Validations and Corrections of the SFD and Planck Reddening Maps Based on LAMOST and Gaia Data

TL;DR

This study evaluates and calibrates the SFD and Planck dust reddening maps using LAMOST and Gaia data, identifying biases and providing corrections to improve extinction accuracy in astronomical observations.

Contribution

It offers the first detailed calibration of SFD and Planck maps using large stellar datasets, revealing spatial biases and dependencies on dust properties, with empirical correction relations.

Findings

Identified spatial biases in SFD and Planck maps.

Biases depend on dust temperature and spectral index.

Provided correction formulas for improved reddening estimates.

Abstract

Precise correction of dust reddening is fundamental to obtain the intrinsic parameters of celestial objects. The Schlegel et al. (SFD) and the Planck 2D extinction maps are widely used for the reddening correction. In this work, using accurate reddening determinations of about two million stars from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) data release 5 (DR5) and Gaia DR2, we check and calibrate the SFD and Planck maps in the middle and high Galactic latitudes. The maps show similar precision in reddening correction. We find small yet significant spatially dependent biases for the four maps, which are similar between the SFD and Planck2014-R maps, and between the Planck2014-Tau and Planck2019-Tau maps. The biases show a clear dependence on the dust temperature and extinction for the SFD and Planck2014-R maps. While those of the Planck2014-Tau and Planck2019-Tau maps have a weak dependence on the dust temperature, they both strongly depend on the dust spectral index. Finally, we present corrections of the SFD and Planck extinction maps within the LAMOST footprint, along with empirical relations for corrections outside the LAMOST footprint. Our results provide important clues for the further improvement of the Galactic all-sky extinction maps and lay an significant foundation for the accurate extinction correction in the era of precision astronomy.