Query:
journal id: "astrophysicalxjournal"
| Authors | R. Iaria, M. Spano, T. di Salvo, N.R. Robba, L. Burderi, R.P. Fender, M. van der Klis, F. Frontera | | Title | On the Soft Excess in the X-Ray Spectrum of Circinus X-1: Revisitation of the Distance to Circinus X-1 |
| Journal | Astrophysical Journal |
| Volume | 619 |
| Year | 2005 |
| Issue | nr.1 part 1 |
| Pages | 503-516 |
| ISSN | 0004637X |
| Faculty | Faculty of Science |
| Institute/dept. | FNWI: Astronomical Institute Anton Pannekoek (IAP) |
| Keywords | accretion disks; neutron stars; X-ray binaries |
| Classification | 39.22 astrofysica |
| Abstract | We report on a 300 ks BeppoSAX (0.12-200 keV) observation of Circinus X-1 (Cir X-1) at phases between 0.62 and 0.84 and on a 90 ks BeppoSAX observation of Cir X-1 at phases 0.11-0.16. Using the canonical model adopted until now to fit the energy spectrum of this source, large residuals appear below 1 keV. These are well fitted using an equivalent hydrogen column of 0.66?10<SUP>22</SUP> cm<SUP>-2</SUP>, adding absorption edges of O VII, O VIII, and Ne IX in the spectra extracted from the observation at phases 0.62-0.84 and adding absorption edges of O VII, O VIII, Mg XI, and Mg XII and absorption lines of O VIII and Mg XII in the spectra extracted from the observation at phases 0.11-0.16. During the observation at phases 0.62-0.84 the electron density associated with the ionized matter is ~10<SUP>13</SUP> cm<SUP>-3</SUP>, remaining quite constant going away from the compact object. During the observation at phases 0.11-0.16, the electron density profile varies along the distance going from ~6?10<SUP>13</SUP> cm<SUP>-3</SUP> at ~10<SUP>11</SUP> cm to ~9?10<SUP>10</SUP> cm<SUP>-3</SUP> at ~10<SUP>13</SUP> cm. The equivalent hydrogen column toward Cir X-1 is 3 times lower than the value obtained from previous models. This low value would imply that Cir X-1 is at a distance of 4.1 kpc. |
| Note | (c)1995 American Astronomical Society |
| Document type | Article |
| Document finder | 
|
Use this url to link to this page: http://dare.uva.nl/en/record/150731
Contact us about this recordNotify a colleague
Add to bookbag
|
previous
