分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We use a semi-analytic galaxy formation model to study the co-evolution of supermassive black holes (SMBHs) with their host galaxies. Although the coalescence of SMBHs is not important, the quasar-mode accretion induced by mergers plays a dominant role in the growth of SMBHs. Mergers play a more important role in the growth of SMBH host galaxies than in the SMBH growth. It is the combined contribution from quasar mode accretion and mergers to the SMBH growth and the combined contribution from starburst and mergers to their host galaxy growth that determine the observed scaling relation between the SMBH masses and their host galaxy masses. We also find that mergers are more important in the growth of SMBH host galaxies compared to normal galaxies which share the same stellar mass range as the SMBH host galaxies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： 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 $M_{*}> 10^{11}$ M$_{\odot}$). Different from previous works, we focus on the ones just formed (e.g. just reach $\simeq 10^{11}$ M$_{\odot}$). 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 hosts 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 $M_{\textrm{SMBH}} > 10^{7.5}$ M$_{\odot}$ have a quenching timescale of $\sim 0.5$ Gyr and the characteristic $M_{\textrm{SMBH}}$ 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.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The multi-peak solitons and their stability are investigated for the nonlocal nonlinear system with the sine-oscillation response, including both the cases of positive and negative Kerr coefficients. The Hermite-Gaussian-type multi-peak solitons and the ranges of the degree of nonlocality within which the solitons exist are analytically obtained by the variational approach. This is the first time, to our knowledge at least, to discuss the solution existence range of the multi-peak solitons analytically, although approximately. The variational analytical results are confirmed by the numerical ones. The stability of the multi-peak solitons are addressed by the linear stability analysis. It is found that the upper thresholds of the peak-number of the stable solitons are five and four for the system with negative and positive Kerr coefficients, respectively.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the relation between halo concentration and mass (c-M relation) using the Seventh and Eighth Data Release of the Sloan Digital Sky Survey (SDSS DR7 and DR8) galaxy catalogue. Assuming that the satellite galaxies follow the distribution of dark matter, we derive the halo concentration by fitting the satellite radial profile with a Nararro Frank and White (NFW) format. The derived c-M relation covers a wide halo mass range from $10^{11.6}$ to $10^{14.1} \rm\ M_\odot$. We confirm the anti-correlation between the halo mass and concentration as predicted in cosmological simulations. Our results are in good agreement with those derived using galaxy dynamics and gravitational lensing for halos of $10^{11.6}-10^{12.9} \rm\ M_\odot$, while they are slightly lower for halos of $10^{12.9}-10^{14.1}\rm\ M_\odot$. It is because blue satellite galaxies are less concentrated, especially in the inner regions. Instead of using all satellite galaxies, red satellites could be better tracers of the underlying dark matter distribution in galaxy groups.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the relation between halo concentration and mass (c-M relation) using the Seventh and Eighth Data Release of the Sloan Digital Sky Survey (SDSS DR7 and DR8) galaxy catalogue. Assuming that the satellite galaxies follow the distribution of dark matter, we derive the halo concentration by fitting the satellite radial profile with a Nararro Frank and White (NFW) format. The derived c-M relation covers a wide halo mass range from $10^{11.6}$ to $10^{14.1} \rm\ M_\odot$. We confirm the anti-correlation between the halo mass and concentration as predicted in cosmological simulations. Our results are in good agreement with those derived using galaxy dynamics and gravitational lensing for halos of $10^{11.6}-10^{12.9} \rm\ M_\odot$, while they are slightly lower for halos of $10^{12.9}-10^{14.1}\rm\ M_\odot$. It is because blue satellite galaxies are less concentrated, especially in the inner regions. Instead of using all satellite galaxies, red satellites could be better tracers of the underlying dark matter distribution in galaxy groups.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The planar distributions of satellite galaxies around the Milky Way and Andromeda have been extensively studied as potential challenges to the standard cosmological model. Using the Sloan Digital Sky Survey and the Millennium simulation we extend such studies to the satellite galaxies of massive galaxy clusters. We find that both observations and simulations of galaxy clusters show an excess of anisotropic satellite distributions. On average, satellites in clusters have a higher degree of anisotropy than their counterparts in Milky-Way-mass hosts once we account for the difference in their radial distributions. The normal vector of the plane of satellites is strongly aligned with the host halo's minor axis, while the alignment with the large-scale structure is weak. At fixed cluster mass, the degree of anisotropy is higher at higher redshift. This reflects the highly anisotropic nature of satellites accretion points, a feature that is partly erased by the subsequent orbital evolution of the satellites. We also find that satellite galaxies are mostly accreted singly so group accretion is not the explanation for the high flattening of the planes of satellites.
分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2023-12-15 合作期刊: 《Research in Astronomy and Astrophysics》
摘要： Environments play an important role in galaxy formation and evolution, particularly in regulating the content of neutral gas. However, current H i surveys have limitations in their depth, which prevents them from adequately studying low H i content galaxies in high-density regions. In this study, we address this issue by employing the Five-hundred-meter Aperture Spherical radio Telescope with extensive integration times to complement the relatively shallow Arecibo Legacy Fast Arecibo L-band Feed Array H i survey. This approach allows us to explore the gas content of dwarf galaxies across various environments. We observe a positive relationship between H i mass and stellar mass in dwarf galaxies, with a well-defined upper boundary for H i mass that holds true in both observations and simulations. Furthermore, we find a decrease in the H i-to-stellar mass ratio (MH I/M*) as the density of the environment increases, irrespective of whether it is determined by the proximity to the nearest group or the projected number density. Comparing our observations to simulations, we note a steeper slope in the relationship, indicating a gradual gas-stripping process in the observational data. Additionally, we find that the scaling relation between the MH I/M* and optical properties can be improved by incorporating galaxy environments.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： With a hydrodynamical simulation using a simple galaxy formation model without taking into account feedback, our previous work has shown that dense and massive filaments at high redshift can provide potential wells to trap and compress gas, and hence affect galaxy formation in their resident low-mass haloes. In this paper, we make use of the Auriga simulations, a suite of high-resolution zoom-in hydrodynamical simulations of Milky Way-like galaxies, to study whether the conclusion still holds in the simulations with a sophisticated galaxy formation model. In agreement with the results of our previous work, we find that, comparing to their counterparts with similar halo masses in field, dwarf galaxies residing in filaments tend to have higher baryonic and stellar fractions. At the fixed parent halo mass, the filament dwarfs tend to have slightly higher star formation rates than those of field ones. But overall we do not find a clear difference in galaxy g - r colours between the filament and field populations. We also show that at high redshifts, the gas components in dwarf galaxies tend to have their spins aligned with the filaments in which they reside. Our results support a picture in which massive filaments at high redshift assist gas accretion and enhance star formation in their resident dwarf sized dark matter haloes.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Based on independent shear measurements using the DECaLS/DR8 imaging data, we measure the weak lensing signals around isolated central galaxies (ICGs) from SDSS/DR7 at $z\sim0.1$. The projected stellar mass density profiles of surrounding satellite galaxies are further deduced, using photometric sources from the Hyper Suprime-Cam (HSC) survey (pDR3). The signals of ICGs $+$ their extended stellar halos are taken from Wang et al.(2021). All measurements are compared with predictions by the Illustris-TNG300-1 simulation. We find, overall, a good agreement between observation and TNG300. In particular, a correction to the stellar mass of massive observed ICGs is applied based on the calibration of He et al.(2013), which brings a much better agreement with TNG300 predicted lensing signals at $\log_{10}M_\ast/M_\odot>11.1$. In real observation, red ICGs are hosted by more massive dark matter halos, have more satellites and more extended stellar halos than blue ICGs at fixed stellar mass. However, in TNG300 there are more satellites around blue ICGs at fixed stellar mass, and the outer stellar halos of red and blue ICGs are similar. The stellar halos of TNG galaxies are more extended compared with real observed galaxies, especially for blue ICGs with $\log_{10}M_\ast/M_\odot>10.8$. We find the same trend for TNG100 galaxies and for true halo central galaxies. The tensions between TNG and real galaxies might indicate that satellite disruptions are stronger in TNG. In both TNG300 and observation, satellites approximately trace the underlying dark matter distribution beyond $0.1R_{200}$, but the fraction of total stellar mass in TNG300 does not show the same radial distribution as real galaxies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Shu-Rui Lin
Wentao Luo
Yi-Fu Cai
Qi Guo
Leyao Wei
Bo Wang
Qinxun Li
Can-Po Su
Vitali Halenka
Alexander Rodriguez
摘要： We report the detection of a 219 $^{+10}_{-28}$ pc-sized dark matter core structure in the center of Milky Way at $68\%$ confidence level by using the micro-lensing event rate sky map data from the Optical Gravitational Lensing Experiment (OGLE) survey. For the first time, we apply the spacial information of the micro-lensing sky map and model it with the detailed Milky Way structure, the Mini Dark Matter Structure (MDMS) fraction ($f_{\rm MDMS}=\Omega_{\rm MDMS}/\Omega_{\rm DM}$) and the core size. We find that this sky map can constrain both $f_{\rm MDMS}$ and the core size simultaneously without strong degeneracy. This discovery provides not only guidance for dark matter particle models, such as self-interacting dark matter (SIDM), but also the baryonic physics of Milky Way.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Shu-Rui Lin
Wentao Luo
Yi-Fu Cai
Qi Guo
Leyao Wei
Bo Wang
Qinxun Li
Can-Po Su
Vitali Halenka
Alexander Rodriguez
摘要： We report the detection of a 219 $^{+10}_{-28}$ pc-sized dark matter core structure in the center of Milky Way at $68\%$ confidence level by using the micro-lensing event rate sky map data from the Optical Gravitational Lensing Experiment (OGLE) survey. For the first time, we apply the spacial information of the micro-lensing sky map and model it with the detailed Milky Way structure, the Mini Dark Matter Structure (MDMS) fraction ($f_{\rm MDMS}=\Omega_{\rm MDMS}/\Omega_{\rm DM}$) and the core size. We find that this sky map can constrain both $f_{\rm MDMS}$ and the core size simultaneously without strong degeneracy. This discovery provides not only guidance for dark matter particle models, such as self-interacting dark matter (SIDM), but also the baryonic physics of Milky Way.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Chengpeng Zhang
Yingjie Peng
Luis C. Ho
Roberto Maiolino
Alvio Renzini
Filippo Mannucci
Avishai Dekel
Qi Guo
Di Li
Feng Yuan
Simon J. Lilly
Jing Dou
Kexin Guo
Zhongyi Man
Qiong Li
Jingjing Shi
摘要： The phenomenological study of evolving galaxy populations has shown that star forming galaxies can be quenched by two distinct processes: mass quenching and environment quenching (Peng et al. 2010). To explore the mass quenching process in local galaxies, we study the massive central disk galaxies with stellar mass above the Schechter characteristic mass. In Zhang et al. (2019), we showed that during the quenching of the massive central disk galaxies as their star formation rate (SFR) decreases, their molecular gas mass and star formation efficiency drop rapidly, but their HI gas mass remains surprisingly constant. To identify the underlying physical mechanisms, in this work we analyze the change during quenching of various structure parameters, bar frequency, and active galactic nucleus (AGN) activity. We find three closely related facts. On average, as SFR decreases in these galaxies: (1) they become progressively more compact, indicated by their significantly increasing concentration index, bulge-to-total mass ratio, and central velocity dispersion, which are mainly driven by the growth and compaction of their bulge component; (2) the frequency of barred galaxies increases dramatically, and at a given concentration index the barred galaxies have a significantly higher quiescent fraction than unbarred galaxies, implying that the galactic bar may play an important role in mass quenching; and (3) the "AGN" frequency increases dramatically from 10% on the main sequence to almost 100% for the most quiescent galaxies, which is mainly driven by the sharp increase of LINERs. These observational results lead to a self-consistent picture of how mass quenching operates.
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