AR_final file_2018-19

Figure 10: Left Panel : Compares the vertical (space) profiles of azimuthal components of mean-field obtained from direct MHD simulations (dashed lines) and from 1-D dynamo simulations (solid lines) at various times in the evolution. Right Panel : Shows time evolution of magnetic energy from direct simulations (black-solid lines) and 1-D simulations (red-dashed lines), to avoid the clutter the red line is shifted up by 2 orders of magnitude, although they match reasonably well as shown in the inset. established in the cosmology community as the most robust and natural measure of violation of statistical isotropy (SI) in the cosmic microwave background anisotropy. One of most intriguing and highlighted results from Planck is a cosmic hemispherical asymmetry (CHA) in the CMB sky challenging the fundamen- tal cosmological principle is established through the BipoSH analysis at about 3 sigma significance. Shabbir Shaikh , Suvodip Mukherjee, Santanu Das, Tarun Souradeep and Ben Wandelt have worked on the Bayesian assessment of the CHA with the Planck maps. Early universe from CMB The remarkable progress in CMB studies over past decade has led to the era of precision cosmology in striking agreement with the LCDM model. How- ever, the estimation of cosmological parameters is based on the assumed form of the primordial power spectrum (typically, power-law). It is important to assess the impact that the assumed specific form of primordial power spectrum may have on the inferred cosmological parameters from CMB data. With Arman Shafieloo and Dhiraj Hazra, Tarun Souradeep has worked on projecting the current tension in the local and global estimates of the Hub- ble constant on the primordial power spectrum. High Energy Astrophysics Cyclotron Resonance Scattering Fea- tures Cyclotron Resonance Scattering Features (CRSFs) in an energy spectrum are an indicator of a strong magnetic field. The central line energy of the CRSF is used to estimate the local magnetic field. Ob- servations of such features in the X-ray spectrum places the observed magnetic field at a few times 10 12 G. Such high fields are expected from neutron star (NS) sources with matter accreting onto its sur- face. Due to the compact nature of NS, the speed of rotation is quite high and it provides views of different parts on the surface which inherently dif- fer. To probe these differences Yash Bhargava performed a pulse-phase resolved spectroscopy of Cepheus X-4, an outbursting high mass neutron star X-ray binary. The outburst of Cepheus X-4 in 2014 was cap- tured by Suzaku and NuSTAR at two epochs, the first one at the peak, and the second during the ( 73 )