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潘志伟 (Zhiwei Pan) edited this page Jul 7, 2023 · 31 revisions

Latest JWST results

SOC: Ruancun Li

Captain: Lulu Zhang

As the first topic review for the newest CSST Galaxy & AGN Science Discussion series, we will discuss about the latest JWST results, which is beneficial for CSST relevant sciences. Since the JWST Image Reveal in July 12, 2022, the astronomical community have posted over 100 (https://ui.adsabs.harvard.edu/public-libraries/-cFx990hTpyIv7SLrUQK7A) papers about analyses of real JWST data. Specifically, Lulu will give a detailed discussion in terms of the latest study that based on the JWST spectroscopy; Wen will discuss about the CEERS survey and relevant science that using images from the CEERS survey; Masafusa will talk about his JWST project for high-z quasars and relevant projects; Gaocheng and Kaiyuan will give an introduction for the approved JWST cycle 1 GO proposals that in the category of “Galaxies” while Huimei will give an introduction for the approved JWST cycle 1 GO proposals that in the category of “Supermassive Black Holes and AGN”, and Haoran will introduce some approved JWST cycle 1 GTO proposals that in the category of “Deep Field” and “High-redshift Quasars and Galaxy Assembly”.

Lulu Zhang

Title: Latest Spectroscopic Study of Nearby and Distant Galaxies with JWST

JWST has triggered a new era of astronomical study, and will revolutionize people’s understanding of the Universe with its unprecedented sensitivity and resolution. Comparing with imaging observation, IFU spectroscopy provides more details about the physical properties of galaxies with the one more dimension of wavelength. Meanwhile, spectroscopic observation is more complicated than imaging observation. In this talk, I will first give a brief introduction of JWST instruments. Then I will talk about in detail the latest results that based on JWST MIRI MSR spectroscopy, which, within the mid-infrared wavelength range from ~5 - 29 micron, furnishes abundant physical indicators and diagnostics (i.e., PAH features, vibrational H_2 lines, ionic emission liens). Specifically, I will give a general introduction for the scientific applications of MIRI IFU spectroscopy based on relevant papers, and I will share with you some caveats when dealing with the MIRI IFU data. As the complementary, I will summarize the spectral observation that taken by NIRSpec and NIRCam in rest-frame optical band for high-z galaxies based on relevant papers.

Reference: arXiv Pereira-Santaella et al. 2022; García-Bernete et al. 2022; Álvarez-Márquez et al. 2022; Schaerer et al. 2022; Arellano-Córdova et al. 2022; Tacchella et al. 2022; Sun et al. 2022

Wen Sun

Title: An Introduction to the CEERS Survey and Relevant Science about Galaxies

The Cosmic Evolution Early Release Science (CEERS) Survey is one of 13 early-release science surveys designed to obtain data covering all areas of astronomy in Cycle 1. CEERS will cover 100 sq. arcmin of the EGS field with JWST imaging and spectroscopy using NIRCam, MIRI, and NIRSpec. CEERS will demonstrate, test, and validate efficient extragalactic surveys with coordinated, overlapping parallel observations in a field supported by a rich set of HST/CANDELS multi-wavelength data. In this talk, I will introduce the overview of CEERS, including the observing modes, project goals, etc. I will also review some related papers using CEERS data, including the discovery of candidate galaxies at very high redshift (z>10), the investigation of quasar host galaxies at high redshift, the properties of modestly-high redshift galaxies, etc.

Reference: Finkelstein et al. 2022; Ding et al. 2022; Kocevski et al. 2022; Robertson et al. 2022; Carnall et al. 2022; Suess et al. 2022

Masafusa Onoue

Title: CEERS Data Analysis for AGN Studies: The First Outcomes

The Cosmic Evolution Early Release Science Survey (CEERS; Finkelstein et al. 2017, 2022) is one of the Cycle 1 Early Release Science programs of the JWST. CEERS obtained NIRCam and MIRI images with four pointings during the June observations, from which a lot of papers have claimed the first detection of z>10 galaxies. In this talk, I will start by sharing the lessons from the data reduction of those first JWST images, especially on the issues such as absolute flux calibration, background subtraction, and astrometry. I will then present some of the very first scientific results that were submitted to journals. Those include detection of AGN host galaxies at 1.6<z<3.5, and the discovery of an extremely low-luminosity AGN candidate at z=5. I will conclude with showing some of the upcoming Cy1 GO programs that KIAA high-z groups are involved.

Reference: Finkelstein et al. 2017,2022

Gaocheng Yin & Kaiyuan Chen

Title: Summary on Galaxy-Observing Prospects in the GO Program of JWST

JWST is a space telescope with multiple instruments on board, whose data is accessible to worldwide community. The observation of JWST primarily covers near-IR and mid-IR wavelength, with both high-resolution photometry and spectroscopy available. Endowed with these advantages, JWST will shade light on cosmic evolution and galaxy properties. JWST enables us to investigate into rest-frame infrared band of low-z galaxies. For high-z galaxies, accurate redshift measurements and other properties (metallicity, temperature, ionizing environment & etc.) would also be available thanks to the single or multi-object spectroscopy of JWST. Detailed information of galaxies at redshift range around 6, the size of which is appropriate for the integral field analysis, can be presented via 3-D spectrum (e.g. inner star forming distribution, kinematics & etc.). What’s more, the slitless spectrum also provides a chance to study the secular cosmic evolution. The promising future of JWST on galaxy researches deserves our attention, and so many exciting proposals exist in the Cycle 1 General Observers (GO) program of JWST. In this talk, we will give an overview of the proposals in the category of “Galaxies”, focusing on the background and objectives of each proposal, with the particular attention on high-z objects.

Reference: JWST Cycle 1 Abstract Catalog

Huimei Wang

A Summary on the Category of "Supermassive Black Holes and AGN" in the Cycle 1 GO Program of JWST

The James Webb Space Telescope (JWST) has already started its science operations in the summer of 2022. The Cycle 1 General Observers (GO) program provides the opportunity for studies of supermassive black holes (SMBH) and AGN at high redshift (z$\gtrsim$6), which are accessible to the worldwide scientific community. This talk briefly look through the proposals in the category of “Supermassive Black Holes and AGN” with an introduction for the background and objectives of each proposal. These proposals show the ambitious targets including the outflow, feedback, AGN-Galaxy connection, distant quasars, supermassive black holes, and several other interesting questions. Given the sensitivity of JWST, these proposals are expected to reveal the SMBH and AGN at high redshift so that people can push the frontier of the reionization science. What is noticeable that there are 7 proposals (29 in total) concerning the feedback of AGN, so I will give a more detailed introduction particularly for this topic.

Reference: JWST Cycle 1 Abstract Catalog

Haoran Yu

Title: Researching Deep Fields with JWST Integral Field Spectroscopy

With the instruments of extraordinary capabilities, the James Webb Space Telescope(JWST) will expand the boundary of near-IR and mid-IR astronomy. JWST is equipped with the Integral Field Spectroscopy (IFS), which has the ability to obtain resolved spectrum of high quality and has never been used on previous near-IR and mid-IR space telescopes. In this talk, I will first introduce the IFS Instrument of JWST, then introduce the projects of Pierre Ferruit, which focuses on the spectroscopy of deep fields. In addition, I will talk about other Cycle 1 GTO proposals in the category of "Deep Fields" and "High-redshift Quasars and Galaxy Assembly".

Reference: Böker, et al. 2022

Lyman alpha and lyC from galaxies

SOC: Yuxuan Pang

Captain: Yuchen Liu

The topic that our group focuses on is three similar types of galaxies: Lyman alpha emitters (LAEs), Lyman break galaxies (LBGs), and Lyman continuum (LyC) galaxies. We will mainly discuss about the surveys and science of these specific kinds of galaxies, which are very important objects especially at high-redshifts (eg. LyC photons contributed to the reionization process). Naturally, we will separate the topic into three parts. In the first talk, Weiyang will introduce the physics of Lyman alpha emission, talk about the surveys of LAEs, and also discuss about some recent results of LAE’s properties and LF. Then, Shuqi will give a short talk about LBG samples as a supplement in form of FREE TALK. At last, Yuchen will discuss about the selection methods of LyC galaxies and their particular properties. CSST ability of searching these galaxies will be discussed at the end of each talk.

Weiyang Liu

Title: Physics of Lyman Alpha Emission and Surveys of Lyman Alpha Emitters

Lyman alpha photons at 1215.67 angstrom, corresponding to the n=2 to n=1 resonant transition in the hydrogen atom, are mainly produced in HII regions of star froming galaxies or broad line region/narrow line region of AGNs. Although theoretically the Lyman alpha emission line is one of the strongest emission lines under the Case B assumption, the radiative transfer of Lyman alpha photons is complicated because they are resonantly scattered by neutral hydrogen in the ISM, which increases the probability of being absorbed by dust. Since the first discovery of high redshift Lyman alpha emitter (LAE, galaxy with strong Lyman alpha emission line) in the mid 1990s, extensive LAE surveys have been carried out, which results in tens of thousands of LAEs to date. Typical LAEs are compact (half light radius ~ 1 kpc), low mass (stellar mass ~ 10^8 - 10^9 solar mass), young stellar age (~ 10 Myr) star forming galaxies with a SFR of ~ 1 - 10 solar mass/yr. In this talk, I will begin with mechanism of radiative transfer of Lyman photons and show various theoretical Lyman alpha emission line profiles. After introducing LAE surveys using different selection methods, I will show the luminosity function and properties of LAEs. Finally, I will make a prediction about the number of LAEs that can be discovered by CSST.

Reference: Verhamme et al. 2006; Ouchi et al. 2008; Schaerer er al. 2011; Dijkstra 2019; Herenz et al. 2019; Ouchi et al. 2020; Zhang et al. 2021

Yuchen Liu

Title: The searching of Lyman continuum galaxies and their properties

Lyman continnum (LyC) photons (rest-frame λ<912 angstrom ), which are produced by OB stars in star-forming galaxies or active super-massive black holes (AGNs), can ionize the neutral hydrogen gas. The ionizing radiation which escapes into the IGM contributes either to the reionization at z>6 or to keep the environment ionized at lower redshifts. Many studies have confirmed that AGNs cannot provide sufficient ionizing photons so that the star-forming galaxies should be considered as dominant ionizing sources. Galaxies who emit LyC photons (LyC galaxies) can reveal the ionizing sources of the early universe and their properties are related with both inner and outer environment. In this talk, I will first basicly introduce some background of LyC photons and LyC galaxies. Then I will talk about the methods to search LyC galaxies, from imaging to spectroscopic observations, from low redshifts to high redshifts. Also, I will present the properties of LyC galaxies, such as escape fraction, ionizing emissivity and their relation with emission lines. Specifically, as CSST can obtain deep UV imaging and spectroscopic information in large sky area, I will show some results of CSST simulation on detecting this kind of galaxies.

Sky surveys

SOC-J: Weibin Sun

Captain: Fengwei Xu

Sky surveys are at the historical core of astronomy. Charting and monitoring the sky gave rise to our science. Sky surveys, unlike targeted observation of a specific object, allow astronomers to catalog celestial objects and perform statistical analyses on them without complex corrections for selection effects. In some cases, an astronomer interested in a particular object will find that survey images are sufficient to make new telescope time entirely unnecessary. Today, large digital sky surveys are transforming the ways astronomy is done.The term “survey” has encompassed a wide range of types of studies and methods. Here, we focus on two major types of surveys: (1) wide-field, panoramic sky surveys, both at a specific wavelength and at multi-wavelength; (2) deep-field or object-specialized sky surveys. In this discussion topic, we review some of currently popular ones, including those in the past, the present, and the future. We note that sky survey is a rapidly evolving field, and therefore readers and listeners should always consult the latest sources of information about the more recent work.

Dong Yang

Title: SDSS-MaNGA

As one of the most well-known sky surveies in the world, SDSS have been continuously observing the skies for roughly 20yr from 1998. The Mapping Nearby Galaxies at APO(MaNGA) survey is one of the three main surveies during the fourth phase of SDSS from 2017 and have been completed this year. Up to now, MaNGA have obtained integral-field spectroscopy for 10,000 nearby galaxies.In this talk, I will introduce some basic information about the MaNGA survey. Besides data introduction, I will also talk about some important results from MaNGA data. It has been accepted that galaxies can be divided into blue cloud and red sequence according to their position on the SFR v.s. stellar mass plane. The blue star-forming galaxies usually follow a tight relation named star-forming sequence. Using MaNGA IFU data for 10,000 galaxies, researchers have gained more information into the star formation process and quenching process. In addition, the spectroscopic analysis can offer more details of galaxy metallicity and stellar kinematics, which can help us learn more for the secular evolution in galaxies. Finally I will discuss what can be done further if we combine the MaNGA data with the CSST data in the future.

Reference: • Aguado et al. 2019, ApJS, 240, 23. • Wake et al. 2017, AJ, 154, 86. • Hsieh et al. 2017, ApJ, 851, L24. • Lin et al. 2019, ApJ, 872, 50. • Bluck et al. 2020, MNRAS, 492, 96. • Ellison et al. 2018, MNRAS, 474, 2039.

Zhiwei Pan

Title:DESI

Aiming to explore the nature of dark energy, the Dark Energy Spectroscopic Instrument (DESI) is conducting a five-year massive survey to map the large structure of universe over one- third of the sky and 11 billion years, with a powerful 5000-fiber multi-object optical spectrograph in Mayall 4-meter telescope at Kitt Peak National Observatory. This ambitious spectroscopic survey began in 2021 May and in total will acquire more than 40 million galaxies and quasars from local univsere to beyond z > 3.5. After determining precise redshifts for these targets, DESI survey will employ the baryon acoustic oscillations, redshift-space distortions, and other methods to study dark energy, general relativity, and other cosmological quantities, such as neutrino mass and primordial non-Gaussianity. In the meantime, this survey will provide an extremely large spectroscopically confirmed sample of emission-line galaxies, luminous red galaxies, quasars, stars, and so on. In this talk, I will firstly give a brief introduction to DESI, including the instrument and big scientific picture, beginning from the DESI legacy imgaing survey to the history, current status, and future expectations of DESI. In the second part, I will focus on the specific science cases, especially quasar related topics. Recent published works from other people and preliminary work or idea from my group would be involved. Finally, I will lead a discussion about the comparison and joint analysis between DESI and CSST. For example, multi-band images with high spatial resolution from CSST combined with high quality spectra from DESI could be very useful for quasar host galaxy decomposition.

Reference: • DESI Collaboration et al. 2016, arXiv:1611.00036. • Martini et al. 2018, SPIE, 107, 021. • Arjun Dey et al. 2019, AJ, 157, 168. • Levi et al. 2019, BAAS, 51, 7. • Christophe Y`eche et al. 2020, Res. Notes AAS, 4, 1,79. • DESI Collaboration et al. 2022, AJ, 164, 207. • Chaussidon et al. 2022, arXiv:2208.08511.

Xuchen Lin

HSC

The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered, multi- band (grizy plus 4 narrow-band filters) imaging survey using the Hyper Suprime-Cam (HSC) on the 8.2 m Subaru Telescope. The wide layer covers 1,400 degrees squared around the equator and reaches a depth of 26mag in r-band, and the deep and ultradeep layers cover smaller regions and provide larger depths. Thanks to the high resolution and depth, the HSC team are able to address many problems in modern cosmology and astrophysics. In this talk, I will briefly introduce the instrument and data release of the survey. CSST is expected to have a much higher resolution than HSC-SSP’s and a similar depth as their wide field’s. Therefore, scientific projects using HSC could provide insights into what we could do with CSST. I will introduce some of their current science results, especially those on low to intermediate redshift galaxies and clusters.

Reference: • Aihara et al. 2022, PASJ, 74, 2, 247. • Yamashita et al. 2018, ApJ, 866, 2, 140. • Willis et al. 2021, MNRAS, 503, 4, 5624. • Jian et al. 2018, PASJ, 70, SP1, S23. • Kado-Fong et al. 2022, arXiv:2209.05492. • Kado-Fong et al. 2020, ApJ, 900, 2, 163. • Kado-Fong et al. 2018, APJ, 866, 2, 103.

Xinkai Chen

GAMA

The Galaxy And Mass Assembly Survey (GAMA), commenced in 2008 with the goal of building upon the legacy of the original 2dFGRS and SDSS surveys to produce a highly com- plete redshift survey with maximal multiwavelength data (xray-to-radio via eROSITA, GALEX, VST, VISTA, WISE, Herschel, SKAP, and MWA). GAMA covers five fields with highly complete spectroscopic coverage (>95%) to intermediate depths (r< 19.8), and collectively spans 250 deg2 of equatorial or southern sky, carried out using the AAOmega multi-object spectrograph on the Anglo- Australian Telescope (AAT). On the imaging side, complementary imaging extends from the UV to the far-IR, i.e. 20-band photometry extending from 0.2–500 μm. In this talk, I will firstly briefly introduce the history and data release of GAMA survey. Then I will review some science results, especially those on galaxy groups, the low-z Universe and galaxy stellar mass function. As CSST is expected to be deeper and wider than GAMA, these science results on GAMA can give us a hint of what we could do with CSST.

Reference: • Driver et al. 2016, MNRAS, 455, 3911. • Driver et al. 2022, MNRAS, 513, 439.

Rui Zhu

CANDELS

Deep imaging surveys represent crucial information for our insights into galaxy evolu- tion. With the installation of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST), deeper imaging can be observed, which enabled the comprehensive investigation of galaxy structural and morphological properties at z > 1 with unprecedented high resolution. The Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) is a 902-orbit HST Multi- Cycle Treasury (MCT) program aimed at documenting the first third of galactic evolution and black holes from z ≈ 1.5 to 8, and investigating Type Ia supernovae at z > 1.5 to better constrain the nature of dark energy. The total database is rich when combined with many other ground-based and space-based surveys, and many science goals are enabled. Up to now, more than 1,000 papers related to CANDELS have been published. In this talk, I will first introduce a synopsis of the CANDELS survey. Then, I will focus on a couple of its primary scientific goals about galaxy sub-structures (i.e., Applying the 2D morphological decomposition technique to high spatial resolution HST images, to understand bulge formation and growth). The CSST will also provide a similar high-resolution but a wider optical survey in the future. At the end of this talk, I will show some ideas about utilizing the wide-field images of the CSST compared to the CANDELS.

Reference: • Grogin et al. 2011, ApJS, 197, 35. • Koekemoer et al. 2011, ApJS, 197, 36. • Kocevski et al. 2012, ApJ, 744, 148. • Papovich et al. 2012, ApJ, 750, 93. • Bruce et al. 2012, MNRAS, 427, 1666-1701. • Lang et al. 2014, ApJ, 788, 11. • Bruce et al. 2014a, MNRAS, 444, 1001-1033. • Bruce et al. 2014b, MNRAS, 444, 1660-1673. • Bruce et al. 2016, MNRAS, 458, 2391-2404. • Dimauro et al. 2018, MNRAS, 478, 5410-5426. • dos Reis et al. 2020, A&A, 634, A11. • Whitney et al. 2021, ApJ, 919, 139.

Yuxi Duan

SKA Pathfinder

The Square Kilometer Array (SKA) will be the next generation large radio telescope, and giving astronomers insight into the formation and evolution of the first stars and galaxies after the Big Bang, the role of cosmic magnetism, the nature of gravity, and possibly life beyond Earth. While the design and development of the SKA moves forward, a number of SKA pathfinders are currently operating and being built around the world. For example, the MeerKAT array consists of 64 receptors with 13.5 m diameter dishes and has a frequency range at 8 GHz - 14.5 GHz, designed to achieve high sensitivity and imaging dynamic range, while providing an array and functionality to provide for a wide range of science. The Australian SKA Pathfinder (ASKAP) is another important SKA pathfinder. It is a next-generation radio interferometer and will consist of 36 12-m antennas, each with a focal plane phased array. With ASKAP’s unique capabilities, surveys are designed to map the structure and evolution of the Universe by observing galaxies and the hydrogen gas that they contain, such as: GASKAP (Galactic ASKAP survey) – to study the 21-cm line of HI and the 18-cm lines of OH in the Galactic plane and Magellanic Clouds; WALLABY (Wide-field ASKAP L-band Legacy All-sky Blind surveY) – an all-sky HI survey to redshift of z=0.25 expected to detect 500,000 galaxies. With so many large surveys, SKA is also supported by an international community to create a shared, distributed data, computing and networking capability called the SKA Regional Centre Alliance. Therefore, The SKA will monitor the sky in unprecedented detail and map it hundreds of times faster than any current facility. We can expect that SKA can conduct groundbreaking science that will transform our understanding of the Universe and of the laws of fundamental physics.

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Qinyue Fei

CARMA-EDGE

The evolution of galaxies is fundamentally related to the rate and efficiency of star formation activity. Since star formation is active in cold molecular phase of the interstellar medium, it is essential to identify the physical processes that govern the molecular gas contents of galaxies and the rate at which gas is converted into stars. However, our conceptional understanding has been hampered by the difficulty of connecting the global properties with the spatially resolved results. Therefore, mappings of a large sample of galaxies are significant in studying galaxy evolution. The CARMA-EDGE survey, constituting the largest interferometric CO survey of galaxies in the nearby universe, provides a unique opportunity of investigating the role of molecular gas in galaxy evolution. In this talk, I will introduce the survey, the background, the motivation, the sample, and the data characteristics. I will address outstanding topics regarding gas and its role in star formation and galaxy evolution, by introducing some interesting papers. In particular, the combination of spatially resolved CO and optical observations provides good opportunity in studying the relation between properties of molecular gas and some local conditions, e.g., stellar mass surface density, star formation rate surface density, dynamical equilibrium pressure, and disk instability. Similar works can be considered for a larger and unbiased sample. The CSST optical survey and joint-up CO observations will expand our knowledge in galaxy evolution.

Reference: • Bolatto et al. 2017, ApJ, 846, 159. • Barrera-Ballesteros et al. 2020, MNRAS, 492, 2651. • Colombo et al. 2020, A&A, 644, A97.

Fengwei Xu

PHANGS-ALMA People have been realizing that the intrinsic distribution of CO emission in galaxies is strongly clumped on scales of giant molecular clouds (GMCs), which is much smaller than the kilo- parsec resolution of the previous generation of large CO mapping surveys, e.g., CARMA-EDGE. In other words, high angular resolution is urgently needed: (1) to verify current models of star formation on individual GMCs; (2) to give access to the temporal domain of interstellar processes, building a picture of the evolutionary sequence of star formation. The dramatically faster survey speed of ALMA provides the first opportunity of surveying a large, representative sample of local galaxies at a high angular resolution and sensitivity. PHANGS–ALMA applies these capabilities to image CO(2-1) emission across almost all massive, nearby, southern, star-forming galaxies with resolution of ∼ 1′′ (i.e., ∼100pc), and sensitivity of ∼ 105 M⊙. These characteristics make PHANGS–ALMA ideally suited to measure the demographics, motions, and organization of molecular gas (clouds) in galaxies. In this talk, I’ll give a detailed introduction towards project PHANGS-ALMA, including its source selection, key science goals, and recent important publications. Since CSST is the next generation of optical space telescope, I’ll also show some prospects of the synergy between CSST and ALMA about the multi-phase of ISM.

Reference: • Leroy et al. 2013, ApJL, 769, L12. • Bolatto et al. 2017, ApJ, 864,159. • Leroy et al. 2021, ApJS, 255, 19. • Leroy et al. 2021, ApJS, 257, 43.

Shun Wang

PHANGS-MUSE Gas is the main character of baryon inflow, star formation and feedback process, con- necting the entire galactic baryonic cycle. With the help of modern IFU instruments, we are able to probe gas properties (e.g., richness, morphology, kinematics and metallicity, etc.) in multiple phases and physical status in a spatially resolved way. We can also obtain critical information about the star formation activity, feedback processes and environmental effects of the galaxies. In this talk, I’ll introduce one of the most powerful IFU instruments, MUSE, and its (dis)advantages compared to other currently working IFU instruments. Specifically, I’d like to highlight its great power in resolving details and helping understand sub-kpc physics in PHANGS-MUSE survey. I’ll then talk about several recent work that made use of MUSE to reveal the gas properties and shed lights on galactic baryonic flow in strong ram pressure stripping system(s).

Reference: • Fumagalli et al. 2014, MNRAS, 445, 4335. • Fossati et al. 2016, MNRAS, 455, 2028. • Poggianti et al. 2017, ApJ, 844, 48. • Sa ́nchez-Menguiano et al. 2018, A&A, 609, 119. • Olivares et al. 2019, A&A, 631, 22. • Mingozzi et al. 2019, A&A, 622, 146. • Emsellem et al. 2022, A&A, 659, 191.

Simulations with different scales

SOC: Cheqiu Lyu

Captain: Kai Wang

Galaxy formation and evolution comprises many multiscale and multiphysics processes. On the large scale, where the perturbation is linear or mildly nonlinear, the analytical and semi-analytical formulation can provide us with accurate descriptions under some reasonable approximations. However, physical processes on small scales, on which galaxy formation and evolution mostly depend, are highly nonlinear and impossible to be described analytically.

To make progress, cosmological computer simulations are used to simulate galaxy formation and evolution processes starting from fundamental physical laws. Recently, these simulations are progressing rapidly along with increasing computational resources. Nevertheless, current computational ability is still insufficient to cover the entire dynamical range of interest from several parsecs for star formation and black hole accretion to several mega-parsecs for cosmic webs and large-scale structures. Therefore, these cosmological simulations can only approximate these small-scale interactions with so-called subgrid modeling. By adopting proper subgrid recipes, these simulations can reproduce several observational results quite well, which also enables us to investigate the physical origin of these phenomenons. Nevertheless, there are still many controversies about the implementation of these subgrid physics, and different simulations give diverse predictions on physical processes that are poorly constrained by current observations, like feedback, inflow/outflow, circum-galactic medium etc.

This series of talks will introduce methodologies and results of current state-of-the-art cosmological simulations. To begin with, Kai will introduce our current understanding of galaxy formation and evolution, which can be used to generate mock catalogs for forecasting future galaxy surveys. Then, Dingyi will introduce the formation and evolution of dark matter halos given by simulations and their impact on galaxy populations. The third talk will be given by Xingye, he will share some results on gas properties in simulated galaxies, which plays a crucial role in the galaxy ecosystem. Ruancun and Haojie will introduce the most exciting and uncertain issue – the growth of central massive black holes and their feedback onto their host galaxies. Later, Yuchen will introduce three intrinsically different but closely related topics – morphology, structure, and kinematics. Zezhong will introduce the interplay between galaxy evolution processes and their environment in simulations. Finally, Cheqiu will introduce the chemical evolution in simulated galaxies.

Kai Wang

Title: Generate galaxy populations to forecast galaxy surveys

Modeling galaxy formation and evolution presents one of the greatest challenges in modern astrophysics due to its multiscale and multiphysics character. In past decades, tremendous progress has been made toward deep insights into these complex processes, with the help of large amounts of observational data and various physical and empirical models. On one hand, observational data helps to validate or falsify physical models. On the other hand, these models can guide us to devise surveys that can settle down controversies and deepen our understanding in the most efficient way, which is the focus of this talk. In this talk, I will introduce different models for generating galaxy populations, in terms of their physical properties and spatial clustering. To begin with, I will introduce cosmological hydrodynamical simulations, which are the most physical and computationally expensive methods. To reduce the computational cost, alternatives like semi-analytical and empirical models are introduced, which are built on our understanding of galaxy formation and evolution processes and their relation with underlying dark matter. Finally, I will end up with some techniques of creating mock surveys for forecasting future galaxy surveys.

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Dingyi Zhao

Title: Dark matter halo-galaxy connection in simulations

In the current concordance ΛCDM paradigm, galaxies form and evolve in dark matter haloes, so the halo-galaxy connection is crucial for understanding the underlying physical processes and constraining cosmological models. However, due to the dissipationless nature of dark matter, it is extremely hard to directly observe it. Nevertheless, cosmological numerical simulations enable us to study the formation and evolution of dark matter under pure gravity. Meanwhile, the incorporation with baryonic physics can also let us study the impact of dark matter halos on galaxy populations. In this talk, I will present the occupation distribution of galaxies in dark matter halos and the relation between their masses, which are the most fundamental properties for galaxies and halos. Then, I will take a step further to discuss the secondary halo - galaxy connection, which is still under debate.

Reference: • Artale et al. 2018, MNRAS, 480, 3978. • Cui et al. 2021, NatAs, 5, 1069. • Matthee et al. 2017, MNRAS, 465, 2381. • Zehavi et al. 2018, APJ, 853, 84.

Xingye Zhu

Title: Gas in simulations

The gas in the Universe is in multi-phase. Some gas dissipates its internal energy through various cooling processes and eventually forms stars, while some is hotter than 10 7 K and remain in the surrounding of galaxies. Gas not only interacts with itself, but also with gravity, radiation, stars, AGN, and magnetic field. To deal with the gas component in simulation is thus challenging both to our understanding of the underlying physical processes on different scales, and to the computational techniques. In this talk, I will briefly summarize various approches used in simulations to handle gas in different phases, including the cold gas, CGM and ICM. Then I show some recent results from simulations, both globally and locally, and compare them with observations. I will show what we can reproduce and what are still challanges, and what we can possibly learn from those discrepancies.

Ruancun Li

Title: Black hole formation and evolution in numerical simulations

Observations suggest that there is a supermassive black hole (SMBH) at the center of each galaxy. On the theoretical part, SMBHs are also required to explain the low efficiency of converting baryons into stars for massive galaxies. However, the formation and growth of SMBHs is still unresolved, especially for those observed in the early Universe. In this talk, I will first review the formation of seed black holes in simulations. Then, I will discuss the growth of SMBHs through gas accretion and mergering with other SMBHs. Finally, I will discuss the coevolution of SMBHs with host galaxies.

Reference: • Hopkins & Quataert et al. 2010, MNRAS, 407, 1529. • Inayoshi et al. et al. 2020, ARAA, 58, 1. • Inayoshi et al. et al. 2022, ApJ, 927, 237.

Haojie Hu

Title: AGN feedback in simulations

Observations on the existence of a supermassive black hole (SMBH) at the center of each galaxy, together with its tight relation to the host galaxy, places a great challenge for the physical modeling of galaxy formation and evolution. Meanwhile, it is widely believed that the feedback from the SMBH accretion, which is also called the active galactic nuclei (AGN) feedback, plays a vital role in recycling gas material and shaping the evolution of their host galaxies. This also leads to the co-evolution of SMBHs and their host galaxies. Along with the rapid development of computational power, current cosmological hydrodynamical simulations are able to simulate the formation and evolution of galaxies in a rather large box with fine resolution, together with physically motivated subgrid modules. Such simulations include IllustrisTNG, EAGLE, FIRE, SIMBA, NIHAO and so on. These simulations commonly adopt two modes of AGN feedback: the kinetic mode is activated when the accretion rate is low and the thermal mode is activated when the accretion rate is high. It is noteworthy that the implementation of AGN feedback is one piece of the subgrid physics and varies among different simulations.

In this talk, I will summarise and compare different AGN feedback implemntations in these simulations, as well as their physical motivations and implications. I will also discuss the impact of AGN feedback on the properties of host galaxies. Finally, I will discuss the potential role of CSST in revealing the underlying physics of AGN feedback.

Reference: • Booth et al. 2009, MNRAS, 398, 53. • Crain et al. 2015, MNRAS, 450, 1937. • Angl´es-Alc´azar et al. 2017, MNRAS Lett., 472, L109. • C¸atmabacak et al. 2022, MNRAS, 511, 506.• Florez et al. 2021, MNRAS, 508, 762. • Habouzit et al. 2021, MNRAS, 503, 1940. • Thomas et al. 2019, MNRAS, 487, 5764. • Dav´e et al. 2019, MNRAS, 486, 2827. • Piotrowska et al. 2022, MNRAS, 512, 1052. • Ramesh et al. 2022, ApJ, 927, 189. • Zinger et al. 2020, MNRAS, 499, 768. • Ward et al. 2022, MNRAS, 514, 2936. • Li et al. 2020, ApJ, 895, 102. • Terrazas et al. 2020, MNRAS, 493, 1888. • Bustamante et al. 2018, MNRAS, 490, 4133. • Weinberger et al. 2017, MNRAS, 465, 3291.• Nelson et al. 2019, MNRAS, 490, 3234. • Macci`o et al. 2020, MNRAS Lett., 495, L46. • Blank et al. 2019, MNRAS, 487, 5476.

Yuchen Wang

Title: The morphology, structure and kinematics of galaxies in cosmological hydrodynamical simulations

The matter distribution and dynamical state of a single galaxy can be fully described by a distribution function in the phase space. They can also be empirically characterized through its morphology, structure, and kinematics. Observations have identified many scaling relations, e.g. the mass-size relation, the Tully-Fisher relation, the Fiber-Jackson relation, and the fundanmental plane, indicating physical relation among morphology, structure, and kinematics. Meanwhile, current hydrodynamical simulations are able to resolve the detailed galaxy structures in a cosmological context, which enables us to perform a statistical investigation of their matter distribution and dynamical states. In this talk, I will briefly review some of the scaling relations from the observational perspective, followed by a discussion about the inference of these scaling relations in simulations. Then, I will compare results in simulation with observation and present predictions of different simulations, which can only be observed by the next generation surveys. I will also investigate the physical origins of these scaling relations from the simulation perspective. Finally, I will briefly discuss how CSST can drive us toward better understanding of the galaxy morphology and structure with its high-quality wide-field image survey.

Zezhong Liang

Title: Using Simulations to Understand the Role of Environmental Effects in Galaxy Quenching

It has been long proposed that the environmental effects play an important role in shaping the evolution and properties of galaxies. Recent advancements in cosmological simulations (e.g, eagle, Illustristng) help us to gain better insights into significance and details of various environmental effects in affecting star formation properties of galaxies in cosmological context. Inside cluster environments, ram pressure, i.e. interaction between hot intercluster medium (icm) and interstellar medium (ism), can strip galaxies from both hot halo gas and star forming cold gas subsequently, quenching most infalling galaxies immediately at or within a period of time after first pericentric passage. Other mechanisms, such as tidal interaction with other satellites, may also perturb gas contents of galaxies. Outside cluster environment, galaxies experience preprocessing, leading a significant fraction of galaxies being pre-processed in low-mass clusters, group analogous of the Local Group and circum-cluster filaments. In this talk I am to review some recent works utilising cosmological simulations to exploit environmental effects in affecting star forming properties of galaxies. Firstly, I am to briefly introduce mechanisms and timescale related to galaxies quenching in dense environment; then, I am to introduce some works focusing on quiescent fractions in different environments, highlighting locations and consequences of pre-processing. These simulations provide general pictures of galaxies quenching, which, upon comparing to observation data provided by, e.g, CSST, may offer better understanding of galaxy evolution in a cosmological context.

References: • Bah´e et al. 2015, MNRAS, 447, 969. • Lotz et al. 2019, MNRAS, 488, 5370. • Bluck et al. 2016, MNRAS, 462, 2559. • Pallero et al. 2019, MNRAS, 488, 847. • Samuel et al. 2022, MNRAS, 514, 5276. • Pallero et al. 2022, MNRAS, 511, 3210. • Kotecha et al. 2022, MNRAS, 512, 926. • Wright et al. 2022, MNRAS, 516, 2891. • Stevens et al. 2019, MNRAS, 483, 5334. • Oman et al. 2021, MNRAS, 501, 5073.

Cheqiu Lyu

Title: The chemical evolution and scaling relations in cosmological simulations

Numerical simulations have become a significant tool for understanding galaxy formation and evolution. Most cosmological models of galaxy formation now include a treatment of chemical evolution. As stars evolve and go into supernovae, they produce and distribute heavy elements throughout the gas that surrounds galaxies. In this review, I first briefly introduce how different cosmological simulations treat chemical evolution. I will mainly review the scaling relations and chemical distribution of galaxies in different simulations and comparison with observations, such as gas-phase and stellar mass-metallicity relation, fundamental metallicity relation, spatially resolved metallicity gradient, and their cosmological evolution. In addition, I will discuss the enlightenment from these simulations and prospects for future sky surveys (e.g. CSST).

Reference: • Somerville et al. 2015, ARAA2015. 53:51–113. • Vogelsberger et al. 2013, MNRAS 436, 3031–3067. • Schaye et al. 2015, MNRAS 446, 521–554. • Hopkins et al. 2014, MNRAS 445, 581–603. • Hopkins et al. 2018, MNRAS 480, 800–863. • Torrey et al. 2014, MNRAS 438, 1985–2004. • Torrey et al. 2019, MNRAS 484, 5587–5607. • Dave et al. 2019, MNRAS 486, 2827–2849. • Yates et al. 2012, MNRAS 508, 3535–3550. • De Rossi et al. 2017, MNRAS 472, 3354–3377. • De Rossi et al. 2018, BAAA, 60, 2018. • Hemler et al. 2021, MNRAS 506, 3024–3048. • Collacchioni et al. 2020, MNRAS 495, 2827–2843.

AGN Torus

SOC: Qinyue Fei Captain: Fuxiang Xu

This series provides a comprehensive exploration of the AGN torus, a crucial component in AGN unification models. Initially, an overview of the torus theory is presented, followed by a discussion of the evolution of torus models from simple dust distributions to complex, multiphase structures. Furthermore, the series addresses advancements in observational techniques, encompassing multi-wavelength studies, SED fitting methods, and the significant roles of X-ray and infrared observations. Of particular importance, dust reverberation mapping (DRM), a key technique for discerning torus geometry and kinematics, is thoroughly analyzed. In addition, recent findings that challenge conventional DRM interpretations are considered. High-spatial resolution imaging, facilitated by infrared and submillimeter interferometry, is also discussed, illustrating breakthroughs in understanding dust and molecular structures in circumnuclear regions. Consequently, the series scrutinizes well-studied AGNs and their multi-band image results. Lastly, the potential impacts of future missions, such as the James Webb Space Telescope, on advancing AGN torus research are explored, emphasizing their contributions to the broader context of AGN studies. Following below is the abstract of each specific talk.

Weibin Sun

Title: Introduction and Physical Explanation

Torus is an important structure through which the major differences between type-I and type- II AGNs can be explained in the original AGN unification scheme. There are different models assuming a certain geometry and dust composition, including continuous models, clumpy models, and composite models. But they all face some observational challenges. The studies on the X-ray reflection features such as Fe K𝛼 line and Compton hump, and the IR SED and spectral feature have got many important results on the nuclear obscuration properties. In the field of time-domain astronomy, variations of the obscuring material in the torus have been found, which is evidence of clumpy torus. From the near- and mid-IR reverberation Mapping, the inner size of the obscuring torus can be measured and a tight correlation with AGN luminosity is obtained. Observations of the outer regions of the torus have come from mid-IR interferometry imaging. The polar dust has also been found in many local AGN using high resolution observations. The ALMA sub-mm observations also lead to a better understanding of the properties of the dusty molecular tori, their connection to the host galaxy and the feedback mechanisms. In this talk, I will give a brief introduce about how is our current picture of the torus formed and some observational evidences.

Reference: • Robert Antonucci 1993, ARA&A, 31, 473 • Hagai Netzer 2015, ARA&A, 53, 365 • Cristina Ramos Almeida & Claudio Ricci 2017, Nature Astronomy, 1, 679 • Ryan C. Hickox & David M. Alexander 2018 ARA&A, 56, 1 • S. García-Burillo et al. 2021, A&A, 652, 98

Fuxiang Xu

Title: Simulation Model

The dusty torus model of active galactic nuclei (AGN) is a crucial aspect of our understanding of the central engine of these objects. The AGN torus model has evolved over time from simple uniform dust distributions to more complex, clumpy geometries. The clumpy formalism is now commonly used in torus models to prevent dust destruction. Additionally, several hydrodynamical simulations predict that the torus is a multiphase structure, containing a combination of smooth and clumpy dust distributions. Recent observations using IR interferometry have shown evidence for a polar dust component, leading to the development of clumpy disc+wind models. In this talk, we will describe the dust geometries and compositions, sublimation temperatures, and main parameters of different models, and then compare the various torus models to assess how well they fit the observed data.

Reference: • Fritz, Franceschini, et al. 2006. MNRAS. 366(3):767–86 • García-Bernete, González-Martín, et al. 2022. A&A. 667:A140 • García-González, Alonso-Herrero, et al. 2017. MNRAS. 470(3):2578–98 • Hickox, Alexander. 2018. ARA&A. 56(1):625–71 • Hönig, Beckert, et al. 2006. A&A. 452(2):459–71 • Hönig, Kishimoto. 2010. A&A. 523:A27 • Hönig, Kishimoto. 2017. ApJ. 838(2):L20 • Krolik. 2007. ApJ. 661(1):52– 59 • Lyu, Rieke. 2021. ApJ. 912(2):126 • Nenkova, Sirocky, et al. 2008a. ApJ 685(1):147–59 • Nenkova, Sirocky, et al. 2008b. ApJ. 685(1):160–80 • Netzer. 2015. ARA&A. 53(1):365–408 • Nikutta, Lopez- Rodriguez, et al. 2021. ApJ. 919(2):136 • Schartmann, Meisenheimer, et al. 2008. A&A. 482(1):67–80 • Siebenmorgen, Heymann, et al. 2015. A&A. 583:A120 • Stalevski, Fritz, et al. 2012. MNRAS. 420(4):2756–72 • Zhuang, Ho, et al. 2018. ApJ. 862(2):118

Bing Lyu

Title: Multiband SED Observation

Multi-wavelength studies have been dedicated to exploring the properties of the obscuring material in active galactic nuclei (AGN). Various models have been developed to describe the structure and distribution of this material and constrain its physical and geometrical parameters through spectral fitting techniques. The various torus models make specific predictions about the emitted SED which can be compared with NIR-MIR observations and X-ray observations. I will briefly introduce recent works on the multi-wavelength SED fitting methods/packages of AGNs from X-ray to infrared band and compare the main parameters (e.g., size/scale, distribution of clouds, inclination angle, cover factor, dust temperature, clump optical depths...) of torus in different AGN samples through SED fitting.

Reference: • Hagai Netzer 2015, ARA&A, 53, 365 • Yamada et al. 2023, ApJS, 265, 37 • Sokol et al. 2023, MNRAS, 521, 818 • Lyu & Rieke et al. 2022, ApJL, 940, L31 • Yamada et al. 2023, ApJS, 265, 37 • Kumar et al. 2023, MNRAS, 519, 3656 • Guo et al. 2023, PASP, 135, 014102 • Lyu & Rieke et al. 2022, ApJL, 940, L31 • Efstathiou et al. 2022, cosp, 44, 1836 • Yan 2022, AAS, 54, 112.05 • Efstathiou et al. 2022, MNRAS, 512, 5183 • Son et al. 2022, ApJ, 927, 107• Lyu & Rieke et al. 2022, Univ, 8, 304 • Yang et al. 2020, MNRAS, 491, 740 • Hickox & Alexander et al. 2018, ARA&A, 56, 625

Qinchun Ma

Title: Reverberation Mapping

Dust reverberation mapping (DRM) is a powerful technique that we can use the time lags between the optical light curves and the infrared light curves to determine the geometry and kinematics of the dust torus. The larger size scale of the dusty torus compared to the disk and BLR leads to longer lags and slower and weaker variability, affording lower cadence monitoring but requiring longer campaigns. In the last 20 years, a number of dedicated dust reverberation campaigns have substantially increased the sample of lags and established the relation between the torus size and luminosity $R_{\rm torus} \propto L^{0.5}$. On average the dust lags are ∼4 times longer than H$\beta$ lags. But recent observation shows that the torus sizes measured from interferometric observations are always larger than that found from DRM. Some papers tried to use the anisotropic bowl-shaped dust torus to explain it. From the high-cadence DRM observations, the NIR echo was found, which means that the varying hot dust is essentially located at the edge rather than along the entire bowl rim. I will introduce the theory and observation results of the DRM, and use some well-studied AGNs to introduce the details.

Reference: • Suganuma et al., 2006; ApJ, 639, 46–63 • Koshida et al. 2014, ApJ, 788, 159 • Kishimoto et al. 2011, A&A, 527, A121 • Kawaguchi, T., & Mori, M. 2010, ApJL, 724, L183 • Minezaki T. et al., 2019, ApJ, 886, 150 • Pozo Nuñez et al. 2014, A&A, 561, L8 • Sobrino Figaredo et al. 2020, AJ, 159, 259 • Mandal et al. 2021, MNRAS, 501, 3905 • Landt et al. 2023, ApJ, 945, 62L

Yuxuan Pang

Title: Revealing AGN torus through High-Spatial Resolution Observation

The spatial resolution has been revolutionary increased since interferometer application in Infrared and Submillimeter bands. Using the reconstruction image with a resolved scale of milli-arcsec, for the first time could people construct the nearby AGN circumnuclear regions in parsec-scale. Recent observations given by Gravity, ALMA, and other infrared interferometers have obtained the size, distribution, shape, and dynamical properties of the ‘torus’ and their relation to other parts of the modern AGN structure. These results changed our understanding of the dust and molecular structure in the circumnuclear region, i.e., the discovery of the polar dust and its relationship to the disk winds. Since the restriction of the observation bands and resolutions, those results were mainly carried out by a few nearby typical Type2 AGNs (such as the Circinus Galaxy) and Seyfert galaxies (such as NGC 1068). In this talk, several standard studied sources will be discussed through multi-band image results, as well as typical studies in low redshift AGNs. I will also give a brief prospect of the how JWST mission could do to help us further understand the ‘torus’ region of AGN.

Reference: • Sebastian F. Hönig 2019, APJ, 884, 171 • Hagai Netzer 2015, ARA&A, 53, 365 • N. López- Gonzaga et al. 2016, A&A, 591, 47 • D. Asmus et al. 2014, MNRAS, 439, 1648 • D. Asmus et al. 2015, MNRAS, 454, 766 • D. Asmus et al. 2016, APJ, 822, 109 • Jacob W. Isbell et al. 2021, APJ, 910, 104 • GRAVITY Collaboration 2020, A&A, 634, 1 • GRA VITY Collaboration 2021, A&A, 648, 117 • Marko Stalevski et al. 2017, MNRAS, 472, 3854 • Marko Stalevski et al. 2019, MNRAS, 484, 3334 • Marko Stalevski et al. 2023, MNRAS, 519,3237 •Takuma Izumi et. al.2018,APJ,867,48•Keiichi Wada et. al. 2018,APJ,867,49 • Jack F. Gallimore et al. 2016, APJ, 829, 7 • Masatoshi Imanishi et al. 2018, APJ, 853, 25 • A. Alonso-Herrero et al. 2018, APJ, 859, 144 • S. García-Burillo et al. 2019, A&A, 632, 61 • S. García-Burillo et al. 2021, A&A, 652, 98 • A. Alonso- Herrero et al. 2021, A&A, 652, 99

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