Search Publications
Lyman Continuum Galaxy Candidates in COSMOS
Hathi, Nimish; Rafelski, Marc; Wang, Xin +11 more
Star-forming galaxies are the sources likely to have reionized the universe. As we cannot observe them directly due to the opacity of the intergalactic medium at z ≳ 5, we study z ~ 3-5 galaxies as proxies to place observational constraints on cosmic reionization. Using new deep Hubble Space Telescope rest-frame UV F336W and F435W imaging (30 orbi…
A Strong Shock During a Nova Outburst: An Origin of Multiple Velocity Systems in Optical Spectra and of High-energy Emissions
Kato, Mariko; Hachisu, Izumi
We propose a theoretical explanation of absorption/emission line systems in classical novae based on a fully self-consistent nova explosion model. We found that a reverse shock is formed far outside the photosphere (≳1013 cm) because later-ejected mass with a faster velocity collides with earlier-ejected matter. Optically thick winds bl…
Discovery, Timing, and Multiwavelength Observations of the Black Widow Millisecond Pulsar PSR J1555-2908
Ransom, Scott M.; Michelson, P. F.; Halpern, Jules P. +21 more
We report the discovery of PSR J1555-2908, a 1.79 ms radio and gamma-ray pulsar in a 5.6 hr binary system with a minimum companion mass of 0.052 M ⊙. This fast and energetic ( $\dot{E}=3\times {10}^{35}$ erg s-1) millisecond pulsar was first detected as a gamma-ray point source in Fermi Large Area Telescope (LAT) sky survey o…
Age Spreads and Systematics in λ Orionis with Gaia DR2 and the SPOTS Tracks
Pinsonneault, Marc H.; Hillenbrand, Lynne A.; Cao, Lyra +1 more
In this paper we investigate the robustness of age measurements, age spreads, and stellar models in young pre-main-sequence stars. For this effort, we study a young cluster, λ Orionis, within the Orion star-forming complex. We use Gaia data to derive a sample of 357 targets with spectroscopic temperatures from spectral types or from the automated …
A "Hyperburst" in the MAXI J0556-332 Neutron Star: Evidence for a New Type of Thermonuclear Explosion
Homan, Jeroen; Wijnands, Rudy; Degenaar, Nathalie +5 more
The study of transiently accreting neutron stars provides a powerful means to elucidate the properties of neutron star crusts. We present extensive numerical simulations of the evolution of the neutron star in the transient low-mass X-ray binary MAXI J0556-332. We model nearly 20 observations obtained during the quiescence phases after four differ…
NuSTAR Observations of Intrinsically X-Ray Weak Quasar Candidates: An Obscuration-only Scenario
Stern, D.; Alexander, D. M.; Bauer, F. E. +6 more
We utilize recent NuSTAR observations (co-added depth ≈55-120 ks) of PG 1001+054, PG 1254+047, and PHL 1811 to constrain their hard X-ray (≳5 keV) weakness and spectral shapes and thus to investigate the nature of their extreme X-ray weakness. These quasars showed very weak soft X-ray emission, and they were proposed to be intrinsically X-ray weak…
Extreme Variation in Star Formation Efficiency across a Compact, Starburst Disk Galaxy
Bolatto, A. D.; Fisher, D. B.; Glazebrook, K. +4 more
We report on the internal distribution of star formation efficiency in IRAS 08339+6517 (hereafter IRAS08), using ~200 pc resolution CO(2 - 1) observations from NOEMA. The molecular gas depletion time changes by 2 orders-of-magnitude from disk-like values in the outer parts to less than 108 yr inside the half-light radius. This translate…
The Stellar-age Dependence of X-Ray Emission from Normal Star-forming Galaxies in the GOODS Fields
Williams, Benjamin F.; Brandt, William N.; Luo, Bin +11 more
The Chandra Deep Field-South and North surveys (CDFs) provide unique windows into the cosmic history of X-ray emission from normal (nonactive) galaxies. Scaling relations of normal-galaxy X-ray luminosity (L X) with star formation rate (SFR) and stellar mass (M ⋆) have been used to show that the formation rates of low-mass an…
Embedded Young Massive Star Clusters in the Antennae Merger
Johnson, Kelsey; He, Hao; Wilson, Christine +3 more
The properties of young massive clusters (YMCs) are key to understanding the star formation mechanism in starburst systems, especially mergers. We present Atacama Large Millimeter/submillimeter Array high-resolution (~10 pc) continuum (100 and 345 GHz) data of YMCs in the overlap region of the Antennae galaxy. We identify six sources in the overla…
Dynamical Masses of the Primary Be Star and Secondary sdB Star in the Single-lined Binary κ Dra (B6 IIIe)
Gies, Douglas R.; Wang, Luqian; Klement, Robert +16 more
Because many classical Be stars may owe their nature to mass and angular-momentum transfer in a close binary, the present masses, temperatures, and radii of their components are of high interest for comparison to stellar evolution models. Object κ Dra is a 61.5 day single-lined binary with a B6 IIIe primary. With the CHARA Array instruments MIRC/M…