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Spectral and timing nature of the symbiotic x-ray binary 4u 1954+319: the slowest rotating neutron star in an x-ray binary system
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Sasano, Makoto Corbet, Robin H. D. Pottschmidt, Katja Enoto, Teruaki Wilms, Jorn Fuerst, Felix Yamada, Shin'Ya Marcu, Diana Tamagawa, Toru Makishima, Kazuo |
| Copyright Year | 2014 |
| Description | The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its approx. 5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (is approx. 7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-K alpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (approx. 60%-80%), and the location in the Corbet diagram favor high B-field (approx. greater than 10(exp12) G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10(exp33)-10(exp35) erg s(expâ1)), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a approx. 10(exp13) G NS, this scheme can explain the approx. 5.4 hr equilibrium rotation without employing the magnetar-like field (approx. 10(exp16) G) required in the disk accretion case. The timescales of multiple irregular flares (approx. 50 s) can also be attributed to the free-fall time from the Alfv´en shell for a approx. 10(exp13) G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed. |
| File Size | 3142764 |
| Page Count | 16 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20150010753 |
| Archival Resource Key | ark:/13960/t8md3xp9b |
| Language | English |
| Publisher Date | 2014-04-24 |
| Access Restriction | Open |
| Subject Keyword | Accretion Disks Aeuro" Binaries: Symbiotic Aeuro" Magnetic Fields Aeuro" Stars: Accretion Stellar Winds Neutron Stars X Ray Binaries Pulsars Continuums Luminosity Symbiotic Stars Spectra Rotation Compton Effect Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
