure confirmed no sample duplication.In downstream validation,data augmentation improved seven classification models'average accuracy by 8.7%(DenseNet peaked at 97%),and SHapley Additive exPlanations analysis showed model decisions focused on spiral arm topology.In conclusion,the program and data set support spiral galaxy morphology deep learning research and are publicly available at https://github.com/TuAstroAILab/AstroGS.
基金Supported by the National Natural Science Foundation of China.
文摘We determined the relative stellar ages and metallicities of about 80 elliptical galaxies in both low and high density environments using the latest binary stellar population （BSP） synthesis model and tested the predictions of a recent hierarchical formation model that adopted the new ACDM cosmology. The stellar ages and metallicities were estimated from two high-quality published spectra line indices, the Hβ and [MgFe] indices. The results show that the stellar populations of elliptical galaxies are older than 3.9 Gyr and more metal rich than 0.02. Most of our results are in agreement with the model predictions; （1） elliptical galaxies in denser environment are redder and have older populations than field galaxies; （2） elliptical galaxies with more massive stellar components are redder and have older and more metal rich populations than less massive ones; （3） the most massive galaxies have the oldest and most metal rich stars. However, some of our results differ from the model predictions on the metallicity distributions of low- and high-density elliptical galaxies and the dependence on the distance to the cluster center.
基金Supported by the National Natural Science Foundation of China.
文摘Chandra observations of the Seyfert-2 galaxies NGC 2110 and NGC 7582 arepresented. With the superb spatial resolution of Chandra we found that in NGC 7582 the soft (≤2keV) and hard (2-10 keV) X-rays are emitted in different regions, consistent with the report by Xueet al. By comparing the present X-ray data with the previous infrared data, we determined that thesoft X-ray region is the site of starburst activities. We found no significant temporal variationsduring our observations. We confirm the previous finding that NGC 2110 and NGC 7582 areflat-spectrum sources. We argue that the flat spectra may result from a cold absorbing material suchas envisaged in the 'dual absorbed' model. Strong FeK_α emission feature is detected in 6～7keV.Its equivalent width is so large that it cannot be reproduced by using the Galactic column densityof ～ 10^(22) cm^(-2).
文摘Collisionless dark matter can only expand adiabatically. To test this idea and constrain the properties of dark matter, we study spiral galaxies in the “Spitzer Photometry and Accurate Rotation Curves” (SPARC) sample. Fitting the rotation curves, we obtain the root-mean-square (rms) velocity and density of dark matter in the core of the galaxies. We then calculate the rms velocity vhrms (1) that dark matter particles would have if expanded adiabatically from the core of the galaxies to the present mean density of dark matter in the universe. We obtain this “adiabatic invariant” vhrms (1) for 40 spiral galaxies. The distribution of vhrms (1) has a mean 0.87 km/s and a standard deviation of 0.27 km/s. This low relative dispersion is noteworthy given the wide range of the properties of these galaxies. The adiabatic invariant vhrms (1) may, therefore, have a cosmological origin. In this case, the rms velocity of non-relativistic dark matter particles in the early universe when density perturbations are still linear is vhrms (a)=vhrms (1)/a, where a is the expansion parameter. The adiabatic invariant obtains the ratio of dark matter temperature Th (a) to mass mh in the early universe.
基金partly supported by the National Natural Science Foundation of China (Grant Nos. 11305133, 11273020 and U1331121)China Scholarship (Grant No. 2011851096)
文摘The distribution of abundance for iron-peak elements in dwarf spheroidal galaxies （dSphs） is important for galaxy evolution and supernova （SN） nucleosynthesis. Nowadays, manganese （Mn） is one of the most observed iron-peak elements in local dSphs. Studies of its distributions allow us to derive and understand the evolution history of these dSphs. We improve a phenomenological model by a two-curve model including a new initial condition, that includes detailed calculations of SN explosion rates and yields. We compare the results with the observed Mn distribution data for three dSphs： Fornax, Sculpture and Sextans. We find that the model can describe the observed Fe and Mn distributions well simultaneously for the three dSphs. The results also indicate that the initial conditions should be determined by the low metallicity sam- ples in the beginning time of the galaxies and the previous assumption of metellicity-dependant Mn yield of SNIa is not needed when a wide mass range of core-collapse SNe is included. Our method is applicable to the chemical evolution of other iron-peak elements in dSphs and can be modified to provide more detailed processes for the evolution of dSphs.
基金supported by the National Natural Science Foundation of China(grants 11573034,11533003,11373036 and 11133002)the National Basic Research Program(973 Program)of China(grant 2014CB845800)the Guangxi Science Foundation(2013GXNSFFA019001)
文摘We compile a sample of spectral energy distributions （SEDs） of 12 GeV radio galaxies （RGs）, including eight FR I RGs and four FR II RGs. These SEDs can be represented with the one-zone leptonic model. No significant unification, as expected in the unification model, is found for the derived jet parameters between FR I RGs and BL Lacertae objects （BL Lacs） and between FR II RGs and flat spectrum radio quasars （FSRQs）. However, on average FR I RGs have a larger ＇Tb （break Lorentz factor of electrons） and lower B （magnetic field strength） than FR II RGs, analogous to the differences be- tween BL Lacs and FSRQs. The derived Doppler factors （~） of RGs are on average smaller than those of blazars, which is consistent with the unification model such that RGs are the misaligned parent pop- ulations of blazars with smaller tS. On the basis of jet parameters from SED fits, we calculate their jet powers and the powers carded by each component, and compare their jet compositions and radiation efficiencies with blazars. Most of the RG jets may be dominated by particles, like BL Lacs, not FSRQs. However, the jets of RGs with higher radiation efficiencies tend to have higher jet magnetization. A strong anticorrelation between synchrotron peak frequency and jet power is observed for GeV RGs and blazars in both the observer and co-moving frames, indicating that the ＂sequence＂ behavior among blazars, together with the GeV RGs, may be intrinsically dominated by jet power.
