Search Publications
Hard X-Ray Morphological and Spectral Studies of the Galactic Center Molecular Cloud Sgr B2: Constraining Past Sgr A* Flaring Activity
Hailey, Charles J.; Mori, Kaya; Bauer, Franz E. +15 more
In 2013, NuSTAR observed the Sgr B2 region and for the first time resolved its hard X-ray emission on subarcminute scales. Two prominent features are detected above 10 keV: a newly emerging cloud, G0.66-0.13, and the central 90″ radius region containing two compact cores, Sgr B2(M) and Sgr B2(N), surrounded by diffuse emission. It is inconclusive …
Evidence of Cross-correlation between the CMB Lensing and the γ-Ray Sky
Fornengo, Nicolao; Perotto, Laurence; Regis, Marco +1 more
We report the measurement of the angular power spectrum of cross-correlation between the unresolved component of the Fermi-LAT γ-ray sky maps and the cosmic microwave background lensing potential map reconstructed by the Planck satellite. The matter distribution in the universe determines the bending of light coming from the last scattering surfac…
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…