arXiv subjects

Samalka Anandagoda

Publications and source records attributed to Samalka Anandagoda.

5 recordsLinked to original sources

arXiv2024

Constraints on the origins of the Galactic neutrino flux

Galactic and extragalactic objects in the universe are sources of high-energy neutrinos {that may contribute to the astrophysical neutrino signal seen by IceCube.} Recently, a study done using cascade-like events seen by IceCube reported neutrino emission from the Galactic plane with $>$4$σ$ significance. In this work, we put a lower limit on the number of Galactic sources required to explain this emission. To achieve this, we {use} a simulation package created to simulate point sources in the Galaxy along with the neutrino and gamma-ray flux emissions originating from them. Along with {using} past IceCube discovery potential curves, we also account for Eddington bias effects due to Poisson fluctuations in the number of detected neutrino events.{We present a toy Monte Carlo simulation to show that there should be at least 8 sources, each with luminosities $1.6 \times 10^{35}$erg/s responsible for the Galactic neutrino emission. } Our results constrain the number of individual point-like emission regions, which applies both to discrete astrophysical sources and to individual points of diffuse emission.

astro-ph.HE↗

arXiv2023

Stellar Neutrino Emission Across The Mass-Metallicity Plane

We explore neutrino emission from nonrotating, single star models across six initial metallicities and seventy initial masses from the zero-age main sequence to the final fate. Overall, across the mass spectrum, we find metal-poor stellar models tend to have denser, hotter and more massive cores with lower envelope opacities, larger surface luminosities, and larger effective temperatures than their metal-rich counterparts. Across the mass-metallicity plane we identify the sequence (initial CNO $\rightarrow$ $^{14}$N $\rightarrow$ $^{22}$Ne $\rightarrow$ $^{25}$Mg $\rightarrow$ $^{26}$Al $\rightarrow$ $^{26}$Mg $\rightarrow$ $^{30}$P $\rightarrow$ $^{30}$Si) as making primary contributions to the neutrino luminosity at different phases of evolution. For the low-mass models we find neutrino emission from the nitrogen flash and thermal pulse phases of evolution depend strongly on the initial metallicity. For the high-mass models, neutrino emission at He-core ignition and He-shell burning depends strongly on the initial metallicity. Anti-neutrino emission during C, Ne, and O burning shows a strong metallicity dependence with $^{22}$Ne($α$,$n$)$^{25}$Mg providing much of the neutron excess available for inverse-$β$ decays. We integrate the stellar tracks over an initial mass function and time to investigate the neutrino emission from a simple stellar population. We find average neutrino emission from simple stellar populations to be 0.5--1.2 MeV electron neutrinos. Lower metallicity stellar populations produce slightly larger neutrino luminosities and average $β$ decay energies. This study can provide targets for neutrino detectors from individual stars and stellar populations. We provide convenient fitting formulae and open access to the photon and neutrino tracks for more sophisticated population synthesis models.

astro-ph.SR↗

arXiv2023

Multi-Messenger Diagnostics of the Engine behind Core-Collapse Supernovae

Core-collapse supernova explosions play a wide role in astrophysics by producing compact remnants (neutron stars, black holes) and the synthesis and injection of many heavy elements into their host Galaxy. Because they are produced in some of the most extreme conditions in the universe, they can also probe physics in extreme conditions (matter at nuclear densities and extreme temperatures and magnetic fields). To quantify the impact of supernovae on both fundamental physics and our understanding of the Universe, we must leverage a broad set of observables of this engine. In this paper, we study a subset of these probes using a suite of 1-dimensional, parameterized mixing models: ejecta remnants from supernovae, ultraviolet, optical and infra-red lightcurves, and transient gamma-ray emission. We review the other diagnostics and show how the different probes tie together to provide a more clear picture of the supernova engine.

astro-ph.HE↗

arXiv2022

Advancing the Landscape of Multimessenger Science in the Next Decade

The last decade has brought about a profound transformation in multimessenger science. Ten years ago, facilities had been built or were under construction that would eventually discover the nature of objects in our universe could be detected through multiple messengers. Nonetheless, multimessenger science was hardly more than a dream. The rewards for our foresight were finally realized through IceCube's discovery of the diffuse astrophysical neutrino flux, the first observation of gravitational waves by LIGO, and the first joint detections in gravitational waves and photons and in neutrinos and photons. Today we live in the dawn of the multimessenger era. The successes of the multimessenger campaigns of the last decade have pushed multimessenger science to the forefront of priority science areas in both the particle physics and the astrophysics communities. Multimessenger science provides new methods of testing fundamental theories about the nature of matter and energy, particularly in conditions that are not reproducible on Earth. This white paper will present the science and facilities that will provide opportunities for the particle physics community renew its commitment and maintain its leadership in multimessenger science.

astro-ph.HE↗

arXiv2020

The Diffuse Supernova Neutrino Background

The Diffuse Supernova Neutrino Background (DSNB) in the MeV regime represents the cumulative cosmic neutrino emission, predominantly due to core collapse supernovae. We estimate the DSNB flux for different Star Formation Rate Density (SFRD) models. We find that the DSNB flux estimated using the SFRD derived from Fermi-LAT Collaboration et al. (2018) is significantly higher ($\approx$ 32$\%$) relative to the flux estimated using the SFRD from Madau & Fragos (2017). This depicts the sensitivity between the DSNB flux and the SFRD estimates which shows that future detection of the DSNB can be used as a valuable tool to constrain the SFRD.

astro-ph.HE↗