THE 5 hr PULSE PERIOD AND BROADBAND SPECTRUM OF THE SYMBIOTIC X-RAY BINARY 3A 1954+319

Journal Article · Sun Nov 20 00:00:00 EST 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/742/1/L11· OSTI ID:22047352

Marcu, Diana M; Pottschmidt, Katja ^[1]; Fuerst, Felix; Grinberg, Victoria; Mueller, Sebastian; Wilms, Joern ^[2]; Postnov, Konstantin A ^[3]; Corbet, Robin H. D. ^[4]; Markwardt, Craig B ^[5]; Cadolle Bel, Marion ^[6]

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1. NASA Goddard Space Flight Center, Astrophysics Science Division, Code 661, Greenbelt, MD 20771 (United States)
2. Dr. Karl Remeis-Observatory and ECAP, University of Erlangen-Nuremberg, 96049 Bamberg (Germany)
3. Sternberg Astronomical Institute, 119992 Moscow (Russian Federation)
4. CRESST and University of Maryland Baltimore County, Baltimore, MD 21250 (United States)
5. NASA Goddard Space Flight Center, Astrophysics Science Division, Code 662, Greenbelt, MD 20771 (United States)
6. European Space Agency, European Space Astronomy Centre, 28691 Villanueva de la Canada, 28692 Madrid (Spain)

We present an analysis of the highly variable accreting X-ray pulsar 3A 1954+319 using 2005-2009 monitoring data obtained with INTEGRAL and Swift. This considerably extends the pulse period history and covers flaring episodes in 2005 and 2008. In 2006 the source was identified as one of only a few known symbiotic X-ray binaries (SyXBs), i.e., systems composed of a neutron star accreting from the inhomogeneous medium around an M-giant star. The extremely long pulse period of {approx}5.3 hr is directly visible in the 2008 INTEGRAL-ISGRI outburst light curve. The pulse profile is double peaked and generally not significantly energy dependent although there is an indication of possible softening during the main pulse. During the outburst a strong spin-up of -1.8 Multiplication-Sign 10{sup -4} hr hr{sup -1} occurred. Between 2005 and 2008 a long-term spin-down trend of 2.1 Multiplication-Sign 10{sup -5} hr hr{sup -1} was observed for the first time for this source. The 3-80 keV pulse peak spectrum of 3A 1954+319 during the 2008 flare could be well described by a thermal Comptonization model. We interpret the results within the framework of a recently developed quasi-spherical accretion model for SyXBs.

• OSTI ID: 22047352
• Journal Information: Astrophysical Journal Letters, Vol. 742, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTROPHYSICS
BINARY STARS
ENERGY DEPENDENCE
GIANT STARS
KEV RANGE
MONITORING
NEUTRON STARS
PULSARS
PULSES
SPIN
STAR ACCRETION
SYMBIOTIC STARS
VISIBLE RADIATION
X RADIATION