分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the Satellite Plane Problem (SP) of the Milky Way (MW) by using the recently published simulation data of TNG50-1. Here, we only consider the satellite plane consisting of the brightest 14 MW satellites (11 classical satellites plus Canes Venatici I(CVn I), Crater II and Antlia II). Only one (among 231 candidates) MW-like halo (haloID=395, at z=0, hereafter halo395 ) possesses a satellite plane as spatially thin and kinematically coherent as the observed one has been found. Halo395 resembles the MW in a number of intriguing ways: it hosts a spiral central galaxy and its satellite plane is almost ($\sim 87^{\circ}$) perpendicular to the central stellar disk. In addition, halo395 is embedded in a sheet plane, with a void on the top and bottom, similar to the local environment of MW. More interestingly, we found that the major subset (11 of 14) of the satellite plane of halo395 arise precisely from the peculiar geometry of its large-scale environment (e.g. sheet and voids). However, the other three members just appeared at the right places with the right velocities by chance at z=0. Although the satellite plane of halo395 is transient and came into existence at z=0, the MW-like Large-scale environment indeed promotes the formation of the satellite plane. Our results support previous conclusions: SP is not a serious challenge to the $\Lambda$CDM model and its formation is ascribed to the right environment.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Galaxies display several well-behaved scaling relations between their properties, such as the star formation rate-stellar mass relation (the main sequence) and the stellar mass-halo mass relation (SHMR). In principle, these scaling relations could imply different star formation histories (SFHs) of galaxies and different constraints on galaxy formation physics. In this paper, we derive the SFHs of galaxies by assuming that they always follow the SHMRs at different redshifts and use an empirical model to constrain key processes in their baryon cycle. It is found that, besides cold accretion due to halo growth, outflow of gas produced by stellar feedback has to be recycled to sustain the derived SFHs of galaxies. The recycled fraction is strongly affected by the baryon fraction in accreted low-mass haloes and the mass loading factor which quantifies the ratio between the galactic outflow rate and star formation rate. Our fiducial model predicts that around $20-60\%$ of outflow is recycled in $\sim0.5-4Gyrs$, while simulations predict a slightly higher recycle fraction and a lower recycle time. We argue that strong constraints on the baryon cycle process can be obtained from future observation of the circum-galactic medium (CGM) of galaxies, such as the gas cooling rate of CGM. We also find that the implied SFHs from the SHMRs indicate that galaxies stay on the main sequences only for part of their lifetimes. Our model reproduces the evolution of the mass-metallicity relation as well.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the Satellite Plane Problem (SP) of the Milky Way (MW) by using the recently published simulation data of TNG50-1. Here, we only consider the satellite plane consisting of the brightest 14 MW satellites (11 classical satellites plus Canes Venatici I(CVn I), Crater II and Antlia II). Only one (among 231 candidates) MW-like halo (haloID=395, at z=0, hereafter halo395 ) possesses a satellite plane as spatially thin and kinematically coherent as the observed one has been found. Halo395 resembles the MW in a number of intriguing ways: it hosts a spiral central galaxy and its satellite plane is almost ($\sim 87^{\circ}$) perpendicular to the central stellar disk. In addition, halo395 is embedded in a sheet plane, with a void on the top and bottom, similar to the local environment of MW. More interestingly, we found that the major subset (11 of 14) of the satellite plane of halo395 arise precisely from the peculiar geometry of its large-scale environment (e.g. sheet and voids). However, the other three members just appeared at the right places with the right velocities by chance at z=0. Although the satellite plane of halo395 is transient and came into existence at z=0, the MW-like Large-scale environment indeed promotes the formation of the satellite plane. Our results support previous conclusions: SP is not a serious challenge to the $\Lambda$CDM model and its formation is ascribed to the right environment.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Galaxies display several well-behaved scaling relations between their properties, such as the star formation rate-stellar mass relation (the main sequence) and the stellar mass-halo mass relation (SHMR). In principle, these scaling relations could imply different star formation histories (SFHs) of galaxies and different constraints on galaxy formation physics. In this paper, we derive the SFHs of galaxies by assuming that they always follow the SHMRs at different redshifts and use an empirical model to constrain key processes in their baryon cycle. It is found that, besides cold accretion due to halo growth, outflow of gas produced by stellar feedback has to be recycled to sustain the derived SFHs of galaxies. The recycled fraction is strongly affected by the baryon fraction in accreted low-mass haloes and the mass loading factor which quantifies the ratio between the galactic outflow rate and star formation rate. Our fiducial model predicts that around $20-60\%$ of outflow is recycled in $\sim0.5-4Gyrs$, while simulations predict a slightly higher recycle fraction and a lower recycle time. We argue that strong constraints on the baryon cycle process can be obtained from future observation of the circum-galactic medium (CGM) of galaxies, such as the gas cooling rate of CGM. We also find that the implied SFHs from the SHMRs indicate that galaxies stay on the main sequences only for part of their lifetimes. Our model reproduces the evolution of the mass-metallicity relation as well.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A rare population of massive disk galaxies have been found to invade the red sequence dominated by early-type galaxies. These red/quenched massive disk galaxies have recently gained great interest into their formation and origins. The usually proposed quenching mechanisms, such as bar quenching and environment quenching, seem not suitable for those bulge-less quenched disks in low-density environment. In this paper, we use the IllustrisTNG-300 simulation to investigate the formation of massive quenched central disk galaxies. It is found that these galaxies contain less gas and harbor giant supermassive black holes(SMBHs) (above $ 10^{8}M_{\odot}$) than their star forming counterparts. By tracing their formation history, we found that quenched disk galaxies formed early and preserved disk morphology for cosmological time scales. They have experienced less than one major merger on average and it is mainly mini-mergers (mass ratio $<$1/10) that contribute to the growth of their SMBHs. In the Illustris-TNG simulation the black hole feedback mode switches from thermal to kinetic feedback when the black hole mass is more massive than $\sim 10^{8}M_{\odot}$, which is more efficient to eject gas outside of the galaxy and to suppress further cooling of hot gaseous halo. We conclude that kinetic AGN feedback in massive red/quenched disk galaxy is the dominant quenching mechanism.
点击量
待评议
点击量
下载量
评论
