Search Publications
Low Gas Fractions Connect Compact Star-forming Galaxies to Their z ~ 2 Quiescent Descendants
Weiner, Benjamin J.; Bezanson, Rachel; Williams, Christina C. +3 more
Early quiescent galaxies at z∼ 2 are known to be remarkably compact compared to their nearby counterparts. Possible progenitors of these systems include galaxies that are structurally similar, but are still rapidly forming stars. Here, we present Karl G. Jansky Very Large Array (VLA) observations of the CO(1-0) line toward three such compact, star…
Absorption-line Spectroscopy of Gravitationally Lensed Galaxies: Further Constraints on the Escape Fraction of Ionizing Photons at High Redshift
Stark, Daniel P.; Ellis, Richard S.; Zitrin, Adi +2 more
The fraction of ionizing photons escaping from high-redshift star-forming galaxies is a key obstacle in evaluating whether galaxies were the primary agents of cosmic reionization. We previously proposed using the covering fraction of low-ionization gas, measured via deep absorption-line spectroscopy, as a proxy. We now present a significant update…
High Spatial Resolution Fe XII Observations of Solar Active Regions
Testa, Paola; De Pontieu, Bart; Hansteen, Viggo
We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal Fe xii 1349.4 Å emission at unprecedented high spatial resolution (∼0.33″). We find that by using appropriate observational strategies (I.e., long exposures, lossless compression), Fe xii emission can…
O VI Emission Imaging of a Galaxy with the Hubble Space Telescope: a Warm Gas Halo Surrounding the Intense Starburst SDSS J115630.63+500822.1
Scarlata, Claudia; Hayes, Matthew; Östlin, Göran +3 more
We report results from a new Hubble Space Telescope campaign that targets the O VI λ λ 1032,1038 Å doublet in emission around intensely star-forming galaxies. The program aims to characterize the energy balance in starburst galaxies and gas cooling in the difficult-to-map coronal temperature regime of 2{--}5× {10}5 K. We present the fir…
He II λ4686 Emission from the Massive Binary System in η Car: Constraints to the Orbital Elements and the Nature of the Periodic Minima
Gull, T. R.; Corcoran, M. F.; Madura, T. I. +27 more
Eta Carinae (η Car) is an extremely massive binary system in which rapid spectrum variations occur near periastron. Most notably, near periastron the He II λ4686 line increases rapidly in strength, drops to a minimum value, then increases briefly before fading away. To understand this behavior, we conducted an intense spectroscopic monitoring of t…
The Solar Internetwork. II. Flux Appearance and Disappearance Rates
Gošić, M.; Bellot Rubio, L. R.; Katsukawa, Y. +2 more
Small-scale internetwork magnetic fields are important ingredients of the quiet Sun. In this paper we analyze how they appear and disappear on the solar surface. Using high resolution Hinode magnetograms, we follow the evolution of individual magnetic elements in the interior of two supergranular cells at the disk center. From up to 38 hr of conti…
Radial Profile of the 3.5 keV Line Out to R200 in the Perseus Cluster
Boyarsky, Alexey; Ruchayskiy, Oleg; Bulbul, Esra +10 more
The recent discovery of the unidentified emission line at 3.5 keV in galaxies and clusters has attracted great interest from the community. As the origin of the line remains uncertain, we study the surface brightness distribution of the line in the Perseus cluster since that information can be used to identify its origin. We examine the flux distr…
Toward a Tomographic Analysis of the Cross-Correlation between Planck CMB Lensing and H-ATLAS Galaxies
Baccigalupi, C.; Bielewicz, P.; Danese, L. +10 more
We present an improved and extended analysis of the cross-correlation between the map of the cosmic microwave background (CMB) lensing potential derived from the Planck mission data and the high-redshift galaxies detected by the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) in the photometric redshift range {z}{{ph}}≥slan…
An HST Survey of the Highest-velocity Ejecta in Cassiopeia A
Milisavljevic, Dan; Fesen, Robert A.
We present Hubble Space Telescope WFC3/IR images of the Cassiopeia A supernova remnant that survey its high-velocity, S-rich debris in the NE jet and SW counterjet regions through [S III] λλ9069, 9531 and [S II] λλ10,287-10,370 line emissions. We identify nearly 3400 sulfur emitting knots concentrated in ∼120° wide opposing streams, almost triple …
Constraining Globular Cluster Age Uncertainties using the IR Color-Magnitude Diagram
Brown, Thomas M.; Gennaro, Mario; Calamida, Annalisa +2 more
Globular Clusters (GCs) in the Milky Way are the primary laboratories for establishing the ages of the oldest stellar populations and for measuring the color-magnitude relation of stars. In infrared (IR) color-magnitude diagrams (CMDs), the stellar main sequence (MS) exhibits a “kink” due to opacity effects in M dwarfs such that lower mass and coo…