Abstract Details
| Name: Kartick C Sarkar Affiliation: Raman Research Institute Conference ID: ASI2016_524 Title : Multi-wavelentgh emission from galactic winds and Fermi Bubbles Authors and Co-Authors : Kartick C Sarkar, Raman Research Institute, Bengaluru, India. Biman Nath, Raman Research Institute, Bengaluru, India. Prateek Sharma, Indian Institute of Science, Bengaluru, India. Yuri Shchekinov, P. N. Lebedev Physical Institute, Moscow, Russia. Abstract Type : Oral Abstract Category : Extragalactic astronomy Abstract : Modelling of emission from multiphase galactic outflows is important to decipher the feedback processes in galaxies. Fermi Bubbles (FBs) are excellent laboratories for such studies as they shine in radio, x-ray, gamma rays and also show kinematic signatures in UV absorption. Based on hydrodynamical simulations, we have studied the origin of FBs and related multi-band emissions. We show that a star formation rate (SFR) of 0.5 Msun/yr at the Galactic centre can give rise to the FBs over a time scale of ~30 Myrs. By modelling X-rays, we constrain the circum-galactic medium (CGM) density of our Galaxy to be ~2e-3 m_p/cc. Modelling of radio and gamma rays, using synchrotron and inverse Compton emission, shows that the magnetics field inside the bubbles is ~3\muG. Our model also provides explanation of the observed kinematics of absorption lines through the FBs. Not only from our Galaxy, X-rays from other star forming galaxies also can be related to the hot phase of the galactic wind. Recent observations show that diffused soft X-ray luminosity (Lx) \propto SFR^{1/3}, with large scatter at lower end of SFRs. We show that this relation can be well understood as the X-ray emission coming from the central star-forming region (Lx \propto SFR^2), and the CGM (Lx ~ constant). Our analysis shows that at higher SFRs (>~ few Msun/yr) the X-ray emission from the central region dominates, whereas, for lower SFRs (<~ 1 Msun/yr) the emission is dominated by the CGM. This approach naturally explains the observed stellar mass dependence of Lx and a large scatter at low SFR end. |