1,503 research outputs found
Absorption Features in the X-ray Spectrum of an Ordinary Radio Pulsar
The vast majority of known non-accreting neutron stars (NSs) are
rotation-powered radio and/or gamma-ray pulsars. So far, their multiwavelength
spectra have all been described satisfactorily by thermal and non-thermal
continuum models, with no spectral lines. Spectral features have, however, been
found in a handful of exotic NSs and thought to be a manifestation of their
unique traits. Here we report the detection of absorption features in the X-ray
spectrum of an ordinary rotation-powered radio pulsar, J1740+1000. Our findings
bridge the gap between the spectra of pulsars and other, more exotic, NSs,
suggesting that the features are more common in the NS spectra than they have
been thought so far.Comment: 18 pages, 4 color figures, 1 Tabl
Alien Registration- Durant, Kenneth G. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/26571/thumbnail.jp
Chandra pulsar survey (ChaPS)
Taking advantage of the high sensitivity of the Chandra Advanced CCD Imaging
Spectrometer, we have conducted a snap-shot survey of pulsars previously
undetected in X-rays. We detected 12 pulsars and established deep flux limits
for 11 pulsars. Using these new results, we revisit the relationship between
the X-ray luminosity, L_psr_x, and spin-down power, Edot. We find that the
obtained limits further increase the extremely large spread in the non-thermal
X-ray efficiencies, eta_psr_x=L_psr_x/Edot, with some of them being now below
1e-5. Such a spread cannot be explained by poorly known distances or by beaming
of pulsar radiation. We also find evidence of a break in the dependence of
L_psr_x on Edot, such that pulsars become more X-ray efficient at Edot<~
1e34-1e35 erg/s. We examine the relationship between the gamma-ray luminosity,
L_psr_g, and Edot, which exhibits a smaller scatter compared to that in X-rays.
This confirms that the very large spread in the X-ray efficiencies cannot be
explained just by beaming because the gamma-ray emission is generally expected
to be beamed stronger than the X-ray emission. Intriguingly, there is also an
indication of a break in the L_psr_g(Edot) dependence at Edot~1e35 erg/s, with
lower-Edot pulsars becoming less gamma-ray efficient. We also examine the
distance-independent L_psr_f/L_psr_x ratio as a function of Edot for a sample
of gamma-ray pulsars observed by Chandra and find that it peaks at Edot~1e35
erg/s, showing that the breaks cannot originate from poorly measured distances.
We discuss the implications of our findings for existing models of
magnetospheric emission and venues for further exploration.Comment: Submitted to Ap
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