Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997aas...19111105h&link_type=abstract
American Astronomical Society, 191st AAS Meeting, #111.05; Bulletin of the American Astronomical Society, Vol. 29, p.1391
Astronomy and Astrophysics
Astronomy
3
Scientific paper
The recently discovered 5.3 ms pulsar J1012+5307 at a distance of 520 pc is in an area of the sky which is particularly deficient in absorbing gas. The column density along the line of sight is less than 7.5 x 10(19) cm(-2) , which facilitates soft X-ray observations. Halpern (1996, ApJ, 459, L9) reported a possible ROSAT PSPC detection of the pulsar in a serendipitous, off-axis observation. We have now confirmed the X-ray emission of PSR J1012+5307 in a 23 ksec observation with the ROSAT HRI. A point source is detected within 3('') of the radio position. Its count rate of 1.6 +/- 0.3 x 10(-3) s(-1) corresponds to an unbsorbed 0.1--2.4 keV flux of 6.4 x 10(-14) ergs cm(-2) s(-1) , similar to that reported previously. This counts-to-flux conversion is valid for N_H = 5 x 10(19) cm(-2) , and either a power-law spectrum of photon index 2.5 or a blackbody of kT = 0.1 keV. The implied X-ray luminosity of 2.0 x 10(30) ergs s(-1) is 5 x 10(-4) of the pulsar's spin-down power dot E, and similar to that of the nearest millisecond pulsar J0437--4715, which is nearly a twin of J1012+5307 in P and dot E. We subjected the 37 photons (and 13 background counts) within the source region to a pulsar search, but no evidence for pulsation was found. The pulsar apparently emits over a large fraction of its rotation cycle, and the absence of sharp modulation can be taken as evidence for surface thermal emission, as is favored for PSR J0437--4715 (Zavlin & Pavlov 1997, A&A, in press), rather than magnetospheric X-ray emission which is apparent in the sharp pulses of the much more energetic millisecond pulsar B1821--24 (Saito et al. 1997, ApJ, 477, L37). A further test of this interpretation will be made with a longer ROSAT observation, which will increase the number of photons collected by a factor of 5, and permit a more sensitive examination of the light curve for modulation due to emission from heated polar caps. If found, such modulation will be further evidence that surface reheating by the impact of particles accelerated along open field lines operates in these ~ 10(9) yr old pulsars.
Halpern Jules P.
Wang Frank Ye-Howe
No associations
LandOfFree
X-ray Emission from the Millisecond Pulsar J1012+5307 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with X-ray Emission from the Millisecond Pulsar J1012+5307, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-ray Emission from the Millisecond Pulsar J1012+5307 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1177899