A5032779962- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Spectroscopy and Laser Applications
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- Black Holes and Theoretical Physics
- Photocathodes and Microchannel Plates
- Atmospheric Ozone and Climate
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Cosmology and Gravitation Theories
- Geometric Analysis and Curvature Flows
- Scientific Research and Discoveries
- Homotopy and Cohomology in Algebraic Topology
- CCD and CMOS Imaging Sensors
- Particle Accelerators and Free-Electron Lasers
- Adaptive optics and wavefront sensing
- Advanced Mathematical Theories and Applications
- Geometry and complex manifolds
Arizona State University
2017-2024
Johns Hopkins University
2011-2017
University of California, Berkeley
2015-2016
University of Massachusetts Amherst
2007-2011
University of Massachusetts Boston
2010
We introduce xCOLD GASS, a legacy survey providing census of molecular gas in the local Universe. Building upon original COLD GASS survey, we present here full sample 532 galaxies with CO(1-0) measurements from IRAM-30m telescope. The is mass-selected redshift interval $0.01<z<0.05$ SDSS, and therefore representative galaxy population M$_{\ast}>10^9$M$_{\odot}$. flux are complemented by observations CO(2-1) line both APEX telescopes, HI Arecibo, photometry WISE GALEX. Combining IRAM data,...
Using ultra-violet absorption-lines, we analyze the systematic properties of warm ionized phase starburst-driven winds in a sample 39 low-redshift objects that spans broad ranges starburst and galaxy properties. Total column densities for outflows are $\sim$10$^{21}$ cm$^{-2}$. The outflow velocity (v$_{out}$) correlates only weakly with stellar mass (M$_*$), or circular (v$_{cir}$), but strongly both SFR SFR/area. normalized (v$_{out}/v_{cir}$) well SFR/area SFR/M$_*$. estimated rates gas...
Abstract The origins of Lyman continuum (LyC) photons responsible for the reionization universe are as yet unknown and highly contested. Detecting LyC from Epoch Reionization is not possible due to absorption by intergalactic medium, which has prompted development several indirect diagnostics infer rate at galaxies contribute reionize studying lower-redshift analogs. We present Low-redshift Continuum Survey (LzLCS) comprising measurements made with Hubble Space Telescope Cosmic Origins...
The Lyman continuum (LyC) cannot be observed at the epoch of reionization (z {\gtrsim} 6) due to intergalactic H I absorption. To identify emitters (LCEs) and infer fraction escaping LyC, astronomers have developed various indirect diagnostics LyC escape. Using measurements from Low-redshift Continuum Survey (LzLCS), we present first statistical test these diagnostics. While optical depth indicators based on Lyα, such as peak velocity separation equivalent width, perform well, also find that...
The source responsible for reionizing the universe at z>6 remains uncertain. While an energetically adequate population of star-forming galaxies may be in place, it is unknown whether a large enough fraction their ionizing radiation can escape into intergalactic medium. Attempts to measure this intensely lower redshifts have largely yielded upper limits. In paper, we present new Hubble Space Telescope Cosmic Origins Spectrograph and archival Far-Ultraviolet Spectroscopic Explorer (FUSE)...
Identifying the population of galaxies that was responsible for reionization universe is a long-standing quest in astronomy. We present possible local analog has an escape fraction ionizing flux 21%. Our detection confirms existence gaps neutral gas enveloping starburst region. The candidate contains massive yet highly compact star-forming are most likely created by unusually strong winds and intense radiation produced this extreme object. study also validates indirect technique using...
A population of early star-forming galaxies is the leading candidate for re-ionization universe. It still unclear, however, what conditions and physical processes would enable a significant fraction ionizing (Lyman continuum) photons to escape from these gas-rich galaxies. In this paper we present results analysis Hubble Space Telescope Cosmic Origins Spectrograph far-UV (FUV) spectroscopy plus ancillary multi-waveband data sample 22 low-redshift that are good analogs typical at high...
We present a study exploring the impact of starburst on properties surrounding circum-galactic medium (CGM): gas located beyond galaxy's stellar body and extending out to virial radius (200 kpc). obtained ultraviolet spectroscopic data from Cosmic Origin Spectrograph (COS) probing CGM 20 low-redshift foreground galaxies using background QSOs. Our sample consists control galaxies. The latter comprises normal star-forming passive with similar masses parameters as starbursts. used optical...
We present a study exploring the nature and properties of Circum-Galactic Medium (CGM) its connection to atomic gas content in interstellar medium (ISM) galaxies as traced by HI 21cm line. Our sample includes 45 low-z (0.026-0.049) from GALEX Arecibo SDSS Survey. Their CGM was probed via absorption spectra background Quasi-Stellar Objects at impact parameters 63 231kpc. The were obtained with Cosmic Origins Spectrograph aboard Hubble Space Telescope. detected neutral hydrogen (Ly$\alpha$...
Interstellar ultraviolet absorption-lines provide crucial information about the properties of galactic outflows. In this paper, we augment our previous analysis systematic starburst-driven outflows by expanding sample to include a rare population starbursts with exceptionally high outflow velocities. principle, these could be qualitatively different phenomenon from more typical However, find that instead lie on, or along extrapolation of, trends defined systems studied previously us. We...
The source responsible for the reionization of Universe is believed to be population star-forming galaxies at $z\sim6$ 12. biggest uncertainty concerns fraction Lyman-continuum photons that actually escape from galaxies. In recent years, several relatively small samples "leaky" have been uncovered, and clues begun emerge as both indirect signposts leakiness conditions/processes enable ionizing radiation. this paper we present results a pilot program aimed test new technique finding leaky...
Abstract Star-forming galaxies are considered the likeliest source of H i ionizing Lyman continuum (LyC) photons that reionized intergalactic medium at high redshifts. However, above z ≳ 6, neutral prevents direct observations LyC. Therefore, recent years have seen development indirect indicators for LyC can be calibrated lower redshifts and applied in epoch reionization. Emission from Mg ii λλ 2796, 2803 doublet has been proposed as a promising proxy. In this paper, we present new Hubble...
Galaxies in compact groups tend to be deficient neutral hydrogen compared isolated galaxies of similar optical properties. In order investigate the role played by a hot intragroup medium (IGM) for removal and destruction HI these systems, we have performed Chandra XMM-Newton study eight most Hickson groups. Diffuse X-ray emission associated with an IGM is detected four groups, suggesting that galaxy-IGM interactions are not dominant mechanism driving cold gas out group members. No clear...
We present new Green Bank Telescope (GBT) 21 cm neutral hydrogen (H i) observations of a complete distance-limited sample 22 Hickson Compact Groups (HCGs) with at least four true members. detected an average H i mass 8 × 109 M☉ (median = 6 M☉), which is significantly larger than previous single-dish measurements. Consequently, the deficiencies for these HCGs have been reduced, although not completely eliminated. Spectral comparison GBT data complementary Very Large Array shows significant...
Abstract We report on observations made with the Cosmic Origins Spectrograph (COS) Hubble Space Telescope ( HST ) using background quasi-stellar objects to probe circum-galactic medium (CGM) around 17 low-redshift galaxies that are undergoing or have recently undergone a strong starburst (the COS-Burst program). The sightlines extend out roughly virial radius of galaxy halo. construct control samples normal star-forming from COS/ archive match starbursts in terms stellar mass and impact...
ABSTRACT We use the combined data from COS-GASS and COS-Halos surveys to characterize Circum-Galactic Medium (CGM) surrounding typical low-redshift galaxies in mass range <?CDATA ${M}_{* }\sim \,{10}^{9.5-11.5}\,{M}_{\odot }$?> , over a of impact parameters extending just beyond halo virial radius ( R vir ). find radial scale length distributions equivalent widths Ly α Si iii absorbers be ∼1 ∼0.4 respectively. The distribution is relatively uniform for blue galaxies, but highly patchy (i.e.,...
Context. The distribution of elements in galaxies forms an important diagnostic tool to characterize the system's formation and evolution. This is however complex use practice, as are subject a range simultaneous physical processes active from pc kpc scales. renders observations full optical extent down sub-kpc scales essential. Aims. Using WiFeS integral field spectrograph, we previously detected abrupt localized variations gas-phase oxygen abundance spiral galaxy HCG91c. Here, follow-up on...
The hypergiant RW Cep is one of the largest stars in our galaxy. evolution and mass loss such has profound effects on their surrounding regions galaxy as a whole. Between 2020 2024, experienced historic mass-loss event known Great Dimming. This study provides spectroscopic analysis during We examine its atmospheric dynamics place it context star's variability behaviour since early 2000s. conducted high-cadence observations dimming using Tartu Observatory 1.5-meter telescope Nordic Optical...
The hypergiant RW,Cep is one of the largest stars in Galaxy. evolution and mass loss such have profound effects on their surrounding regions galaxy as a whole. Between 2020 2024, experienced historic mass-loss event known Great Dimming. This study provides spectroscopic analysis during We examine its atmospheric dynamics place it context star's variability behaviour since early 2000s. conducted high-cadence observations dimming using Tartu Observatory 1.5-meter telescope Nordic Optical...
As part of the Deciphering Interplay between Interstellar medium, Stars, and Circumgalactic medium (DIISC) survey, we present UV metal absorption features in Medium (CGM) near H I gas disk ($<$4.5$R_\mathrm{HI}$) 31 nearby galaxies through quasar line spectroscopy. Of ions under study, Si III $\lambda1206$ was most frequently detected (18 sight lines), while C II $\lambda1334$ $\lambda1260$ were 17 15 lines, respectively. Many components consistent with photoionization equilibrium models,...
Context: Hickson Compact Groups (HCGs) are dense gravitationally-bound collections of 4-10 galaxies ideal for studying gas and star formation quenching processes. Aims: We aim to understand the transition HCGs from possessing complex HI tidal structures (so-called phase 2 groups) a where have lost most or all their (phase 3). also seek detect diffuse H i that was previously missed by Very Large Array (VLA). Methods: observed three 3 with MeerKAT reduced data using Containerized Automated...
Hickson Compact Groups (HCGs) are dense gravitationally bound collections of four to ten galaxies and ideal for studying gas star formation quenching processes. We aim understand the transition HCGs from possessing complex tidal structures (so-called phase 2 groups) a where have lost most or all their (phase 3). also seek detect diffuse that was previously missed by Very Large Array (VLA). observed three 3 with MeerKAT reduced data using Containerized Automated Radio Astronomy Calibration...
Hickson compact groups (HCGs) offer an ideal environment for investigating galaxy transformation as a result of interactions. It has been established that the evolutionary sequence HCGs is marked by intermediate stage characterised substantial amount in their intragroup medium (IGrM) form tidal tails and bridges (phase 2), rapidly followed final which no IGrM gas found i member galaxies are highly deficient 3). Despite numerous single-dish interferometric studies on HCGs, clear picture...
Abstract Feedback is widely recognized as an essential condition for Lyman continuum (LyC) escape in star-forming galaxies. However, the mechanisms by which galactic outflows clear neutral gas and dust remain unclear. In this paper, we model Mg ii 2796 Å, 2804 Å absorption emission lines 29 galaxies taken from Low- z LyC Survey to investigate impact of (radiation mechanical) feedback on escape. Using constraints + photoionization models, map outflows’ hydrogen content predict <mml:math...
Abstract As part of the Deciphering Interplay between Interstellar medium, Stars, and Circumgalactic medium (DIISC) survey, we present UV metal absorption features in circumgalactic (CGM) near H i gas disk (<4.5 R HI ) 31 nearby galaxies through quasar absorption-line spectroscopy. Of ions under study, Si iii λ 1206 was most frequently detected (18 sight lines), while C ii 1334 1260 were 17 15 lines, respectively. Many components consistent with photoionization equilibrium models; cold...