About me

Welcome! I'm a Phoenix native currently living in Cologne, Germany as a postdoctoral researcher in Prof. Stefanie Walch's research group. I received my PhD from the University of Massachusetts in 2019.

Star formation is, by necessity, viewed through the a lens of emission from a wide range of molecules. Therefore, it is essential to determine the footprint various physical processes make on the chemistry of molecular clouds. My research focuses on high-energy feedback processes on molecular gas, predominately from protostars. The gas accreting onto protostars can be 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 moleculars). Typically, astrochemical models make very simple assumptions about the cosmic ray flux. We are working on implementing more sophisticated treatments of cosmic rays into astrochemistry models, in-situ. 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 results 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 forming stars have on their natal environment. Prior work has quantified the acceleration of cosmic rays in the accretion shocks of cosmic rays. Current work is including protostellar x-ray emission in star-formation simulations.

Relevant Paper

Short-Lived Radionuclides

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

Relevant Paper

Publications and Presentations


  • 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: AG2020 ISM Splinter
  • Talk: Astrochemistry Discussions
  • Seminar: Jan 2020 - MPE
  • Contributed: 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
  • Contributed: The Olympian Symposium 2018 - Paralia Katerini, Mount Olympus, Greece