# The extinction properties of long GRB host galaxies from H and He I recombination lines

Source: [The extinction properties of long GRB host galaxies from H and He I recombination lines](<https://www.sota2.com/research/paper/68fa2f921e209131ce86d494>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T17:39:09.170Z

Authors: K. Wiersema

Published: 2011-01-04T21:00:26.000Z

## Abstract

In this paper we show how a self-consistent treatment of hydrogen and helium emission line fluxes of the hosts of long gamma-ray bursts can result in improved understanding of the dust properties in these galaxies. In particular, we find that even with modest signal to noise spectroscopy we can differentiate different values for R\_V, the ratio of total to selective extinction. The inclusion of Paschen and Brackett lines, even at low signal to noise, greatly increase the accuracy of the derived reddening. This method is often associated with strong systematic errors, caused by the need for multiple instruments to cover the wide wavelength range, the requirement to separate stellar hydrogen absorption from the nebular emission, and because of the dependancy of the predicted line fluxes on the electron temperature. We show how these three systematic errors can be negated, by using suitable instrumentation (in particular X-shooter on the Very Large Telescope) and wide wavelength coverage. We demonstrate this method using an extensive optical and near-infrared spectroscopic campaign of the host galaxy of gamma-ray burst 060218 (SN 2006aj), obtained with FORS1, UVES and ISAAC on the VLT, covering a broad wavelength range with both high and low spectral resolution. We contrast our findings of this source with X-shooter data of a star forming region in the host of GRB 100316D, and show the improvement over existing published fluxes of long GRB hosts.

## Recorded benchmark results

A research result applies to its stated dataset, split, metric and evaluation configuration. Compare like-for-like settings, preserve the metric's unit and direction, and distinguish paper-reported results from independent reproduction. The best result recorded here is not a claim of exhaustive, current global coverage.

## Original sources and implementation

[Original paper](<https://arxiv.org/abs/1101.0814>)

[PDF](<https://arxiv.org/pdf/1101.0814.pdf>)