2004ApJ...605..368G -
Astrophys. J., 605, 368-377 (2004/April-2)
Imaging X-ray, optical, and infrared observations of the transient anomalous X-ray pulsar XTE J1810-197.
GOTTHELF E.V., HALPERN J.P., BUXTON M. and BAILYN C.
Abstract (from CDS):
We report X-ray imaging, timing, and spectral studies of XTE J1810-197, a 5.54 s pulsar discovered by Ibrahim and coworkers in recent Rossi X-Ray Timing Explorer (RXTE) observations. In a set of short exposures with the High Resolution Camera on board the Chandra X-Ray Observatory, we detect a strongly modulated signal (55%±4% pulsed fraction) with the expected period located at (J2000) 18h09m51{fs}08, -19°43'51".7, with a uncertainty radius of 0".6 (90% confidence level). Spectra obtained with XMM-Newton are well fitted by a two-component model that typically describes anomalous X-ray pulsars (AXPs), an absorbed blackbody plus power law with parameters kT=0.67±0.01 keV, Γ=3.7±0.2, NH=(1.05±0.05)x1022/cm2, and FX(0.5-10keV)=3.98x10–11 ergs/cm2/s. Alternatively, a two-temperature blackbody fit is just as acceptable. The location of CXOU J180951.0-194351 is consistent with a point source seen in archival Einstein, ROSAT, and ASCA images, when its flux was nearly 2 orders of magnitude fainter, and from which no pulsations are found. The spectrum changed dramatically between the ``quiescent'' and ``active'' states; the former can be modeled as a softer blackbody. Using XMM-Newton timing data, we place an upper limit of 0.03 lt-s on any orbital motion in the period range 10 minutes-8 hr. Optical and infrared images obtained on the SMARTS 1.3 m telescope at the Cerro Tololo Inter-American Observatory (CTIO) show no object in the Chandra error circle to limits V=22.5, I=21.3, J=18.9, and K=17.5. Together, these results argue that CXOU J180951.0-194351 is an isolated neutron star, one most similar to the transient AXP AX J1844.8-0256. Continuing study of XTE J1810-197 in various states of luminosity is important for understanding and possibly unifying a growing class of isolated, young neutron stars that are not powered by rotation.
Abstract Copyright:
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Journal keyword(s):
Stars: Pulsars: General - stars: individual (CXOU J180951.0) - stars: individual (XTE J1810-197) - Stars: Neutron - X-Rays: Stars
CDS comments:
Parag.7 : SNR G26.6+0.1 is a misprint for SNR 29.6+0.1
Simbad objects:
10
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