Recent Results from SPLASH: Chemical Abundances and Kinematics of Andromeda's Stellar Halo

TL;DR

This paper reviews recent findings from the SPLASH survey, which uses photometric and spectroscopic data to analyze the structure, metallicity, and kinematics of Andromeda's stellar halo, revealing its extended profile, metallicity gradient, and heated disk stars.

Contribution

It presents new observational results from the SPLASH survey, including detailed measurements of Andromeda's stellar halo properties and insights into its structure and dynamics.

Findings

Power-law surface brightness profile extends to two-thirds of virial radius

Metallicity gradient observed up to 100 kpc from galaxy center

Evidence of heated disk stars in the inner halo

Abstract

Large scale surveys of Andromeda's resolved stellar populations have revolutionized our view of this galaxy over the past decade. The combination of large-scale, contiguous photometric surveys and pointed spectroscopic surveys has been particularly powerful for discovering substructure and disentangling the structural components of Andromeda. The SPLASH (Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo) survey consists of broad- and narrow-band imaging and spectroscopy of red giant branch stars in lines of sight ranging in distance from 2 kpc to more than 200 kpc from Andromeda's center. The SPLASH data reveal a power-law surface brightness profile extending to at least two-thirds of Andromeda's virial radius (Gilbert et al. 2012), a metallicity gradient extending to at least 100 kpc from Andromeda's center (Gilbert et al. 2014), and evidence of a significant population of heated disk stars in Andromeda's inner halo (Dorman et al. 2013). We are also using the velocity distribution of halo stars to measure the tangential motion of Andromeda (Beaton et al., in prep).