About me

Welcome! I'm a Phoenix native living in Gothenburg, Sweden as a Cosmic Origins postdoctoral fellow part of the Chalmers Institute of Cosmic Origins 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.

In regions shielded from ultraviolet radiation, the molecular chemistry of the interstellar medium is regulated by energetic, charged particles called cosmic rays. These ionizations and excitations produced by interactions of these particles, dominately protons, lead to a diverse zoo of molecules. My research focuses primarily on the interactions of cosmic rays with dense, molecular gas and exploring novel sources of particle accelration associate with molecular gas and star formation.

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

Cosmic-ray Acceleration

Cosmic rays are produced by accelerating particles, most commonly protons, to significantly higher energies. For proton energies most important for chemistry, between 1 keV and 1 GeV, these particles lose energy rapidly as they travel into molecular clouds. Therefore, novel sources of these low-energy cosmic rays are being searched for! I have explored the acceleration of protons in the enegetic regions near newly forming, accreting stars, called protostars and their impact on chemistry. I have also proposed a novel source of these particles: acceleration in the ubiquitous turbulence within molecular clouds, which would provide a general source available for molecular chemistry.

Relevant Paper

Molecular Data

Molecular data for chemical processes is of fundamental importance for astrochemical modelling. The importance of energetic particle interactions on gas- and ice-phase chemistry, from high-energy protons to low-energy electrons, necessitates as much high-fidelity molecular and atomic data for these interactions. I have initiated the Astrochemistry Low-energy electron Cross Section (ALeCS) database with a collaboration between astronomers and chemists. The initial release includes molecular geometries, electron orbitals and ionization cross sections for over 200 molecules and atoms of astrochemical interest, along with ionization rates in both the UMIST and KIDA formats.

GitHub Repo

Public Talks

Publications and Presentations


  • 2023: Gaches, Grassi, Vogt-Geisse, Bovolenta, Vallance, Heathcote, Padovani, Bovino, Gorai, A&A submitted, The Astrochemistry Low-energy Electron Cross-Section (ALeCS) database I. Semi-empirical electron-impact ionization cross-section calculations and ionization rates [ADS]
  • 2023: Hsu, Tan, Holdship, Xu, Viti, Wu, Gaches, MNRAS submitted, GMC Collisions As Triggers of Star Formation. IX. Chemical Evolution [ADS]
  • 2023: Gaches, Walch, Wünsch, Mackey, MNRAS, Tree-based solvers for adaptive mesh refinement code FLASH -- IV: An X-ray radiation scheme to couple discrete and diffuse X-ray emission sources to the thermochemistry of the interstellar medium [ADS]
  • 2023: Panessa, Seifried, Walch, Gaches, Barnes, Bigel, Neumann, MNRAS, The evolution of HCO+ in molecular clouds using a novel chemical post-processing algorithm [ADS]
  • 2022: Gaches, Bialy, Bisbas, Padovani, Seifried, Walch, A&A, Cosmic-ray-induced H2 line emission: Astrochemical modeling and implications for JWST observations [ADS]
  • 2022: Gaches, Bisbas, Bialy, A&A, The impact of cosmic-ray attenuation on the carbon cycle emission in molecular clouds [ADS]
  • 2021: Li, P.S., Cunningham, Gaches, Klein, Krumholz, Lee, McKee, Offner, Rosen, Skinner, JOSS, 6(68), 3771, 2021, ORION2: A magnetohydrodynamics code for star formation [ADS]
  • 2021: Gaches, B. A. L., Walch, S., Lazarian, A. , ApJL, CRAFT (Cosmic Ray Acceleration From Turbulence) in Molecular Clouds [ADS]
  • 2021: Yun, Lee, J., Evans, Offner, Heyer, Cho, Gaches, Yang, Chen, Choi, Y., Lee, Y., Baek, Choi, M., Kim, Kang, Lee, S., Tetematsu, ApJ, 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: Olympian Symposium, June 1, 2023, Paralia, Greece
  • Invited: NASA Universe of Learning: Science Briefing, December 1, 2022, virtual
  • Invited: Cosmic Rays 2: The Salt of Star Formation, Florence, Italy, November 10, 2022
  • Talk: Midwest Magnetic Field Workshop 2022, Virtual, May 26, 2022
  • Talk: Early Phases of Star Formation, Ringberg Castle, Germany, April 27, 2022
  • Seminar: Kapteyn Institute Lunch Seminar, Virtual, April 6, 2022
  • Seminar: Center for Astrochemical Studies Seminar, Virtual, September 27, 2021
  • 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