Milky Way dust extinction measured with QSOs

TL;DR

This study uses over 50,000 quasars from SDSS to measure Milky Way dust extinction, revealing that the Schlafly & Finkbeiner (2011) extinction vector fits better than previous models and identifying non-linearity in the SFD reddening map.

Contribution

It provides empirical evidence that the Schlafly & Finkbeiner (2011) extinction vector is more accurate and uncovers non-linearity in the SFD reddening map across different probes.

Findings

Schlafly & Finkbeiner (2011) extinction vector fits data better.

Evidence of non-linearity in the SFD reddening map.

Non-linearity observed with quasars, galaxies, and stars as probes.

Abstract

We investigate reddening by Milky Way dust in the low-extinction regime of $E_{B-V}<0.15$. Using over 50,000 QSOs at $0.5<z<2.5$ from the SDSS DR7 QSO Catalogue we probe the residual SDSS colours after dereddening and correcting for the known spectroscopic redshifts. We find that the extinction vector of Schlafly & Finkbeiner (2011) is a better fit to the data than that used by Schlegel et al. (1998, SFD). There is evidence for a non-linearity in the SFD reddening map, which is similarly present in the V1.2 map of the Planck Collaboration. This non-linearity is similarly seen when galaxies or stars are used as probes of the SFD map.