A5039380547- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Spectroscopy and Laser Applications
- Scientific Research and Discoveries
- Atmospheric Ozone and Climate
- Advanced Statistical Methods and Models
- Remote Sensing in Agriculture
- Space Exploration and Technology
- Laser-induced spectroscopy and plasma
- Advanced MRI Techniques and Applications
- Brain Tumor Detection and Classification
- Astronomical and nuclear sciences
- Impact of Light on Environment and Health
- Fullerene Chemistry and Applications
- Quantum chaos and dynamical systems
- High-pressure geophysics and materials
- Calibration and Measurement Techniques
- Advanced Chemical Physics Studies
University of Washington
2020-2024
Johns Hopkins University
2014-2020
Bloomberg (United States)
2014-2019
Oberlin College
2013
ABSTRACT The dust extinction curve is a critical component of many observational programs and an important diagnostic the physics interstellar medium. Here we present new measurements its variation toward tens thousands stars, hundred-fold larger sample than in existing detailed studies. We use data from APOGEE spectroscopic survey combination with ten-band photometry Pan-STARRS1, Two Micron All-Sky Survey, Wide-field Infrared Survey Explorer . find that optical through infrared well...
The dust properties in the Large and Small Magellanic clouds (LMC/SMC) are studied using HERITAGE Herschel Key Project photometric data five bands from 100 to 500 μm. Three simple models of emission were fit observations: a single temperature blackbody modified by power-law emissivity (SMBB), broken (BEMBB), two blackbodies with different temperatures, both same (TTMBB). Using these models, we investigate origin submillimeter excess, defined as above that expected SMBB observations <200 We...
Abstract We present initial results from the Cosmic Origins Spectrograph (COS) and Gemini Mapping Circumgalactic Medium (CGMCGM ≡ CGM 2 ) survey. The survey consists of 1689 galaxies, all with high-quality Gemini-GMOS spectra, within 1 Mpc 22 z ≲ quasars, a signal-to-noise ratio ∼10 Hubble Space Telescope/COS G130M+G160M spectra. For 572 these galaxies stellar masses 10 7 M ⊙ < ⋆ 11 0.5, we show that H i covering fraction above threshold N HI > 14 cm −2 is ≳0.5 1.5 virial radii ( R vir...
We study the stellar mass Tully-Fisher relation (TFR, versus rotation velocity) for a morphologically blind selection of emission line galaxies in field at redshifts 0.1 $<$ z 0.375. Kinematics ($\sigma_g$, V$_{rot}$) are measured from lines Keck/DEIMOS spectra and quantitative morphology is V- I-band Hubble images. find transition TFR, $\log$ M$_*$ = 9.5 M$_{\odot}$. Above this mass, nearly all rotation-dominated, on average more disk-like according to morphology, lie relatively tight TFR....
The nature, composition, abundance, and size distribution of dust in galaxies is determined by the rate at which it created different stellar sources destroyed interstellar shocks. Because their extensive wavelength coverage, proximity, nearly face-on geometry, Magellanic Clouds (MCs) provide a unique opportunity to study these processes great detail. In this paper we use complete sample supernova remnants (SNRs) MCs calculate lifetime destruction efficiencies silicate carbon galaxies. We...
Using deep HST/ACS observations, we demonstrate that the sub-solar stellar initial mass function (IMF) of 6 ultra-faint dwarf Milky Way Satellites (UFDs) is more bottom light than IMF disk. Our data have a lower limit about 0.45 M$_{\odot}$, while upper $\sim 0.8$ M$_\odot$, set by turn-off these old, metal poor systems. If formulated as single power law, obtain shallower slope "Salpeter" value $-2.3$, ranging from $-1.01$ for Leo IV, to $-1.87$ Boötes I. The significance such deviations...
The metallicity and gas density dependence of interstellar depletions, the dust-to-gas (D/G), dust-to-metal (D/M) ratios have important implications for how accurately we can trace chemical enrichment universe; either by using FIR dust emission as a tracer ISM; or spectroscopy damped Lyman-alpha systems (DLAs) to measure abundances over wide range redshifts. We collect compare large samples depletion measurements in Milky Way (MW), LMC (Z=0.5 Zsun), SMC (Z=0.2 Zsun). relation between...
We combine 126 new galaxy-O VI absorber pairs from the CGM$^2$ survey with 123 drawn literature to examine simultaneous dependence of column density O absorbers ($N_{\rm VI}$) on galaxy stellar mass, star formation rate, and impact parameter. The combined sample consists 249 covering $z=0$-$0.6$, host masses $M^*=10^{7.8}$-$10^{11.2}$ $M_\odot$ galaxy-absorber parameters $R_\perp=0$-$400$ proper kiloparsecs. In this work, we focus variation $N_{\rm VI}$ mass parameter among star-forming...
Abstract This study addresses how the incidence rate of strong O vi absorbers in a galaxy’s circumgalactic medium (CGM) depends on galaxy mass and, independently, amount star formation galaxy. We use Hubble Space Telescope/Cosmic Origins Spectrograph absorption spectroscopy quasars to measure within 400 projected kpc and 300 km s −1 52 galaxies with M * ∼ 3 × 10 ⊙ . The have redshifts 0.12 < z 0.6, stellar masses 10.1 10.9 , spectroscopic classifications as star-forming or passive....
Abstract The evolution of the metal content universe can be tracked through rest-frame UV spectroscopy damped Ly α systems (DLAs). Gas-phase abundances in DLAs must corrected for dust depletion effects, which accomplished by calibrating relation between abundance ratios such as [Zn/Fe] and depletions (the fraction metals gas, opposed to dust). Using samples gas-phase Milky Way (MW), LMC, SMC, we demonstrate that other does not change significantly these local galaxies DLAs, indicating should...
Abstract We use deep Hubble Space Telescope ( HST ) WFC3/IR imaging to study the initial mass function (IMF) of ultra-faint dwarf galaxy Coma Berenices (Com Ber). Our observations reach lowest stellar ever probed in a resolved galaxy, with 50% completeness at ∼0.17 M ⊙ . Unresolved background galaxies, however, limit our purity below ∼0.23 If modeled single power law, we find that IMF slope is <?CDATA $-{1.45}_{-0.3}^{+0.29}$?> (68% credible intervals), compared Milky Way value −2.3. For...
We present a study of the composition gas and dust in Large Small Magellanic Clouds (LMC SMC, together -- MCs) as measured by UV absorption spectroscopy. have P II Fe along 85 sightlines toward MCs using archival FUSE observations. For 16 those sightlines, we Si II, Cr Zn from new HST COS combined these measurements with H I H$_2$ column densities reference stellar abundances literature to derive gas-phase abundances, depletions, gas-to-dust ratios (GDRs). 80 our 84 13 are depleted more than...
We analyse 2015 mid-infrared (MIR) spectra of galaxies observed with Spitzer's Infrared Spectrograph, including objects growing supermassive black holes (SMBHs) and where most the infrared emission originates from newly formed stars. determine if how accreting SMBHs at centre – known as active galactic nuclei (AGNs) heat ionize their host galaxies' dust molecular gas. use four MIR diagnostics to estimate contribution AGN total emission. refer whose AGNs contribute more than 50 per cent...
ABSTRACT We present the Bayesian Extinction And Stellar Tool (BEAST), a probabilistic approach to modeling dust extinguished photometric spectral energy distribution of an individual star while accounting for observational uncertainties common large resolved surveys. Given set measurements and uncertainty model, BEAST infers physical properties stellar source using evolution atmosphere models constrains line sight extinction newly developed mixture model that encompasses full range curves...
We use hydrodynamical simulations of two Milky Way-mass galaxies to demonstrate the impact cosmic-ray pressure on kinematics cool and warm circumgalactic gas. Consistent with previous studies, we find that can dominate over thermal in inner 50 kpc medium (CGM), creating an overall cooler CGM than similar galaxy run without cosmic rays. generate synthetic sightlines simulated galaxies' Voigt profile fitting methods extract ion column densities, Doppler-b parameters, velocity centroids...
Abstract The Large Magellanic Cloud (LMC) is home to many H ii regions, which may lead significant outflows. We examine the LMC’s multiphase gas ( T ∼10 4-5 K) in i , S Si iv and C using 110 stellar sight lines from Hubble Space Telescope’s Ultraviolet Legacy Library of Young Stars as Essential Standards program. develop a continuum fitting algorithm based on concept Gaussian process regression identify reliable LMC interstellar absorption over v helio = 175–375 km s −1 . Our analyses show...
We present an analysis of \textit{HST}/COS/G160M observations CIV in the inner circumgalactic medium (CGM) a novel sample eight z$\sim$0, L$\approx$L$^{\star}$ galaxies, paired with UV-bright QSOs at impact parameters ($R_\mathrm{proj}$) between 25-130 kpc. The galaxies this stellar-mass-controlled (log$_{10}$M$_{\star}$/M$_{\odot}$ $\sim$ 10.2-10.9 M$_{\odot}$) host super-massive black holes (SMBHs) dynamically-measured masses spanning log$_{10}$M$_\mathrm{BH}$/M$_{\odot}$ 6.8-8.4; allows...
In this work, we derive a spatially resolved map of the line-of-sight velocity interstellar medium and use it, along with second from Paper I series, to determine nature gaseous spiral structure in Milky Way. This is derived measurements 1.527 $\mu$m diffuse band (DIB) stellar spectra APOGEE survey covers nearest 4-5 kpc Northern Galactic plane. We cross-check new DIB-based find that they agree. then compare these maps simulations quasi-stationary density wave dynamic, or material, Way-like...
Photodissociation regions (PDRs) are parts of the ISM consisting predominantly neutral gas, located at interface between H II and molecular clouds. The physical conditions within these show variations on very short spatial scales, therefore PDRs constitute ideal laboratories for investigating properties evolution dust grains. We have mapped IC 63 high resolution from UV to NIR (275 nm 1.6 $\mu$m), using Hubble Space Telescope WFC3. Using a Bayesian SED fitting tool, we simultaneously derive...
For over 60 years, the scientific community has studied actively growing central super-massive black holes (active galactic nuclei -- AGN) but fundamental questions on their genesis remain unanswered. Numerical simulations and theoretical arguments show that hole growth occurs during short-lived periods ($\sim$ 10$^{7}$ -10$^{8}$ yr) of powerful accretion. Major mergers are commonly invoked as most likely dissipative process to trigger rapid fueling AGN. If AGN-merger paradigm is true, we...
Abstract We combine data sets from the CGM 2 and CASBaH surveys to model a transition point, R cross , between circumgalactic intergalactic media (CGM IGM, respectively). In total, our consist of 7244 galaxies at z < 0.5 with precisely measured spectroscopic redshifts, all having impact parameters 0.01–20 comoving Mpc 28 QSO sightlines high-resolution UV spectra that cover H i Ly α . Our best-fitting is two-component combines 3D absorber–galaxy cross-correlation function simple Gaussian...
Abstract Metal Evolution, Transport, and Abundance in the LMC (METAL) is a large Cycle 24 program on Hubble Space Telescope aimed at measuring dust extinction properties interstellar depletions Large Magellanic Cloud (LMC) half-solar metallicity. The 101-orbit composed of Cosmic Origins Spectrograph Imaging spectroscopy toward 33 massive stars between 1150 3180 Å parallel Wide Field Camera 3 imaging seven near-UV to near-IR filters. fraction silicon gas phase (depletion) obtained from...
We present a new method for deriving the stellar birth function (SBF) of resolved populations. The SBF (stars born per unit mass, time, and metallicity) is combination initial mass (IMF), star-formation history (SFH), metallicity distribution (MDF). framework our analysis that Poisson Point Processes (PPPs), class statistical models suitable when dealing with points (stars) in multidimensional space (the measurement multiple photometric bands). theory PPPs easily accommodates modeling errors...
We have developed a method for deriving the distribution of Milky Way's interstellar medium as function longitude, latitude, distance and line-of-sight velocity. This takes input maps reddening line emission applied this to datasets covering much Galactic plane. The output correctly reproduces velocities high-mass star forming regions with known distances from Reid et al. (2014) qualitatively agrees results Way kinematics literature. These will be useful measuring flows gas around spiral...