Bulletin of the American Physical Society
APS April Meeting 2024
Wednesday–Saturday, April 3–6, 2024; Sacramento & Virtual
Session G03: Particle Astrophysics and the Galactic Center |
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Sponsoring Units: DAP Chair: Erika Holmbeck, LLNL Room: SAFE Credit Union Convention Center Ballroom A4, Floor 2 |
Thursday, April 4, 2024 10:45AM - 10:57AM |
G03.00001: High-Energy Cosmic-Rays Detected by Antarctic Ross Ice-Shelf Antenna Neutrino Array (ARIANNA) at South Pole Tingwei Liu The goal of my research is to find the cosmic rays at the South Pole at high elevation(about 3000 meters above the sea levels), testing the physics of radio production by cosmic ray showers that are still developing in the atmosphere. To achieve this goal, a surface array of radio antennas in Project ARIANNA has been planted on the south pole, and detecting the radio shower around it. More than 30,000 events have been recorded, from Feb.16th, 2018 to Oct.1st, 2018. Most of these events are background radio noise. They are usually caused by human activities such as the activity of the wind turbine, planes/cars going by, and human's phone calls. To filter the noise out, we simulated the cosmic-rays, and compared the simulation with the detected data in different criteria, including waveform similarity, trigger rate, direction distribution and arrival time distribution. There are approximately 25 events that have been identified as high-energy cosmic-ray candidates. |
Thursday, April 4, 2024 10:57AM - 11:09AM |
G03.00002: TIGERISS Instrument Science and Status Brian F Rauch, Wolfgang V Zober The Trans-Iron Galactic Element Recorder for the International Space Station (TIGERISS) is a NASA Astrophysics Pioneers mission planned for launch to the ISS in 2026 to measure the Galactic cosmic rays (GCRs) from 5B to 82Pb. TIGERISS is past the formulation stage of Phase A and working toward its preliminary design review (PDR) in July/August of this year. An ISS accommodation location was not assigned in Phase A and payload designs were being developed for both ESA Columbus and JAXA Japanese Experiment Module-Exposed Facility (JEM-EF) locations, and we hope to have a site selection in advance of the PDR to report as well as the selected flight instrument performance. TIGERISS advances on the TIGER and SuperTIGER long-duration balloon instruments by incorporating pairs of crossed silicon strip detectors (SSDs) in place of both scintillating fiber hodoscopes and scintiallator detectors for trajectory, energy and charge measurement. Cherenkov light-collection boxes with silica aerogel and acrylic radiators will still provide velocity and charge measurement, but they will have the radiators at the tops of the boxes for improved light collection and be read out with silicon photomultipliers (SiPMs) instead of photomultiplier tubes (PMTs) to maximize detector size within the payload envelope and eliminate high voltage. The SSDs and SiPMs have been tested at CERN/SPS beam runs that demonstrated they will provide TIGERISS with high fidelity charge assignment and resolution σZ <0.25. In one-year TIGERISS is expected to measure with superior resolution statistics that match those of SuperTIGER from 16S to 56Ba. Observations that could be extended to the end of the ISS will allow TIGERISS to make the best single-element resolution measurements through 82Pb to probe GCR origins and acceleration. TIGERISS measurements of s- and r-process neutron capture nucleosynthesis production will contribute to the multi-messenger effort to determine the relative contributions of supernova (SN) and Neutron Star Merger (NSM) events to GCRs and galactic nucleosynthesis. |
Thursday, April 4, 2024 11:09AM - 11:21AM |
G03.00003: SiPM Readouts for the Compton Spectrometer and Imager's Anti-Coincidence Shield Parshad Patel, Clio Sleator, Lee Mitchell, Anthony L Hutcheson, Eric Wulf, Emily Kong, John T Tomsick The Compton Spectrometer and Imager (COSI) is a NASA Small Explorer mission focused on exploring the "MeV Gap" (0.2-5 MeV) in the electromagnetic spectrum. Utilizing sixteen 3-D high-resolution germanium detectors (GeDs) and an Anti-Coincidence Shield (ACS) comprising of Bismuth Germanate (BGO) scintillation crystals coupled with Silicon Photomultipliers (SiPMs), COSI aims to conduct spectroscopy, imaging, and polarimetry of cosmic gamma-ray sources. The ACS, providing passive shielding and anti-coincidence monitoring, detects escaped gamma-rays and tracks background radiation. For COSI's ACS, SiPMs are the preferred read-out method to Photomultiplier Tubes (PMT) due to their low voltage, weight and volume. This presentation covers the SiPM and crystal studies used to find the optimal conditions and parameters for operation. In tests using laboratory electronics, we find that a 3x3 SiPM array centered on the narrow side of a BGO slab with a bias voltage ~3V over SiPM breakdown maximizes the threshold. To simplify the overall COSI electronics, the SiPM readout reuses the NRL4 Application Specific Integrated Circuit (ASIC) that is used to read out the GeDs. Results from coupling the NRL4 ASIC to the SiPM and BGO crystals for an ACS side wall will also be presented. |
Thursday, April 4, 2024 11:21AM - 11:33AM |
G03.00004: The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) Mission: summary and some first results Lawrence R Wiencke The Extreme Universe Space Observatory on a Super Pressure Balloon II (EUSO-SPB2) was launched as an Ultra Long Duration Balloon (ULDB) mission of opportunity flight May 13th , 2023, from Wanaka NZ. Its science objectives were to search for PeV energy neutrinos, observe PeV and EeV cosmic rays, measure backgrounds, and explore new techniques as a pathfinder toward the Probe of Extreme Multi-Messenger Astrophysics (POEMMA) space observatory. The payload featured two astroparticle telescopes and an IR cloud camera. All were field-tested in the Utah desert prior to launch. A fluorescence telescope was pointed down to measure EeV-energy cosmic rays. A Cherenkov telescope pointed toward the earth's limb measure PeV energy air showers. In flight it was tilted a few degrees above the limb to explore Cherenkov emission from PeV cosmic-rays and tilted a few degrees below the limb to search for air showers induced through neutrino interactions in the earth's limb. The gondola could be rotated in azimuth to aim the CT at neutrino candidate sources. Unfortunately, the flight was terminated in the Pacific Ocean 36 hours after launch due to a balloon leak. Despite this setback, both telescopes collected data and the mission achieved the first observation of PeV cosmic ray air-showers from near-space. This presentation will summarize the mission and present some first results. Planning for a follow-up flight, POEMMA Balloon Radio (PBR), is in progress. |
Thursday, April 4, 2024 11:33AM - 11:45AM |
G03.00005: EUSO-SPB2 Cherenkov Telescope Performance and Above-the-Limb Observations Eliza A Gazda We report on the development and operation of an imaging atmospheric Cherenkov telescope (IACT) designed to detect extensive air showers (EAS) from Earth-emergent tau neutrinos and cosmic rays from sub-orbital altitudes. The telescope flew on the Extreme Universe Space Observatory Super Pressure Balloon 2 (EUSO-SPB2) on May 13th and 14th, 2023. Successfully operating an IACT for the first time at such altitudes was a crucial step towards opening a new window in high-energy astrophysics, the very-high energy (VHE: >1 PeV) neutrino band. VHE neutrinos probe hadronic processes in cosmic accelerators, including those producing Ultra-High Energy Cosmic Rays (UHECRs) while providing a measure of the composition of UHECRs and exploring neutrino/particle physics at the highest energies. During our short flight, the telescope was pointed above and below the Earth's limb and at different azimuth angles, assessing the telescope operation and exploring the ambient background light levels while detecting EAS images initiated by horizontal cosmic rays in the atmosphere for the first time. In this presentation, the performance of our telescope, recorded air-shower images, and preliminary results searching for Earth-skimming neutrinos will be discussed. |
Thursday, April 4, 2024 11:45AM - 11:57AM |
G03.00006: A Multi-messenger Search for Galactic PeVatrons using data from LHAASO, HAWC, and IceCube Leo Seen, Lu Lu, Pierpaolo Savina, Tianlu Yuan Galactic PeVatrons, proposed sources within our galaxy capable of accelerating cosmic rays to Peta-electronvolt (PeV) energies, are believed to produce gamma rays and neutrinos through interactions with the interstellar medium. Recent observations from experiments like LHAASO and HAWC have detected gamma-ray sources emitting energies surpassing 100 TeV, suggesting the possibility of neutrino emissions. Our analysis primarily focuses on seeking correlations within data collected from LHAASO, HAWC, and IceCube, aiming to validate the hadronic PeVatron hypothesis. Furthermore, we aim to investigate the feasibility of characterizing diffuse neutrino emissions originating from segmented regions of the galactic plane. |
Thursday, April 4, 2024 11:57AM - 12:09PM |
G03.00007: POEMMA-Balloon with radio: A balloon born Multi-Messenger Multi-Detector Observatory Johannes Eser, Angela V Olinto, Giuseppe Osteria
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Thursday, April 4, 2024 12:09PM - 12:21PM |
G03.00008: Multi-Flavor Neutrino Search from Cygnus Cocoon with IceCube Lu Lu, Pierpaolo Savina, Tianlu Yuan, Albrecht Karle The Cygnus Cocoon is among the most luminous extended galactic γ-ray sources. It has been observed by various instruments, including Fermi, ARGO, HAWC, and most recently, LHAASO, detecting photons with energies up to ~1.4 PeV. Confirming the hadronic origin of these high-energy photons relies on detecting a neutrino excess. Our study focuses on searching for electron neutrinos, muon neutrinos, and tau neutrinos originating from the direction of the Cygnus Cocoon, utilizing data collected at the IceCube Neutrino Observatory. Additionally, we will present results obtained from template-based measurements of galactic diffuse neutrinos, using all three neutrino flavors. |
Thursday, April 4, 2024 12:21PM - 12:33PM |
G03.00009: Stellar Collisions in the Galactic Center Sanaea C Rose, Smadar Naoz, Re'em Sari, Itai Linial, Morgan MacLeod Like most galaxies, the Milky Way harbors a supermassive black hole (SMBH) at its center, surrounded by a dense nuclear star cluster. Most stars within 0.1 pc of the SMBH will experience one or more direct collisions with another star before evolving off the main-sequence. Using a statistical approach, we characterize the outcomes of these stellar collisions within the inner parsec of the Galactic Center (GC). Close to the SMBH, where the velocity dispersion is larger than the escape speed from a Sun-like star, collisions lead to mass loss. We find that the stellar population within 0.01 pc is halved within about a Gyr because of destructive collisions. Additionally, we predict a diffuse population of peculiar low-mass stars in the GC. These stars have been divested of their outer layers in the inner 0.01 pc before migrating to larger distances from the SMBH. Between 0.01 and 0.1 pc from the SMBH, collisions can result in mergers. Our results suggest that repeated collisions between lower mass stars can produce massive (> 10 M⊙) stars. We comment on G objects, dust and gas enshrouded stellar objects, that may result from main-sequence stellar collisions. Lastly, I will discuss the role collisions play in shaping the stellar density profile in the vicinity of the SMBH using both an analytic framework and semianalytic models. |
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