Megan Donahue
A5074191093- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- History and Developments in Astronomy
- Radio Astronomy Observations and Technology
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Spectroscopy and Laser Applications
- Dark Matter and Cosmic Phenomena
- Scientific Research and Discoveries
- Distributed and Parallel Computing Systems
- Solar and Space Plasma Dynamics
- Radioactive element chemistry and processing
- Particle Detector Development and Performance
- Computational Physics and Python Applications
- Atmospheric Ozone and Climate
- Phase Equilibria and Thermodynamics
- Radioactive contamination and transfer
Michigan State University
2015-2024
University of Michigan–Ann Arbor
2017-2023
Max Planck Institute for Astronomy
2019
Max Planck Society
2019
Australian Astronomical Observatory
2018
Leiden University
2018
Leiden Observatory
2018
University of Virginia
2011
Center for Astrophysics Harvard & Smithsonian
2011
University of Waterloo
2011
The Sloan Digital Sky Survey (SDSS) is an imaging and spectroscopic survey that will eventually cover approximately one-quarter of the celestial sphere collect spectra ≈106 galaxies, 100,000 quasars, 30,000 stars, serendipity targets. In 2001 June, SDSS released to general astronomical community its early data release, roughly 462 deg2 including almost 14 million detected objects 54,008 follow-up spectra. were collected in drift-scan mode five bandpasses (u, g, r, i, z); our 95% completeness...
We present Advanced Camera for Surveys, NICMOS, and Keck adaptive-optics-assisted photometry of 20 Type Ia supernovae (SNe Ia) from the Hubble Space Telescope (HST) Cluster Supernova Survey. The SNe were discovered over redshift interval 0.623 < z 1.415. Of these Ia, 14 pass our strict selection cuts are used in combination with world's sample to derive best current constraints on dark energy. new 10 beyond = 1, thereby nearly doubling statistical weight HST-discovered this redshift. Our...
This report describes the 2014 study by Science Definition Team (SDT) of Wide-Field Infrared Survey Telescope (WFIRST) mission. It is a space observatory that will address most compelling scientific problems in dark energy, exoplanets and general astrophysics using 2.4-m telescope with wide-field infrared instrument an optical coronagraph. The Astro2010 Decadal recommended Wide Field as its top priority for new large As conceived decadal survey, WFIRST would carry out energy science program,...
The Cluster Lensing And Supernova survey with Hubble (CLASH) is a 524-orbit multi-cycle treasury program to use the gravitational lensing properties of 25 galaxy clusters accurately constrain their mass distributions. survey, described in detail this paper, will definitively establish degree concentration dark matter cluster cores, key prediction CDM. CLASH sample larger and less biased than current samples space-based imaging studies similar depth, as we have minimized lensing-based...
We present a systematic analysis of 43 nearby galaxy groups (kT500 = 0.7–2.7 keV or M500 1013–1014 h−1 M☉, 0.012 <z< 0.12), based on Chandra archival data. With robust background subtraction and modeling, we trace gas properties to at least r2500 for all groups. For 11 groups, can be robustly derived r500. an additional 12 derive r1000 estimate r500 from extrapolation. show that in spite the large variation temperature profiles inside 0.15 r500, these are similar > consistent with "universal...
We present radial entropy profiles of the intracluster medium (ICM) for a collection 239 clusters taken from Chandra X-ray Observatory's Data Archive. Entropy is great interest because it controls ICM global properties and records thermal history cluster. therefore useful quantity studying effects feedback on cluster environment investigating any breakdown self-similarity. find that most are well-fit by model which power-law at large radii approaches constant value small radii: K(r) = K0 +...
We present a candidate for the most distant galaxy known to date with photometric redshift of z = 10.7+0.6−0.4 (95% confidence limits; < 9.5 galaxies types ruled out at 7.2σ). This J-dropout Lyman break galaxy, named MACS0647-JD, was discovered as part Cluster Lensing and Supernova survey Hubble (CLASH). observe three magnified images this due strong gravitational lensing by cluster MACSJ0647.7+7015 0.591. The are factors ∼80, 7, 2, brighter two observed ∼26th magnitude AB (∼0.15 μJy) in...
We present a joint shear-and-magnification weak-lensing analysis of sample 16 X-ray-regular and 4 high-magnification galaxy clusters at 0.19 ≲ z 0.69 selected from the Cluster Lensing And Supernova survey with Hubble (CLASH). Our uses wide-field multi-color imaging, taken primarily Suprime-Cam on Subaru Telescope. From stacked-shear-only X-ray-selected subsample, we detect ensemble-averaged lensing signal total signal-to-noise ratio ≃ 25 in radial range 200–3500 kpc h−1, providing integrated...
Growing observational evidence now indicates that nebular line emission has a significant impact on the rest-frame optical fluxes of z~5-7 galaxies observed with Spitzer. This makes appear more massive, lower specific star formation rates. However, corrections for this have been very difficult to perform reliably due huge uncertainties overall strength such at z>~5.5. Here, we present most direct yet ubiquitous high-EW [OIII]+Hbeta in Lyman-break z~7, while also presenting strategy an...
The universe's biggest galaxies have both vast atmospheres and supermassive central black holes. This article reviews how those two components of a large galaxy couple regulate the galaxy's star formation rate. Models interactions between hole large-scale atmosphere suggest that energy released as cold gas clouds accrete onto suspends in state is marginally stable to clouds. A growing body observational evidence indicates many massive galaxies, ranging from huge clusters down our own Milky...
Abstract We present JWST/NIRSpec prism spectroscopy of MACS0647−JD, a triply lensed z ∼ 11 candidate discovered in Hubble Space Telescope imaging and spatially resolved by JWST into two components, A B. Spectroscopy component yields spectroscopic redshift = 10.17 based on seven detected emission lines: C iii ] λ 1907, 1909, [O ii 3727, [Ne 3869, 3968, H δ 4101, γ 4340, 4363. These are the second-most distant detections these lines to date, galaxy observed just 460 million years after Big...
Context.The largest uncertainty for cosmological studies using clusters of galaxies is introduced by our limited knowledge the statistics galaxy cluster structure, and scaling relations between observables mass.
Our Chandra X-Ray Observatory archival study of intracluster entropy in a sample 222 galaxy clusters shows that Hα and radio emission from the brightest cluster are much more pronounced when cluster's core gas is ≲30 keV cm2. The prevalence below this threshold indicates it marks dichotomy between can harbor multiphase star formation their cores those cannot. fact strong central also appears boundary suggests AGN feedback turns on medium starts to condense, strengthening case for as...
Quillen et al. presented an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies optical line emission located in cores X-ray-luminous clusters. They found that at least half these sources have signs excess IR emission. Here we discuss nature and its implications for cool core The strength mid-IR correlates luminosity lines. Excluding four systems dominated by AGN, remaining is likely related to star formation. mass molecular gas (estimated from CO observations)...
A Chandra image of the central 100 kpc Abell 2597 cluster galaxies shows bright irregular X-ray emission within dominant galaxy (CDG) and two low surface brightness cavities located 30 from nucleus CDG. Unlike commonly seen in other clusters, "ghost" are not coincident with radio source. Instead, they appear to be associated faint extended a deep Very Large Array map. We interpret ghost as buoyantly rising relics outburst that occurred between 50 Myr ago. The demography few clusters studied...
We present a study of the structural and scaling properties gas distributions in intracluster medium (ICM) 31 nearby () clusters observed with XMM-Newton, which together comprise Representative XMM-Newton Cluster Structure Survey (REXCESS). In contrast to previous studies, this sample is unbiased respect X-ray surface brightness cluster dynamical state, it fully samples luminosity function. The cover temperature range 2.0-8.5 keV possess variety morphologies. sampling strategy allows us...
We present the discovery of a 40 kpc Hα tail and at least 29 emission-line objects downstream star-forming galaxy, ESO 137-001, in rich, nearby cluster A3627. The galaxy is known to possess dramatic 70 X-ray tail. detected coincides positionally with emission sharply truncated on front sides near nucleus, indicating significant ram pressure stripping. 137-001 thus first late-type unambiguously have both an are all distributed projected distances up 39 from galaxy. From analysis Hαoff frame...
We present results from new Chandra, GMRT, and SOAR observations of NGC 5813, the dominant central galaxy in a nearby group. The system shows three pairs collinear cavities at 1 kpc, 8 20 kpc source, distinct outbursts AGN, which occurred 3x10^6, 2x10^7, 9x10^7 yr ago. H-alpha X-ray reveal filaments cool gas that has been uplifted by cavities. inner two cavity are filled with radio emitting plasma, each pair is associated an elliptical surface brightness edge, we unambiguously identify as...
We utilise a two-color Lyman-Break selection criterion to search for z~9-10 galaxies over the first 19 clusters in CLASH program. A systematic yields three candidates. While we have already reported most robust of these candidates, MACS1149-JD, two additional z~9 candidates are also found and H_{160}-band magnitudes ~26.2-26.9. careful assessment various sources contamination suggests <~1 contaminants our selection. To determine implications results LF SFR density at z~9, introduce new...
We present a new determination of the concentration–mass (c–M) relation for galaxy clusters based on our comprehensive lensing analysis 19 X-ray selected from Cluster Lensing and Supernova Survey with Hubble (CLASH). Our sample spans redshift range between 0.19 0.89. combine weak-lensing constraints Space Telescope (HST) ground-based wide-field data strong HST. The results are reconstructions surface-mass density all CLASH multi-scale grids. derivation Navarro–Frenk–White parameters yields...
We present a systematic investigation of X-ray thermal coronae in 157 early-type galaxies and 22 late-type from survey 25 hot (kT>3 keV), nearby (z<0.05) clusters, based on CHANDRA archival data. Cool galactic (kT=0.5-1.1 keV generally) have been found to be very common, >60% NIR selected that are more luminous than 2L*, >40% L* < L_Ks 2L* galaxies. These embedded clusters generally smaller (1.5-4 kpc radii), less (100, which implies the gas is magnetized magnetic field plays...