Zoekopdracht:
journal id: "astronomyxandxastrophysics"
| Auteurs | L. Nicastro, G. Cusumano, O. Lohmer, M. Kramer, L. Kuiper, W. Hermsen, T. Mineo, W. Becker | | Titel | BeppoSAX observation of PSR B1937+21 |
| Tijdschrift | Astronomy and Astrophysics |
| Jaargang | 413 |
| Jaar | 2004 |
| Pagina's | 1065-1072 |
| ISSN | 00046361 |
| Faculteit | Faculteit der Natuurwetenschappen, Wiskunde en Informatica |
| Instituut/afd. | FNWI: Astronomical Institute Anton Pannekoek (IAP) |
| Trefwoorden | - |
| Samenvatting | We present the results of a BeppoSAX observation of the fastest rotating pulsar known: PSR B1937+21. The ~200 ks observation (78.5 ks MECS/34 ks LECS on-source time) allowed us to investigate with high statistical significance both the spectral properties and the pulse profile shape. The pulse profile is clearly double peaked at energies ≳4 keV. Peak widths are compatible with the instrumental time resolution and the second pulse lags the main pulse 0.52 in phase, like is the case in the radio. In the 1.3-4 keV band we detect a ~45% DC component; conversely the 4-10 keV pulsed fraction is consistent with 100%. The on-pulse spectrum is fitted with an absorbed power-law of spectral index ~1.2, harder than that of the total flux which is ~1.9. The total unabsorbed (2-10 keV) flux is F<SUB>2-10</SUB> = 4.1? 10<SUP>-13</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP>, implying a luminosity of L<SUB>X</SUB> = 5.0? 10<SUP>31</SUP> Theta (d/3.6 kpc)<SUP>2</SUP> erg s<SUP>-1</SUP> and a X-ray efficiency of eta = 4.5? 10<SUP>-5</SUP> Theta, where Theta is the solid angle spanned by the emission beam. These results are in agreement with those obtained by ASCA and a more recent Rossi-XTE observation. The hydrogen column density N<SUB>H</SUB> ~ 2? 10<SUP>22</SUP> cm<SUP>-2</SUP> is ~10 times higher than expected from the radio dispersion measure and average Galactic density of e<SUP>-</SUP>. Though it is compatible (within 2 sigma) with the Galactic (H I derived) value of ~ 1? 10<SUP>22</SUP> cm<SUP>-2</SUP>, inspection of dust extinction maps reveal that the pulsar falls in a highly absorbed region. In addition, 1.4 GHz radio map shows that the nearby (likely unrelated) H II source 4C21.53W is part of a circular emission region ~4' across. |
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