XMM-Newton Observation of the composite SNR G0.9+0.1

and the discovery of a new transient source

Lara Sidoli (IASF Milano)Fabrizio Bocchino (Oss. Palermo) Sandro Mereghetti (IASF Milano) Rino Bandiera (Oss. Arcetri)

OverviewOverview

● Preliminary XMM results on the SNR G0.9+0.1● X-ray emission from the Pulsar Wind Nebula● X-ray emission from the radio shell ?● Discovery of a new X-ray Transient in the

Galactic Center region

The Composite SNS G0.9+0.1: radio vs X-rays

● Radio polarized core (2'diameter) and a radio shell (8' diameter)

● Galactic Center region: the high absorption hampered the discovery at soft X-rays

● BeppoSAX discovery of X-rays from the PWN (Mereghetti, Sidoli, Israel 1998)

XMM-Newton Observation

XMM-Newton vs Chandra

● Expanded view of the central part of the XMM-Newton PN image (2-10 keV)

● Comparison with the different substructures resolved with Chandra inside the PWN

Radial profile

● Comparison of the G0.9+0.1 radial profile with the LMC X-3 profile taken as reference for the PSF

● --- 2-5 keV● --- 2-10 keV● --- 5-10 keV

Spectral Analysis: the entire PWN

● We extracted PN and both MOS counts from within 1' from the PWN peak and corrected with a local background

PWN spectral results

Spectral Softening at larger distance

● Analysis of 3 spectra extracted from 3 annular regions centered on the PWN shows a spectral softening

● Powerlaw fits performed fixing the column density at the entire PWN spectrum best fit

Preliminary results on the X-ray emission from the radio shell

● Net rate from the radio shell region 0.0097 +/- 0.0011 counts/s (3-6 keV)

X-rays from the shell region

Discovery of a NEW TRANSIENT Source in the Galactic Center region

● A new X-ray source at R.A.=17h 47m 16.0s Dec= -28deg 10' 45''

● Comparison between a GC survey observation performed on Sept.23, 2000 (Porquet et al. 2003) and our observation performed on March 12, 2003

Spectral Analysis of the New Transient

● Powerlaw model fit to the X-ray Transient Spectrum:

● Absorption Column Density ~ 8 E22 cm-2

● Photon Index = 2.1 +/- 0.1

● Unabs. Flux = 6.8 E-12 erg/cm2/s

● Luminosity (2-10 keV) ~ 7 E34 erg/s (@ 10 kpc)

● It's likely a transient LMXB located in the GC region

Conclusions

● Preliminary results on the Composite SNR G0.9+0.1:

● Entire PWN spectrum well fit with a power law with typical parameters of other PWNs

– No hardness variations inside the nebula, with respect to XMM 2000 observation

– Spectral Softening of the X-ray emission in the PWN with increasing distance from its brightness peak

● Possible detection of X-rays from the radio shell (confirming Porquet et al. 2003 discovery), maybe of non-thermal origin

Conclusions 2

● Discovery of a New X-ray Transient source – High absorption– Spectrum well fit with a single powerlaw– Change in the observed flux of at least a factor of 80

between 2000 and 2003 XMM-Newton observation● It is likely a transient LMXB in the GC region