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XMM-Newton and Chandra have ushered in a new era for the study of dwarf galaxies in the Local Group. We provide an overview of the opportunities, challenges, and some early results. The large number of background sources relative to galaxy sources is a major theme. Despite this challenge, the identification of counterparts has been possible, providing hints(More)
Massive stars end their short lives in spectacular explosions--supernovae--that synthesize new elements and drive galaxy evolution. Historically, supernovae were discovered mainly through their 'delayed' optical light (some days after the burst of neutrinos that marks the actual event), preventing observations in the first moments following the explosion.(More)
We present Chandra observations of black hole X-ray novae V404 Cyg, A0620–00, GRO J1655–40 and XTE J1550–564 in quiescence. Their quiescent spectra can be well fitted by a power-law model with number slope α ∼ 2. While a coronal (Raymond-Smith) model is also a statistically acceptable representation of the spectra , the best fit temperatures of these models(More)
Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. ABSTRACT We report on the Chandra X-ray Observatory and Hubble Space(More)
We report the discovery of an eclipsing X-ray binary in M101, the first such system to be discovered outside the Local Group. Based on a sequence of 25 Chandra observations that sample a wide range of orbital phases, we find a period of 32.688 ± 0.002 hours, which we interpret as an orbital period. The folded light curve exhibits an eclipse lasting about 8(More)
We have obtained snapshot images of an X-ray nova in M31 from Chandra ACIS-I and the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS). The Chandra position of the X-ray nova was R. During this time period, the X-ray flux decayed linearly from (3.6±0.2)×10 −4 to <(6.9±0.09)×10 −5 ct cm −2 s −1. The HST identification of an optical source in the(More)
Results of observations of the Galactic bulge X-ray source GX 9+9 by the All-Sky Monitor (ASM) and Proportional Counter Array (PCA) onboard the Rossi X-ray Timing Explorer are presented. The ASM results show that the 4.19 hour X-ray periodicity first reported by Hertz and Wood in 1987 was weak or not detected for most of the mission prior to late 2004, but(More)