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Titolo: ROSAT PSPC OBSERVATION OF THE NORTHEAST REGION OF THE VELA SUPERNOVA REMNANT .2. SPECTRAL-ANALYSIS WITH A NONEQUILIBRIUM OF IONIZATION EMISSION MODEL
Autore: BOCCHINO F; MAGGIO A; SCIORTINO S;
- Indirizzi:
- IST & OSSERVATORIO ASTRON PALERMO,PIAZZA PARLAMENTO 1 I-90134 PALERMOITALY
- Titolo Testata:
- The Astrophysical journal
fascicolo: 2,
volume: 481,
anno: 1997,
parte:, 1
pagine: 872 - 882
- SICI:
- 0004-637X(1997)481:2<872:RPOOTN>2.0.ZU;2-J
- Fonte:
- ISI
- Lingua:
- ENG
- Soggetto:
- X-RAY-EMISSION; INTERSTELLAR CLOUDS; NOVA REMNANTS; SHOCK-WAVES; CYGNUS LOOP; SPECTROSCOPY; PLASMA; ASCA;
- Keywords:
- ISM, INDIVIDUAL (VELA SUPERNOVA REMNANT); ISM, STRUCTURE; SUPERNOVA REMNANTS; X-RAYS, ISM;
- Tipo documento:
- Article
- Natura:
- Periodico
- Settore Disciplinare:
- Science Citation Index Expanded
- Citazioni:
- 42
- Recensione:
- Indirizzi per estratti:
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- Citazione:
- F. Bocchino et al., "ROSAT PSPC OBSERVATION OF THE NORTHEAST REGION OF THE VELA SUPERNOVA REMNANT .2. SPECTRAL-ANALYSIS WITH A NONEQUILIBRIUM OF IONIZATION EMISSION MODEL", The Astrophysical journal, 481(2), 1997, pp. 872-882
Abstract
We have developed a grid of nonequilibrium of ionization (NEI) modelsthat depends on the electron temperature and ionization time and thatis suitable for use in fitting X-ray spectra. Using this grid, we have carried out a spatially resolved spectral analysis of a ROSAT Position Sensitive Proportional Counter (PSPC) observation of the northeast shock region of the Vela supernova remnant on an angular scale of 10' (similar to 1.0 pc at the distance of the remnant). The adopted model passes the X-2 test at the 95% confidence level for 45% of the considered spatial bins, giving unexpectedly low values of the ionization time (log tau similar to 0-1 yr cm(-3)). We discuss the possibility that this result may be due to a reduced contribution from a line emission,which may be related to the locking of metals in grains. We also findsignificant temperature gradients on the scale explored, and we arguethat they are correlated to interstellar matter inhomogeneities encountered by the shock front. The emission from the remaining 55% of the bins is incompatible with the single-tau single-temperature NEI model,and a feasible description rests on the two-temperature collisional equilibrium of ionization model we have adopted in our previous analysis of the same data set. We tentatively interpret our results in terms of the superposition of shocks propagating in an inhomogeneous medium,which produces a multitemperature and multi-ionization stage plasma.
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/06/13 alle ore 09:16:01