Search Publications
Extended Structure and Fate of the Nucleus in Henize 2-10
Seth, Anil C.; Nguyen, Dieu D.; den Brok, Mark +3 more
We investigate the structure and nuclear region of the black hole (BH) hosting galaxy Henize 2-10. Surface brightness profiles are analyzed using Magellan/Megacam g- and r-band images. Excluding the central starburst, we find a best-fit two-component Sérsic profile with n in ~ 0.6, r eff, in ~ 260 pc and n out ~ 1.…
Plasma Dynamics Above Solar Flare Soft X-Ray Loop Tops
Doschek, G. A.; Warren, H. P.; McKenzie, D. E.
We measure non-thermal motions in flare loop tops and above the loop tops using profiles of highly ionized spectral lines of Fe XXIV and Fe XXIII formed at multimillion-degree temperatures. Non-thermal motions that may be due to turbulence or multiple flow regions along the line of sight are extracted from the line profiles. The non-thermal motion…
RBS 1032: A Tidal Disruption Event in Another Dwarf Galaxy?
Maksym, W. Peter; Lin, Dacheng; Irwin, Jimmy A.
RBS 1032 is a supersoft (Γ ~ 5), luminous (~1043 erg s-1) ROSAT PSPC source which has been associated with an inactive dwarf galaxy at z = 0.026, SDSS J114726.69+494257.8. We have analyzed an XMM-Newton observation that confirms that RBS 1032 is indeed associated with the dwarf galaxy. Moreover, RBS 1032 has undergone a facto…
CO/H2 Abundance Ratio ≈ 10-4 in a Protoplanetary Disk
Herczeg, Gregory J.; France, Kevin; Penton, Steven V. +1 more
The relative abundances of atomic and molecular species in planet-forming disks around young stars provide important constraints on photochemical disk models and provide a baseline for calculating disk masses from measurements of trace species. A knowledge of absolute abundances, those relative to molecular hydrogen (H2), are challengin…
On the Detection of Molecules in the Atmosphere of HD 189733b Using HST NICMOS Transmission Spectroscopy
Line, Michael R.; Swain, Mark R.; Deroo, Pieter
The Hubble Space Telescope/NICMOS transmission spectrum measurements of HD 189733b that suggest the detection of methane (CH4) in an exoplanet atmosphere have been a source of significant controversy. With what is probably the best analyzed exoplanet spectroscopy data set to date, different teams, using different methods, have claimed e…
The X-Ray Luminosity Functions of Field Low-mass X-Ray Binaries in Early-type Galaxies: Evidence for a Stellar Age Dependence
Lehmer, B. D.; Hornschemeier, A. E.; Yukita, M. +11 more
We present direct constraints on how the formation of low-mass X-ray binary (LMXB) populations in galactic fields depends on stellar age. In this pilot study, we utilize Chandra and Hubble Space Telescope (HST) data to detect and characterize the X-ray point source populations of three nearby early-type galaxies: NGC 3115, 3379, and 3384. The lumi…
A Tale of Two Feedbacks: Star Formation in the Host Galaxies of Radio AGNs
Kim, Seong Jin; Ohyama, Youichi; Pearson, Chris +19 more
Several lines of argument support the existence of a link between activity at the nuclei of galaxies, in the form of an accreting supermassive black hole, and star formation activity in these galaxies. Radio jets have long been argued to be an ideal mechanism that allows active galactic nuclei (AGNs) to interact with their host galaxies and affect…
Tracing the Outer Halo in a Giant Elliptical to 25 R eff
Rejkuba, M.; Greggio, L.; Jerjen, H. +3 more
We have used the Advanced Camera for Surveys and Wide Field Camera 3 cameras on board the Hubble Space Telescope to resolve stars in the halo of the nearest giant elliptical (gE) galaxy NGC 5128 out to a projected distance of 140 kpc (25 effective radii, R eff) along the major axis and 90 kpc (16 R eff) along the minor axis. …
Expectations for the Hard X-Ray Continuum and Gamma-Ray Line Fluxes from the Type Ia Supernova SN 2014J in M82
Burrows, Adam; The, Lih-Sin
The hard X-ray continuum and gamma-ray lines from a Type Ia supernova dominate its integrated photon emissions and can provide unique diagnostics of the mass of the ejecta, the 56Ni yield and spatial distribution, its kinetic energy and expansion speed, and the mechanism of explosion. Such signatures and their time behavior "X-ray" the …
HZ Her: Stellar Radius from X-Ray Eclipse Observations, Evolutionary State, and a New Distance
Leahy, D. A.; Abdallah, M. H.
Observations of HZ Her/Her X-1 by the Rossi X-Ray Timing Explorer (RXTE) covering high state eclipses of the neutron star are analyzed here. Models of the eclipse are used to measure the radius and atmospheric scale height of HZ Her, the stellar companion to the neutron star. The radius is 2.58-3.01 × 1011 cm, depending on system inclin…