Search Publications
Improving the Flux Calibration in Reverberation Mapping by Spectral Fitting:Application to the Seyfert Galaxy MCG-6-30-15
Ho, Luis C.; Du, Pu; Hu, Chen +4 more
We propose a method for the flux calibration of reverberation mapping spectra, based on accurate measurement of [O III] λ5007 emission by spectral fitting. Our method can achieve better accuracy than the traditional method of Groningen & Wanders, allowing reverberation mapping measurements for objects with variability amplitudes as low as ∼5%.…
Hard X-Ray Emissions from Cassiopeia A Observed by INTEGRAL
Wang, Wei; Li, Zhuo
Cassiopeia A (Cas A), as the nearby young remnant of a core-collapse supernova, is the best candidate for astrophysical studies in supernova explosion and its environment. We studied the hard X-ray emission from Cas A using the 10 year data of INTEGRAL observations, and first detected non-thermal continuum emission from the source up to 220 keV. T…
MHD-Kinetic Transition in Imbalanced Alfvénic Turbulence
De Keyser, Johan; Voitenko, Yuriy
Alfvénic turbulence in space is usually imbalanced: amplitudes of waves propagating parallel and anti-parallel to the mean magnetic field {{\boldsymbol{B}}}0 are unequal. It is commonly accepted that the turbulence is driven by (counter-)collisions between these counter-propagating wave fractions. Contrary to this, we found a new ion-sc…
A Search for Short-period Rocky Planets around WDs with the Cosmic Origins Spectrograph (COS)
Debes, John H.; Hines, Dean C.; Bourque, Matthew +2 more
The search for transiting habitable exoplanets has broadened to include several types of stars that are smaller than the Sun in an attempt to increase the observed transit depth and hence the atmospheric signal of the planet. Of all spectral types, white dwarfs (WDs) are the most favorable for this type of investigation. The fraction of WDs that p…
On Understanding the Nature of Collisions of Coronal Mass Ejections Observed by STEREO
Wang, Yuming; Srivastava, Nandita; Mishra, Wageesh
We attempt to understand the collision characteristics of two coronal mass ejections (CMEs) launched successively from the Sun on 2013 October 25. The estimated kinematics, from three-dimensional (3D) reconstruction techniques applied to observations of CMEs by the SECCHI/Coronagraphic (COR) and Heliospheric Imagers, reveal their collision around …
The Evolution of Far-infrared CO Emission from Protostars
Henning, T.; Manoj, P.; Megeath, S. T. +7 more
We investigate the evolution of far-IR CO emission from protostars observed with Herschel/PACS for 50 sources from the combined sample of HOPS and DIGIT Herschel key programs. From the uniformly sampled spectral energy distributions, whose peaks are well sampled, we computed the {L}{bol}, {T}{bol}, and {L}{bol}/{L}…
The Geometry of the Infrared and X-Ray Obscurer in a Dusty Hyperluminous Quasar
Brandt, William N.; Koss, Michael; Ricci, Claudio +24 more
We study the geometry of the active galactic nucleus (AGN) obscurer in IRAS 09104+4109, an IR-luminous, radio-intermediate FR-I source at z = 0.442, using infrared data from Spitzer and Herschel, X-ray data from NuSTAR, Swift, Suzaku, and Chandra, and an optical spectrum from Palomar. The infrared data imply a total rest-frame 1-1000 µm lumi…
Ordinary X-Rays from Three Extraordinary Millisecond Pulsars: XMM-Newton Observations of PSRs J0337+1715, J0636+5129, and J0645+5158
Kaplan, David L.; Stairs, Ingrid; Spiewak, Renée +8 more
We present the first X-ray observations of three recently discovered millisecond pulsars (MSPs) with interesting characteristics: PSR J0337+1715, PSR J0636+5129, and PSR J0645+5158. PSR J0337+1715 is a fast-spinning, bright, and so-far unique MSP in a hierarchical triple system with two white dwarf companions. PSR J0636+5129 is an MSP in a very ti…
The Wide-angle Outflow of the Lensed z = 1.51 AGN HS 0810+2554
Cappi, M.; Chartas, G.; Giustini, M. +4 more
We present results from X-ray observations of the gravitationally lensed z = 1.51 active galactic nucleus (AGN) HS 0810+2554 performed with the Chandra X-ray Observatory and XMM-Newton. Blueshifted absorption lines are detected in both observations at rest-frame energies ranging between ∼1 and 12 keV at ≳99% confidence. The inferred velocities of …
Photometric and Astrometric Vagaries of the Enigma Star KIC 8462852
Makarov, Valeri V.; Goldin, Alexey
We apply a principal component analysis (PCA)-based pre-whitening method to the entire collection of main Kepler mission long-cadence data for KIC 8462852 spanning four years. This technique removes the correlated variations of instrumental origin in both the detected light curves and astrometry, resolving intrinsic changes in flux and image posit…