arXiv: Astrophysics of Galaxies最新文献_第6页

Disk dominated galaxies retain their shapes below $z = 1.0$ 盘形星系在z = 1.0以下保持其形状

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-26 DOI: 10.5167/UZH-193016

K. Hoffmann, C. Laigle, N. E. Chisari, P. Tallada, Y. Dubois, J. Devriendt

{"title":"Disk dominated galaxies retain their shapes below $z = 1.0$","authors":"K. Hoffmann, C. Laigle, N. E. Chisari, P. Tallada, Y. Dubois, J. Devriendt","doi":"10.5167/UZH-193016","DOIUrl":"https://doi.org/10.5167/UZH-193016","url":null,"abstract":"The high abundance of disk galaxies without a large central bulge challenges predictions of current hydrodynamic simulations of galaxy formation. We aim to shed light on the formation of these objects by studying the redshift and mass dependence of their 3D shape distribution in the COSMOS galaxy survey. This distribution is inferred from the observed distribution of 2D shapes, using a reconstruction method which we test using hydrodynamic simulations. We find a moderate bias for the inferred average disk circularity and relative thickness with respect to the disk radius, but a large bias on the dispersion of these quantities. Applying the 3D shape reconstruction method on COSMOS data, we find no significant dependence of the inferred 3D shape distribution on redshift. The relative disk thickness shows a significant mass dependence which can be accounted for by the scaling of disk radius with galaxy mass. We conclude that the shapes of disk dominated galaxies are overall not subject to disruptive merging or feedback events below redshift $z=1.0$. This favours a scenario where these disks form early and subsequently undergo a tranquil evolution in isolation. In addition, our study shows that the observed 2D shapes of disk dominated galaxies can be well fitted using an ellipsoidal model for the galaxy 3D morphology combined with a Gaussian model for the 3D axes ratio distribution, confirming findings from similar work reported in the literature. Such an approach allows to build realistic mock catalogs with intrinsic galaxy shapes that will be essential for the study of intrinsic galaxy alignment as a contaminant of weak lensing surveys.","PeriodicalId":8452,"journal":{"name":"arXiv: Astrophysics of Galaxies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91287808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The mass of the Milky Way out to 100 kpc using halo stars 银河系的质量可以用光晕恒星计算到100kpc

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-26 DOI: 10.1093/mnras/staa3984

A. Deason, D. Erkal, V. Belokurov, Azadeh Fattahi, F. G'omez, R. Grand, R. Pakmor, X. Xue, Chao Liu, Chengqun Yang, Lan Zhang, Gang Zhao

{"title":"The mass of the Milky Way out to 100 kpc using halo stars","authors":"A. Deason, D. Erkal, V. Belokurov, Azadeh Fattahi, F. G'omez, R. Grand, R. Pakmor, X. Xue, Chao Liu, Chengqun Yang, Lan Zhang, Gang Zhao","doi":"10.1093/mnras/staa3984","DOIUrl":"https://doi.org/10.1093/mnras/staa3984","url":null,"abstract":"We use a distribution function analysis to estimate the mass of the Milky Way out to 100 kpc using a large sample of halo stars. These stars are compiled from the literature, and the majority (~95%) have 6D phase-space information. We pay particular attention to systematic effects, such as the dynamical influence of the Large Magellanic Cloud (LMC), and the effect of unrelaxed substructure. The LMC biases the (pre-LMC infall) halo mass estimates towards higher values, while realistic stellar halos from cosmological simulations tend to underestimate the true halo mass. After applying our method to the Milky Way data we find a mass within 100 kpc of M(< 100 kpc) = 6.31 +/- 0.32 (stat.) +/- 1.26 (sys.) x 10^11 M_Sun. For this estimate, we have approximately corrected for the reflex motion induced by the LMC using the Erkal et al. model, which assumes a rigid potential for the LMC and MW. Furthermore, stars that likely belong to the Sagittarius stream are removed, and we include a 5% systematic bias, and a 20% systematic uncertainty based on our tests with cosmological simulations. Assuming the mass-concentration relation for Navarro-Frenk-White haloes, our mass estimate favours a total (pre-LMC infall) Milky Way mass of M_200c = 1.05 +/- 0.25 x 10^12 M_Sun, or (post-LMC infall) mass of M_200c = 1.20 +/- 0.25 x 10^12 M_Sun when a 1.5 x 10^11 M_Sun mass of a rigid LMC is included.","PeriodicalId":8452,"journal":{"name":"arXiv: Astrophysics of Galaxies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81846215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 26

ARTIFICIAL NEURAL NETWORK MODELING OF THE CONFORMABLE FRACTIONAL ISOTHERMAL GAS SPHERES 适形分数等温气球的人工神经网络建模

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-24 DOI: 10.22201/IA.01851101P.2021.57.01.14

Y. A. Azzam, E. Abdel-salam, M. Nouh

引用次数: 10

Coronal-line forest active galactic nuclei – I. Physical properties of the emission-line regions 日冕线森林活动星系核。1 .发射线区域的物理性质

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-23 DOI: 10.1093/mnras/staa3320

F. C. Cerqueira-Campos, A. Rodríguez-Ardila, R. Riffell, M. Marinello, Almudena Prieto, L. Dahmer-Hahn

{"title":"Coronal-line forest active galactic nuclei – I. Physical properties of the emission-line regions","authors":"F. C. Cerqueira-Campos, A. Rodríguez-Ardila, R. Riffell, M. Marinello, Almudena Prieto, L. Dahmer-Hahn","doi":"10.1093/mnras/staa3320","DOIUrl":"https://doi.org/10.1093/mnras/staa3320","url":null,"abstract":"Coronal-Line Forest Active Galactic Nuclei (CLiF AGN) are characterized by strong high-ionization lines, which contrast to what is found in most AGNs. Here, we carry out a multiwavelength analysis aimed at understanding the physical processes in the Narrow Line Region (NLR) of these objects and unveiling if they are indeed a special class of AGN. By comparing coronal emission-line ratios we conclude that there are no differences between CLiF and non-CLiF AGNs. We derive physical conditions of the narrow line region (NLR) gas and found electron densities in the range $3.6times$10$^{2}$ - $1.7times$10$^{4}$ cm$^{-3}$ and temperatures of $3.7times$10$^{3}$ - $6.3times$10$^{4}$ K, suggesting that the ionization mechanism is associated primarily with photoionization by the AGN. We suggest a NLR dominated by matter-bounded clouds to explain the high-ionization line spectrum observed. The mass of the central black hole, derived from the stellar velocity dispersion show that most of the objects have values in the interval 10$^{7-8}$~M$odot$. Our results imply that CLiF AGN is not a separate category of AGNs. In all optical/near-infrared emission-line properties analyzed, they represent an extension to the low/high ends of the distribution within the AGN class.","PeriodicalId":8452,"journal":{"name":"arXiv: Astrophysics of Galaxies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86762430","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 7

Study of central intensity ratio of early-type galaxies from low-density environment 低密度环境下早期星系中心强度比的研究

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-23 DOI: 10.1093/mnras/staa3334

K. Sruthi, C. D. Ravikumar

引用次数: 0

Extreme kinematic misalignment in IllustrisTNG galaxies: the origin, structure, and internal dynamics of galaxies with a large-scale counterrotation 在IllustrisTNG星系的极端运动失调:起源，结构和内部动力学与大规模的逆旋转星系

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-22 DOI: 10.1093/mnras/staa3330

S. Khoperskov, I. Zinchenko, Branislav Avramov, S. Khrapov, P. Berczik, A. Saburova, M. A. Ishchenko, A. Khoperskov, C. Pulsoni, Yulia A. Venichenko, D. Bizyaev, A. Moiseev

{"title":"Extreme kinematic misalignment in IllustrisTNG galaxies: the origin, structure, and internal dynamics of galaxies with a large-scale counterrotation","authors":"S. Khoperskov, I. Zinchenko, Branislav Avramov, S. Khrapov, P. Berczik, A. Saburova, M. A. Ishchenko, A. Khoperskov, C. Pulsoni, Yulia A. Venichenko, D. Bizyaev, A. Moiseev","doi":"10.1093/mnras/staa3330","DOIUrl":"https://doi.org/10.1093/mnras/staa3330","url":null,"abstract":"Modern galaxy formation theory suggests that the misalignment between stellar and gaseous components usually results from an external gas accretion and/or interaction with other galaxies. The extreme case of the kinematic misalignment is demonstrated by so-called galaxies with counterrotation that possess two distinct components rotating in opposite directions with respect to each other. We provide an in-deep analysis of galaxies with counterrotation from IllustrisTNG100 cosmological simulations. We have found $25$ galaxies with substantial stellar counterrotation in the stellar mass range of $2times10^{9}-3times10^{10}$~Msun. In our sample the stellar counterrotation is a result of an external gas infall happened $approx 2-8$~Gyr ago. The infall leads to the initial removal of pre-existing gas, which is captured and mixed together with the infalling component. The gas mixture ends up in the counterrotating gaseous disc. We show that $approx 90%$ of the stellar counterrotation formed in-situ, in the counterrotating gas. During the early phases of the infall, gas can be found in inclined extended and rather thin disc-like structures, and in some galaxies they are similar to (nearly-)~polar disc or ring-like structures. We discuss a possible link between the gas infall, AGN activity and the formation of misaligned components. In particular, we suggest that the AGN activity does not cause the counterrotation, although it is efficiently triggered by the retrograde gas infall, and it correlates well with the misaligned component appearance. We also find evidence of the stellar disc heating visible as an increase of the vertical-to-radial velocity dispersion ratio above unity in both co- and counterrotating components, which implies the importance of the kinematical misalignment in shaping the velocity ellipsoids in disc galaxies.","PeriodicalId":8452,"journal":{"name":"arXiv: Astrophysics of Galaxies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81144700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 14

Runaway stars masquerading as star formation in galactic outskirts 在银河系外围伪装成恒星形成的逃逸恒星

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-22 DOI: 10.1093/mnrasl/slaa201

Eric P Andersson, F. Renaud, O. Agertz

引用次数: 4

The quiescent fraction of isolated low surface brightness galaxies: observational constraints 孤立低表面亮度星系的静止部分:观测约束

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-21 DOI: 10.1093/mnras/staa3296

D. Prole, R. V. D. van der Burg, M. Hilker, L. Spitler

{"title":"The quiescent fraction of isolated low surface brightness galaxies: observational constraints","authors":"D. Prole, R. V. D. van der Burg, M. Hilker, L. Spitler","doi":"10.1093/mnras/staa3296","DOIUrl":"https://doi.org/10.1093/mnras/staa3296","url":null,"abstract":"Understanding the formation and evolution of low surface brightness galaxies (LSBGs) is critical for explaining their wide-ranging properties. However, studies of LSBGs in deep photometric surveys are often hindered by a lack of distance estimates. In this work, we present a new catalogue of 479 LSBGs, identified in deep optical imaging data from the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). These galaxies are found across a range of environments, from the field to groups. Many are likely to be ultra-diffuse galaxies (UDGs). We see clear evidence for a bimodal population in colour - Sersic index space, and split our sample into red and blue LSBG populations. We estimate environmental densities for a subsample of 215 sources by statistically associating them with nearby spectroscopic galaxies from the overlapping GAMA spectroscopic survey. We find that the blue LSBGs are statistically consistent with being spatially randomised with respect to local spectroscopic galaxies, implying they exist predominantly in low-density environments. However, the red LSBG population is significantly spatially correlated with local structure. We find that 26+/-5% of isolated, local LSBGs belong to the red population, which we interpret as quiescent. This indicates that high environmental density plays a dominant, but not exclusive, role in producing quiescent LSBGs. Our analysis method may prove to be very useful given the large samples of LSB galaxies without distance information expected from e.g. the Vera C. Rubin observatory (aka LSST), especially in combination with upcoming comprehensive wide field spectroscopic surveys.","PeriodicalId":8452,"journal":{"name":"arXiv: Astrophysics of Galaxies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90710661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 15

uGMRT detection of associated H i 21-cm absorption at z ≈ 3.5 uGMRT检测伴生H在z≈3.5的21cm吸收

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-20 DOI: 10.1093/mnras/staa3306

J. Aditya, R. Jorgenson, V. Joshi, Veeresh Singh, T. An, Y. Chandola

{"title":"uGMRT detection of associated H i 21-cm absorption at z ≈ 3.5","authors":"J. Aditya, R. Jorgenson, V. Joshi, Veeresh Singh, T. An, Y. Chandola","doi":"10.1093/mnras/staa3306","DOIUrl":"https://doi.org/10.1093/mnras/staa3306","url":null,"abstract":"We report a uGMRT detection of Hi 21-cm absorption associated with the radio source 8C 0604+728, at z = 3.52965. The source is at the highest redshift at which associated Hi 21-cm absorption has been discovered to date, surpassing earlier known absorber at z approx 3.39. We estimate ultraviolet luminosities of (3.2 plus or minus 0.1) times 10 23 W Hz -1 and (6.2 plus or minus 0.2) times 10 23 W Hz -1 , and ionising photon rates of (1.8 plus or minus 0.1) times 10 56 s -1 and (5.0 plus or minus 0.1) times 10 56 s -1, using data at different epochs; the source shows year-scale variability in both its luminosity and photon rate. The luminosity and photon rate at later epochs are approx 6.2 and approx 1.7 times higher than thresholds suggested in the literature above which all the neutral hydrogen in the AGN host galaxy is expected to be ionised. The detection demonstrates that neutral hydrogen can survive in the host galaxies of AGNs with high ultraviolet luminosities. We estimate a high equivalent width ratio of 15.2 for the Ly{alpha} and HeII emission lines detected in the optical spectrum, that is consistent with AGN photoionisation models. However, a significant contribution from young stellar populations to the excess Ly{alpha} flux cannot be ruled out.","PeriodicalId":8452,"journal":{"name":"arXiv: Astrophysics of Galaxies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78786026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Hydrodynamic simulations of an isolated star-forming gas cloud in the Virgo cluster 室女座星团中形成恒星的孤立气体云的流体动力学模拟

arXiv: Astrophysics of Galaxies Pub Date : 2020-10-19 DOI: 10.1093/mnras/staa3133

F. Calura, M. Bellazzini, A. D'ercole

{"title":"Hydrodynamic simulations of an isolated star-forming gas cloud in the Virgo cluster","authors":"F. Calura, M. Bellazzini, A. D'ercole","doi":"10.1093/mnras/staa3133","DOIUrl":"https://doi.org/10.1093/mnras/staa3133","url":null,"abstract":"We present a suite of three-dimensional, high-resolution hydrodynamic simulations that follow the evolution of a massive (10^7 M_sun) pressure confined, star-forming neutral gas cloud moving through a hot intra-cluster medium (ICM). The main goal of the analysis is to get theoretical insight into the lifetimes and evolution of stellar systems like the recently discovered star-forming cloud SECCO~1 in the Virgo cluster of galaxies, but it may be of general interest for the study of the star-forming gas clumps that are observed in the tails of ram pressure stripped galaxies. Building upon a previous, simple simulation, we explored the effect of different relative velocity of the cloud and larger temperature of the ICM, as well as the effect of the cloud self-gravity. Moreover, we performed a simulation including star-formation and stellar feedback, allowing for a first time a direct comparison with the observed properties of the stars in the system. The survivability of the cold gas in the simulated clouds is granted on timescales of the order of 1 Gyr, with final cold gas fractions generally $>0.75$. In all cases, the simulated systems end up, after 1 Gyr of evolution, as symmetric clouds in pressure equilibrium with the external hot gas. We also confirm that gravity played a negligible role at the largest scales on the evolution of the clouds. In our simulation with star formation, star formation begins immediately, it peaks at the earliest times and decreases monotonically with time. Inhomogeneous supernova explosions are the cause of an asymmetric shape of the gas cloud, facilitating the development of instabilities and the decrease of the cold gas fraction.","PeriodicalId":8452,"journal":{"name":"arXiv: Astrophysics of Galaxies","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79290570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9