分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We study the structural and environmental dependence of the star formation on the plane of stellar mass versus central core density ($\Sigma_{\rm 1\ kpc}$) in the nearby universe. We study the central galaxies in the sparse environment and find a characteristic population-averaged $\rm \Sigma_{1\ kpc} \sim 10^9-10^{9.2}\ M_{\odot}\ kpc^{-2}$, above which quenching is operating. This $\rm \Sigma^{crit}_{1\ kpc}$ only weakly depends on the stellar mass, suggesting that the mass-quenching of the central galaxies is more closely related to the processes that operate in the central regions than over the entire galaxies. For satellites, at a given stellar mass, environment-quenching appears to operate in a similar fashion as mass-quenching in centrals, also starting from galaxies with high $\rm \Sigma_{1\ kpc}$ to low $\rm \Sigma_{1kpc}$, and $\rm \Sigma^{crit}_{1\ kpc}$ becomes strongly mass-dependent, in particular in dense regions. This is because (1) more low-mass satellites are quenched by the environmental effects in denser regions and (2) at fixed stellar mass and environment, the environment-quenched satellites have, on average, larger $\Sigma_{\rm 1\ kpc}$, $\rm M_{1\ kpc}/M_{\star}$ and Sersic index $n$, and as well as smaller size. These results imply that either some dynamical processes change the structure of the satellites during quenching or the satellites with higher $\Sigma_{\rm 1\ kpc}$ are more susceptible to the environmental effects.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The cosmological inflow of a galaxy is speculated to be able to enter the galaxy and enhance the star formation rate (SFR) and black hole accretion rate (BHAR). In this paper, by performing high-resolution hydrodynamic simulations in the framework of {\it MACER}, we investigate the fate of the inflow and its impacts on the evolution of a massive elliptical galaxy. The inflow properties are adopted from the cosmological simulation IllustrisTNG. We find that, the inflow gas hardly enters but is blocked beyond $\sim 20$ kpc from the central galaxy and becomes part of the circumgalactic medium (CGM). The gas pressure gradient, mainly contributed by the thermalized stellar wind and subdominantly by the energy input from the AGN, balances gravity and prevents the inflow from entering the galaxy. The SFR and BHAR are almost not affected by the normal inflow. However, if the rate of cosmological inflow were increased by a factor of 3, a small fraction of the inflow would enter the galaxy and contribute about 10\% of the gas in the galaxy. In this case, the gas density in the galaxy would increase by a factor of $\ga$ 20. This increase is not because of the additional gas supply by the inflow but the increase of gas density in the CGM caused by the inflow. Consequently, the SFR and BHAR would increase by a factor of $\sim$ 5 and $\sim 1000$ respectively. Finally, AGN feedback can perturb the motion of the inflow and heat the CGM through its intermittent outbursts.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Rui Shi
Wenting Wang
Zhaozhou Li
Jiaxin Han
Jingjing Shi
Vicente Rodriguez-Gomez
Yingjie Peng
Qingyang Li
摘要： We propose a random forest (RF) machine learning approach to determine the accreted stellar mass fractions ($f_\mathrm{acc}$) of central galaxies, based on various dark matter halo and galaxy features. The RF is trained and tested using 2,710 galaxies with stellar mass $\log_{10}M_\ast/M_\odot>10.16$ from the TNG100 simulation. Galaxy size is the most important individual feature when calculated in 3-dimensions, which becomes less important after accounting for observational effects. For smaller galaxies, the rankings for features related to merger histories increase. When an entire set of halo and galaxy features are used, the prediction is almost unbiased, with root-mean-square error (RMSE) of $\sim$0.068. A combination of up to three features with different types (galaxy size, merger history and morphology) already saturates the power of prediction. If using observable features, the RMSE increases to $\sim$0.104, and a combined usage of stellar mass, galaxy size plus galaxy concentration achieves similar predictions. Lastly, when using galaxy density, velocity and velocity dispersion profiles as features, which approximately represent the maximum amount of information extracted from galaxy images and velocity maps, the prediction is not improved much. Hence the limiting precision of predicting $f_\mathrm{acc}$ is $\sim$0.1 with observables, and the multi-component decomposition of galaxy images should have similar or larger uncertainties. If the central black hole mass and the spin parameter of galaxies can be accurately measured in future observations, the RMSE is promising to be further decreased by $\sim$20%.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The cosmological inflow of a galaxy is speculated to be able to enter the galaxy and enhance the star formation rate (SFR) and black hole accretion rate (BHAR). In this paper, by performing high-resolution hydrodynamic simulations in the framework of {\it MACER}, we investigate the fate of the inflow and its impacts on the evolution of a massive elliptical galaxy. The inflow properties are adopted from the cosmological simulation IllustrisTNG. We find that, the inflow gas hardly enters but is blocked beyond $\sim 20$ kpc from the central galaxy and becomes part of the circumgalactic medium (CGM). The gas pressure gradient, mainly contributed by the thermalized stellar wind and subdominantly by the energy input from the AGN, balances gravity and prevents the inflow from entering the galaxy. The SFR and BHAR are almost not affected by the normal inflow. However, if the rate of cosmological inflow were increased by a factor of 3, a small fraction of the inflow would enter the galaxy and contribute about 10\% of the gas in the galaxy. In this case, the gas density in the galaxy would increase by a factor of $\ga$ 20. This increase is not because of the additional gas supply by the inflow but the increase of gas density in the CGM caused by the inflow. Consequently, the SFR and BHAR would increase by a factor of $\sim$ 5 and $\sim 1000$ respectively. Finally, AGN feedback can perturb the motion of the inflow and heat the CGM through its intermittent outbursts.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jing Dou
Yingjie Peng
Alvio Renzini
Luis C. Ho
Filippo Mannucci
Emanuele Daddi
Yu Gao
Roberto Maiolino
Chengpeng Zhang
Qiusheng Gu
Di Li
Simon J. Lilly
Zhizheng Pan
Feng Yuan
Xianzhong Zheng
摘要： In Dou et al. (2021), we introduced the Fundamental Formation Relation (FFR), a tight relation between specific SFR (sSFR), H$_2$ star formation efficiency (SFE$_{\rm H_2}$), and the ratio of H$_2$ to stellar mass. Here we show that atomic gas HI does not follow a similar FFR as H$_2$. The relation between SFE$_{\rm HI}$ and sSFR shows significant scatter and strong systematic dependence on all of the key galaxy properties that we have explored. The dramatic difference between HI and H$_2$ indicates that different processes (e.g., quenching by different mechanisms) may have very different effects on the HI in different galaxies and hence produce different SFE$_{\rm HI}$-sSFR relations, while the SFE$_{\rm H_2}$-sSFR relation remains unaffected. The facts that SFE$_{\rm H_2}$-sSFR relation is independent of other key galaxy properties, and that sSFR is directly related to the cosmic time and acts as the cosmic clock, make it natural and very simple to study how different galaxy populations (with different properties and undergoing different processes) evolve on the same SFE$_{\rm H_2}$-sSFR $\sim t$ relation. In the gas regulator model (GRM), the evolution of a galaxy on the SFE$_{\rm H_2}$-sSFR($t$) relation is uniquely set by a single mass-loading parameter $\lambda_{\rm net,H_2}$. This simplicity allows us to accurately derive the H$_2$ supply and removal rates of the local galaxy populations with different stellar masses, from star-forming galaxies to the galaxies in the process of being quenched. This combination of FFR and GRM, together with the stellar metallicity requirement, provide a new powerful tool to study galaxy formation and evolution.
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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jianbo Qin
Xian Zhong Zheng
Min Fang
Zhizheng Pan
Stijn Wuyts
Yong Shi
Yingjie Peng
Valentino Gonzalez
Fuyan Bian
Jia-Sheng Huang
Qiu-Sheng Gu
Wenhao Liu
Qinghua Tan
Dong Dong Shi
Jian Ren
Yuheng Zhang
Man Qiao
Run Wen
Shuang Liu
摘要： While the slope of the dust attenuation curve ($\delta$) is found to correlate with effective dust attenuation ($A_V$) as obtained through spectral energy distribution (SED) fitting, it remains unknown how the fitting degeneracies shape this relation. We examine the degeneracy effects by fitting SEDs of a sample of local star-forming galaxies (SFGs) selected from the Galaxy And Mass Assembly survey, in conjunction with mock galaxy SEDs of known attenuation parameters. A well-designed declining starburst star formation history is adopted to generate model SED templates with intrinsic UV slope ($\beta_0$) spanning over a reasonably wide range. The best-fitting $\beta_0$ for our sample SFGs shows a wide coverage, dramatically differing from the limited range of $\beta_0<-2.2$ for a starburst of constant star formation. Our results show that strong degeneracies between $\beta_0$, $\delta$, and $A_V$ in the SED fitting induce systematic biases leading to a false $A_V$--$\delta$ correlation. Our simulation tests reveal that this relationship can be well reproduced even when a flat $A_V$--$\delta$ relation is taken to build the input model galaxy SEDs. The variations in best-fitting $\delta$ are dominated by the fitting errors. We show that assuming a starburst with constant star formation in SED fitting will result in a steeper attenuation curve, smaller degeneracy errors, and a stronger $A_V$--$\delta$ relation. Our findings confirm that the $A_V$--$\delta$ relation obtained through SED fitting is likely driven by the systematic biases induced by the fitting degeneracies between $\beta_0$, $\delta$, and $A_V$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Jingjing Shi
Yingjie Peng
Benedikt Diemer
Adam R. H. Stevens
Annalisa Pillepich
Alvio Renzini
Jing Dou
Yu Gao
Qiusheng Gu
Luis C. Ho
Xu Kong
Claudia del P. Lagos
Di Li
Jiaxuan Li
Roberto Maiolino
Filippo Mannucci
Lizhi Xie
Chengpeng Zhang
摘要： Black hole feedback has been widely implemented as the key recipe to quench star formation in massive galaxies in modern semi-analytic models and hydrodynamical simulations. As the theoretical details surrounding the accretion and feedback of black holes continue to be refined, various feedback models have been implemented across simulations, with notable differences in their outcomes. Yet, most of these simulations have successfully reproduced some observations, such as stellar mass function and star formation rate density in the local Universe. We use the recent observation on the change of neutral hydrogen gas mass (including both ${\rm H_2}$ and ${\rm HI}$) with star formation rate of massive central disc galaxies as a critical constraint of black hole feedback models across several simulations. We find that the predictions of IllustrisTNG agree with the observations much better than the other models tested in this work. This favors IllustrisTNG's treatment of active galactic nuclei - where kinetic winds are driven by black holes at low accretion rates - as more plausible amongst those we test. In turn, this also indirectly supports the idea that the massive central disc galaxy population in the local Universe was likely quenched by AGN feedback.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Andrés Almeida
Scott F. Anderson
Maria Argudo-Fernández
Carles Badenes
Kat Barger
Jorge K. Barrera-Ballesteros
Chad F. Bender
Erika Benitez
Felipe Besser
Dmitry Bizyaev
Michael R. Blanton
John Bochanski
Jo Bovy
William Nielsen Brandt
Joel R. Brownstein
Johannes Buchner
Esra Bulbul
Joseph N. Burchett
Mariana Cano Díaz
Joleen K. Carlberg
摘要： The eighteenth data release of the Sloan Digital Sky Surveys (SDSS) is the first one for SDSS-V, the fifth generation of the survey. SDSS-V comprises three primary scientific programs, or "Mappers": Milky Way Mapper (MWM), Black Hole Mapper (BHM), and Local Volume Mapper (LVM). This data release contains extensive targeting information for the two multi-object spectroscopy programs (MWM and BHM), including input catalogs and selection functions for their numerous scientific objectives. We describe the production of the targeting databases and their calibration- and scientifically-focused components. DR18 also includes ~25,000 new SDSS spectra and supplemental information for X-ray sources identified by eROSITA in its eFEDS field. We present updates to some of the SDSS software pipelines and preview changes anticipated for DR19. We also describe three value-added catalogs (VACs) based on SDSS-IV data that have been published since DR17, and one VAC based on the SDSS-V data in the eFEDS field.
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