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I am a postdoctoral fellow at the Center for Cosmology and AstroParticle Physics (CCAPP) of The Ohio State University in Columbus, OHUSA, where I work on theoretical astroparticle physics.

One of my main interests is the flux of high-energy astrophysical neutrinos recently discovered by IceCube: finding its sources, spectra, distribution, and flavor composition.

I am also interested in the connection between these neutrinos and ultra-high-energy cosmic rays. Over the past years, we have been improving the neutrino and cosmic-ray predictions from gamma-ray bursts.

Coming from a particle-physics background, I also seem to be drawn to exploring Beyond the Standard Model physics occasionally, such as Lorentz and CPT invariance violation, neutrino decay, and modified dispersion relations, in connection to neutrinos.

See more in my Publications page.

Current research interests

Neutrino flavor ratios at Earth for selected flavor ratios at the source, normal hierarchy
Fluxes of cosmogenic neutrinos for all combination of UHECR proton fits that agree with the latest measured spectrum by the Telescope Array. All of the fluxes are disfavored by the recent IceCube upper bounds.
Cosmogenic neutrinos challenge the cosmic ray proton dip model
Jonas Heinze, Denise Boncioli, Mauricio Bustamante, Walter Winter
ApJ 825, 122 (2016)

The origin and composition of ultra-high-energy cosmic rays (UHECRs) remain a mystery. In the simplest model –the proton dip model– they are mainly protons of extragalactic origin above 109 GeV and their spectral features can be explained by interactions on the cosmic microwave background. These interactions also produce cosmogenic neutrinos, with ~109 GeV. We test whether this model is still viable using recent UHECR spectrum measurements from the Telescope Array and upper limits on the cosmogenic neutrino flux from IceCube. [...] The predicted cosmogenic neutrino flux exceeds the IceCube limit for any parameter combination. As a result, they challenge the proton dip model at more than 95% C.L. This is the first strong evidence against this model independently of mass composition measurements.

Go to the paper (arXiv)

Neutrino flavor ratios at Earth for selected flavor ratios at the source, normal hierarchy
Astrophysical neutrino flavor ratios at Earth for selected ratios at the sources
Standard flavor ratios with new physics, normal hierarchy
Allowed neutrino flavor ratios at Earth including a broad class of new physics
Flavor composition of astrophysical neutrinos
Mauricio Bustamante, John F. Beacom,
Walter Winter
Phys. Rev. Lett. 115, 161302 (2015)

After decades of searching, IceCube has finally observed the first high-energy astrophysical neutrino events; recently, they have published the first determination of the flavor composition of the flux. This is one of the richest and most rewarding physical observables: its determination will reveal important information about production conditions at the sources and about neutrino properties, including whether there is new physics. It is therefore timely to study its theoretical expectations. We have done so and found that, contrary to naive expectations, the allowed region of flavor composition is quite small, even under a general class of new physics models. Furthermore, a possible volume upgrade of IceCube will likely achieve excellent determination of the flavor composition, thus constraining astrophysical production scenarios.

Go to the paper (arXiv)

Shell collisions in a GRB jet
Simulated cumulative plasma shell collisions in a GRB jet
High-energy neutrino emission from gamma-ray bursts
Mauricio Bustamante, Philipp Baerwald,
Kohta Murase, Walter Winter
Nat. Commun. 6, 6783 (2015) [arXiv:1409.2874]

In the classical theory of gamma-ray bursts, it is expected that particles are accelerated at mildly relativistic shocks generated by the collisions of material ejected from a central engine. We consider neutrino and cosmic-ray emission from multiple emission regions since these internal collisions must occur at very different radii, from below the photosphere all the way out to the circumburst medium, as a consequence of the efficient dissipation of kinetic energy. We demonstrate that the different messengers originate from different collision radii, which means that multimessenger observations open windows for revealing the evolving GRB outflows. We find that, even in the internal shock model, the neutrino production can be dominated by emission from around the photosphere, i.e., the radius where the ejecta become transparent to gamma-ray emission.

Go to the paper (Nat. Commun.)

Mauricio Bustamante
CCAPP Fellow
Center for Cosmology and
    Astroparticle Physics
The Ohio State University

Last updated: 2016.11.30