Friends-of-friends is a simple yet powerful algorithm for identifying groups of galaxies that likely share a common dark matter halo. However, an evolutionary perspective on gas in galaxy groups would lead us to prefer an algorithm that can identify groups in an early stage of formation that may not yet share a common halo. To address this, we are developing alternative definitions of galaxy...
There is a deep connection between the evolution of a galaxy and its magnetic field, which can act in both directions; magnetic fields appear strongly dependent on galaxy interactions, whilst magnetic fields contribute significantly in many processes that occur in the interstellar medium. Thus it is crucial to understand how environment can affect magnetic fields of large scales. However, so...
Hydrogen is the fuel for star formation, but relatively little is known about the role of cold gas in galaxy evolution. The COSMOS HI Large Extragalactic Survey (CHILES) is an on-going deep (1000 hr) HI survey being carried out with the Karl G. Jansky Very Large Array (VLA), probing a 0.5 degree region within the COSMOS field in the 21 cm line of neutral hydrogen. CHILES is the first survey to...
The 21 cm Spectral Line Observations of Neutral Gas with the VLA (21-SPONGE) survey detected HI absorption with exceptional optical depth sensitivity ($\sigma < 10^{-3}$) and matching HI emission with high angular resolution ($\sim 4^\prime$) towards 47 extragalactic radio continuum sources to study the physical properties of neutral hydrogen in the Milky Way. 9 of the background sources have...
The COSMOS HI Large Extragalactic Survey (CHILES) is a 1000-hour survey using the Very Large Array covering a continuous redshift range of $0 < z < 0.45$, a $40\times40$ arcmin pointing, and with 5 arcsec resolution ($z = 0$). The CHILES survey is studying the growth of galaxies as a function of location in the cosmic web. Luber et al. (2019) uses DisPerSE (Sousbie et al. 2011) to identify...
Almost all cosmological simulations of galaxy formation include the effect of photoionization and photoheating only via an homogeneous and redshift dependent Ultra Violet Background (UVB). While on large cosmological scales, the UVB can be approximated as homogeneous, on galaxy scales the high energy photon sources (stars, hot gas, black holes) are distributed highly non-uniformly. In zoom-in...