| Author(s) and Co-Author(s) with Affiliation: Swagat Bordoloi(Tezpur University, Napaam, 784028, Assam, India), Jayant Murthy(Indian Institute of Astrophysics, Bengaluru, 560034, Karnataka, India), P. Shalima(Manipal Centre for Natural Sciences, Manipal Academy of Higher Education, Karnataka, Manipal, 576104, India), Rupjyoti Gogoi(Tezpur University, Napaam, 784028, Assam, India), Oleg Malkov(Institute of Astronomy, 48 Pyatnitskaya St., Moscow 119017, Russia) |
| Abstract: We investigate the use of Far-Ultraviolet (FUV) data from Galaxy Evolution Explorer (GALEX) as a tracer for interstellar extinction towards the North Galactic Pole (NGP) of the Milky Way Galaxy. We prepare 6’ resolution maps of GALEX. We analyze the region at the high galactic latitudes (b > 70o) with low optical depth (τ < 0.1). We compare the GALEX map to Planck’s extinction data and find a moderate correlation between them (ρ = 0.578). Using the fit between GALEX and Planck’s, we convert the FUV surface brightness to FUV-derived E(B-V) map, and test the validity of the map. We test our extinction map using quasars observed by Sloan Digital Sky Survey (SDSS) as standard calibrators. We find a better fit between observed colors of the quasar colors and GALEX extinction, to estimate the intrinsic color for increasing redshift (z) for moderate starlight heating intensity (0.4 < Umin < 1.04). We calculate the extinction of quasars using the GALEX extinction map, and compare the extinctions for the quasars using Planck and Schlafly. We find a very good correlation between the quasar extinction estimates (0.986) stating the quasar extinction estimates are consistent with previous works. We finally compare the quasar extinctions, with the GALEX and Planck’s normalized value. We find a higher correlation of the quasar extinction values with the GALEX map, than Planck concluding the GALEX is a better tracer of extinction than Planck or Schlegel. To further conclude that our analysis is concrete, we find quasar extinctions using reddening from stellar observations. We find a lower standard deviation and mean difference using the GALEX.
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