2023/11/24 by Joseph Thornton, A. Amon, Thornton, Joseph +17 · 1 citation
Environmental Science · Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Impact of Light on Environment and Health
paper · pdf · doi:10.48550/arxiv.2311.14659
openalex publication_date 2023/11/24 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We present a novel approach to extracting dwarf galaxies from photometric data to measure their average halo mass profile with weak lensing. We characterise their stellar mass and redshift distributions with a spectroscopic calibration sample. Using the ∼5000deg2 multi-band photometry from Dark Energy Survey and redshifts from the Satellites Around Galactic Analogs (SAGA) survey with an unsupervised machine learning method, we select a low-mass galaxy sample spanning redshifts z<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 log10(M_*/M\odot)= [8.52+0.57-0.76, 9.02+0.50_ -0.64, 9.49+0.50-0.58]. We measure the stacked excess surface mass density profiles, ΔΣ(R), of these galaxies using galaxy--galaxy lensing with a signal-to-noise 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 log10(M\rm halo/M\odot) = [10.67\substack+0.2 -0.4, 11.01\substack+0.14 -0.27,11.40\substack+0.08 -0.15]. The CDM profiles are consistent with NFW profiles over scales \lesssim0.15 \rmh-1Mpc. We find that ∼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.