Loading...
Please wait, while we are loading the content...
Similar Documents
Photoionization modeling of oxygen k absorption in the interstellar medium:. [the chandra grating spectra of xte j1817-330]
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Gatuzz, E. Quinet, P. Garcia, J. Palmeri, P. Kallman, T. R. Bautista, M. A. Mendoza, C. Witthoeft, M. Lohfink, A. |
| Copyright Year | 2013 |
| Description | We present detailed analyses of oxygen K absorption in the interstellar medium (ISM) using four high-resolution Chandra spectra toward the X-ray low-mass binary XTE J1817-330. The 11-25 Angstrom broadband is described with a simple absorption model that takes into account the pile-up effect and results in an estimate of the hydrogen column density. The oxygen K-edge region (21-25 Angstroms) is fitted with the physical warmabs model, which is based on a photoionization model grid generated with the xstar code with the most up-to-date atomic database. This approach allows a benchmark of the atomic data which involves wavelength shifts of both the K lines and photoionization cross sections in order to fit the observed spectra accurately. As a result we obtain a column density of N(sub H) = 1.38 +/- 0.01 Ã 10(exp 21) cm(exp â2); an ionization parameter of log xi = â2.70 +/- 0.023; an oxygen abundance of A(sub O) = 0.689 (+0.015/â0.010); and ionization fractions of O(sub I)/O = 0.911, O(sub II)/O = 0.077, and O(sub III)/O = 0.012 that are in good agreement with results from previous studies. Since the oxygen abundance in warmabs is given relative to the solar standard of Grevesse & Sauval, a rescaling with the revision by Asplund et al. yields A(sub O) = 0.952(+0.020/â0.013), a value close to solar that reinforces the new standard.We identify several atomic absorption lines-K(alpha), K(beta), and K(gamma) in O(sub I) and O(sub II) and K(alpha) in O(sub III), O(sub VI), and O(sub VII)-the last two probably residing in the neighborhood of the source rather than in the ISM. This is the first firm detection of oxygen K resonances with principal quantum numbers n greater than 2 associated with ISM cold absorption. |
| File Size | 947758 |
| Page Count | 11 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20140017168 |
| Archival Resource Key | ark:/13960/t1sf7rz6w |
| Language | English |
| Publisher Date | 2013-04-15 |
| Access Restriction | Open |
| Subject Keyword | Oxygen Modeling Photoionization Quantum Numbers Hydrogen Estimates Data Reduction Data Bases Oxygen Spectra Mass X Ray Binaries Astronomical Models X Ray Spectra Absorption Spectra K Lines X Ray Astrophysics Facility Interstellar Matter Xmm-newton Telescope Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
