Seminar:"The scarcely known X-ray pulsar 4U 1909+07-An overlooked pearl"

The scarcely known X-ray pulsar 4U 1909+07 - an overlooked pearl




Speaker: Ingo Kreykenbohm, University of Erlangen, Germany



Abstract: After an introduction in general X-ray astronomy I
will present an overview of X-ray binaries and accretion onto a compact
object with special emphasis on accretion from the stellar wind. In the
second


half of the talk, I will present a detailed spectral and temporal
analysis of the accreting High Mass X-ray Binary (HMXB) pulsar 4U
1909+07 using INTEGRAL and RXTE data. The source was only in the last
years discovered to be a pulsar, although it is known since the early
1970s. 4U 1909+07 is typically detected at a level of about 15 mCrab in
INTEGRAL/ISGRI, but can reach about 300 mCrab during flaring


activity. The neutron star exhibits a very long pulse period of 605s
and a surprising strongly energy dependent pulse profile. While phase
averaged spectra of accreting X-ray pulsars are usually well described


by a powerlaw modified at higher energies by an exponential cutoff, the
spectrum of 4U 1909+07 requires an additional blackbody component at
low energies. Pulse phase resolved spectroscopy reveals that this
blackbody component as well as the cutoff energy are strongly variable
with pulse phase while.



23 June Wednesday 2010, at 13.40 FENS G025