Session Z03: Astrophysical Neutrinos II

Towards the Calibration of Askaryan Radio Array (ARA) Station 1

The Askaryan Radio Array (ARA) is an ultra-highly neutrino detector based the on Askaryan effect that uses Antarctic ice as the detector medium. Its five autonomous station’s radio antennas (four strings of receiving antennas; each string consists of with 2 Vertically Polarized (VPol) & 2 Horizontally Polarized (HPol) receivers, & 2 strings of calibration antennas each with 1 VPol & 1 HPol channel) are deployed at a depth of 180-200 m, save for ARA station 1 (A1) which was deployed at 100 m owing to drilling difficulties. We apply various methods to calibrate the Ice Ray Sampler second generation (IRS2) chip of A1 for timing offset. We use a known continuous wave input signal to calibrate time base of the digitizer. After timing calibration to a precision of sub-nanoseconds, we find that odd samples behave better than even samples & that the HPols under-perform relative to the VPol channels. Our timing calibration data will be used to further calibrate the ADC-to-Voltage conversion for A1, as well as precise antenna locations, as a pre-cursor to vertex reconstruction. These calibrated data will then be analyzed for ultra-high energy neutrino signals in a final step of data compression. The calibrated analyzed data will then inform design of the planned IceCube Gen-2 radio array.   

Sensitivity Study of Radio Neutrino Observation at Glashow Resonance

Radio neutrino observation aims to achieve sufficient sensitivity for detection of high energy neutrinos above 10 PeV to which current IceCube’s sensitivity is limited. Interaction between anti-electron neutrino and electron resonate at 6.3 PeV, called the Glashow resonance. With the future planned IceCube Gen-2 radio array and the existing and under construction Askaryan Radio Array and Radio Neutrino Observatory in Greenland (RNO-G), observations of Glashow resonance with radio array is possible. Therefore, understanding the response of the detectors between 1 to 10 PeV is imperative. In this study, sensitivity of the proposed neutrino radio array is evaluated at Glashow resonance.

Modeling TXS 0506+056 Neutrino Flares & AMEGO-X

TXS 0506+056 is the first multi-messenger blazar. The IceCube neutrino flares were detected once during a FermiLAT gamma-ray flare, and once during an apparently quiescent period electromagnetically.  We apply a new one-zone, leptohadronic particle transport model to the broadband SED simultaneous with each neutrino event. The model is designed to examine the effects of particle acceleration on the observable data through self-consistent implementation of both acceleration and cooling processes. Additionally, we compare with other successful models from the literature that suggest divergent physical interpretations, and suggest that AMEGO-X is well poised to differentiate between these models through multi-messenger collaboration on  future blazar flares.   

Observing ultra-high energy cosmic rays and cosmic neutrinos with POEMMA

The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) is designed to detect ultra-high energy (UHE) cosmic rays and possibly cosmic neutrinos above 20 EeV by observing the air fluorescence produced by extensive air showers (EASs), and cosmic neutrinos above 20 PeV by sensing the Cherenkov signal from upward-moving EASs induced by Earth-interacting tau neutrinos. POEMMA consists of two identical satellites flying in loose formation in 525 km altitude orbits, both equipped with a a wide field-of-view (45º) Schmidt optical design with an optical collecting area of over 6 m2. The hybrid focal surface of each telescope includes a fast (1 μs) near-ultraviolet camera for fluorescence observations and an ultrafast (10 ns) optical camera for Cherenkov observations. The POEMMA spacecraft will have sensitivity over the full celestial sky, and is designed to quickly re-orientate to follow up transient neutrino sources and obtain currently unparalleled neutrino flux sensitivity. In a 5-year mission, POEMMA will probe the most energetic phenomena of the universe, enabling unprecedented studies of transient and steady sources of UHE cosmic rays and cosmic neutrinos, and of physics beyond the standard model.   

An Improved Calculation of the Yield of High-Energy Neutrinos from the Sun

The observation of high-energy gamma-rays from the Sun using Fermi-LAT data suggests hadronic activity in the solar atmosphere. High-energy gamma-rays can be produced by the collision of cosmic rays producing neutral pions that subsequently decay into high-energy gamma-rays. Associated production of high-energy neutrinos, from GeV to 100 TeV in energy, is also expected. This contribution has been recently estimated but has yet to be observed. The most stringent upper limits arise from searches by Super-Kamiokande and IceCube on high-energy neutrinos from the Sun. This contribution presents a new calculation of the solar neutrino flux from the interaction of energetic cosmic rays in the solar atmosphere. In our updated calculation, we considered the effect of magnetic fields around the Sun and performed a detailed Monte Carlo simulation of the interactions of cosmic rays in the solar atmosphere.   

Halosat — A Cubesat That Studied The Hot Galactic Halo

HaloSat was the first CubeSat competitively funded by NASA's Astrophysics Division and performed a two-year, all-sky survey in the soft X-ray band (0.4-2 keV). HaloSat's primary goal was to measure line emission from highly ionized oxygen within the halo or circumgalactic medium of the Milky Way. HaloSat data have also been used to study extended soft X-ray sources such as the North Polar Spur and the Cygnus superbubble and to search for 3.5 keV line emission from a putative sterile neutrino. The full HaloSat data set has been archived at NASA's HEASARC and is publicly available for analysis by the astronomical community. We describe some key results from HaloSat.   

νSol: Space-based Neutrion Detection

Understanding our Sun and its interior is a very difficult task because very little makes it directly out of the Sun’s core. The energy we see today was generated ~80,000 years ago and is only now coming to the earth. However, neutrinos penetrate matter almost without interaction and make it to Earth at the speed of light. Since neutrinos interact only weakly they are hard to detect; never-the-less within the last ten years neutrino detectors on Earth have started to reliably detect neutrinos from the fusion reactions in the interior of the Sun and scientists have started to use this information to investigate the Sun’s nuclear furnace. Traditional detectors have masses on the order of kilotons, but we propose something different. We can take advantage of the inverse square scaling of the neutrino flux using a space-based detector. A probe as close as 7 solar radii would have a one thousandfold increase in neutrino flux relative to earth. To measure the neutrinos, we use the neutrino's transmutation of gallium into germanium. This emits an electron and a gamma ray with characteristic timing, and we can use this double pulse to reject backgrounds that earth-based detectors typically have to contend with.   

Using Secondary Tau Neutrinos to Probe Heavy Dark Matter Decays in Earth

Dark matter particles can be gravitationally trapped by celestial bodies, motivating searches for localized annihilation or decay. If neutrinos are among the decay products, then IceCube and other neutrino observatories could detect them. We investigate this scenario for dark matter particles above m_χ ≥ PeV producing tau neutrino signals, using updated modeling of dark matter capture and thermalization. At these energies, tau neutrino regeneration is an important effect during propagation through Earth, allowing detection at distances far longer than one interaction length. We show how large energy loss of tau leptons above ~ PeV drives a wide range of initial energies to the same final energy spectrum of “secondary” tau neutrinos at the detector, and we provide an analytic approximation to the numerical results. This effect enables an experiment to constrain decays that occur at very high energies, and we examine the reach of the IceCube high-energy starting event (HESE) sample in the parameter space of trapped dark matter annihilations and decays above PeV. As a result, we see that it is difficult to explain Earth-emerging taus in terms of heavy dark matter decays.   

Searching for Southern Sky Neutrino Sources with IceCube Starting Track Events

The IceCube detector is an array of photomultiplier tubes embedded deep in the South Pole ice that aims to discover the origins of astrophysical neutrinos. Due to the detector location, the southern sky astrophysical neutrino signal lies under a large background of muons generated in cosmic ray interactions in the atmosphere. Therefore, IceCube's sensitivity to astrophysical neutrino sources has always been stronger in the Northern Sky where the main background is atmospheric neutrinos created by cosmic ray air showers. In this talk, we will present a selection method which looks to improve IceCube's sensitivity to southern sky sources by selecting for starting tracks created by muon neutrinos that interact inside of the IceCube detector volume. By selecting for starting tracks, we not only reduce the atmospheric muon background but also the atmospheric neutrino background, allowing for a high purity sample of astrophysical neutrinos in the southern sky. We will show our results for four types of neutrino source searches: a whole sky neutrino source search, an individual source search with locations from bright gamma ray objects, a stacked source search which looks for a signal from multiple sources of the same type, and a galactic plane template search which looks for neutrinos created in the galactic plane medium.