898 research outputs found
X- and gamma-ray studies of HESS J1731-347 coincident with a newly discovered SNR
In the survey of the Galactic plane conducted with H.E.S.S., many VHE
gamma-ray sources were discovered for which no clear counterpart at other
wavelengths could be identified. HESS J1731-347 initially belonged to this
source class. Recently however, the new shell-type supernova remnant (SNR)
G353.6-0.7 was discovered in radio data, positionally coinciding with the VHE
source. We will present new X-ray observations that cover a fraction of the VHE
source, revealing nonthermal emission that most likely can be interpreted as
synchrotron emission from high-energy electrons. This, along with a larger
H.E.S.S. data set which comprises more than twice the observation time used in
the discovery paper, allows us to test whether the VHE source may indeed be
attributed to shell-type emission from that new SNR. If true, this would make
HESS J1731-347 a new object in the small but growing class of non-thermal
shell-type supernova remnants with VHE emission.Comment: 4 pages, 5 figures, to appear in proceedings of the 31st ICRC, Lodz,
Polan
The H.E.S.S. multi-messenger program
Based on fundamental particle physics processes like the production and
subsequent decay of pions in interactions of high-energy particles, close
connections exist between the acceleration sites of high-energy cosmic rays and
the emission of high-energy gamma rays and high-energy neutrinos. In most cases
these connections provide both spatial and temporal correlations of the
different emitted particles. The combination of the complementary information
provided by these messengers allows to lift ambiguities in the interpretation
of the data and enables novel and highly sensitive analyses. In this
contribution the H.E.S.S. multi-messenger program is introduced and described.
The current core of this newly installed program is the combination of
high-energy neutrinos and high-energy gamma rays. The search for gamma-ray
emission following gravitational wave triggers is also discussed. Furthermore,
the existing program for following triggers in the electromagnetic regime was
extended by the search for gamma-ray emission from Fast Radio Bursts (FRBs). An
overview over current and planned analyses is given and recent results are
presented.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherland
The H.E.S.S. II GRB Program
Gamma-ray bursts (GRBs) are some of the most energetic and exotic events in
the Universe, however their behaviour at the highest energies (>10 GeV) is
largely unknown. Although the Fermi-LAT space telescope has detected several
GRBs in this energy range, it is limited by the relatively small collection
area of the instrument. The H.E.S.S. experiment has now entered its second
phase by adding a fifth telescope of 600 m mirror area to the centre of
the array. This new telescope increases the energy range of the array, allowing
it to probe the sub-100 GeV range while maintaining the large collection area
of ground based gamma-ray observatories, essential to probing short-term
variability at these energies. We will present a description of the GRB
observation scheme used by the H.E.S.S. experiment, summarising the behaviour
and performance of the rapid GRB repointing system, the conditions under which
potential GRB repointings are made and the data analysis scheme used for these
observations.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherland
IGR J11014-6103: a newly discovered pulsar wind nebula?
Context: IGRJ11014-6103 is one of the still unidentified hard X-ray INTEGRAL
sources, reported for the first time in the 4th IBIS/ISGRI catalog. Aims: We
investigated the nature of IGR J11014-6103 by carrying out a multiwavelength
analysis of the available archival observations performed in the direction of
the source. Methods: We present first the results of the timing and spectral
analysis of all the X-ray observations of IGR J11014-6103 carried out with
ROSAT, ASCA, Einstein, Swift, and XMM-Newton, and then use them to search for
possible counterparts to the source in the optical, infra-red, radio and
gamma-ray domain. Results: Our analysis revealed that IGR J11014-6103 is
comprised of three different X-ray emitting regions: a point-like source, an
extended object and a cometary-like "tail" (~4 arcmin). A possible radio
counterpart positionally coincident with the source was also identified.
Conclusions: Based on these results, we suggest that the emission from IGR
J11014-6103 is generated by a pulsar wind nebula produced by a high-velocity
pulsar. IGR J11014-6103 might be the first of these systems detected with
INTEGRAL IBIS/ISGRI.Comment: A&A accepted, 8 pages, 8 figures, 2 table
H.E.S.S. observations of PSR B1259-63 during its 2014 periastron passage
An extended observation campaign of the gamma-ray binary system PSR
B125963 has been conducted with the H.E.S.S. (High Energy Stereoscopic
System) II 5-telescope array during the system's periastron passage in 2014. We
report on the outcome of this campaign, which consists of more than 85 h of
data covering both pre- and post-periastron orbital phases. The lower energy
threshold of the H.E.S.S. II array allows very-high-energy (VHE; GeV) gamma-ray emission from PSR B125963 to be studied for the first
time down to 200 GeV. The new dataset partly overlaps with and extends in phase
previous H.E.S.S. campaigns on this source in 2004, 2007 and 2011, allowing for
a detailed long-term characterisation of the flux level at VHEs. In addition,
the 2014 campaign reported here includes VHE observations during the exact
periastron time, , as well as data taken simultaneously to the
gamma-ray flare detected with the Fermi-LAT. Our results will be discussed in a
multiwavelength context, thanks to the dense broad-band monitoring campaign
conducted on the system during this last periastron passage.Comment: 8 pages, 5 figures. In Proceedings of the 34th International Cosmic
Ray Conference (ICRC2015), The Hague, The Netherland
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