7 research outputs found
XMMU J0541.8-6659, a new supernova remnant in the Large Magellanic Cloud
The high sensitivity of the XMM-Newton instrumentation offers the opportunity
to study faint and extended sources in the Milky Way and nearby galaxies such
as the Large Magellanic Cloud (LMC) in detail. The ROSAT PSPC survey of the LMC
has revealed more than 700 X-ray sources, among which there are 46 supernova
remnants (SNRs) and candidates. We have observed the field around one of the
most promising SNR candidates in the ROSAT PSPC catalogue, labelled [HP99] 456
with XMM-Newton, to determine its nature. We investigated the XMM-Newton data
along with new radio-continuum, near infrared and optical data. In particular,
spectral and morphological studies of the X-ray and radio data were performed.
The X-ray images obtained in different energy bands reveal two different
structures. Below 1.0 keV the X-ray emission shows the shell-like morphology of
an SNR with a diameter of ~73 pc, one of the largest known in the LMC. For its
thermal spectrum we estimate an electron temperature of (0.49 +/- 0.12)keV
assuming non-equilibrium ionisation. The X-ray images above 1.0 keV reveal a
less extended source within the SNR emission, located ~1' west of the centre of
the SNR and coincident with bright point sources detected in radio-continuum.
This hard component has an extent of 0.9' (i.e. ~13 pc at a distance of ~50
kpc) and a non-thermal spectrum. The hard source coincides in position with the
ROSAT source [HP99] 456 and shows an indication for substructure. We firmly
identify a new SNR in the LMC with a shell-like morphology and a thermal
spectrum. Assuming the SNR to be in the Sedov phase yields an age of ~23 kyr.
We explore possible associations of the hard non-thermal emitting component
with a pulsar wind nebula (PWN) or background active galactic nuclei (AGN).Comment: 8 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Multi-frequency study of supernova remnants in the Large Magellanic Cloud. Confirmation of the supernova remnant status of DEM L205
We present new X-ray and radio data of the LMC SNR candidate DEM L205,
obtained by XMM-Newton and ATCA, along with archival optical and infrared
observations. We use data at various wavelengths to study this object and its
complex neighbourhood, in particular in the context of the star formation
activity, past and present, around the source. We analyse the X-ray spectrum to
derive some remnant's properties, such as age and explosion energy. Supernova
remnant features are detected at all observed wavelengths: soft and extended
X-ray emission is observed, arising from a thermal plasma with a temperature kT
between 0.2 keV and 0.3 keV. Optical line emission is characterised by an
enhanced [SII]/Halpha ratio and a shell-like morphology, correlating with the
X-ray emission. The source is not or only tentatively detected at near-infrared
wavelengths (< 10 microns), but there is a detection of arc-like emission at
mid and far-infrared wavelengths (24 and 70 micron) that can be unambiguously
associated with the remnant. We suggest that thermal emission from dust heated
by stellar radiation and shock waves is the main contributor to the infrared
emission. Finally, an extended and faint non-thermal radio emission correlates
with the remnant at other wavelengths and we find a radio spectral index
between -0.7 and -0.9, within the range for SNRs. The size of the remnant is
~79x64 pc and we estimate a dynamical age of about 35000 years. We definitely
confirm DEM L205 as a new SNR. This object ranks amongst the largest remnants
known in the LMC. The numerous massive stars and the recent outburst in star
formation around the source strongly suggest that a core-collapse supernova is
the progenitor of this remnant. (abridged)Comment: 11 pages, 6 figures, accepted for publication in A&
ALICE A Large Ion Collider Experiment
POLAR-2 is a follow-up GRB mission of POLAR, which has observed low levels of polarization degree and a temporal evolution of the polarization angle, indicating that time resolved studies of photons polarization are required to constrain theoretical emission models of GRB’s. POLAR-2 detector aim to put in space a detector with one order of magnitude sensitivity improvement versus POLAR. POLAR-2 will be the most sensitive GRB detector covering half of the sky. The instrument, proposed by an international collaboration, was selected to be launched in 2024 to the China Space Station and operate for at least 2 years. POLAR-2 will use same plastic bar concept then POLAR but will be readout by SiPMT. The payload will also feature a spectrometer. The instrument is foreseen to perform detailed polarization measurements of at least 100 GRBs