Research

STAR FORMATION

Starburst Galaxy NGC 253
Credit: SSRO/PROMPT/CTIO

I am interested in tracing the entire process of star formation in galaxies, from the large-scale inflows of gas onto the galaxy disk down the cloud-scale, sub-kpc regions within the interstellar medium (ISM) that form individual stars. I am working within several collaborations to understand this process. I work within the PHANGS collaboration as the head of the HI working group, with a goal of collecting the highest resolution HI observations of all ~100 nearby PHANGS galaxies. I am also working on the core data team of a new extra-large program on the VLA called the Local Group L-Band Survey, imaging six Local Group galaxies down to cloud-scale resolution HI and continuum, where we will be able to detect and identify individual star forming regions.

Examples of extreme star formation are upcoming with our new 8” HI observations with the MeerKAT telescope of the nearby starburst galaxy, NGC 253.  We will examine the inflowing and outflowing gas in all of its phases with new+archival multiwavelength data to better understand this extreme source.

DWARF GALAXIES

Dwarf galaxies allow us to test our knowledge of the Universe. Thus far, it has been challenging to successfully apply the standard cosmological model of the Universe (ΛCDM) at small scales, specifically dwarf galaxy sized scales.  This challenge is apparent in the cusp/core problem, the missing satellites problem, and in the too-big-to-fail problem, to name a few. I am using extremely sensitive, high spectral resolution observations of dwarf galaxies to understand the kinematics within the dark matter halos of these galaxies, and to particularly shine a light on the too-big-to-fail in the field challenge. I have used the Parkes radio telescope to measure the HI in nearby dwarf galaxies with stellar masses below 10⁷ M_⊙.

Target sample of dwarf galaxies. Images from the Legacy Survey DR9.

Stellar mass – HI mass relation for dwarf galaxies. Constraint on the HI mass for NGC1052-DF2 shown with red star marker.

I am also working with the Merian team to understand the nature of dark matter in dwarf galaxies. The goal of this survey is to characterize the dark matter, feedback, and black holes in star forming dwarf galaxies. We are sampling 100,000 dwarf galaxies within an 800 square degree area using the Blanco telescope in Chile. We will also use the gas kinematics to probe the dark matter halo in a subset of galaxies which can help to explain the baryonic effects on dwarf galaxy rotation and dark matter kinematics.

I have been able to make the tightest constraint on the HI mass (Sardone et al. 2019) in NGC1052-DF2, the ultra-diffuse galaxy lacking dark matter. I used the GBT to observe this strange galaxy, which not only lacks dark matter, but also lacks a reservoir of gas as our constraints determined it to be extremely gas-poor.