Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： The connection between halo gas acquisition through the circumgalactic medium (CGM) and galaxy star formation has long been studied. In this series of two papers, we put this interplay within the context of the galaxy environment on large scales (several hundreds of kpc), which, to a certain degree, maps out various paths for galaxy interactions. We use the IllustrisTNG-100 simulation to demonstrate that the large-scale environment modulates the circumgalactic gas angular momentum, resulting in either enhanced (Paper I) or suppressed (Paper II) star formation inside a galaxy. In this paper (Paper I), we show that the large-scale environment around a star-forming galaxy is often responsible for triggering new episodes of star formation. Such an episodic star formation pattern is well synced with a pulsating motion of the circumgalactic gas, which, on the one hand receives angular momentum modulations from the large-scale environment, yielding in-spiralling gas to fuel the star-forming reservoir, while, on the other hand, is affected by the feedback activities from the galaxy centre. As a result, a present-day star-forming galaxy may have gone through several cycles of star-forming and quiescent phases during its evolutionary history, with the circumgalactic gas carrying out a synchronized cadence of "breathing in and out" motions out to $\sim 100$ kpc.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Shengdong Lu
Dandan Xu
Sen Wang
Yunchong Wang
Shude Mao
Xiaoyang Xia
Mark Vogelsberger
Lars Hernquist
Abstract： Galaxy morphologies, kinematics, and stellar populations are thought to be linked to each other. However, both simulations and observations have pointed out mismatches therein. In this work, we study the nature and origin of the present-day quenched, bulge-dominated, but dynamically cold galaxies within a stellar mass range of $10.3\,\leqslant\,\log\,M_{\ast}/\mathrm{M_{\odot}}\,\leqslant\,11.2$ in the IllustrisTNG-100 Simulation. We compare these galaxies with a population of normal star-forming dynamically cold disc galaxies and a population of normal quenched dynamically hot elliptical galaxies within the same mass range. The populations of the present-day quenched and bulge-dominated galaxies (both being dynamically cold and hot) used to have significantly higher star-formation rates and flatter morphologies at redshift of $z\sim 2$. They have experienced more frequent larger mass-ratio mergers below $z \sim 0.7$ in comparison to their star-forming disc counterparts, which is responsible for the formation of their bulge-dominated morphologies. The dynamically cold populations (both being star-forming and quenched) have experienced more frequent prograde and tangential mergers especially below $z \sim 1$, in contrast to the dynamically hot ellipticals, which have had more retrograde and radial mergers. Such different merging histories can well explain the differences on the cold and hot dynamical status among these galaxies. We point out that the real-world counterparts of these dynamically cold and hot bulge-dominated quenched populations are the fast- and slow-rotating early-type galaxies, respectively, as seen in observations and hence reveal the different evolution paths of these two distinct populations of early-type galaxies.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： The lack of adequate X-ray observing capability is seriously impeding the progress in understanding the hot phase of circumgalactic medium (CGM), which is predicted to extend to the virial radius of a galaxy or beyond, and thus in acquiring key boundary conditions for studying galaxy evolution. To this end, the Hot Universe Baryon Surveyor (\textit{HUBS}) is proposed. \textit{HUBS} is designed to probe hot CGM by detecting its emission or absorption lines with a non-dispersive X-ray spectrometer of high resolution and high throughput. The spectrometer consists of a $60\times60$ array of microcalorimeters, with each detector providing an energy resolution of $2~\mathrm{eV}$, and is placed in the focal plane of an X-ray telescope of $1^{\circ}$ field-of-view. With such a design, the spectrometer is also expected to enable studies of intra-group medium (IGrM) and the outer region of intra-cluster medium (ICM). To assess the scientific potential of \textit{HUBS}, we created mock observations of galaxies, groups, and clusters at different redshifts with the \tng simulation. Focusing exclusively on emission studies in this work, we took into account the effects of light cone, Galactic foreground emission, and background AGN contribution in the mock observations. From the observations, we made mock X-ray images and spectra, analyzed them to derive the properties of the emitting gas in each case, and compared the results with the input parameters from the simulation. The results show that \textit{HUBS} is well suited for studying hot CGM at low redshifts. The redshift range is significantly extended for measuring IGrM and ICM.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Shengdong Lu
Dandan Xu
Sen Wang
Zheng Cai
Chuan He
C. Kevin Xu
Xiaoyang Xia
Shude Mao
Volker Springel
Lars Hernquist
Abstract： The gas needed to sustain star formation in galaxies is supplied by the circumgalactic medium (CGM), which in turn is affected by accretion from large scales. In a series of two papers, we examine the interplay between a galaxy's ambient CGM and central star formation within the context of the large-scale environment. We use the IllustrisTNG-100 simulation to show that the influence exerted by the large-scale galaxy environment on the CGM gas angular momentum results in either enhanced (Paper I) or suppressed (Paper II, this paper) star formation inside a galaxy. We find that for present-day quenched galaxies, both the large-scale environments and the ambient CGM have always had higher angular momenta throughout their evolutionary history since at least $z=2$, in comparison to those around present-day star-forming disk galaxies, resulting in less efficient gas inflow into the central star-forming gas reservoirs. A sufficiently high CGM angular momentum, as inherited from the larger-scale environment, is thus an important factor in keeping a galaxy quenched, once it is quenched. The process above naturally renders two key observational signatures: (1) a coherent rotation pattern existing across multiple distances from the large-scale galaxy environment, to the circumgalactic gas, to the central stellar disk; and (2) an anti-correlation between galaxy star-formation rates and orbital angular momenta of interacting galaxy pairs or groups.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Lei Zhang
Zhi-Yu Zhang
James. W. Nightingale
Ze-Cheng Zou
Xiaoyue Cao
Chao-Wei Tsai
Chentao Yang
Yong Shi
Junzhi Wang
Dandan Xu
Ling-Rui Lin
Jing Zhou
Ran Li
Abstract： The fast growth of supermassive black holes and their feedback to the host galaxies play an important role in regulating the evolution of galaxies, especially in the early Universe. However, due to cosmological dimming and the limited angular resolution of most observations, it is difficult to resolve the feedback from the active galactic nuclei (AGN) to their host galaxies. Gravitational lensing, for its magnification, provides a powerful tool to spatially differentiate emission originated from AGN and host galaxy at high redshifts. Here we report a discovery of a radio lobe in a strongly lensed starburst quasar, H1413+117 or Cloverleaf at redshift $z= 2.56$, based on observational data at optical, sub-millimetre, and radio wavelengths. With both parametric and non-parametric lens models and with reconstructed images on the source plane, we find a differentially lensed, kpc scaled, single-sided radio lobe, located at ${\sim}1.2\,\mathrm{kpc}$ to the north west of the host galaxy on the source plane. From the spectral energy distribution in radio bands, we find that the radio lobe has an energy turning point residing between 1.5 GHz and 8 GHz, indicating an age of 20--50 Myr. This could indicate a feedback switching of Cloverleaf quasar from the jet mode to the quasar mode.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Lei Zhang
Zhi-Yu Zhang
James. W. Nightingale
Ze-Cheng Zou
Xiaoyue Cao
Chao-Wei Tsai
Chentao Yang
Yong Shi
Junzhi Wang
Dandan Xu
Ling-Rui Lin
Jing Zhou
Ran Li
Abstract： The fast growth of supermassive black holes and their feedback to the host galaxies play an important role in regulating the evolution of galaxies, especially in the early Universe. However, due to cosmological dimming and the limited angular resolution of most observations, it is difficult to resolve the feedback from the active galactic nuclei (AGN) to their host galaxies. Gravitational lensing, for its magnification, provides a powerful tool to spatially differentiate emission originated from AGN and host galaxy at high redshifts. Here we report a discovery of a radio lobe in a strongly lensed starburst quasar, H1413+117 or Cloverleaf at redshift $z= 2.56$, based on observational data at optical, sub-millimetre, and radio wavelengths. With both parametric and non-parametric lens models and with reconstructed images on the source plane, we find a differentially lensed, kpc scaled, single-sided radio lobe, located at ${\sim}1.2\,\mathrm{kpc}$ to the north west of the host galaxy on the source plane. From the spectral energy distribution in radio bands, we find that the radio lobe has an energy turning point residing between 1.5 GHz and 8 GHz, indicating an age of 20--50 Myr. This could indicate a feedback switching of Cloverleaf quasar from the jet mode to the quasar mode.
Peer Review Status:Awaiting Review
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