Search Publications
Eridanus II: A Fossil from Reionization with an Off-center Star Cluster
Brown, Thomas M.; Strader, Jay; Geha, Marla +10 more
We present deep Hubble Space Telescope (HST) photometry of the ultra-faint dwarf galaxy Eridanus II (Eri II). Eri II, which has an absolute magnitude of MV = -7.1, is located at a distance of 339 kpc, just beyond the virial radius of the Milky Way. We determine the star formation history of Eri II and measure the structure of the galaxy…
On the Observational Difference between the Accretion Disk-Corona Connections among Super- and Sub-Eddington Accreting Active Galactic Nuclei
Brandt, W. N.; Luo, B.; Gallagher, S. C. +5 more
We present a systematic X-ray and multiwavelength study of a sample of 47 active galactic nuclei (AGNs) with reverberation mapping measurements. This sample includes 21 super-Eddington accreting AGNs and 26 sub-Eddington accreting AGNs. Using high-state observations with simultaneous X-ray and UV/optical measurements, we investigate whether super-…
Does the Magnetic Field Suppress Fragmentation in Massive Dense Cores?
Ching, Tao-Chung; Qiu, Keping; Chen, Huei-Ru Vivien +15 more
Theoretical and numerical works indicate that a strong magnetic field should suppress fragmentation in dense cores. However, this has never been tested observationally in a relatively large sample of fragmenting massive dense cores. Here, we use the polarization data obtained in the Submillimeter Array Legacy Survey of Zhang et al. to build a samp…
X-Ray Superflares from Pre-main-sequence Stars: Flare Energetics and Frequency
Feigelson, Eric D.; Getman, Konstantin V.
Solar-type stars exhibit their highest levels of magnetic activity during their early convective pre-main-sequence (PMS) phase of evolution. The most powerful PMS flares, superflares and megaflares, have peak X-ray luminosities of $\mathrm{log}({L}_{{\rm{X}}})=30.5\mbox{-}34.0$ erg s-1 and total energies $\mathrm{log}({E}_{{\rm{X}}})=34…
Galaxy Evolution in All Five CANDELS Fields and IllustrisTNG: Morphological, Structural, and the Major Merger Evolution to z 3
Conselice, C. J.; Duncan, K.; Whitney, A. +1 more
A fundamental feature of galaxies is their structure, yet we are just now understanding the evolution of structural properties in quantitative ways. As such, we explore the quantitative nonparametric structural evolution of 16,778 galaxies up to z ~ 3 in all five CANDELS fields, the largest collection of high-resolution images of distant galaxies …
Systematic Difference between Ionized and Molecular Gas Velocity Dispersions in z ∼ 1-2 Disks and Local Analogs
Bolatto, A. D.; Fisher, D. B.; Glazebrook, K. +7 more
We compare the molecular and ionized gas velocity dispersions of nine nearby turbulent disks, analogs to high-redshift galaxies, from the DYNAMO sample using new Atacama Large Millimeter/submillimeter Array and GMOS/Gemini observations. We combine our sample with 12 galaxies at z ∼ 0.5-2.5 from the literature. We find that the resolved velocity di…
The Influence of Metallicity on the Leavitt Law from Geometrical Distances of Milky Way and Magellanic Cloud Cepheids
Breuval, Louise; Gieren, Wolfgang; Pietrzyński, Grzegorz +7 more
The Cepheid period-luminosity (PL) relation is the key tool for measuring astronomical distances and for establishing the extragalactic distance scale. In particular, the local value of the Hubble constant (H0) strongly depends on Cepheid distance measurements. The recent Gaia Data Releases and other parallax measurements from the Hubbl…
Spectral Shapes of the Lyα Emission from Galaxies. I. Blueshifted Emission and Intrinsic Invariance with Redshift
Scarlata, Claudia; Gronke, Max; Hayes, Matthew J. +1 more
We demonstrate the redshift evolution of the spectral profile of H I Lyα emission from star-forming galaxies. In this first study we pay special attention to the contribution of blueshifted emission. At redshift z = 2.9-6.6, we compile spectra of a sample of 229 Lyα-selected galaxies identified with the Multi-Unit Spectroscopic Explorer at the Ver…
A Number of nearby Moving Groups May Be Fragments of Dissolving Open Clusters
Faherty, Jacqueline K.; Gagné, Jonathan; Moranta, Leslie +1 more
We propose that 14 co-moving groups of stars uncovered by Kounkel & Covey may be related to known nearby moving groups and bridge those and nearby open clusters with similar ages and space velocities. This indicates that known nearby moving groups may be spatially much more extended than previously thought, and some of them might be parts of t…
Dwarf Galaxies in the MATLAS Survey: Hubble Space Telescope Observations of the Globular Cluster System in the Ultra-diffuse Galaxy MATLAS-2019
Emsellem, Eric; Müller, Oliver; Agnello, Adriano +11 more
Ultra-diffuse galaxies (UDGs) are very-low-surface-brightness galaxies with large effective radii. Spectroscopic measurements of a few UDGs have revealed a low dark-matter content based on the internal motion of stars or globular clusters (GCs). This is in contrast to the large number of GCs found for these systems, from which it would be expected…