A5045518880- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Cosmology and Gravitation Theories
- Advanced Bandit Algorithms Research
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Astronomical Observations and Instrumentation
- Big Data Technologies and Applications
- Risk and Safety Analysis
- Black Holes and Theoretical Physics
- Semiconductor Quantum Structures and Devices
- Probabilistic and Robust Engineering Design
- Astro and Planetary Science
- Smart Grid Energy Management
- Ethics in Business and Education
- Optimal Experimental Design Methods
- Reinforcement Learning in Robotics
- Data Stream Mining Techniques
University of Illinois Urbana-Champaign
2014-2024
National Center for Supercomputing Applications
2016-2024
Intel (United States)
2023-2024
Donghua University
2024
Huaneng Clean Energy Research Institute
2024
Sinopec (China)
2024
Argonne National Laboratory
2022-2023
Chizhou University
2023
Chongqing Metrology Quality Inspection and Research Institute
2023
University of Chicago
2022-2023
The Very Large Array Sky Survey (VLASS) is a synoptic, all-sky radio sky survey with unique combination of high angular resolution ($\approx$2.5"), sensitivity (a 1$\sigma$ goal 70 $\mu$Jy/beam in the coadded data), full linear Stokes polarimetry, time domain coverage, and wide bandwidth (2-4 GHz). first observations began September 2017, observing for will finish 2024. VLASS use approximately 5500 hours on Karl G. Jansky (VLA) to cover whole visible VLA (Declination $>-40^{\circ}$), total...
The prevalence and energetics of quasar feedback is a major unresolved problem in galaxy formation theory. In this paper, we present Gemini Integral Field Unit observations ionized gas around eleven luminous, obscured, radio-quiet quasars at z~0.5 out to ~15 kpc from the quasar; specifically, measure kinematics morphology [O III]5007 emission. round morphologies nebulae large line-of-sight velocity widths (with velocities containing 80% emission as high 1000 km/s combined with relatively...
Single-epoch virial black hole (BH) mass estimators utilizing broad emission lines have been routinely applied to high-redshift quasars estimate their BH masses. Depending on the redshift, different line (Halpha, Hbeta, MgII, CIV) are often used with optical/near-infrared spectroscopy. Here we use a homogeneous sample of 60 intermediate-redshift (z~1.5-2.2) SDSS optical and near-infrared spectra covering CIV through Halpha investigate consistency between estimators. We critically compare...
The eighteenth data release of the Sloan Digital Sky Surveys (SDSS) is first one for SDSS-V, fifth generation survey. SDSS-V comprises three primary scientific programs, or "Mappers": Milky Way Mapper (MWM), Black Hole (BHM), and Local Volume (LVM). This contains extensive targeting information two multi-object spectroscopy programs (MWM BHM), including input catalogs selection functions their numerous objectives. We describe production databases calibration- scientifically-focused...
Black hole feedback -- the strong interaction between energy output of supermassive black holes and their surrounding environments is routinely invoked to explain absence overly luminous galaxies, vs. bulge correlations similarity accretion star formation histories. Yet direct probes this process in action are scarce limited small samples active nuclei. We present Gemini IFU observations distribution ionized gas around luminous, obscured, radio-quiet (RQ) quasars at z~0.5. detect extended...
We present a study of the mass-metallicity (M-Z) relation and H II region physical conditions in sample 20 star-forming galaxies at 1.0
We present a sample of 167 type 2 AGNs with double-peaked [O III] 4959,5007 narrow emission lines, selected from the Seventh Data Release Sloan Digital Sky Survey. The profiles can be well modeled by two velocity components, blueshifted and redshifted systemic velocity. Half these objects have more prominent component. In cases where H-beta line is strong, it also shows components whose line-of-sight (LOS) offsets are consistent those III]. relative LOS offset between typically few hundred...
We report the discovery of four kpc-scale binary active galactic nuclei (AGNs). These objects were originally selected from Sloan Digital Sky Survey based on double-peaked [O iii] λλ4959, 5007 emission lines in their fiber spectra. The double peaks could result pairing supermassive black holes (SMBHs) a galaxy merger or be due to bulk motions narrow-line region gas around single SMBH. Deep near-infrared (NIR) images and optical slit spectra obtained Magellan 6.5 m Apache Point Observatory...
(Abridged) Approximately 1% of low redshift (z<0.3) optically-selected type 2 AGNs show a double-peaked [OIII] narrow emission line profile in their spatially-integrated spectra. Such features are usually interpreted as due either to kinematics, such biconical outflows and/or disk rotation the region (NLR) around single black holes, or relative motion two distinct NLRs merging pair AGNs. Here we report follow-up near infrared (NIR) imaging and optical slit spectroscopy 31 drawn from SDSS...
Abstract We perform a systematic search for long-term extreme variability quasars (EVQs) in the overlapping Sloan Digital Sky Survey and 3 Year Dark Energy imaging, which provide light curves spanning more than 15 years. identified ∼1000 EVQs with maximum change g- band magnitude of 1 mag over this period, about 10% all searched. The have L bol ∼ 10 45 –10 47 erg s −1 / Edd 0.01–1. Accounting selection effects, we estimate an intrinsic EVQ fraction ∼30%–50% among baseline ∼15 yr. performed...
Variability time scales in active galaxies Active galactic nuclei contain a supermassive black hole (SMBH) surrounded by an accretion disk. As disk material falls toward the SMBH, it heats up enough to emit optical light. Burke et al . investigated how such emission varies over sample of 67 (see Perspective Lira and Arevalo). They observed characteristic variability timing that scaled with SMBH mass. The results elucidate physical processes within disks provide method estimate mass from...
The recent report of an association the gravitational-wave (GW) binary black hole (BBH) merger GW190521 with a flare in Active Galactic Nuclei (AGN) J124942.3+344929 has generated tremendous excitement. However, one largest localization volumes amongst all GW events detected so far. 90\% volume likely contains $7,400$ unobscured AGN brighter than $g \leq 20.5$ AB mag, and it results $\gtrsim 70\%$ probability chance coincidence for consistent event. We present Bayesian formalism to estimate...
Abstract Dual supermassive black holes (SMBHs) at ∼kiloparsec scales are the progenitor population of SMBH mergers and play an important role in understanding pairing dynamical evolution massive galaxy mergers. Because stringent resolution requirement apparent rareness these small-separation pairs, there scarce observational constraints on this population, with few confirmed dual SMBHs <10 kpc separations z > 1. Here we present results from a pilot search for kiloparsec-scale quasars...
ABSTRACT We study the optical gri photometric variability of a sample 190 quasars within SDSS Stripe 82 region that have long-term coverage during ∼1998−2020 with SDSS, PanSTARRS-1, Dark Energy Survey, and dedicated follow-up monitoring Blanco 4m/DECam. With on average ∼200 nightly epochs per quasar filter band, we improve parameter constraints from Damped Random Walk (DRW) model fit to light curves over previous studies 10–15 yr baselines ≲ 100 epochs. find damping time-scale τDRW continues...
Abstract “Changing-look” active galactic nuclei (CL-AGNs) challenge our basic ideas about the physics of accretion flows and circumnuclear gas around supermassive black holes. Using first-year Sloan Digital Sky Survey V (SDSS-V) repeated spectroscopy nearly 29,000 previously known (AGNs), combined with dedicated follow-up spectroscopy, publicly available optical light curves, we have identified 116 CL-AGNs where (at least) one broad emission line has essentially (dis-)appeared, as well 88...
We perform a systematic search for sub-parsec binary supermassive black holes (BHs) in normal broad line quasars at z<0.8, using multi-epoch SDSS spectroscopy of the Hbeta line. Our working model is that: only one two BHs active, and dynamically dominates its own region (BLR); inactive companion BH orbiting distance few R_BLR, where R_BLR~0.01-0.1 pc BLR size. expected line-of-sight acceleration velocity from orbital motion by cross-correlating spectra epochs separated up to several years...
Galaxy-galaxy mergers and close interactions have long been regarded as a viable mechanism for channeling gas toward the central supermassive black holes (SMBHs) of galaxies which are triggered active galactic nuclei (AGNs). AGN pairs, in SMBHs galaxy merger both active, expected to be common from such events. We conduct systematic study 1286 pairs at z ~ 0.1 with line-of-sight velocity offsets dv < 600 km/s projected separations r_p 100 kpc, selected Seventh Data Release Sloan Digital Sky...
A small fraction of quasars have long been known to show bulk velocity offsets (of a few hundred thousands km s−1) in the broad Balmer lines with respect systemic redshift host galaxy. Models explain these usually invoke broad-line region gas kinematics/asymmetry around single black holes (BHs), orbital motion massive (∼sub-parsec (sub-pc)) binary (BBHs), or recoil BHs, but single-epoch spectra are unable distinguish between scenarios. The line-of-sight (LOS) radial (RV) shifts from...
Kiloparsec-scale binary active galactic nuclei (AGNs) signal supermassive black hole (SMBH) pairs in merging galaxies. Despite their significance, unambiguously confirmed cases remain scarce and most have been discovered serendipitously. In a previous systematic search, we optically identified four kpc-scale AGNs from candidates selected with double-peaked narrow emission lines at redshifts of 0.1--0.2. Here present Chandra Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging these...
ABSTRACT We apply a new deep learning technique to detect, classify, and deblend sources in multiband astronomical images. train evaluate the performance of an artificial neural network built on Mask Region-based Convolutional Neural Network image processing framework, general code for efficient object detection, classification, instance segmentation. After evaluating our against simulated ground truth images star galaxy classes, we find precision 92 per cent at 80 recall stars 98 galaxies...
We examine the spatial extent of narrow-line regions (NLRs) a sample 30 luminous obscured quasars at 0.4 < z 0.7 observed with spatially resolved Gemini-N GMOS long-slit spectroscopy. Using [O iii] λ5007 emission feature, we estimate size NLR using cosmology-independent measurement: radius where surface brightness falls to 10−15 erg s−1 cm−2 arcsec−2. then explore effects atmospheric seeing on measurements and conclude that direct from profiles are too large by 0.1–0.2 dex average, as...
Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed with median redshift of 1.8 4.6 deg$^2$ overlapping region the Dark Energy Survey Supernova (DES-SN) fields and Sloan Digital Sky Stripe 82 (SDSS-S82). Our sample has unique 20-year long multi-color ($griz$) curve enabled by combining DES-SN Y6 observations archival SDSS-S82 data. The deep imaging allows us to...
Abstract The broad Mg ii line in quasars has distinct variability properties compared with Balmer lines: it is less variable and usually does not display a “breathing” mode, the increase average cloud distance when luminosity increases. We demonstrate that these of can be reasonably well explained by simple locally optimally emitting (LOC) photoionization models, confirming earlier results. In fiducial LOC model, -emitting gas on more distant from ionizing source than H α /H β responds lower...