ORBITAL DECAY AND EVIDENCE OF DISK FORMATION IN THE X-RAY BINARY PULSAR OAO 1657-415

Journal Article · Sat Nov 10 00:00:00 EST 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/759/2/124· OSTI ID:22086359

Jenke, P A ^[1]; Finger, M H ^[2]; Wilson-Hodge, C A ^[3]; Camero-Arranz, A ^[4]

---

1. MSFC/NPP, Huntsville, AL 35812 (United States)
2. Universities Space Research Association, Huntsville, AL 35806 (United States)
3. Space Science Office, VP62, NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States)
4. Institut de Ciencies de l'Espai (CSIC-IEEC), Campus UAB, Facultat de Ciencies, Torre C5-parell, E-08193, Barcelona (Spain)

OAO 1657-415 is an eclipsing X-ray binary wind-fed pulsar that has exhibited smooth spin-up/spin-down episodes and has undergone several torque reversals throughout its long history of observation. We present a frequency history spanning nearly 19 years of observations from the Burst and Transient Source Experiment and from the Gamma-Ray Burst Monitor (Fermi/GBM). Our analysis suggests two modes of accretion: one resulting in steady spin-up correlated with flux during which we believe a stable accretion disk is present and one in which the neutron star is spinning down at a lesser rate which is uncorrelated with flux. Orbital elements of the pulsar system are determined at several intervals throughout this history. With these ephemerides, statistically significant orbital decay with a P-dot {sub orb}=(-9.74{+-}0.78) Multiplication-Sign 10{sup -8} is established.

• OSTI ID: 22086359
• Journal Information: Astrophysical Journal, Vol. 759, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCRETION DISKS
ASTRONOMY
ASTROPHYSICS
BINARY STARS
COSMIC GAMMA BURSTS
DECAY
NEUTRON STARS
PULSARS
SPIN
STAR ACCRETION
STELLAR WINDS
TORQUE
TRANSIENTS
X RADIATION