Search Publications
NuSTAR Observations of Heavily Obscured Quasars at z ~ 0.5
Harrison, F. A.; Stern, D.; Zhang, W. W. +23 more
We present NuSTAR hard X-ray observations of three Type 2 quasars at z ≈ 0.4-0.5, optically selected from the Sloan Digital Sky Survey. Although the quasars show evidence for being heavily obscured, Compton-thick systems on the basis of the 2-10 keV to [O III] luminosity ratio and multiwavelength diagnostics, their X-ray absorbing column densities…
Solar Transition Region Lines Observed by the Interface Region Imaging Spectrograph: Diagnostics for the O IV and Si IV Lines
Mason, H. E.; Golub, L.; Del Zanna, G. +2 more
The formation of the transition region O IV and Si IV lines observable by the Interface Region Imaging Spectrograph (IRIS) is investigated for both Maxwellian and non-Maxwellian conditions characterized by a κ-distribution exhibiting a high-energy tail. The Si IV lines are formed at lower temperatures than the O IV lines for all κ. In non-Maxwelli…
A Hard X-Ray Power-law Spectral Cutoff in Centaurus X-4
Hailey, Charles J.; Chakrabarty, Deepto; Kaspi, Victoria M. +17 more
The low-mass X-ray binary (LMXB) Cen X-4 is the brightest and closest (<1.2 kpc) quiescent neutron star transient. Previous 0.5-10 keV X-ray observations of Cen X-4 in quiescence identified two spectral components: soft thermal emission from the neutron star atmosphere and a hard power-law tail of unknown origin. We report here on a simultaneou…
Is Solar Cycle 24 Producing More Coronal Mass Ejections Than Cycle 23?
Wang, Y. -M.; Colaninno, R.
Although sunspot numbers are roughly a factor of two lower in the current cycle than in cycle 23, the rate of coronal mass ejections (CMEs) appears to be at least as high in 2011-2013 as during the corresponding phase of the previous cycle, according to three catalogs that list events observed with the Large Angle and Spectrometric Coronagraph (LA…
Recoiling Supermassive Black Holes: A Search in the Nearby Universe
Marconi, A.; Capetti, A.; Batcheldor, D. +4 more
The coalescence of a binary black hole can be accompanied by a large gravitational recoil due to anisotropic emission of gravitational waves. A recoiling supermassive black hole (SBH) can subsequently undergo long-lived oscillations in the potential well of its host galaxy, suggesting that offset SBHs may be common in the cores of massive elliptic…
H I, CO, and Planck/IRAS Dust Properties in the High Latitude Cloud Complex, MBM 53, 54, 55 and HLCG 92 - 35. Possible Evidence for an Optically Thick H I Envelope around the CO Clouds
Tachihara, Kengo; Fukui, Yasuo; Dickey, John M. +9 more
We present an analysis of the H I and CO gas in conjunction with the Planck/IRAS submillimeter/far-infrared dust properties toward the most outstanding high latitude clouds MBM 53, 54, 55 and HLCG 92 - 35 at b = -30° to - 45°. The CO emission, dust opacity at 353 GHz (τ353), and dust temperature (T d) show generally good spat…
The Panchromatic Hubble Andromeda Treasury. V. Ages and Masses of the Year 1 Stellar Clusters
Bell, Eric F.; Gouliermis, Dimitrios A.; Skillman, Evan D. +12 more
We present ages and masses for 601 star clusters in M31 from the analysis of the six filter integrated light measurements from near-ultraviolet to near-infrared wavelengths, made as part of the Panchromatic Hubble Andromeda Treasury (PHAT). We derive the ages and masses using a probabilistic technique, which accounts for the effects of stochastic …
The Emergent 1.1-1.7 µm Spectrum of the Exoplanet CoRoT-2b as Measured Using the Hubble Space Telescope
Wilkins, Ashlee N.; Deming, Drake; Madhusudhan, Nikku +4 more
We have used Hubble/WFC3 and the G141 grism to measure the secondary eclipse of the transiting, very hot Jupiter CoRoT-2b in the 1.1-1.7 µm spectral region. We find an eclipse depth averaged over this band equal to 395^{+69}_{-45} parts per million, equivalent to a blackbody temperature of 1788 ± 18 K. We study and characterize several WFC3 …
The Optical, Ultraviolet, and X-Ray Structure of the Quasar HE 0435-1223
Chen, Bin; Kochanek, Christopher S.; Dai, Xinyu +2 more
Microlensing has proved an effective probe of the structure of the innermost regions of quasars and an important test of accretion disk models. We present light curves of the lensed quasar HE 0435-1223 in the R band and in the ultraviolet (UV), and consider them together with X-ray light curves in two energy bands that are presented in a companion…
Clouds on the Hot Jupiter HD189733b: Constraints from the Reflection Spectrum
Aigrain, S.; Fletcher, L. N.; Irwin, P. G. J. +4 more
The hot Jupiter HD 189733b is probably the best studied of the known extrasolar planets, with published transit and eclipse spectra covering the near UV to mid-IR range. Recent work on the transmission spectrum has shown clear evidence for the presence of clouds in its atmosphere, which significantly increases the model atmosphere parameter space …