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Titolo:
The Crab pulsar in the 0.75-30 MeV range as seen by CGRO COMPTEL - A coherent high-energy picture from soft X-rays up to high-energy gamma-rays
Autore:
Kuiper, L; Hermsen, W; Cusumano, G; Diehl, R; Schonfelder, V; Strong, A; Bennett, K; McConnell, ML;
Indirizzi:
SRON, Natl Inst Space Res, NL-3584 CA Utrecht, Netherlands SRON Utrecht Netherlands NL-3584 CA Res, NL-3584 CA Utrecht, Netherlands Max Planck Inst Extraterr Phys, D-85741 Garching, Germany Max Planck Inst Extraterr Phys Garching Germany D-85741 arching, Germany European Space Technol Ctr, Div Astrophys, NL-2200 AG Noordwijk, Netherlands European Space Technol Ctr Noordwijk Netherlands NL-2200 AG Netherlands Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA Univ New Hampshire Durham NH USA 03824 tr Space Sci, Durham, NH 03824 USA CNR, Ist Fis Cosm & Applicaz Informat, I-90146 Palermo, Italy CNR Palermo Italy I-90146 sm & Applicaz Informat, I-90146 Palermo, Italy
Titolo Testata:
ASTRONOMY & ASTROPHYSICS
fascicolo: 3, volume: 378, anno: 2001,
pagine: 918 - 935
SICI:
1432-0746(200111)378:3<918:TCPIT0>2.0.ZU;2-Q
Fonte:
ISI
Lingua:
ENG
Soggetto:
RAPIDLY SPINNING PULSARS; NEBULA PULSAR; OUTER MAGNETOSPHERE; ASTRONOMY SATELLITE; POWERED PULSARS; VELA PULSARS; PSR 0531+21; FIGARO-II; GAP MODEL; ON-BOARD;
Keywords:
pulsars : individual : PSR B0531+21; stars : neutron; supernovae : individual : Crab nebula; gamma rays : observations; X-rays : stars;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
82
Recensione:
Indirizzi per estratti:
Indirizzo: Kuiper, L SRON, Natl Inst Space Res, Sorbonnelaan 2, NL-3584 CA Utrecht, Netherlands SRON Sorbonnelaan 2 Utrecht Netherlands NL-3584 CA Netherlands
Citazione:
L. Kuiper et al., "The Crab pulsar in the 0.75-30 MeV range as seen by CGRO COMPTEL - A coherent high-energy picture from soft X-rays up to high-energy gamma-rays", ASTRON ASTR, 378(3), 2001, pp. 918-935

Abstract

We present the time-averaged characteristics of the Crab pulsar in the 0.75-30 MeV energy window using data from the imaging Compton Telescope COMPTEL aboard the Compton Gamma-Ray Observatory (CGRO) collected over its 9 yearmission. Exploiting the exceptionally long COMPTEL exposure on the Crab allowed us to derive significantly improved COMPTEL spectra for the Crab nebula and pulsar emissions, and for the first time to accurately determine at low-energy gamma -rays the pulse profile as a function of energy. These timing data, showing the well-known main pulse and second pulse at a phase separation of similar to0.4 with strong bridge emission, are studied together with data obtained at soft/hard X-ray energies from the ROSAT HRI, BeppoSAXLECS, MECS and PDS, at soft gamma -rays from CGRO BATSE and at high-energygamma -rays from CGRO EGRET in order to obtain a coherent high-energy picture of the Crab pulsar from 0.1 keV up to 10 GeV. The morphology of the pulse profile of the Crab pulsar is continuously changing as a function of energy: the intensities of both the second pulse and the bridge emission increase relative to that of the first pulse for increasing energies up to similar to1 MeV. Over the COMPTEL energy range above 1 MeV an abrupt morphology change happens: the first pulse becomes again dominant over the second pulse and the bridge emission loses significance such that the pulse profile above 30 MeV is similar to the one observed at optical wavelengths. A pulse-phase-resolved spectral analysis performed in 7 narrow phase slices consistently applied over the 0.1 keV-10 GeV energy interval shows that the pulsed emission can empirically be described with 3 distinct spectral components: i) a power-law emission component (1 keV-5 GeV; photon index 2.022+/-0.014), present in the phase intervals of the two pulses; ii) a curved spectral component required to describe soft (less than or similar to 100 keV) excessemission present in the same pulse-phase intervals; iii) a broad curved spectral component reflecting the bridge emission from 0.1 keV to similar to 10 MeV. This broad spectral component extends in phase over the full pulse profile in an approximately triangular shape, peaking under the second pulse. Recent model calculations for a three-dimensional pulsar magnetosphere with outer magnetospheric gap acceleration by Cheng et al. (2000) appear at present most successful in explaining the above complex high-energy characteristics of the Crab pulsar.
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Documento generato il 19/06/13 alle ore 20:59:21