Publication:
The Impact of Protostellar Feedback on Astrochemistry

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dc.contributor.advisorStella Offner
dc.contributor.advisorRon Snell
dc.contributor.advisorMark Heyer
dc.contributor.advisorBret Jackson
dc.contributor.authorGaches, Brandt
dc.contributor.departmentUniversity of Massachusetts Amherst
dc.date2024-03-28T16:21:21.000
dc.date.accessioned2024-04-26T15:33:16Z
dc.date.available2024-04-26T15:33:16Z
dc.date.submittedSeptember
dc.date.submitted2019
dc.description.abstractStar formation is the lynch pin that lies in between the scales of galaxy and planet formation. Observational studies of molecular clouds, the sites of star formation, primarly use molecular line emission, providing dynamical and chemical information. Two of the key parameters of astrochemical models are far-ultraviolet (FUV) flux and the cosmic ray ionization rate. We use analytic accretion histories to predict the bolometric and FUV luminosities of protostar clusters and compare different histories with observed bolometric luminosities. We find that the Tapered Turbulent Core model best represents the observed luminosities and their dispersion. We extend the models to calculate the cosmic ray spectrum of protons accelerated in protostellar accretion shocks. We find that protostars are able to accelerate cosmic rays up to 10 GeV. We predict increased ionization rates within protostellar cores and molecular clouds hosting over 100 protostars. Our model is able to explain the substantial ionization rate, over 1000 times the typical, observed towards the OMC-2 FIR 4 protocluster. We model the impact of the protostellar FUV and cosmic rays on the astrochemistry on the natal molecular cloud. We couple the chemistry to the cosmic ray attenuation to solve the cosmic ray attenuation self-consistently. We find the inclusion of the embedded feedback significantly changes the Carbon chemistry and the CO-to-H2 conversion factor. High-density, optically-thin tracers such as ammonia are noticeably affected. The inclusion of embedded protostellar feedback alters the chemistry throughout molecular clouds, coupling the physics ongoing on the smallest scales of star formation to molecular cloud scale. Our results show that astrochemical modeling should account for ongoing star formation to correctly account for embedded FUV radiation and cosmic rays.
dc.description.degreeDoctor of Philosophy (PhD)
dc.description.departmentAstronomy
dc.identifier.doihttps://doi.org/10.7275/14754153
dc.identifier.orcidhttps://orcid.org/0000-0003-4224-6829
dc.identifier.urihttps://hdl.handle.net/20.500.14394/17971
dc.relation.urlhttps://scholarworks.umass.edu/cgi/viewcontent.cgi?article=2730&context=dissertations_2&unstamped=1
dc.source.statuspublished
dc.subjectastrochemistry
dc.subjectcosmic rays
dc.subjectstar formation
dc.subjectprotostars
dc.subjectsimulation
dc.subjectphoto-dissociation region
dc.subjectStars, Interstellar Medium and the Galaxy
dc.titleThe Impact of Protostellar Feedback on Astrochemistry
dc.typeopenaccess
dc.typearticle
dc.typedissertation
digcom.contributor.authorisAuthorOfPublication|email:gaches@gmail.com|institution:University of Massachusetts Amherst|Gaches, Brandt
digcom.identifierdissertations_2/1721
digcom.identifier.contextkey14754153
digcom.identifier.submissionpathdissertations_2/1721
dspace.entity.typePublication
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