Foreground of Gamma-Ray Bursts (Grbs) From Akari Fis Data

Abstract

A significant number of the parameters of a gamma-ray burst (GRB) and its host galaxy are calculated from the afterglow. There are various methods obtaining extinction values for the necessary correction for galactic foreground. These are: galaxy counts, from HI 21 cm surveys, from spectroscopic measurements and colors of nearby Galactic stars, or using extinction maps calculated from infrared surveys towards the GRB. We demonstrate that AKARI Far-Infrared Surveyor sky surface brightness maps are useful uncovering the fine structure of the galactic foreground of GRBs. Galactic cirrus structures of a number of GRBs are calculated with a 2 arcminute resolution, and the results are compared to that of other methods.

Studying the variability of the X‐ray spectral parameters of high‐redshift GRBs' afterglows

“…The time evolution of the intrinsic N ( H ) shows that a precise galactic foreground estimation is essential, because that might significantly modify the calculated values in certain cases. We also note that, as the galactic foreground seems to show filamentary structures as was suggested by Toth et al (), this structure can cause over an order of magnitude change in the measured column density in small scales.…”

“…The galactic foreground is not as homogeneous as we have previously thought (Rácz et al, 2017;Toth et al, 2017). It seems to be heavily structured and clumpy.…”

“…The long GRBs are believed to be indicators of star formation and, as such, indicate the large scale structures of the Universe Balázs, Mészáros, Horváth, & Vavrek, 1999;A. Mészáros, Bagoly, Horváth, Balázs, & Vavrek, 2000;Vavrek, Balázs, Mészáros, Horváth, & Bagoly, 2008;Veres, Bagoly, Horváth, Balázs, et al, 2010). Horváth, Hakkila, & Bagoly (2014) and the Giant GRB Ring was found by Balázs et al (2015); Balázs, Rejtó, & Tusnády (2018).…”

Multi‐messenger studies of γ‐ray bursts and their cosmic environment

“…Using AKARI FIS-based estimates, Tóth et al (2018Tóth et al ( , 2017 noted that the use of high-resolution maps for calculating the column density of the galactic cirrus foreground may increase the accuracy of the estimation of intrinsic column densities. As a representation of the differences between the Galactic foreground N(H) column densities derived from observations with various spatial resolutions, we show our results based on the 5 ′ -resolution Planck and the 40 ′′ -resolution Herschel SPIRE (Griffin et al 2010) observations.…”

The structure of the ISM in the Zone of Avoidance by high-resolution multi-wavelength observations

“…AKARI FIS full sky FIR images were recently published by Doi et al (2015) with a detection limit of about < 10 MJysr −1 and a relative photometric accuracy of about < 20%. We substracted 30 by 30 images centered on GRBs with known spectroscopic redshifts from Horváth et al (2014), and smoothed those to 2 spatial resolution to calculate hydrogen column densities as described in Toth et al(2017).…”