Search Publications
Measurements of the Soft Gamma-Ray Emission from SN2014J with Suzaku
Fukazawa, Y.; Takahashi, T.; Diehl, R. +9 more
The hard X-ray detector (HXD) on board Suzaku measured soft γ-rays from the SN Ia SN2014J at 77 ± 2 days after the explosion. Although the confidence level of the signal is about 90% (I.e., 2σ), the 3σ upper limit has been derived at <2.2 × 10-4 ph s-1 cm-2 in the 170-250 keV band as the first independent measur…
X-Ray Spectral and Temporal Analysis of Narrow Line Seyfert 1 Galaxy Was 61
Yuan, Weimin; Zhou, Hongyan; Wang, Ting-Gui +3 more
We present an analysis of spectrum and variability of the bright reddened narrow line Seyfert 1 galaxy Was 61 using 90 ks archival XMM-Newton data. The X-ray spectrum in 0.2-10 keV can be characterized by an absorbed power-law plus soft excess and an Fe Kα emission line. The power-law spectral index remains constant during the flux variation. The …
Transient X-Ray Source Population in the Magellanic-type Galaxy NGC 55
Jithesh, V.; Wang, Zhongxiang
We present the spectral and temporal properties of 15 candidate transient X-ray sources detected in archival XMM-Newton and Chandra observations of the nearby Magellanic-type, SB(s)m galaxy NGC 55. Based on an X-ray color classification scheme, the majority of the sources may be identified as X-ray binaries (XRBs), and six sources are soft, includ…
Photoionization Modeling of the Low-luminosity Seyfert 1 Nucleus in NGC 3516
Devereux, Nick
Spectroscopic observations of the low-luminosity Seyfert 1 nucleus in NGC 3516 obtained with the Hubble Space Telescope show that the visible spectrum is dominated by Balmer emission lines of hydrogen (H) and a continuum luminosity that rises into the UV. The anomalous {{H}}α /Hβ emission line ratio, the Balmer emission line luminosity, and the di…
Resolving Gas Flows in the Ultraluminous Starburst IRAS 23365+3604 with Keck LGSAO/OSIRIS
Martin, Crystal L.; Soto, Kurt T.
Keck OSIRIS/LGSAO observations of the ultraluminous galaxy IRAS 23365+3604 resolve a circumnuclear bar (or irregular disk) of semimajor axis 0.″42 (520 pc) in Paα emission. The line-of-sight velocity of the ionized gas increases from the northeast toward the southwest; this gradient is perpendicular to the photometric major axis of the infrared em…
The Global Implications of the Hard Excess. II. Analysis of the Local Population of Radio-quiet AGNs
Turner, T. J.; Reeves, J. N.; Gofford, J. +5 more
Active galactic nuclei (AGNs) show evidence for reprocessing gas, outflowing from the accreting black hole. The combined effects of absorption and scattering from the circumnuclear material likely explain the “hard excess” of X-ray emission above 20 keV, compared with the extrapolation of spectra from lower X-ray energies. In a recent Suzaku study…
Evidence for a Very Low-column Density Hole in the Galactic Halo in the Direction of the High Latitude Molecular Cloud MBM 16
Liu, W.; Galeazzi, M.; Ursino, E.
Shadow observations are the only way to observe emission from the galactic halo (GH) and/or the circumgalactic medium (CGM) free of any foreground contamination from local hot bubble (LHB) and solar wind charge exchange (SWCX). We analyzed data from a shadow observation in the direction of the high latitude, neutral hydrogen cloud MBM 16 with Suza…
Inferring the Coronal Density Irregularity from EUV Spectra
Hahn, M.; Savin, D. W.
Understanding the density structure of the solar corona is important for modeling both coronal heating and the solar wind. Direct measurements are difficult because of line-of-sight integration and possible unresolved structures. We present a new method for quantifying such structures using density-sensitive extreme ultraviolet line intensities to…
The Intragroup versus the Intracluster Medium
Lapi, A.; Cavaliere, A.; Fusco-Femiano, R.
Galaxy groups differ from clusters primarily by way of their lower masses, M ∼ 1014 M ⊙ versus M ∼ 1015 M ⊙. We discuss how mass affects the thermal state of the intracluster or the intragroup medium, specifically as to their entropy levels and radial profiles. We show that entropy is produced in both ca…
Detecting Planet Pairs in Mean Motion Resonances via the Astrometry Method
Zhang, Hui; Zhou, Ji-Lin; Liu, Hui-Gen +2 more
Gaia is leading us into a new era with a high astrometry precision of ∼10 µas. Under such precision, astrometry can play an important role in detecting and characterizing exoplanets. In particular, we can identify planet pairs in mean motion resonances (MMRs), which constrain the formation and evolution of planetary systems. In accordance wi…