ﻻ يوجد ملخص باللغة العربية
We summarize three recent publications which suggest that the Galactic center region Sagittarius B (Sgr B) may contain non-thermal radio components (Crocker et al. 2007, Hollis et al. 2007 and Yusef-Zadeh et al. 2007a). Based on new VLA matched-resolution continuum data at 327 MHz and 1.4 GHz, we find no evidence for large scale non-thermal radio emission at these frequencies; the spectral behavior is likely determined by the complex summation of multiple HII region components with a wide range of emission measures and hence radio turn-over frequencies. Also, we discuss a possible additional interpretation of the radio continuum spectrum of individual component Sgr B2-F carried out by Yusef-Zadeh et al; confusion from nearby HII components with widely different turn-over frequencies may contribute to the the change in slope of the radio continuum in this direction at low frequencies. Finally, we discuss the uncertainties in the determination of the spectral index of the GBT continuum data of Sgr B carried out by Hollis et al. We find that the apparent spectral index determined by their procedure is also likely due to a summation over the many diverse thermal components in this direction.
Sagittarius A* exhibits regular variability in its multiwavelength emission, including daily X-ray flares and roughly continuous near-infrared (NIR) flickering. The origin of this variability is still ambiguous since both inverse Compton and synchrot
The giant molecular cloud Sagittarius B2 (hereafter SgrB2) is the most massive region with ongoing high-mass star formation in the Galaxy. In the southern region of the 40-pc large envelope of SgrB2, we encounter the SgrB2(DS) region which hosts more
Radio and $gamma$-ray measurements of large lobes of several radio galaxies provide adequate basis for determining whether emission in these widely separated spectral regions is largely by energetic electrons. This is very much of interest as there i
I briefly review our current knowledge of the non thermal emission from galaxy clusters and discuss future prospect with Simbol-X. Simbol-X will map the hard X-ray emission in clusters, determine its origin and disentangle the thermal and non-thermal
Radio continuum observations detect non-thermal synchrotron and thermal bremsstrahlung radiation. Separation of the two different emission components is crucial to study the properties of diffuse interstellar medium. The Cygnus X region is one of the