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start [2024/04/18 01:55] Cheng Li |
start [2024/11/06 06:27] (current) Cheng Li |
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| ===== What can you find from this site? ===== | ===== What can you find from this site? ===== | ||
| - | Please look at [[wiki:about|this page]] if you're interested to know about myself. Please refer to the [[wiki:research|Research Page]] for a brief introduction to my research and lists of my students/postdocs. More details about my research and my group can be found on [[https://lig.astro.tsinghua.edu.cn/|the website of my group]]. My courses are listed on the [[wiki:teaching|Teaching Page]]. You're welcome to [[wiki:contact|Contact]] me, if you're interested to visit and talk with me on my research or courses, but before that you may want to consult my [[wiki:schedule|Weekly Schedule and Travel plan]]. | + | Look at [[wiki:about|this page]] if you're interested about myself, and refer to the [[wiki:research|Research Page]] for a brief introduction to my research and lists of my students/postdocs. My publications are listed on [[wiki:publications|this page]]. My courses are listed on the [[wiki:teaching|Teaching Page]]. You're welcome to [[wiki:contact|Contact]] me, if you're interested to visit and talk with me on my research or courses, but before that you may want to consult my [[wiki:schedule|Weekly Schedule and Travel plan]]. |
| - | ==== My recent research works ==== | + | ==== Selected recent works ==== |
| - | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...964..161M|Measuring Galaxy Abundance and Clustering at High Redshift from Incomplete Spectroscopic Data: Tests on Mock Catalogs (2024, The Astrophysical Journal )]] | + | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...975...17J/abstract|On the Origin of Quenched but Gas-rich Regions at Kiloparsec Scales in Nearby Galaxies]] |
| + | * We use resolved spectroscopy from MaNGA to investigate the significance of both local and global properties of galaxies to the cessation of star formation at kpc scales. Quenched regions are identified from a sample of isolated disk galaxies by a single-parameter criterion D n (4000) - EW(Hα) , and are divided into gas-rich quenched regions (GRQRs) and gas-poor quenched regions according to the surface density of cold gas (Σgas). Both types of quenched regions tend to be hosted by non-AGN galaxies with relatively high mass (M * ≳ 1010 M ⊙) and red colors (NUV ‑ r ≳ 3), as well as low star formation rate and high central density at fixed mass. They span wide ranges in other properties including structural parameters that are similar to the parent sample, indicating that the conditions responsible for quenching in gas-rich regions are largely independent of the global properties of galaxies. We train random forest classifiers and regressors for predicting quenching in our sample with 15 local/global properties. Σ* is the most important property for quenching, especially for GRQRs. These results strongly indicate the important roles of low-mass hot evolved stars, which are numerous and long-lived in quenched regions and can provide substantial radiation pressure to support the surrounding gas against gravitational collapse. The different feature importance for quenching, as found previously by A. F. L. Bluck et al., is partly due to the different definitions of quenched regions, particularly the different requirements on EW(Hα). | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...963...86L|On the Existence, Rareness, and Uniqueness of Quenched H I-rich Galaxies in the Local Universe (2024, The Astrophysical Journal )]] | + | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...963...86L|On the Existence, Rareness, and Uniqueness of Quenched H I-rich Galaxies in the Local Universe]] |
| + | * Using data from ALFALFA, xGASS, H I-MaNGA, and the Sloan Digital Sky Survey (SDSS), we identify a sample of 47 "red but H I-rich" (RR) galaxies with near-UV (NUV) ‑ r > 5 and unusually high H I-to-stellar mass ratios. We compare the optical properties and local environments between the RR galaxies and a control sample of "red and H I-normal" (RN) galaxies that are matched in stellar mass and color. The two samples are similar in the optical properties typical of massive red (quenched) galaxies in the local Universe. The RR sample tends to be associated with slightly lower-density environments and has lower clustering amplitudes and smaller neighbor counts at scales from several hundred kiloparsecs to a few megaparsecs. The results are consistent with the RR galaxies being preferentially located at the center of low-mass halos, with a median halo mass ∼1012 h ‑1 M ⊙ compared to ∼1012.5 h ‑1 M ⊙ for the RN sample. This result is confirmed by the SDSS group catalog, which reveals a central fraction of 89% for the RR sample, compared to ∼60% for the RN sample. If assumed to follow the H I size–mass relation of normal galaxies, the RR galaxies have an average H I-to-optical radius ratio of R HI/R 90 ∼ 4, four times the average ratio for the RN sample. We compare our RR sample with similar samples in previous studies, and quantify the population of RR galaxies using the SDSS complete sample. We conclude that the RR galaxies form a unique but rare population, accounting for only a small fraction of the massive quiescent galaxy population. We discuss the formation scenarios of the RR galaxies. | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...962...51J|Criss-cross Nebula: A Case Study of Shock Regions with Resolved Microstructures at Scales of ∼1000 au (2024, The Astrophysical Journal )]] | + | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...962...51J|Criss-cross Nebula: A Case Study of Shock Regions with Resolved Microstructures at Scales of ∼1000 au]] |
| + | * Using integral field spectroscopy (IFS) from MaNGA, we study the resolved microstructures in a shocked region in the Criss-cross Nebula (CCN), with an unprecedentedly high resolution of ≲1000 au. We measure surface brightness maps for 34 emission lines, which can be broadly divided into three categories: (1) the [O III] λ5007-like group including seven high-ionization lines and two [O II] auroral lines that uniformly present a remarkable lane structure, (2) the Hα λ6563-like group, including 23 low-ionization or recombination lines that present a clump-like structure, and (3) [O II] λ3726 and [O II] λ3729 showing high densities at both the [O III] λ5007 lane and the Hα clump. We use these measurements to constrain resolved shock models implemented in MAPPINGS V. We find our data can be reasonably well fitted by a model that includes a plane-parallel shock with a velocity of 133 ± 5 km s ‑1, plus an isotropic two-dimensional Gaussian component, which is likely another clump of gas ionized by photons from the shocked region, and a constant background. We compare the electron density and temperature profiles as predicted by our model with those calculated using observed emission-line ratios. We find different line ratios to provide inconsistent temperature maps, and the discrepancies can be attributed to observational effects caused by limited spatial resolution and projection of the shock geometry, as well as contamination of the additional Gaussian component. Implications on shock properties and perspectives on future IFS-based studies of the CCN are discussed. | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...961..216C|Post-starburst Galaxies in SDSS-IV MaNGA: Two Broad Categories of Evolutionary Pathways (2024, The Astrophysical Journal )]] | + | * [[https://ui.adsabs.harvard.edu/abs/2024ApJ...961..216C|Post-starburst Galaxies in SDSS-IV MaNGA: Two Broad Categories of Evolutionary Pathways]] |
| + | * We study the size–mass relation (SMR) and recent star formation history (SFH) of post-starburst (PSB) galaxies in the local Universe using spatially resolved spectroscopy from the final data release of MaNGA. Our sample includes 489 PSB galaxies: 94 cPSB galaxies with central PSB regions, 85 rPSB galaxies with ringlike PSB regions, and 310 iPSB galaxies with irregular PSB regions. When compared to control galaxies of similar star formation rate, redshift, and mass, a similar SMR is found for all types of PSB samples except the cPSB galaxies, which have smaller sizes at intermediate masses ( $9.5\lesssim {\mathrm{log}}_{10}({M}_{* }/{M}_{\odot })\lesssim 10.5$ ). The iPSB galaxies in the star-forming sequence (iPSB-SF) show no/weak gradients in D n (4000), EW(Hδ A ), and EW(Hα), consistent with the global star-forming status of this type of galaxy, while the quiescent iPSB (iPSB-Q) sample shows negative gradients in D n (4000) and positive gradients in EW(Hδ A ), indicating older stellar populations in the inner regions. Both the cPSB and rPSB samples show positive gradients in D n (4000) and negative gradients in EW(Hδ A ), indicating younger stellar populations in the inner regions. These results imply that the four types of PSB galaxies can be broadly divided into two distinct categories in terms of evolutionary pathway: (1) iPSB-SF and iPSB-Q, which have SMRs and SFHs similar to control galaxies, preferring an inside-out quenching process, and (2) rPSB and cPSB, which appear to be different stages of the same event and likely to follow the outside-in quenching process driven by disruption events such as mergers that result in a more compact structure as quenching proceeds. | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2023ApJ...957...75Z|Mapping Dust Attenuation and the 2175 Å Bump at Kiloparsec Scales in Nearby Galaxies (2023, The Astrophysical Journal )]] | + | * [[https://ui.adsabs.harvard.edu/abs/2023ApJ...957...75Z|Mapping Dust Attenuation and the 2175 Å Bump at Kiloparsec Scales in Nearby Galaxies]] |
| + | * We develop a novel approach to measure the dust attenuation properties of galaxies, including the dust opacity, the shape of the attenuation curve, and the strength of the 2175 Å absorption feature. From an observed spectrum, the method uses a model-independent approach to derive a relative attenuation curve with an absolute amplitude calibrated using NIR photometry. The dust-corrected spectrum is fitted with stellar population models to derive the dust-free model spectrum, which is compared with the observed SED/spectrum from NUV to NIR to determine the dust attenuation properties. We apply this method to investigate dust attenuation on kiloparsec scales using a sample of 134 galaxies with integral field spectroscopy from MaNGA, NIR imaging from 2MASS, and NUV imaging from Swift/UVOT. We find that the attenuation curve slope and the 2175 Å bump in both the optical and NUV span a wide range at kiloparsec scales. The slope is shallower at higher optical opacity, regardless of the specific star formation rate (sSFR), the minor-to-major axis ratio (b/a) of the galaxies, and the location of spaxels within individual galaxies. The 2175 Å bump presents a strong negative correlation with the sSFR, while the correlations with the optical opacity, b/a, and the locations within individual galaxies are all weak. All of these trends appear to be independent of the stellar mass of the galaxies. Our results support the scenario that the variation of the 2175 Å bump is driven predominantly by processes related to star formation, such as the destruction of small dust grains by UV radiation in star-forming regions. | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2023MNRAS.525.1254C|A conditional abundance matching method of extending simulated halo merger trees to resolve low-mass progenitors and subhalos (2023, Monthly Notices of the Royal Astronomical Society )]] | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2023MNRAS.520.1774W|Relating galaxies across different redshift to study galaxy evolution (2023, Monthly Notices of the Royal Astronomical Society )]] | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2023ChPhB..32c9801L|Measuring stellar populations, dust attenuation and ionized gas at kpc scales in 10010 nearby galaxies using the integral field spectroscopy from MaNGA (2023, Chinese Physics B )]] | ||
| - | * [[https://ui.adsabs.harvard.edu/abs/2023ApJ...944...75M|Galaxy Populations in Groups and Clusters: Evidence for a Characteristic Stellar Mass Scale at M <SUB>∗</SUB> 10<SUP>9.5</SUP> M <SUB>⊙</SUB> (2023, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2022ApJ...941...48L|Conditional H I Mass Functions and the H I-to-halo Mass Relation in the Local Universe (2022, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2021MNRAS.508.3943J|SDSS-IV MaNGA: the physical origin of off-galaxy H α blobs in the local Universe (2021, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2021ApJ...923..120L|Wolf-Rayet Galaxies in SDSS-IV MaNGA. II. Metallicity Dependence of the High-mass Slope of the Stellar Initial Mass Function (2021, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2021MNRAS.507.2510C|MAHGIC: a Model Adapter for the Halo-Galaxy Inter-Connection (2021, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2021MNRAS.505.3892W|Finding protoclusters to trace galaxy evolution - I. The finder and its performance (2021, Monthly Notices of the Royal Astronomical Society )]] | ||
| - | |||
| - | * [[https://ui.adsabs.harvard.edu/abs/2021ApJ...917...72L|Estimating Dust Attenuation From Galactic Spectra. II. Stellar and Gas Attenuation in Star-forming and Diffuse Ionized Gas Regions in MaNGA (2021, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2021MNRAS.504.4865C|How to empirically model star formation in dark matter haloes - I. Inferences about central galaxies from numerical simulations (2021, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2021ApJ...916...38Z|Star Formation Histories of Massive Red Spiral Galaxies in the Local Universe (2021, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2021MNRAS.500.1261C|A new estimator of resolved molecular gas in nearby galaxies (2021, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2020MNRAS.499.1406L|SDSS-IV MaNGA: the indispensable role of bars in enhancing the central star formation of low-z galaxies (2020, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2020MNRAS.499...89W|Identifying galaxy groups at high redshift from incomplete spectroscopic data - I. The group finder and application to zCOSMOS (2020, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2020ApJ...903...26W|Constraints on Circumgalactic Media from Sunyaev-Zel'dovich Effects and X-Ray Data (2020, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2020MNRAS.497.4753Z|SDSS-IV MaNGA: Bayesian analysis of the star formation history of low-mass galaxies in the local Universe (2020, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2020ApJ...899...81C|Relating the Structure of Dark Matter Halos to Their Assembly and Environment (2020, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2020ApJ...896..121L|Wolf-Rayet Galaxies in SDSS-IV MaNGA. I. Catalog Construction and Sample Properties (2020, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2020ApJ...896...38L|Estimating Dust Attenuation from Galactic Spectra. I. Methodology and Tests (2020, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019RAA....19..171D|Photometrically estimating the spatially-resolved stellar mass-to-light ratios for low-redshift galaxies (2019, Research in Astronomy and Astrophysics )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019ApJ...887..172G|Estimating the Molecular Gas Mass of Low-redshift Galaxies from a Combination of Mid-infrared Luminosity and Optical Properties (2019, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019MNRAS.489.1436L|SDSS-IV MaNGA: environmental dependence of gas metallicity gradients in local star-forming galaxies (2019, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019MNRAS.485.5256Z|SDSS-IV MaNGA: stellar initial mass function variation inferred from Bayesian analysis of the integral field spectroscopy of early-type galaxies (2019, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019MNRAS.484.5192C|Linking bar- and interaction-driven molecular gas concentration with centrally enhanced star formation in EDGE-CALIFA galaxies (2019, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019MNRAS.484.3865W|The clustering of galaxies with pseudo-bulge and classical bulge in the local Universe (2019, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019ApJ...873...63Z|SDSS-IV MaNGA: Environmental Dependence of the Mgb/<{Fe}>-σ<SUB>*</SUB> Relation for Nearby Galaxies (2019, The Astrophysical Journal )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019MNRAS.483.1452W|Revisiting the clustering of narrow-line AGN in the local Universe: Joint dependence on stellar mass and colour (2019, Monthly Notices of the Royal Astronomical Society )]] | ||
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| - | * [[https://ui.adsabs.harvard.edu/abs/2019ApJ...872..180C|ELUCID. VI. Cosmic Variance of the Galaxy Distribution in the Local Universe (2019, The Astrophysical Journal )]] | ||
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