Two Suzaku Observations of the Cyclotron Line Source 4U 1907+09
Abstract
Suzaku observed the accreting pulsar 4U 1907+09 in May 2006 and in April 2007. We present and compare the light curves and broad band spectra of both observations. The 10 mCrab source is strongly variable and shows a rich phenomenology. While the 2006 observation is dominated by typical, non-absorption-related dipping behavior, the 2007 observation shows equally typical flaring behavior in both the XIS and PIN light curves. Above 2 keV the average combined XIS and PIN broad band spectrum can be well described by standard pulsar continuum models, modified by the fundamental cyclotron resonant scattering feature at 19 keV. We model the cyclotron line using the standard phenomenological Gaussian model as well as a new physically motivated Green's functions based approach (Schoenherr et al., 2007, A&A 472, 353). Below 2 keV the XIS spectra allow for the first detection of a soft excess in this source, in addition to providing the best determination of the parameters of the weak iron line at 6.4 keV (EW 70 eV) to date.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AAS...211.0301P