Sign on

SAO/NASA ADS Astronomy Abstract Service

· Find Similar Abstracts (with default settings below)
· Table of Contents
· Also-Read Articles (Reads History)
·
· Translate This Page
Title:
Pulse variations in XTE J1814-338
Authors:
Chung, Christine; Galloway, Duncan; Melatos, Andrew
Affiliation:
AA(University of Melbourne),AB(Monash University),AC(University of Melbourne)
Publication:
37th COSPAR Scientific Assembly. Held 13-20 July 2008, in Montréal, Canada., p.551
Publication Date:
00/2008
Origin:
ADS
Comment:
Symposium E, session 15 (poster). Paper number: E15-0045-08
Bibliographic Code:
2008cosp...37..551C

Abstract

Accreting millisecond pulsars have been predicted to precess with periods of order hours to days, resulting in characteristic variations in their pulse properties. We compute theoretically the periodic modulation of the mean flux, phase residuals and fractional amplitude of a pulsar with assumed surface intensity patterns featuring one and two hotspots. Using observations taken by the Rossi X-ray Timing Explorer, we then search for these signatures from the accreting millisecond pulsar XTE J1814‑338 (pulse frequency 314.4 Hz), which has previously shown long-term, approximately periodic variations in the pulse arrival times. We measure the period of these variations at 12.2 days, and also detect variations at a consistent period in the pulse amplitude and mean (pulse-averaged) X-ray intensity. These variations are consistent with a freely precessing neutron star only if the inclination angle is < 0.1, an a priori unlikely configuration. Our study suggests that: 1) if the observed flux variations are not due to precession, we place an upper limit on the product cos θ ≤ 10‑9 for XTE J1814‑338, where is the ellipticity and θ is the tilt angle of the pulsar. 2) if the observed flux variations are due to precession, our model insufficiently describes the pulsar's surface intensity map. We can place an upper limit of ≤ 3.0 × 10‑9 and estimate 5° ≤ θ ≤ 10° . This translates to a gravitational wave strain of ≤ 10‑27 and Advanced LIGO signal-to-noise ratio of ≤ 10‑2 (for a 120 day integration time). We will discuss how these results, together with gravitational wave observations in the future, can be used to constrain the nuclear equation of state and the transport coefficients of bulk nuclear matter, e.g. viscosity.
Bibtex entry for this abstract   Preferred format for this abstract (see Preferences)
   

Find Similar Abstracts:

Use: Authors
Title
Abstract Text
Return: Query Results Return    items starting with number
Query Form
Database: Astronomy
Physics
arXiv e-prints