Year: 2018
Type: article
Abstract: We use cosmological hydrodynamical simulations of Milky Way–mass galaxies from the FIRE project to evaluate various strategies for estimating the mass of a galaxy’s stellar halo from deep, integrated-light images. We find good agreement with integrated-light observations if we mimic observational methods to measure the mass of the stellar halo by selecting regions of an image via projected radius relative to the disk scale length or by their surface density in stellar mass. However, these observational methods systematically underestimate the accreted stellar component, defined in our (and most) simulations as the mass of stars formed outside of the host galaxy, by up to a factor of 10, since the accreted component is centrally concentrated and therefore substantially obscured by the galactic disk. Furthermore, these observational methods introduce spurious dependencies of the estimated accreted stellar component on the stellar mass and size of galaxies that can obscure the trends in accreted stellar mass predicted by cosmological simulations, since we find that in our simulations, the size and shape of the central galaxy are not strongly correlated with the assembly history of the accreted stellar halo. This effect persists whether galaxies are viewed edge-on or face-on. We show that metallicity or color information may provide a way to more cleanly delineate in observations the regions dominated by accreted stars. Absent additional data, we caution that estimates of the mass of the accreted stellar component from single-band images alone should be taken as lower limits.
Source: The Astrophysical Journal
Authors: Robyn E. Sanderson, Shea Garrison-Kimmel, Andrew Wetzel, Tsang Keung Chan, Philip F. Hopkins, Dušan Kereš, Ivanna Escala, Claude-André Faucher-Giguère, Xiangcheng Ma
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,499
Awards: G1018901574, G1390571956, G2046453982, Collaborative Research: CDS&E: Mining Physically Predictive Cosmological Simulations, THE INSTALLATION OF THE COSMIC ORIGINS SPECTROGRAPH (COS) ON THE HUBBLE SPACE TELESCOPE (HST) AS PART OF ITS LAST SERVICING MISSION HAS REVOLUTIONIZE, G2527561626, G2567323416, Collaborative Research: CDS&E: FIRE: Physically-Predictive Cosmological Simulations of Galaxy Formation with Resolved Feedback, G3253680200, G3360376885, G3428510315, G3561758408, G3591616885, CAREER: The Physics of Stellar Feedback and Star Formation Regulation in Galaxies, G3815726687, G407650688, G4211193789, Collaborative Research: CDS&E: Mining Physically Predictive Cosmological Simulations, G4818530208, G4843946229, Weighing and measuring the Milky Way and other galaxies, G503113663, G5519527588, CAREER: The Ties that (Un)Bind: Understanding the Connection Between Galaxies, Stars, and Black Holes, G5780980149, G5996804137, G6125920559, Collaborative Research: CDS&E: FIRE: Physically-Predictive Cosmological Simulations of Galaxy Formation with Resolved Feedback, G6389167996, G6549248135, G6653398072, G6671297155, Toward physically-predictive modeling of massive black hole growth and feedback in galaxy formation, G7515644704, G7618195524, Collaborative Research: CDS&E: Mining Physically Predictive Cosmological Simulations, G7857352519, G8086438903, G8432928527, G8493109902, G8561699031, Probing New Physics in Galaxy Formation at Ultra-High Resolution, G8970859722
OpenAlex ID: W2776351085