Despite being one of the longest known classes of astrophysical transients, novae continue to present modern surprises. The Fermi-LAT discovered that many if not all novae are GeV gamma ray sources, ...even though theoretical models had not even considered them as a possible source class. More recently, MAGIC and H.E.S.S. detected TeV gamma rays from a nova. Moreover, there is strong evidence that the gamma rays are produced hadronically, and that the long-studied optical emission by novae is also shock-powered. If this is true, novae should emit a neutrino signal correlated with their gamma-ray and optical signals. We present the first search for neutrinos from novae. Because the neutrino energy spectrum is expected to match the gamma-ray spectrum, we use an IceCube DeepCore event selection focused on GeV-TeV neutrinos. We present results from two searches, one for neutrinos correlated with gamma-ray emission and one for neutrinos correlated with optical emission. The event selection presented here is promising for additional astrophysical transients including gamma-ray bursts and gravitational wave sources.
The Distributed Electronic Cosmic-ray Observatory (DECO) is a cell phone app
that uses a cell phone camera image sensor to detect cosmic-ray particles and
particles from radioactive decay. Images ...recorded by DECO are classified by a
convolutional neural network (CNN) according to their morphology. In this
project, we develop a GEANT4-derived simulation of particle interactions inside
the CMOS sensor using the Allpix$^2$ modular framework. We simulate muons,
electrons, and photons with energy range 10 keV to 100 GeV, and their deposited
energy agrees well with expectations. Simulated events are recorded and
processed in a similar way as data images taken by DECO, and the result shows
both similar image morphology with data events and good quantitative data-Monte
Carlo agreement.
We present a custom MacOS-based application,
adam, for analysis of data collected by a three-dimensional atom probe (3DAP). The application is designed to carry out a common set of analysis tasks, to ...be customizable, to provide easy export and import of data, and to be simple enough for novice users to understand quickly. The integration of both graphical (GUI) and scripting (SUI) user interfaces and the functionality accessible from both is discussed. Different types of visualization can be used for best presentation of 3DAP data.
Astrophysical neutrinos detected by the IceCube observatory can be of Galactic or extragalactic origin. The collective contribution of all the detected neutrinos allows us to measure the total ...diffuse neutrino Galactic and extragalactic signal. In this work, we describe a simulation package that makes use of this diffuse Galactic contribution information to simulate a population of Galactic sources distributed in a manner similar to our own galaxy. This is then compared with the sensitivities reported by different IceCube data samples to estimate the number of sources that IceCube can detect. We provide the results of the simulation that allows us to make statements about the nature of the sources contributing to the IceCube diffuse signal.
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\(\sigma\) 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.
On 22 September 2017, IceCube reported a high-energy neutrino event which was found to be coincident with a flaring blazar, TXS 0506+056. This multi-messenger observation hinted at blazars ...contributing to the observed high-energy astrophysical neutrinos and raised a need for extensive correlation studies. Recent work shows that the internal absorption of gamma rays, and their interactions intrinsic to the source and with the extragalactic background, will cause a lack of energetic gamma-ray and neutrino correlation while hinting towards a correlation between neutrinos and lower photon energy observations in the X-ray and radio bands. Studies based on published IceCube alerts and radio observations report a possible radio-neutrino correlation in both gamma-ray bright and gamma-ray dim active galactic nuclei (AGN). However, they have marginal statistical significance due to limited available data. We present a correlation analysis between 15 GHz radio observations of AGN reported in the MOJAVE XV catalog and 10 years of IceCube detector data and discuss the results derived from a time-averaged stacking analysis.
When high-energy particles interact in dense media to produce a particle shower, most of the shower energy is deposited in the medium as heat. This causes the medium to expand locally and emit a ...shock wave with a medium-dependent peak frequency on the order of 10 kHz. In South Pole ice in particular, the elastic properties of the medium have been theorized to provide good coupling of particle energy to acoustic energy. The acoustic attenuation length has been theorized to be several km, which could enable a sparsely instrumented large-volume detector to search for rare signals from high-energy astrophysical neutrinos. We simulated a hybrid optical/radio/acoustic extension to the IceCube array, specifically intended to detect cosmogenic (GZK) neutrinos with multiple methods simultaneously in order to achieve high confidence in a discovered signal and to measure angular, temporal, and spectral distributions of GZK neutrinos. This work motivated the design, deployment, and operation of the South Pole Acoustic Test Setup (SPATS). The main purpose of SPATS is to measure the acoustic attenuation length, sound speed profile, noise floor, and transient noise sources \emph{in situ} at the South Pole. We describe the design, performance, and results from SPATS. We measured the sound speed in the fully dense ice between 200 m and 500 m depth to be 3878 \(\pm\) 12 m/s for pressure waves and 1975.8 \(\pm\) 8.0 m/s for shear waves. We measured the acoustic amplitude attenuation length to be 316 \(\pm\) 105 m. We measured the background noise floor to be Gaussian and very stable on all time scales from one second to two years. Finally, we have detected an interesting set of well-reconstructed transient events in over one year of high quality transient data acquisition. We conclude with a discussion of what is next for SPATS and of the prospects for acoustic neutrino detection in ice.
In the past decade IceCube's observations have revealed a flux of astrophysical neutrinos extending to \(10^{7}~\rm{GeV}\). The forthcoming generation of neutrino observatories promises to grant ...further insight into the high-energy neutrino sky, with sensitivity reaching energies up to \(10^{12}~\rm{GeV}\). At such high energies, a new set of effects becomes relevant, which was not accounted for in the last generation of neutrino propagation software. Thus, it is important to develop new simulations which efficiently and accurately model lepton behavior at this scale. We present TauRunner a PYTHON-based package that propagates neutral and charged leptons. TauRunner supports propagation between \(10~\rm{GeV}\) and \(10^{12}~\rm{GeV}\). The package accounts for all relevant secondary neutrinos produced in charged-current tau neutrino interactions. Additionally, tau energy losses of taus produced in neutrino interactions is taken into account, and treated stochastically. Finally, TauRunner is broadly adaptable to divers experimental setups, allowing for user-specified trajectories and propagation media, neutrino cross sections, and initial spectra.
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