Search Publications
Design, implementation, and performance of the Astro-H soft x-ray spectrometer aperture assembly and blocking filters
Eckart, Megan E.; Kilbourne, Caroline A.; Leutenegger, Maurice A. +21 more
The calorimeter array of the JAXA Astro-H (renamed Hitomi) soft x-ray spectrometer (SXS) was designed to provide unprecedented spectral resolution of spatially extended cosmic x-ray sources and of all cosmic x-ray sources in the Fe-K band around 6 keV. The properties that made the SXS array a powerful x-ray spectrometer also made it sensitive to p…
The changing source of X-ray reflection in the radio-intermediate Seyfert 1 galaxy III Zw 2
Gallo, L. C.; Gonzalez, A. G.; Waddell, S. G. H.
We report on X-ray observations of the radio-intermediate, X-ray bright Seyfert 1 galaxy, III Zw 2, obtained with XMM-Newton, Suzaku, and Swift over the past 17 yr. The source brightness varies significantly over yearly time-scales, but more modestly over periods of days. Pointed observations with XMM-Newton in 2000 and Suzaku in 2011 show spectra…
Chemical Evolution of N2H+ in Six Massive Star-forming Regions
Wang, Jun-Jie; Xu, Jin-Long; Liu, Xiao-Lan +1 more
To investigate how the abundance of N2H+ varies as massive clumps evolve, here we present a multiwavelength study toward six molecular clouds. All of these clouds contain several massive clumps in different evolutionary stages of star formation. Using archival data of the Herschel infrared Galactic Plane Survey (Hi-GAL), we m…
The optical/UV excess of X-ray-dim isolated neutron star II. Nonuniformity of plasma on a strangeon star surface
Chen, Xuelei; Xu, Ren-Xin; Feng, Yi +4 more
Several X-ray-dim isolated neutron stars (XDINSs), also known as the Magnificent Seven, exhibit a Planck-like soft X-ray spectrum. In the optical/ultraviolet (UV) band, there is an excess of radiation compared to an extrapolation from the X-ray spectrum. However, the majority exhibits “spectral deviations”: the fact that there is more flux at long…
X-ray limits on the progenitor system of the Type Ia supernova 2017ejb
Kilpatrick, Charles D.; Coulter, David A.; Foley, Ryan J. +6 more
We present deep X-ray limits on the presence of a pre-explosion counterpart to the low-luminosity Type Ia supernova (SN Ia) 2017ejb. SN 2017ejb was discovered in NGC 4696, a well-studied elliptical galaxy in the Centaurus cluster with 894 ks of Chandra imaging between 14 and 3 yr before SN 2017ejb was discovered. Using post-explosion photometry an…
86 GHz SiO maser survey of late-type stars in the Inner Galaxy. IV. SiO emission and infrared data for sources in the Scutum and Sagittarius-Carina arms, 20° < l < 50°
Menten, K. M.; Omont, A.; Habing, H. J. +2 more
We present an 86 GHz SiO (v = 1, J = 2 → 1) maser search toward late-type stars located within |b|< 0.°5 and 20° < l < 50°. This search is an extension at longer longitudes of a previously published work. We selected 135 stars from the MSX catalog using color and flux criteria and detected 92 (86 new detections). The detection rate is 6…
The Year-long Flux Variations in Boyajian's Star Are Asymmetric or Aperiodic
Hippke, Michael; Angerhausen, Daniel
We combine and calibrate publicly available data for Boyajian’s star, including photometry from ASAS (SN, V, I), Kepler, Gaia, SuperWASP, and citizen scientist observations (AAVSO, HAO, and Burke-Gaffney). Precise (mmag) photometry covers the years 2006-2017. We show that the year-long flux variations with an amplitude of ≈4% cannot be explained w…
Four-Spacecraft Magnetic Curvature and Vorticity Analyses on Kelvin-Helmholtz Waves in MHD Simulations
Lavraud, Benoit; Kieokaew, Rungployphan; Foullon, Claire
Four-spacecraft missions are probing the Earth's magnetospheric environment with high potential for revealing spatial and temporal scales of a variety of in situ phenomena. The techniques allowed by these four spacecraft include the calculation of vorticity and the magnetic curvature analysis (MCA), both of which have been used in the study of var…
Correcting the extended-source calibration for the Herschel-SPIRE Fourier-transform spectrometer
Valtchanov, I.; Spencer, L. D.; Wu, R. +20 more
We describe an update to the Herschel-Spectral and Photometric Imaging Receiver (SPIRE) Fourier-transform spectrometer (FTS) calibration for extended sources, which incorporates a correction for the frequency-dependent far-field feedhorn efficiency, ηff. This significant correction affects all FTS extended-source calibrated spectra in s…
Evolution of the anti-truncated stellar profiles of S0 galaxies since z = 0.6 in the SHARDS survey. II. Structural and photometric evolution
Barro, Guillermo; Pérez-González, Pablo G.; Borlaff, Alejandro +7 more
Context. Anti-truncated lenticular galaxies (Type-III S0s) present tight scaling relations between their surface brightness photometric and structural parameters. Although several evolutionary models have been proposed for the formation of these structures, the observations of Type-III S0 galaxies are usually limited to the local Universe.
Ai…