Eric Bell

Scaling relations are a key aspect to understanding galaxy evolution, especially the co-evolution between galaxies and their central supermassive black holes (SMBHs). The tight correlations between black hole mass (M BH) and quantities like velocity dispersion, stellar mass (M*), and dark matter halo mass (M halo) are strongly suggestive of a causal connection between black hole growth and galaxy evolution. M BH has also been shown to correlate strongly with star formation rate (SFR), with quiescent galaxies hosting more massive SMBHs for a given stellar mass than ones actively forming stars. One important limiting factor in the analysis of scaling relations between M BH, M*, M halo, and SFR is the relative rarity of high-quality M halo measurements using consistent methodology. With this in mind, we used the globular cluster mass-halo mass relationship (η=(3.9±0.9) x 10-5= M GCS/M halo, where M GCS is …

The 3D geometries of high-redshift galaxies remain poorly understood. We build a differentiable Bayesian model and use Hamiltonian Monte Carlo to efficiently and robustly infer the 3D shapes of star-forming galaxies in James Webb Space Telescope Cosmic Evolution Early Release Science observations with

Aims. We test whether we can predict optical spectra from deep-field photometry of distant galaxies. Our goal is to perform a comparison in data space, highlighting the differences between predicted and observed spectra.Methods. The Large Early Galaxy Astrophysics Census (LEGA-C) provides high-quality optical spectra of thousands of galaxies at redshift 0.6 < z < 1. Broadband photometry of the same galaxies, drawn from the recent COSMOS2020 catalog, is used to predict the optical spectra with the spectral energy distribution (SED) fitting code Prospector and the MILES stellar library. The observed and predicted spectra are compared in terms of two age and metallicity-sensitive absorption features (HδA and Fe4383).Results. The global bimodality of star-forming and quiescent galaxies in photometric space is recovered with the model spectra. However, the presence of a systematic offset in the Fe4383 line …

Recent discoveries of faint satellite systems challenge the distinction between star clusters and dwarf satellites. Classifying these systems are pivotal for understanding the physics of dark matter (DM) on smaller scales and constraining the number of DM sub-halos in larger galaxies. With more satellite systems than the Milky Way, Andromeda (M31) offers a unique environment for this investigation. We present three ultra-faint dwarf (UFD) galaxy candidates in the halo of M31, initially discovered in the Pan-Andromeda Archaeological Survey (PAndAS). Hubble Space Telescope (HST) follow-up imaging indicates that these candidates lie in the boundary between the largest and most diffuse star clusters and the smallest UFD galaxies in the luminosity-size plane, making classification challenging. We derived their structural parameters using an elliptical exponential profile model through a Markov Chain Monte Carlo …

We used data from LEGA-C Data Release 3 (DR3; van der Wel+ 2016ApJS.. 223... 29V; see J/ApJS/239/27 & 2021, J/ApJS/256/44). LEGA-C is an ESO 130-night public spectroscopic survey of COSMOS conducted with VIMOS on the Very Large Telescope. In total, 4209 exceptionally deep, spatially extended slit spectra were taken of 3855 unique sources in the UltraVISTA photometric catalog (Muzzin+ 2013, J/ApJS/206/8). The resolution properties of the LEGA-C spectra are R~ 3500 and FWHM= 86km/s (σ= 36km/s). See Section 2.

Ultra-diffuse galaxies (UDGs) are a relatively new classification of dwarf galaxies, characterized by low stellar mass (< 10 8 M sun) high radii (> 2 kpc), and low surface brightness (~ 25 mag/arcsec 2). These galaxies have been observed throughout the universe, and understanding how they form is critical to filling a gap in our knowledge of galactic evolution. Until now, these galaxies have only been studied as a population, but the proximity of F8D1 allows us to deeply analyze the stellar populations within this UDG to understand the inner workings of these galaxies. Recently,(Zemaitis, et. al. 2022) discovered that F8D1 has been tidally disrupted, estimating a tidal tail length of around 60 kpcs. We have used the ratio of AGB to RGB stars both in the main body of the galaxy and in its tidal tails to constrain its star formation history (SFH); in two central deep HST fields we also have deep enough color-magnitude …

We propose a NIRCam imaging survey of the nearby starburst galaxy, M82. As the prototypical massive starburst, which is also engaged in the nearest major galaxy interaction in the universe, M82 is a galaxy evolutionary laboratory. Imaging M82's disk out to R~ 8 kpc, we will for the first time break through its horrific line-of-sight dust extinction to reveal the bulk of its luminous stellar population, which are uniquely accessible with JWST. We will resolve at least 10 million individual stars across M82's disk, generating a stellar catalog that will have a lasting legacy value to the astrophysical community for decades. The key science goals of this proposal are to: measure M82's globally resolved star formation history over at least the past 6 Gyr, including the evolution of its recent starburst; map the metallicity of its stellar populations; and constrain dynamical models of its interaction history in the M81 Group. These will …

The PHAST survey is creating a legacy map of the southern half of M31 with photometric data from Hubble Space Telescope observations with the Advanced Camera for Surveys (ACS) in the optical (F475W, F814W), and the Wide Field Camera 3 (WFC3) in the near ultraviolet (F275W, F336W). The near-infrared observations of this region can be added later with the Roman Space Telescope for a higher efficiency. The PHAST survey goes~ 13 kpc along the southern major axis of M31 and should add roughly 100 million resolved stars to M31's stellar photometry archive. Our preliminary reductions of the first half of the observations suggest a similar depth in the UV to the completed Panchromatic Hubble Andromeda Treasury (PHAT) Survey, and a few tenths of a magnitude shallower in the optical because of shorter visit time. The PHAST survey will cover several structurally unique regions that belong to the …