Search Publications
A Remarkable Long-term Light Curve and Deep, Low-state Spectroscopy: Swift and XMM-Newton Monitoring of the NLS1 Galaxy Mkn 335
Fabian, Andrew C.; Komossa, S.; Gallo, Luigi C. +5 more
The narrow-line Seyfert 1 galaxy (NLS1) Mkn 335 is remarkable because it has repeatedly shown deep, long X-ray low states that show pronounced spectral structure. It has become one of the prototype active galactic nuclei (AGNs) in deep minimum X-ray states. Here we report on the continuation of our ongoing monitoring campaign with Swift and the ex…
Non-diffusive resonant acceleration of electrons in the radiation belts
Artemyev, A. V.; Agapitov, O. V.; Krasnoselskikh, V. V. +2 more
We describe a mechanism of resonant electron acceleration by oblique high-amplitude whistler waves under conditions typical for the Earth radiation belts. We use statistics of spacecraft observations of whistlers in the Earth radiation belts to obtain the dependence of the angle θ between the wave-normal and the background magnetic field on magnet…
Unidentified sources in the Fermi-LAT second source catalog: the case for DM subhalos
Horns, Dieter; Zechlin, Hannes-S.
The Large Area Telescope (LAT) aboard the Fermi satellite allows us to study the high-energy γ-ray sky with unprecedented sensitivity. However, the origin of 31% of the detected γ-ray sources remains unknown. This population of unassociated γ-ray sources may contain new object classes, among them sources of photons from self-annihilating or decayi…
The Assembly History of Disk Galaxies. II. Probing the Emerging Tully-Fisher Relation during 1 < z < 1.7
Treu, Tommaso; Ellis, Richard S.; Newman, Andrew B. +3 more
Through extended integrations using the recently installed deep depletion CCD on the red arm of the Keck I Low Resolution Imaging Spectrograph, we present new measurements of the resolved spectra of 70 morphologically selected star-forming galaxies with i AB < 24.1 in the redshift range 1 <~ z < 1.7. Using the formalism introdu…
IDCS J1426.5+3508: Sunyaev-Zel'dovich Measurement of a Massive Infrared-selected Cluster at z = 1.75
Stern, D.; Carlstrom, J. E.; Leitch, E. M. +14 more
We report 31 GHz CARMA observations of IDCS J1426.5+3508, an infrared-selected galaxy cluster at z = 1.75. A Sunyaev-Zel'dovich (SZ) decrement is detected toward this cluster, indicating a total mass of M 200, m = (4.3 ± 1.1) × 1014 M ⊙ in agreement with the approximate X-ray mass of ~5 × 1014 M ⊙<…
Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-tail Morphology, and Relationship to New Cluster of Bright Sungrazers
Sekanina, Zdenek; Chodas, Paul W.
We describe the physical and orbital properties of C/2011 W3. After surviving perihelion passage, the comet was observed to undergo major physical changes. The permanent loss of the nuclear condensation and the formation of a narrow spine tail were observed first at Malargue, Argentina, on December 20 and then systematically at Siding Spring, Aust…
X-ray observations of the galaxy cluster Abell 2029 to the virial radius
Fabian, A. C.; Sanders, J. S.; Walker, S. A. +2 more
We present Suzaku observations of the galaxy cluster Abell 2029, which exploit Suzaku's low particle background to probe the intracluster medium at radii beyond that which is possible with previous observations, and with better azimuthal coverage. We find significant anisotropies in the temperature and entropy profiles, with a region of lower temp…
The Black Hole Spin and Soft X-Ray Excess of the Luminous Seyfert Galaxy Fairall 9
Fabian, Andrew C.; Brenneman, Laura W.; Reynolds, Christopher S. +4 more
We present an analysis of all XMM-Newton and Suzaku X-ray spectra of the nearby luminous Seyfert galaxy Fairall 9. Confirming previous analyses, we find robust evidence for a broad iron line associated with X-ray reflection from the innermost accretion disk. By fitting a spectral model that includes a relativistically ionized reflection component,…
Initiation of Coronal Mass Ejection and Associated Flare Caused by Helical Kink Instability Observed by SDO/AIA
Cho, K. -S.; Park, Sung-Hong; Kumar, Pankaj +2 more
In this paper, we present multiwavelength observations of helical kink instability as a trigger of a coronal mass ejection (CME) which occurred in active region NOAA 11163 on 2011 February 24. The CME was associated with an M3.5 limb flare. High-resolution observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly suggest the de…
Spatial and temporal variations in Titan's surface temperatures from Cassini CIRS observations
Irwin, P. G. J.; Teanby, N. A.; de Kok, R. +4 more
We report a wide-ranging study of Titan's surface temperatures by analysis of the Moon's outgoing radiance through a spectral window in the thermal infrared at 19 µm (530 cm-1) characterized by lower atmospheric opacity. We begin by modeling Cassini Composite Infrared Spectrometer (CIRS) far infrared spectra collected in the perio…