About me

Welcome! I'm a Phoenix native currently living in Cologne, Germany as a postdoctoral researcher in Prof. Stefanie Walch's research group and a member of the Center for Planetary Systems Habitability at the University of Texas at Austin. I received my PhD from the University of Massachusetts in 2019.

Star formation is, by necessity, viewed through the emission from a diverse zoo of molecules. Therefore, it is essential to determine the footprint various physical processes make on the chemistry of molecular clouds. My research focuses on the impact of high-energy feedback processes, predominately from protostars, on molecular gas. The gas accreting onto protostars is heated to nearly a million degrees, emitting x-ray radiation and accelerating charged particles to relativistic energies. The resulting particle acceleration and radiation has a significant impact on chemistry of molecular clouds.

Public Talks

Research Interests

Cosmic Ray Chemistry

Relativistic charged particles, so-call cosmic rays, are the primary drivers of chemistry in molecular clouds in regions shielded from intense radiation. Cosmic rays affect molecular gas in numerous ways: charging dust grains, heating gas, and driving chemistry through ionizing molecular hydrogen (and other molecules). Typically, astrochemical models make very simple assumptions about the cosmic ray flux. I am working on implementing more sophisticated treatments of cosmic rays physics into astrochemical models. These cosmic ray-chemistry models provide more sensitive and accurate predictions on the abundances of molecules in star-forming regions.

Relevant Paper

Protostellar Feedback

The gas accreting onto protostars heats to nearly a million degrees as it falls onto the surface, resulting in a shock near the surface of the forming protostar. The hot temperatures and high densities result in x-ray radiation and the acceleration of charged particles to relativistic energies. Modeling these high energy processes, and their transport through the protostellar envelope and cloud, is crucial to understanding the impact young stars have on their natal environment. Prior work has quantified the acceleration of cosmic rays in the accretion shocks of accreting protostars. I am currently implementing protostellar x-ray emission in star-formation simulations.

Relevant Paper

Short-Lived Radionuclides

Short-lived radioactive nuclei (radionuclides) have half-lives of less than a few million years. Excess amounts of specific radioactive isotopes measured in meteorites indicate the early solar system was contaminated by a wide-range of radionuclides. These isotopes provide fingerprints of the galactic and protostellar environment during the formation of the solar system. Theoretical models typically explain this enrichment by supposing the existence nearby supernova or high-mass stars. I have recently proposed a novel local mechanism of isotope enrichment. My student and I are currently investigating how radioactive isotopes from supernova mix into cold, dense, star-forming gas.

Relevant Paper

Publications and Presentations


  • 2021: Gaches, B. A. L., Walch, S., Lazarian, A. , ApJL Accepted, CRAFT (Cosmic Ray Acceleration From Turbulence) in Molecular Clouds
  • 2021: Yun, Lee, J., Evans, Offner, Heyer, Cho, Gaches, Yang, Chen, Choi, Y., Lee, Y., Baek, Choi, M., Kim, Kang, Lee, S., Tetematsu, ApJ Accepted, TIMES II: Investigating the Relation Between Turbulence and Star-forming Environments in Molecular Clouds [ADS]
  • 2021: Yun, Lee, J. , Choi, Evans, Offner, Heyer, Gaches, Lee, Y-H., Baek, Choi, Kang, Lee, S. , Tatematsu, Yang, Chen, Lee, Y., Jung, Lee, C., Cho, ApJS, TIMES I: a Systematic Observation in Multiple Molecular Lines Toward the Orion A and Ophiuchus Clouds [ADS]
  • 2021: Fitz Axen, M., Offner, S. S. R., Gaches, B. A. L., Fryer, C. L., Hungerford, A., ApJ, Transport of Protostellar Cosmic Rays in Turbulent Dense Cores [ADS]
  • 2020: Gaches, B. A. L., Walch S., Offner, S. S. R., Münker, C., ApJ, Aluminum-26 Enrichment in the Surface of Protostellar Disks Due to Protostellar Cosmic Rays [ADS] [Sky and Telescope]
  • 2019: Offner, S. S. R., Gaches, B. A. L., Holdship, J., ApJ, Impact of Cosmic-Ray Feedback on Accretion and Chemistry in Circumstellar Disks [ADS]
  • 2019: Gaches, B. A. L., Offner, S. S. R., Bisbas, T. G., ApJ, The Astrochemical Impact of Cosmic Rays in Protoclusters. II. CI-to-H2 and CO-to-H2 Conversion Factors [ADS]
  • 2019: Gaches, B. A. L., Offner, S. S. R., Bisbas, T. G., ApJ, The Astrochemical Impact of Cosmic Rays in Protoclusters. I. Molecular Cloud Chemistry [ADS]
  • 2018: Gaches, B. A. L., Offner, S. S. R., ApJ, Exploration of Cosmic Ray Acceleration in Protostellar Accretion Shocks and A Model for Ionization Rates in Embedded Protoclusters [ADS]
  • 2018: Gaches, B. A. L., Offner, S. S. R., ApJ, A Model for the CO-H2 Conversion Factor of Molecular Clouds with Embedded Star Clusters [ADS]
  • 2015: Gaches, B. A. L., Offner, S. S. R., Rosolowsky, E. W., Bisbas, T. G., ApJ, Astrochemical Correlations in Molecular Clouds - [ADS]

Recent Talks

  • Talk: Astrochemical Frontiers 2021, Virtual, July 5, 2021
  • Talk: Midwest Magnetic Field Workshop, Madison, WI, Virtual, June 14, 2021
  • Invited: SSDC, Agenzia Spaziale Italiana, Virtual, June 10, 2021
  • Talk: Beirut ISM 2021, Virtual
  • Seminar: ANU Astrocoffee
  • Talk: AG2020 ISM Splinter
  • Talk: Astrochemistry Discussions
  • Seminar: Jan 2020 - MPE
  • Talk: AAS Winter 2019 - Seattle, WA
  • Seminar: ITC Seminar October 2018 - Center for Astrophysics, Cambridge, MA
  • Seminar: Origins Seminar October 2018 - Steward Obsevatory, Tucson, AZ
  • Seminar: TUNA Talk September 2018 - NRAO, Charlottesville, VA
  • Talk: The Olympian Symposium 2018 - Paralia Katerini, Mount Olympus, Greece