A5002305315- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Nuclear and radioactivity studies
- Graphite, nuclear technology, radiation studies
- Dark Matter and Cosmic Phenomena
- History and Developments in Astronomy
- Radioactive contamination and transfer
- Cosmology and Gravitation Theories
- Advanced Measurement and Metrology Techniques
- Nuclear reactor physics and engineering
- Adaptive optics and wavefront sensing
- Industrial Vision Systems and Defect Detection
- Nuclear Engineering Thermal-Hydraulics
- Scientific Research and Discoveries
- Impact of Light on Environment and Health
- Computational Physics and Python Applications
- Risk and Safety Analysis
- Geophysics and Gravity Measurements
- Scientific Measurement and Uncertainty Evaluation
Dartmouth College
2014-2023
Washington State University
2022-2023
We present the Young Supernova Experiment Data Release 1 (YSE DR1), comprised of processed multi-color Pan-STARRS1 (PS1) griz and Zwicky Transient Facility (ZTF) gr photometry 1975 transients with host-galaxy associations, redshifts, spectroscopic/photometric classifications, additional data products from 2019 November 24 to 2021 December 20. YSE DR1 spans discoveries observations young fast-rising supernovae (SNe) that persist for over a year, redshift distribution reaching z~0.5. relative...
We use time-domain optical spectroscopy to distinguish between broad emission lines powered by accreting black holes (BHs) or stellar processes (i.e., supernovae) for 16 galaxies identified as AGN candidates Reines \etal (2013). Our study is primarily focused on those objects with narrow emission-line ratios dominated star formation. Based follow-up spectra taken the Magellan Echellette Spectrograph (MagE), Dual Imaging Spectrograph, and Ohio State Multi-Object we find that H$\alpha$ has...
We present a new, ambitious survey performed with the Chandra X-ray Observatory of 9.3 deg2 Boötes field NOAO Deep Wide-Field Survey. The wide probes statistically representative volume universe at high redshift. Wide-field Survey exploits excellent sensitivity and angular resolution over area, combining 281 observations spanning 15 yr, for total exposure time 3.4 Ms, detects 6891 point sources down to limiting fluxes 4.7 × 10−16, 1.5 9 ×10−16 erg cm−2 s−1 in 0.5–7, 0.5–2, 2–7 keV bands,...
We present the results of an optical spectroscopic survey a sample 40 candidate obscured quasars identified on basis their mid-infrared emission detected by Wide-Field Infrared Survey Explorer (WISE). Optical spectra for this were obtained using Robert Stobie Spectrograph Southern African Large Telescope. Our was selected with WISE colors characteristic active galactic nuclei (AGNs), as well red to mid-IR indicating that optical/UV AGN continuum is dust. obtain secure redshifts majority...
Abstract We present new estimates on the fraction of heavily X-ray-obscured, Compton-thick (CT) active galactic nuclei (AGNs) out to a redshift z ≤ 0.8. From sample 540 AGNs selected by mid-infrared (MIR) properties in observed X-ray survey fields, we forward model observed-to-intrinsic luminosity ratio ( <?CDATA ${R}_{{L}_{{\rm{X}}}}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>R</mml:mi> </mml:mrow> <mml:mi>L</mml:mi> <mml:mi...
We present a large sample of infrared-luminous candidate active galactic nuclei (AGNs) that lack X-ray detections in Chandra, XMM-Newton, and NuSTAR fields. selected all optically detected SDSS sources with redshift measurements, combined additional broadband photometry from WISE, UKIDSS, 2MASS, GALEX, modeled the spectral energy distributions (SEDs) our sources. parameterize nuclear obscuration SEDs $E(B\!-\!V)_{\text{AGN}}$ uncover thousands powerful obscured AGNs counterparts, many which...
We explore the kinematics of ionized gas via [O III] $\lambda$5007 emission lines in active galactic nuclei (AGN) selected on basis their mid-infrared (IR) emission, and split into obscured unobscured populations based optical-IR colors. After correcting for differences redshift distributions, we provide composite spectra spectroscopically photometrically defined obscured/Type 2 unobscured/Type 1 AGN from 3500 to 7000 \AA. The IR-selected sources contain a mixture narrow-lined Type...
Abstract The absence of high-Eddington-ratio, obscured active galactic nuclei (AGNs) in local ( z ≲ 0.1) samples moderate-luminosity AGNs has generally been explained to result from radiation pressure on the dusty gas governing level nuclear (≲10 pc) obscuration. However, very high accretion rates are routinely reported among quasars at higher luminosities and may require a different feedback mechanism. We compile constraints obscuration Eddington ratio for X-ray, optical, infrared,...
We present the results of an optical spectroscopic survey 46 heavily obscured quasar candidates. Objects are selected using their mid-infrared (mid-IR) colours and magnitudes from Wide-Field Infrared Survey Explorer (WISE) Sloan Digital Sky (SDSS). Candidate Active Galactic Nuclei (AGNs) to have mid-IR indicative activity lie in a region colour space outside previously published X-ray based selection regions. obtain spectra for our sample Robert Stobie Spectrograph on Southern African Large...
Abstract We searched the northern hemisphere fields of Galaxy Evolution Explorer Time Domain Survey for galaxies with UV variability indicative active galactic nuclei (AGNs). identified 48 high-probability candidate AGNs from a parent sample 1819 in NASA Sloan Atlas catalog. further characterized these systems using optical spectroscopic diagnostics, Wide-field Infrared IR color selection criteria, and spectral energy distribution modeling. Of candidates, eight were as emission lines, two by...
ABSTRACT We explore the gas ionization and kinematics, as well optical-IR spectral energy distributions for UGC 11185, a nearby pair of merging galaxies hosting obscured active galactic nuclei (AGNs), also known SDSS J181611.72+423941.6 J181609.37+423923.0 (J1816NE J1816SW, z ≈ 0.04). Due to wide separation between these interacting (∼23 kpc), observations objects provide rare glimpse concurrent growth supermassive black holes at an early merger stage. use BPT line diagnostics show that full...
Abstract Many X-ray bright active galactic nuclei (AGNs) are predicted to follow an extended stage of obscured black hole growth. In support this picture we examine the undetected AGNs in COSMOS field and compare their host galaxies with AGNs. We M * > 10 9.5 ⊙ for presence at redshifts z = 0.5–3. select infrared using Spitzer Herschel detections use color selection techniques within strongly star-forming hosts. stack Chandra data (IR) detection but lacking obtain soft hard fluxes,...
Abstract A primary aim of the <?CDATA ${Nuclear}\,{Spectroscopic}\,{Telescope}\,{Array}$?> ( NuSTAR ) mission is to find and characterize heavily obscured Active Galactic Nuclei (AGNs). Based on mid-infrared photometry from Wide-Field Infrared Survey Explorer WISE optical Sloan Digital Sky Surveys, we have selected a large population luminous AGNs (i.e., “obscured quasars”). Here report observations four -selected quasars for which spectroscopy Southern African Large Telescope W. M. Keck...
Abstract We report on the results of active galactic nuclei (AGNs) detection by NuSTAR performed in three extragalactic survey fields (COSMic Evolutionary Survey field (COSMOS), Ultra Deep (UDS), and Extended Chandra Field-South (ECDFS)) hard bands, namely H1 (8–16 keV), H2 (16–24 VH (35–55 keV). The aggregated area surveys is ∼2.7 deg 2 . While a large number sources detected band (72 at 97% level reliability), directly probing close to peak Cosmic X-ray Background (CXB) returns four...
The Large Synoptic Survey Telescope (LSST) will explore the entire southern sky over 10 years starting in 2022 with unprecedented depth and time sampling six filters, $ugrizy$. Artificial power on scale of 3.5 deg LSST field-of-view contaminate measurements baryonic acoustic oscillations (BAO), which fall at same angular redshift $z \sim 1$. Using HEALPix framework, we demonstrate impact an "un-dithered" survey, $17\%$ each is overlapped by neighboring observations, generating a honeycomb...
We present new estimates on the fraction of heavily X-ray obscured, Compton-thick (CT) active galactic nuclei (AGNs) out to a redshift $z \leq$ 0.8. From sample 540 AGNs selected by mid-IR (MIR) properties in observed survey fields, we forward model observed-to-intrinsic luminosity ratio ($R_{L_{\text{X}}}$) with Markov chain Monte Carlo (MCMC) simulation estimate total CT ($f_{\text{CT}}$), many which are missed typical observations. create $N_{\text{H}}$ distributions and convert these...