Search Publications
The Black Hole in the Compact, High-dispersion Galaxy NGC 1271
Gebhardt, Karl; Richstone, Douglas O.; Husemann, Bernd +4 more
Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2 kpc and a large bulge stellar velocity dispersion of 276 km s-1 for its K-band luminosity of 8.9× {10}10 {L}⊙ . We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observa…
A Connection between Obscuration and Star Formation in Luminous Quasars
Gorjian, Varoujan; Alberts, Stacey; Jones, Christine +16 more
We present a measurement of the star formation properties of a uniform sample of mid-IR-selected, optically unobscured, and obscured quasars (QSO1s and QSO2s) in the Boötes survey region. We use a spectral energy distribution analysis for photometric data spanning optical to far-IR wavelengths to separate the active galactic nucleus (AGN) and host…
The Composition of Interstellar Grains toward ζ Ophiuchi: Constraining the Elemental Budget near the Diffuse-dense Cloud Transition
Draine, Bruce T.; Poteet, Charles A.; Whittet, Douglas C. B.
We investigate the composition of interstellar grains along the line of sight toward ζ Ophiuchi, a well-studied environment near the diffuse-dense cloud transition. A spectral decomposition analysis of the solid-state absorbers is performed using archival spectroscopic observations from the Spitzer Space Telescope and Infrared Space Observatory. W…
Fermi-LAT Observations of High- and Intermediate-velocity Clouds: Tracing Cosmic Rays in the Halo of the Milky Way
Marshall, D. J.; Orlando, E.; Strong, A. W. +10 more
It is widely accepted that cosmic rays (CRs) up to at least PeV energies are Galactic in origin. Accelerated particles are injected into the interstellar medium where they propagate to the farthest reaches of the Milky Way, including a surrounding halo. The composition of CRs coming to the solar system can be measured directly and has been used to…
On the Morphology and Chemical Composition of the HR 4796A Debris Disk
Stark, Christopher C.; Debes, John H.; Schneider, Glenn +17 more
We present resolved images of the HR 4796A debris disk using the Magellan adaptive optics system paired with Clio-2 and VisAO. We detect the disk at 0.77 µm, 0.91 µm, 0.99 µm, 2.15 µm, 3.1 µm, 3.3 µm, and 3.8 µm. We find that the deprojected center of the ring is offset from the star by 4.76 ± 1.6 AU and t…
Lord of the Rings: A Kinematic Distance to Circinus X-1 from a Giant X-Ray Light Echo
Brandt, W. N.; Nowak, M. A.; Fender, R. P. +6 more
Circinus X-1 exhibited a bright X-ray flare in late 2013. Follow-up observations with Chandra and XMM-Newton from 40 to 80 days after the flare reveal a bright X-ray light echo in the form of four well-defined rings with radii from 5 to 13 arcmin, growing in radius with time. The large fluence of the flare and the large column density of interstel…
Frontier Fields Clusters: Chandra and JVLA View of the Pre-merging Cluster MACS J0416.1-2403
Churazov, E.; Zitrin, A.; Rosati, P. +26 more
Merging galaxy clusters leave long-lasting signatures on the baryonic and non-baryonic cluster constituents, including shock fronts, cold fronts, X-ray substructure, radio halos, and offsets between the dark matter (DM) and the gas components. Using observations from Chandra, the Jansky Very Large Array, the Giant Metrewave Radio Telescope, and th…
A Steady-state Picture of Solar Wind Acceleration and Charge State Composition Derived from a Global Wave-driven MHD Model
Gombosi, T. I.; Lepri, S. T.; Landi, E. +7 more
The higher charge states found in slow (<400 km s-1) solar wind streams compared to fast streams have supported the hypothesis that the slow wind originates in closed coronal loops and is released intermittently through reconnection. Here we examine whether a highly ionized slow wind can also form along steady and open magnetic field…
On Estimating the High-energy Cutoff in the X-Ray Spectra of Black Holes via Reflection Spectroscopy
Steiner, James F.; McClintock, Jeffrey E.; Wilms, Jörn +3 more
The fundamental parameters describing the coronal spectrum of an accreting black hole are the slope Γ of the power-law continuum and the energy Ecut at which it rolls over. Remarkably, this latter parameter can be accurately measured for values as high as 1 MeV by modeling the spectrum of X-rays reflected from a black hole accretion dis…
A Hard X-Ray Study of the Ultraluminous X-Ray Source NGC 5204 X-1 with NuSTAR and XMM-Newton
Harrison, F. A.; Stern, D.; Fabian, A. C. +16 more
We present the results from coordinated X-ray observations of the ultraluminous X-ray source NGC 5204 X-1 performed by the Nuclear Spectroscopic Telescope Array and XMM-Newton in early 2013. These observations provide the first detection of NGC 5204 X-1 above 10 {keV}, extending the broadband coverage to 0.3-20 {keV}. The observations were carried…