Search Publications
The Ultraluminous X-Ray Source NGC 1313 X-2 (MS 0317.7-6647) and Its Environment
Kaaret, Philip; Turolla, Roberto; Zampieri, Luca +5 more
We present new optical and Chandra observations of the field containing the ultraluminous X-ray source NGC 1313 X-2. On an ESO 3.6 m image, the Chandra error box embraces an R=21.6 pointlike object and excludes a previously proposed optical counterpart. The resulting X-ray/optical flux ratio of NGC 1313 X-2 is ~500. The value of fX/f
Evidence of Rapid Flux Emergence Associated with the M8.7 Flare on 2002 July 26
Qiu, Jiong; Jing, Ju; Wang, Haimin +5 more
In this paper, we present a detailed study of the M8.7 flare that occurred on 2002 July 26 using data from the Big Bear Solar Observatory (BBSO), Ramaty High Energy Solar Spectroscopic Imager (RHESSI), the Transition Region and Coronal Explorer (TRACE), and the Solar and Heliospheric Observatory (SOHO). This flare has interesting properties simila…
The Purple Haze of η Carinae: Binary-induced Variability?
Smith, Nathan; Gull, Theodore R.; Collins, Nicholas R. +1 more
Asymmetric variability in ultraviolet images of the Homunculus obtained with the Advanced Camera for Surveys/High Resolution Camera on the Hubble Space Telescope suggests that η Carinae is indeed a binary system. Images obtained before, during, and after the recent ``spectroscopic event'' in 2003.5 show alternating patterns of bright spots and sha…
XMM-Newton Observations of the Galactic Supernova Remnant CTB 109 (G109.1-1.0)
Sasaki, Manami; Smith, Randall K.; Plucinsky, Paul P. +3 more
We present the analysis of the X-ray Multimirror Mission (XMM-Newton) European Photon Imaging Camera (EPIC) data of the Galactic supernova remnant (SNR) CTB 109 (G109.1-1.0). CTB 109 is associated with the anomalous X-ray pulsar (AXP) 1E 2259+586 and has an unusual semicircular morphology in both the X-ray and the radio and an extended X-ray brigh…
Rapid Penumbral Decay following Three X-Class Solar Flares
Liu, C.; Qiu, J.; Wang, H. +3 more
We show strong evidence that penumbral segments decayed rapidly and permanently right after three X-class solar flares. Two of the three events occurred very recently in NOAA Active Region 10486, an X17 flare on 2003 October 28 and an X10 flare on 2003 October 29. The third X2.3 flare was observed in solar active region NOAA AR 9026 on 2000 June 6…
RHESSI Observations of a Simple Large X-Ray Flare on 2003 November 3
Liu, Wei; Liu, Siming; Jiang, Yan Wei +1 more
We present data analysis and interpretation of a simple X-class flare observed with RHESSI on 2003 November 3. In contrast to other X-class flares observed previously, this flare shows a very simple morphology with well-defined looptop (LT) and footpoint (FP) sources. The almost monotonic upward motion of the LT source and increase in separation o…
Solar Cycle 23: An Anomalous Cycle?
de Toma, Giuliana; White, Oran R.; Chapman, Gary A. +3 more
The latest SOHO VIRGO total solar irradiance (TSI) time series is analyzed using new solar variability measures obtained from full-disk solar images made at the San Fernando Observatory and the Mg II 280 nm index. We discuss the importance of solar cycle 23 as a magnetically simpler cycle and a variant from recent cycles. Our results show the cont…
The Mid-Infrared Luminosity Function of Galaxies in the European Large Area Infrared Space Observatory Survey Southern Fields
Pozzi, F.; Franceschini, A.; Serjeant, S. +7 more
We present the first determination of the 15 µm luminosity function of galaxies from the European Large Area ISO Survey (ELAIS) southern fields. We have adopted a new criterion to separate the quiescent, nonevolving and the starburst, evolving populations based on the ratio of mid-infrared to optical luminosity. Strong evolution is suggested…
The Variable Quiescence of Centaurus X-4
Campana, S.; Mereghetti, S.; Stella, L. +2 more
Centaurus X-4 is one of the best-studied low-mass neutron star transients in quiescence. Thanks to XMM-Newton's large throughput, Centaurus X-4 was observed at the highest signal-to-noise ratio ever. This allowed us to discern rapid (>100 s), large (45%+/-7% rms in the 10-4 to 1 Hz range) intensity variability, especially at low ener…
Time Dependence in Relativistic Collisionless Shocks: Theory of the Variable ``Wisps'' in the Crab Nebula
Spitkovsky, Anatoly; Arons, Jonathan
We describe results from time-dependent numerical modeling of the collisionless reverse shock terminating the pulsar wind in the Crab Nebula. We treat the upstream relativistic wind as composed of ions and electron-positron plasma embedded in a toroidal magnetic field, flowing radially outward from the pulsar in a sector around the rotational equa…