Dr. Ashley R. Bemis

Allegro Fellow &
Leiden Observatory Research Associate

Curriculum Vitae

RESEARCH FOCUS:
Resolved Star Formation, Dense gas,
z~0 Galaxies (Mergers, Galaxy Centers),
Radio Astronomy, Interferometry

Recently Completed:

PhD, Astrophysics
McMaster University

Thesis word cloud

My PhD thesis work (completed October 2020) focused on the relationship between dense gas (primarily as traced by HCN) and star formation (as traced by IR and radio continuum emission) in more-extreme environments than those found in the disks of normal galaxies (mergers, Ultra-Luminous Infrared Galaxies, and galaxy centers). The data were compared to the predictions of theoretical models of star formation (cf. Krumholz & McKee 2005, Padoan & Nordlund 2011, Hennebelle & Chabrier 2011, Federrath & Klessen 2012, Burkhart 2018), in addition to emissivities modeled using the radiative transfer code RADEX (van der Tak et al. 2007).

Ongoing:

HCN AND HCO+ EMISSION IN THE EXTREME ENVIRONMENTS OF MERGERS AND GALAXY CENTERS

HCN and HCO+ emission is compared at sub-kpc scales across a sample of 10 galaxies using ALMA archival data. Preliminary results were presented at The Laws of Star Formation Conference, Cambdridge, UK in 2018 without modeling incorporated. Initial results with modeling incorporated (excluding HCO+) were presented in an invited talk at the AAS Summer 2020 meeting.

M83, NASA, ESA, and the Hubble Heritage Team (STScI/AURA); Acknowledgment: W. Blair (STScI/JHU), Carnegie Institution of Washington (Las Campanas Observatory), and NOAO
NGC 3627 / M66, ESO/P. Barthel
NGC 3351 / M95, NASA/JPL-Caltech/R. Kennicutt (University of Arizona) and the SINGS Team
Circinus Galaxy / IRAS 14092-6506, Credit: Andrew S. Wilson (University of Maryland); Patrick L. Shopbell (Caltech); Chris Simpson (Subaru Telescope); Thaisa Storchi-Bergmann and F. K. B. Barbosa (UFRGS, Brazil); and Martin J. Ward (University of Leicester, U.K.) and NASA/ESA
NGC 1808 / IRAS 05059-3734, Jim Flood, an amateur astronomer affiliated with Sperry Observatory at Union College in New Jersey, and Max Mutchler, a member of the Space Telescope Science Institute staff who volunteered to work with Jim
The Antennae Galaxies / NGC 4038/9, Image Credit: Hubble/European Space Agency
NGC 3256, ESA/Hubble, NASA
VV114 / IC 1623, Copyright: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)
NGC 7469, Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)
IRAS 13120+5453, Digitized Sky Survey (DSS)

ONGOING:

Directly Determining Molecular Emissivities in Milky Way Clouds

This project aims to determine molecular emissivities by comparing molecular emission, including multi-J emission of dense gas tracers HCN & HCO+, to independent gas mass tracers (i.e. dust) in Milky Way clouds. This makes use of archival data from the Herschel Gould Belt Survey (2010A&A...518L.102A).

JCMT HCN 4-3 data overlaid on the Aquila H2 column density map from the Herschel Gould Belt Survey (2010A&A...518L.102A).

Upcoming:

A multi-J anlaysis of HCN and HCO+ emission at selected sightlines across the Antennae using SMA data (PI project SMA 2018B-S022).

UPCOMING:

I am currently imaging cloud-scale CN emission across the Antennae Galaxies for eventual comparison with cloud-scale CO emission, star formation rate tracers, and the predictions of analytical models of star formation (see thesis work).