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The formation and evolution of massive galaxies

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Research in Astronomy and Astrophysics 2021年第9期21卷 53-62页

作者： Ying-Jie Jing Yu Rong Jie Wang Qi Guo Liang Gao Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Instituto de Astrofísica Pontificia Universidad Católica de ChileAv.Vicuña Mackenna 4860MaculSantiagoChile Institute of Computational Cosmology Department of PhysicsUniversity of DurhamScience LaboratoriesSouth RoadDurham DH13LEUK FONDECYT

The discovery of massive galaxies at high redshifts,especially the passive ones,poses a big challenge for the current standard galaxy formation models.Here we use the semi-analytic galaxy formation model developed by Henriques et al.to explore the formation and evolution of massive galaxies(MGs,stellar-mass M*>1011 M⊙).Different from previous works,we focus on the ones just formed(e.***.just reach?1011 M⊙).We find that most of the MGs are formed around z=0.6,with the earliest formation at z>4.Interestingly,although most of the MGs in the local Universe are passive,we find that only 13%of the MGs are quenched at the formation time.Most of the quenched MGs at formation already host a very massive supermassive black hole(SMBH)which could power the very effective AGN feedback.For the star-forming MGs,the ones with more massive SMBH prefer to quench in shorter timescales;in particular,those with MSMBH>107.5 M⊙have a quenching timescale of~0.5 Gyr and the characteristic MSMBH depends on the chosen stellar mass threshold in the definition of MGs as a result of their co-evolution.We also find that the"in-situ"star formation dominates the stellar mass growth of MGs until they are formed.Over the whole redshift range,we find the quiescent MGs prefer to stay in more massive dark matter halos,and have more massive SMBH and less cold gas masses.Our results provide a new angle on the whole life of the growth of MGs in the Universe.

关键词： galaxies:evolution galaxies:formation galaxies:star formation galaxies:high-redshift methods:numerical

formation and Evolution of galaxies and Its Black Holes and Quasars

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Journal of Physical Science and Application 2021年第2期11卷 9-20页

作者： Cuixiang Zhong Department of Science and Technology Jiangxi Normal UniversityChina

Galaxy formation and evolution is one of the most active research areas in astrophysics,so many people have studied this area.But since they didn’t understand thoroughly the evolution law from satellite to planet then to star,their theories are very weak.In their theories,they proposed that large gas clouds collapsing to form a galaxy or more recently that matter started out in smaller clumps merged to form galaxy,which is incredible.Hence,the author of this paper,through studying the formation and orbit-variation of satellites,planets and stars,has put forward a new theory of galaxy formation and evolution,therefore revealing the hierarchical structure of galaxies and the formation and evolution of black holes and quasars.

关键词： galaxies:structure galaxies:formation galaxies:evolution stars:black holes stars:quasars

AGN Lifetimes in UV-selected galaxies: A Clue to Supermassive Black Hole-galaxy Coevolution

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Research in Astronomy and Astrophysics 2022年第1期22卷 104-113页

作者： Xiaozhi Lin Yongquan Xue Guanwen Fang Lulu Fan Huynh Anh N Le Ashraf Ayubinia CAS Key Laboratory for Research in galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China School of Mathematics and Physics Anqing Normal UniversityAnqing 246133China Shandong Provincial Key Lab of Optical Astronomy and Solar-Terrestrial Environment Institute of Space ScienceShandong UniversityWeihai264209China

The coevolution between supermassive black holes(SMBHs) and their host galaxies has been proposed for more than a decade,albeit with little direct evidence about black hole accretion activities regulating galaxy star formation at z> 1.In this paper,we study the lifetimes of X-ray active galactic nuclei(AGNs) in UV-selected red sequence(RS),blue cloud(BC) and green valley(GV) galaxies,finding that AGN accretion activities are most prominent in GV galaxies at z ~1.5-2,compared with RS and BC galaxies.We also compare AGN accretion timescales with typical color transition timescales of UV-selected galaxies.We find that the lifetime of GV galaxies at z~1.5-2 is very close to the typical timescale when the AGNs residing in them stay in the high-accretion-rate mode at these redshifts;for BC galaxies,the consistency between the color transition timescale and the black hole strong accretion lifetime is more likely to happen at lower redshifts(z galaxies,making galaxies and their central SMBHs coevolve with each other.

关键词： galaxies:active galaxies:formation galaxies:evolution galaxies:high-redshift galaxies:nuclei (galaxies:)quasars:supermassive black holes galaxies:star formation galaxies:statistics

The HⅠGas Fraction Scaling Relation of the Green Pea galaxies

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Research in Astronomy and Astrophysics 2023年第6期23卷 56-64页

作者：刘思琦罗阿理张伟张彦霞孔啸赵永恒 CAS Key Laboratory of Optical Astronomy National Astronomical ObservatoriesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China College of Computer and Information Management&Institute for Astronomical Science Dezhou UniversityDezhou 253023China

Green Pea galaxies are compact galaxies with high star formation rates.However,limited samples of Green Pea galaxies have H I 21 cm measurements.Whether the H I gas fraction(fH I≡MH I/M_(★))of Green Pea galaxies follows the existing scaling relations between the fH Iand NUV-r color or linear combinations of color and other physical quantities needs checking.Using archival data of H I 21 cm observations,we investigate the scaling relation of the NUV-r color with the MH I/M_(★)of 38 Green Pea galaxies,including 17 detections and 21 nondetections.The H I to stellar mass ratios(fH I)of Green Pea galaxies deviate from the polynomial form,where a higher H I gas fraction is predicted given the current NUV-r color,even with the emission lines removed.The blue sources(NUV-rgalaxies.In order to obtain accurate linear combined forms,higher-resolution photometry from space-based telescopes is needed.

关键词： galaxies:general galaxies:dwarf galaxies:formation

The formation of a blue cluster in the local Universe

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Research in Astronomy and Astrophysics 2020年第12期20卷 337-346页

作者：温庆新罗煜康熙 Purple Mountain Observatory Chinese Academy of SciencesNanjing 210033China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China Zhejiang University-Purple Mountain Observatory Joint Research Center for Astronomy Zhejiang UniversityHangzhou 310037China

It is well known from the Butcher-Oemler effect that galaxies in dense environment are mostly red with little star formation and the fraction of blue galaxies in galaxy groups/clusters also declines rapidly with redshifts.A recent work by Hashimoto et al.reported a local ‘blue cluster’ with a high fraction of blue galaxies(∼0.57),higher than the model predictions.They ascribed this blue cluster to the feeding of gas along a filamentary structure around the cluster.In this work we use group catalog from the Sloan Digital Sky Survey Data Release 7(SDSS DR7) and the state-of-art of semi-analytic model(SAM) to investigate the formation of blue clusters in the local Universe.In total,we find four blue clusters with halo mass ∼10^14 M⊙ at 0.02 formation time and most blue satellite galaxies are recently accreted.We conclude that the formation of blue clusters is mainly governed by newly accreted blue satellites,rather than the effect of large-scale environment.

关键词： galaxies:clusters:statistical galaxies:evolution galaxies:formation galaxies:blue fraction

Chemo-dynamical modelling with Schwarzschild's method

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Research in Astronomy and Astrophysics 2018年第12期18卷 1-8页

作者： Richard John Long Shude Mao National Astronomical Observatories Chinese Academy of Sciences Jodrell Bank Centre for Astrophysics School of Physics and Astronomy The University of Manchester Physics Department and Tsinghua Centre for Astrophysics Tsinghua University

We extend Schwarzschild’s dynamical modelling method to model absorption line strength data as well as the more usual luminosity and kinematic data.Our approach draws on earlier published work by the first author with the Syer & Tremaine made-to-measure(M2M) dynamical modelling method and uses similar ideas to create a chemo-Schwarzschild method.We apply our extended Schwarzschild method to the same four early type galaxies(NGC 1248, NGC 3838, NGC 4452,NGC 4551) as the chemo-M2M work, and are able to recover successfully the 2D absorption line strength for the three lines we model(Hβ, Fe5015, Mg b).We believe that this is the first time Schwarzschild’s method has been used in this way.The techniques developed can be applied to modelling other aspects of galaxies, for example age and metallicity data coming from stellar population modelling, and are not specific to absorption line strength data.

关键词： galaxies:abundances galaxies:formation galaxies:individual(NGC 1248,NGC 3838,NGC 4452,NGC 4551) galaxies:kinematics and dynamics galaxies:structure methods:numerical

The physical properties of galaxies with unusually high gas-phase metallicity

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Research in Astronomy and Astrophysics 2020年第2期20卷 53-66页

作者： Yong-Yun Chen Qiu-Sheng Gu Xue Ge School of Astronomy and Space Science Nanjing University

We use 1221 galaxies with unusually high gas-phase metallicity to study their physical properties.The scope of redshift is 0.02 < z < 0.25 for these galaxies with unusually high gas-phase metallicity.Our goal is to un... 详细信息

We use 1221 galaxies with unusually high gas-phase metallicity to study their physical properties.The scope of redshift is 0.02 galaxies with unusually high gas-phase metallicity.Our goal is to understand the physical origins of the high gas-phase metallicity.To address this study,we select a control sample matching similar redshift and stellar mass.Our main results are as follows.(i) Compared with the control sample,the high-metallicity sample shows lower ionization parameter,higher electron density and more dust content.(ii) We also find that the high-metallicity sample has older stellar age and higher [Mgb/] ratio,which indicates that the high-metallicity sample has shorter timescale of star formation.(iii) According to the plane of Hδ_A vs.D_n4000,we can see that the control sample has higher HδAand lower D_n4000 than the high-metallicity sample,which may imply that the control sample experiences recent star formation.(iv) There is a significant difference in gas distribution between the highmetallicity and control samples.The high-metallicity sample has lower gas fraction than control sample,which indicates that galaxies have high gas-phase metallicity probably due to their low HI gas fraction.(v) There is no significant difference between the high-metallicity and control samples in environment,which may suggest that the environment has no effect on gas-phase metallicity.

关键词： galaxies:evolution galaxies:formation galaxies:abundance galaxies:ISM galaxies:star formation

Automated classification technique for edge-on galaxies based on mathematical treatment of brightness data

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Research in Astronomy and Astrophysics 2021年第10期21卷 231-238页

作者： Mohamed Eassa Ibrahim Mohamed Selim Walid Dabour Passent Elkafrawy Computer Science Department Integrated Thebes InstituteCairoEgypt Faculty of Computer&Artificial Intelligence Sadat City UniversitySadat CityEgypt Math and Computer Science Dept. Faculty of ScienceMenoufia UniversityEgypt Computer Science Dept. Taibah UniversityAlula BranchKingdom of Saudi Arabia School of Information Technology and Computer Science(ITCS) Nile UniversityEgypt

Classification of edge-on galaxies is important to astronomical studies due to our Milky Way galaxy being an edge-on galaxy.Edge-on galaxies pose a problem to classification due to their less overall brightness levels and smaller numbers of pixels.In the current work,a novel technique for the classification of edge-on galaxies has been developed.This technique is based on the mathematical treatment of galaxy brightness data from their images.A special treatment for galaxies’brightness data is developed to enhance faint galaxies and eliminate adverse effects of high brightness backgrounds as well as adverse effects of background bright stars.A novel slimness weighting factor is developed to classify edge-on galaxies based on their slimness.The technique has the capacity to be optimized for different catalogs with different brightness levels.In the current work,the developed technique is optimized for the EFIGI catalog and is trained using a set of 1800 galaxies from this catalog.Upon classification of the full set of 4458 galaxies from the EFIGI catalog,an accuracy of 97.5% has been achieved,with an average processing time of about 0.26 seconds per galaxy on an average laptop.

关键词： techniques:image processing methods:data analysis galaxies:formation

Conditions for galaxy quenching at 0.5

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Research in Astronomy and Astrophysics 2020年第8期20卷 143-156页

作者： Xue Ge Feng-Shan Liu Qiu-Sheng Gu Emanuele Contini Yi-Zhou Gu School of Astronomy and Space Science Nanjing UniversityNanjing 210093China Key Laboratory of Modern Astronomy and Astrophysics Nanjing UniversityNanjing 210093China Collaborative Innovation Center of Modern Astronomy and Space Exploration Nanjing 210093China Key Laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Department of Physics and Institute of Theoretical Physics Nanjing Normal UniversityNanjing 210023China

We investigate two classes of conditions for galaxy quenching at 0.510^10 M⊙)have much higher stellar mass surface densities within the central 1 kpc(∑1)and smaller sizes than star-forming galaxies in the same stellar mass range.In addition,the quiescent fractions significantly increase with the increase of∑1 regardless of whether galaxies are centrals or satellites.In contrast,we find that the overall lower-mass quiescent galaxies(M*galaxies of the same mass and at the same redshift.At zgalaxies since z^2.5,while the environmental effect plays an important role in the quenching of low-mass galaxies at z≤1.5.

关键词： galaxies:evolution galaxies:formation galaxies:high-redshift