Irregular dwarf galaxies of the Local Group have very varied properties and star formation histories. Some of them formed the majority of their stars very late compared to the others. Extreme examples are Leo A and Aquarius which reached the peak of star formation at $z<1$ ( > 6 Gyr after BB). This fact seemingly challenges the LCDM cosmology because the dark matter halos of these galaxies on average should assemble the majority of their masses before z~2 (<3 Gyr after BB). In this work we investigate whether the delayed star formation histories of some irregular dwarf galaxies could be explained purely by the stochasticity of their mass assembly histories coupled with the effect of cosmic reionization. We develop a semi-analytic model to follow the accretion of baryonic matter, star formation and stellar feedback in dark matter halos with present day virial masses 10^9 M_Sun < M < 10^11 M_Sun and with different stochastic growth histories obtained using the PINOCCHIO code based on Lagrangian perturbation theory. We obtain the distributions of observable parameters and the evolution histories for these galaxies. Accretion of baryonic matter is strongly suppressed after the epoch of reionization in some models but they continue to accrete dark matter and eventually reach enough mass for accretion of baryonic matter to begin again. These "reborn" model galaxies show very similar delayed star formation histories to those of Leo A and Aquarius. We find that the stochasticity caused by mass assembly histories is enhanced in systems with virial masses ~10^10 M_Sun because of their sensitivity to the photoionizing intergalactic radiation field after the epoch of reionization. This results in qualitatively different star formation histories in late- and early-forming galaxies and it might explain the peculiar star formation histories of irregular dwarf galaxies such as Leo A and Aquarius.
Lyman continuum leakage versus quenching with the James Webb Space Telescope: The spectral signatures of quenched star formation activity in reionization-epoch galaxies
MEGATRON: Dwarf Galaxy Quenching in the Epoch of Reionization
University of Sussex（萨塞克斯大学）；DISCnet Centre for Doctoral Training, University of Sussex（萨塞克斯大学 DISCnet 博士培训中心）；University of Bath（巴斯大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）；Institut d’Astrophysique de Paris, Sorbonne Université, CNRS（巴黎天体物理研究所，索邦大学，法国国家科学研究中心）；University of Oxford（牛津大学）
Star formation histories and gas content limits of three ultra-faint dwarfs on the periphery of M31
University of Arizona（亚利桑那大学）；Caltech（加州理工学院）；Space Telescope Science Institute（太空望远镜科学研究所）；University of Tampa（坦帕大学）；University of Surrey（萨里大学）；Dartmouth College（达特茅斯学院）；University of Toronto（多伦多大学）
Co-evolution of baryons and dark matter halos of LYRA dwarf galaxies
Durham University（杜伦大学）；European Southern Observatory（欧洲南方天文台）；Stockholm University（斯德哥尔摩大学）；University of Hawaii（夏威夷大学）；Max-Planck-Institut für Astrophysik（马克斯·普朗克天体物理学研究所）
POLAR-II: modeling star formation history of galaxies on the 21-cm signal from Epoch of Reionization
Guizhou Normal University（贵州师范大学）；Indian Institute of Science Education and Research Kolkata（印度科学教育研究所加尔各答分校）；Max-Planck Institute für Astrophysics（马克斯·普朗克天体物理学研究所）；University of California, Berkeley（加州大学伯克利分校）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；University of Sussex（萨塞克斯大学）；University of Groningen（格罗宁根大学）；Stockholm University（斯德哥尔摩大学）
A Bimodal Metallicity Distribution Function in the Ultra-Faint Dwarf Galaxy Reticulum II
University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙物理学研究所）；Kyung Hee University（庆熙大学）；Princeton University（普林斯顿大学）；University of Toronto（多伦多大学）；Massachusetts Institute of Technology（麻省理工学院）
Caught Napping by JWST UNCOVER+MegaScience: Constraining bursty star formation histories and number densities of mini-quenched galaxies at redshifts 4-7
University of Washington（华盛顿大学）；University of Pittsburgh（匹兹堡大学）；University of Colorado, Boulder（科罗拉多大学博尔德分校）；University of California, Santa Cruz（加州大学圣克鲁兹分校）；Princeton University（普林斯顿大学）
CLEAR II: Evidence for Early Formation of the Most Compact Quiescent Galaxies at High Redshift
星系中质量、形态、淬灭分数和形成历史之间的相关性的起源很难定义，主要是由于星系恒星形成历史的不确定性。恒星形成的历史，更好地约束高红移星系，观察更接近他们的形成和淬火时代。在这里，我们使用“非参数”的恒星形成的历史和嵌套的采样方法，以获得在$0.7<z<2.5$静止星系的形成和淬火时间尺度的约束。我们从CLEAR（CANDELS Lyman PDMATHAMN再电离发射）调查中模拟了深HST棱镜光谱和光度学。星系形成的红移，$z_{50}$（定义为它们形成50%恒星质量的点）的范围从$z_{50}\sim 2$（在观察到的时期之前不久）到$z_{50} \simeq 5-8$。\editone{We find that early formation redshifts are correlated with high stellar-mass surface densities, $\log Σ_1 / (M_\odot\ \mathrm{kpc}^{-2}) >$10.25, where $Σ_1$ is the stellar mass within 1~pkpc (proper kpc). Quiescent galaxies with the highest stellar-mass surface density, $\logΣ_1 / (M_\odot\ \mathr…
SEAMLESS Survey: Four Faint Dwarf Galaxies Tracing Low-Mass Galaxy Evolution Across Environments
Steward Observatory, University of Arizona（亚利桑那大学斯图尔德天文台）；Department of Physics and Astronomy, University of Tampa（坦帕大学物理与天文学系）；Department of Physics and Astronomy, Dartmouth College（达特茅斯学院物理与天文学系）；Space Telescope Science Institute（太空望远镜科学研究所）；Department of Physics, University of Surrey（萨里大学物理系）；Department of Astronomy & Astrophysics, University of Toronto（多伦多大学天文学与天体物理学系）；Dunlap Institute for Astronomy and Astrophysics, University of Toronto（多伦多大学邓普天文学与天体物理研究所）；Department of Physics, Engineering Physics and Astronomy, Queen’s University（女王大学物理、工程物理与天文学系）
The abundance and properties of the lowest luminosity dwarf galaxies around the Milky Way: Insights from Semi-Analytic Models
Department of Astronomy, University of Virginia（弗吉尼亚大学天文学系）；Virginia Institute for Theoretical Astronomy, University of Virginia（弗吉尼亚理论天文研究所）；Carnegie Observatories（卡内基观测站）
