HESS J1616-508: likely powered by PSR J1617-5055 ?
HESS J1616-508 is one of the brightest sources in the TeV sky and is located
in a complex region containing two known supernova remnants: RCW 103 and
Kes 32, which do not coincide with the HESS extension.
A detailed X-ray analysis of the region surrounding HESS J1616-508 provides
one clear result: there is no fully convincing X-ray counterpart within the
TeV extension. Furthermore, the compact object, 1E 161348-5055.1, located at
the centre of RCW 103, is too variable to be associated with the stable HESS
source.
Recent observations with INTEGRAL/IBIS have revealed that a young, nearby and
energetic pulsar, PSR J1617-5055, is a powerful emitter of soft gamma-rays in
the 20-100 keV energy domain. The upper left panel of the picture shows the
18-60 keV energy band INTEGRAL image of the region surrounding HESS J1616-508.
Co-ordinates are in RA and delta. The green circle represents the HESS TeV
extension, while pulsar PSR J1617-5055 (labelled as A) is within the IBIS
error box (small yellow circle).
The INTEGRAL detection combined with the lack of any counterpart to the HESS
source obtained with Swift, XMM-Newton (upper right panel) and BeppoSAX data
(central panels) covering the TeV region, make the offset pulsar PSR J1617-5055
the likely candidate for the TeV emission. This hypothesis is also supported by
the fact that the INTEGRAL spectrum smoothly connects with the BeppoSAX and
XMM-Newton spectra (lower panel), and that the luminosity is consistent with
that expected from a young radio pulsar.
The relative sizes of the X/gamma-ray and VHE sources are consistent with the
expected lifetimes against synchrotron and Compton losses for a single source
of parent electrons emitted from the pulsar.
The observed spectral index (Gamma = 1.4) of the combined X/soft gamma-ray
emission (lower panel), and that of the TeV emission (Gamma = 2.4) are
consistent with this scenario.
This suggests that the HESS J1616-508 source is driven by PSR J1617-5055
in which synchrotron and inverse Compton processes combine to create the
observed morphology of a broad-band emitter from keV to TeV energies.
Credit: R. Landi, IASF-Bologna, INAF. Details of this observations are
described in R. Landi et al. 2007,
astro-ph(0707.0832), M.N.R.A.S in press
