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The giant Hα/X-ray filament in the cluster of galaxies A1795
Fabian, A. C.; Sanders, J. S.; Crawford, C. S.
The cluster of galaxies A1795 hosts a 46 kpc long filament at its core, which is clearly visible in the light of Hα and X-ray emission. We present optical slit spectroscopy and deeper Chandra X-ray data of the filament. The optical spectra reveal that the bulk of the filament is quiescent (with σ < 130 km s-1), although considerable …
The mass of the black hole in 3C 273
Paltani, S.; Türler, M.
In this paper we apply the reverberation method to determine the mass of the black hole in 3C 273 from the Lyα and Civ emission lines using archival IUE observations. Following the standard assumptions of the method, we find a maximum-likelihood estimate of the mass of 6.59× 10^9 M_⊙, with a 1σ confidence interval 5.69{-}8.27× 109 M_⊙. …
Forecast evaluation of the coronal mass ejection (CME) geoeffectiveness using halo CMEs from 1997 to 2003
Cho, K. -S.; Kim, Y. -H.; Moon, Y. -J. +5 more
In this study we have made a forecast evaluation of geoeffective coronal mass ejections (CMEs) by using frontside halo CMEs and the magnetospheric ring current index, Dst. This is the first time, to our knowledge, that an attempt has been made to construct contingency tables depending on the geoeffectiveness criteria as well as to estimate the pro…
A Chandra and XMM-Newton study of the wide-angle tail radio galaxy 3C465
Hardcastle, M. J.; Worrall, D. M.; Sakelliou, I.
We have observed the prototypical wide-angle tail (WAT) radio galaxy 3C465 with Chandra and XMM-Newton. X-ray emission is detected from the active nucleus and the inner radio jet, as well as a small-scale, cool component of thermal emission, a number of the individual galaxies of the host cluster (Abell 2634), and the hotter thermal emission from …
A Coherent Timing Solution for the Nearby Isolated Neutron Star RX J1308.6+2127/RBS 1223
van Kerkwijk, M. H.; Kaplan, D. L.
We present a phase-connected timing solution for the nearby isolated neutron star RX J1308.6+2127 (RBS 1223). From dedicated Chandra observations as well as archival Chandra and XMM-Newton data spanning a period of 5 years, we demonstrate that the 10.31 s pulsations are slowing down steadily at a rate of P˙=1.120(3)×10-13 s s-1
HST/ACS observations of the old and metal-poor Sagittarius dwarf irregular galaxy
Gullieuszik, M.; Momany, Y.; Clemens, M. +6 more
We have obtained deep color-magnitude diagrams (CMDs) of the Sagittarius dwarf irregular galaxy with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope. The new diagrams show for the first time the star formation history of SagDIG. The young main-sequence is traced down to mF606W ≃27.5, well separated from the old…
Chandra X-Ray Observation of a Mature Cloud-Shock Interaction in the Bright Eastern Knot Region of Puppis A
Petre, Robert; Hwang, Una; Flanagan, Kathryn A.
We present Chandra X-ray images and spectra of the most prominent cloud-shock interaction region in the Puppis A supernova remnant. The bright eastern knot (BEK) has two main morphological components: (1) a bright compact knot that lies directly behind the apex of an indentation in the eastern X-ray boundary; and (2) lying 1' westward behind the s…
Detection of γ-ray lines from interstellar 60Fe by the high resolution spectrometer SPI
Knödlseder, J.; Schanne, S.; Diehl, R. +6 more
It is believed that core-collapse supernovae (CCSN), occurring at a rate ~once per century, have seeded the interstellar medium with long-lived radioisotopes such as 60Fe (half-life 1.5 Myr), which can be detected by the γ-rays emitted when they β-decay. Here we report the detection of the 60Fe decay lines at 1173 keV and 133…
The Chandra deep field South/GOODS survey. Optically faint X-ray sources
Alexander, D. M.; Zheng, W.; Gilli, R. +11 more
We provide important new constraints on the nature and redshift distribution of optically faint (R≥ 25) X-ray sources in the Chandra Deep Field South Survey. We use a large multi-wavelength data set, including the GOODS/ACS survey, the recently released Hubble Ultra Deep Field (UDF) data, and the new public VLT/ISAAC imaging. We show that we can d…
XMM-Newton View of PKS 2155-304: Characterizing the X-Ray Variability Properties with EPIC pn
Treves, A.; Celotti, A.; Zhang, Y. H. +2 more
Starting from XMM-Newton EPIC pn data, we present the X-ray variability characteristics of PKS 2155-304 using a simple analysis of the excess variance, σ2XS, and of the fractional rms variability amplitude, Fvar. The scatter in σ2XS and Fvar, calculated using 500 s long segments of …