Abstract Details
| Name: Arnab Chakraborty Affiliation: Center Of Astronomy,IIT-Indore Conference ID: ASI2018_1681 Title : Recent uGMRT observations of ELAIS-N1 field Authors and Co-Authors : Dr.Abhirup Datta,IIT-Indore Dr.Nirupam Roy,IISC Bangalore, Dr.Samir Choudhury, NCRA-TIFR Abstract Type : Poster Abstract Category : Extragalactic astronomy Abstract : Detection of the redshifted 21-cm radiation from the large scale distribution of neutral hydrogen against cosmic microwave background is considered as a promising probe for the cosmic Dark ages, Cosmic Dawn and Epoch of Reionization.This radiation appears as a very faint,diffuse background radiation in all low frequency radio observation below 1420 Mhz. At these frequencies the signal is largely dominated by bright foregrounds which are four to five orders of magnitude stronger than the redshifted signal.In addition, the ground based experiment are affected by the human generated RFI , like the FM band, and Earth’s ionosphere.The galactic synchrotron emission is expected to be the most dominant foreground at angular scale greater than 10 arcsec. Accuracy of the extraction of the 21-cm signal depends on the ability to characterize and remove the foregrounds from the observed data-sets. There are mainly three techniques used to deal with foregrounds --- foreground avoidance, foreground suppression and foreground removal. These techniques would require the knowledge of spatial and frequency characteristics of foregrounds.Here, we present our attempt to quantify the point source flux density distribution in frequency range 300-500 Mhz with a pilot observation of target field ELAISN1 with uGMRT. We estimate the accuracy of different point source subtraction techniques. With this wide-band observation we use different imaging and calibration methods to understand the relative performance of individual technique to produce the best possible image from the data. This best possible image then serves as a starting point to estimate the foregrounds. This will allow us to converge to few optimal algorithms to characterize and remove foregrounds for upcoming uGMRT 150 MHz band observations as well as international projects like SKA, HERA, etc. |