The mass profiles of dwarf galaxies from Dark Energy Survey lensing

doi:10.1093/mnras/stae2040

Authors

RefereedArticle

Abstract

We present a novel approach to extracting dwarf galaxies from photometric data to measure their average halo mass profile with weak lensing. We characterize their stellar mass and redshift distributions with a spectroscopic calibration sample. By combining the

${\sim} 5000\,\mathrm{deg}^2$

multiband photometry from the Dark Energy Survey and redshifts from the Satellites Around Galactic Analogs Survey with an unsupervised machine learning method, we select a low-mass galaxy sample spanning redshifts

$z\lt 0.3$

and divide it into three mass bins. From low to high median mass, the bins contain [146 420, 330 146, 275 028] galaxies and have median stellar masses of

$\log _{10}(M_*/\text{M}_\odot)=\left[8.52\substack{+0.57 -0.76},\, 9.02\substack{+0.50 -0.64},\, 9.49\substack{+0.50 -0.58}\right]$

. We measure the stacked excess surface mass density profiles,

$\Delta \Sigma (R)$

, of these galaxies using galaxy-galaxy lensing with a signal-to-noise ratio of [14, 23, 28]. Through a simulation-based forward-modelling approach, we fit the measurements to constrain the stellar-to-halo mass relation and find the median halo mass of these samples to be

$\log _{10}(M_{\rm halo}/\text{M}_\odot)$

= [

$10.67\substack{+0.2 -0.4}$

,

$11.01\substack{+0.14 -0.27}$

,

$11.40\substack{+0.08 -0.15}$

]. The cold dark matter profiles are consistent with NFW (Navarro, Frenk, and White) profiles over scales

${\lesssim} 0.15 \, {h}^{-1}$

Mpc. We find that

${\sim} 20$

per cent of the dwarf galaxy sample are satellites. This is the first measurement of the halo profiles and masses of such a comprehensive, low-mass galaxy sample. The techniques presented here pave the way for extracting and analysing even lower mass dwarf galaxies and for more finely splitting galaxies by their properties with future photometric and spectroscopic survey data.

Details

Publication

Monthly Notices of the Royal Astronomical Society, Volume 535, Issue 1, pp.1-20

Publication Date

November 2024

DOI

10.1093/mnras/stae2040

10.48550/arXiv.2311.14659

arXiv

arXiv:2311.14659

Bibcode

2024MNRAS.535....1T

Collection

astronomy

Keywords

Astrophysics - Astrophysics of Galaxies

Astrophysics - Cosmology and Nongalactic Astrophysics

UAT Keywords (generated)BETA

observational cosmology

weak gravitational lensing

Bibgroup

NOIRLab

E-Print Comment(s)

Measurements available at: https://github.com/aamon/Dwarf-Lensing ; 22 pages, 16 figures

.css-mcpu91{font-size:var(--chakra-fontSizes-xl);} The mass profiles of dwarf galaxies from Dark Energy Survey lensing

Authors

Abstract

Details

The mass profiles of dwarf galaxies from Dark Energy Survey lensing