Publication Date:
2019-07-18
Description:
I report on the results of ongoing campaigns with Chandra to precisely time the X-ray pulsations from two candidate ultra-compact white dwarf systems; V407 Vu1 and RX J0806.3+1527. If these objects are ultra-compact binaries, then the gravitational radiation-driven evolution of the orbital period can be probed with precise X-ray timing observations. Recent Chandra data have confirmed that the X-ray frequency of V407 Vu1 is increasing at a mean rate of about 8 x 10-18 Hz s-1, a value consistent with loss of gravitational radition from the system. However, the frequency derivative, X-ray variability and phase timing noise could also be explained in an accretion driven, intermediate polar scenario. Previous studies suggested that RX J0806.3+1527 is spinning up at an even faster rate than V407 Vul, however, preliminary analysis of Chandra data do not confirm this. Indeed, the present evidence suggests we may be seeing a torque reversal in this source.
Keywords:
Astronomy
Type:
HEAD 2004; Sep 08, 2004 - Sep 11, 2004; New Orleans, LA; United States
Format:
text
