arXiv subjects

A. Nepomuk Otte

Publications and source records attributed to A. Nepomuk Otte.

17 recordsLinked to original sources

arXiv2025

The Trinity-One PeV-Neutrino Telescope

Following the Trinity Demonstrator, Trinity One will be the first of the 18 Cherenkov telescopes that make up the Trinity PeV-Neutrino Observatory. Located on Frisco Peak in Utah, Trinity One can observe 64\% of the sky, allowing it to detect potential neutrino point sources with unprecedented sensitivity, ranging from 1 PeV to 10 EeV. We outline the design of Trinity One, which features a 60 m$^2$ light-collection surface and the ability to rotate in azimuth. It has a field of view measuring $5^\circ$ by $60^\circ$, which is equipped with a silicon photomultiplier camera with a resolution of $0.3^\circ$. Utilizing the design of Trinity One, we present performance calculations in relation to various source classes.

astro-ph.HE↗

arXiv2025

The Extreme Universe Observatory on a Super-Pressure Balloon II: Mission, Payload, and Flight

The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) is a pathfinder mission toward a space-based observatory such as the Probe of Extreme Multi-Messenger Astrophysics (POEMMA). The aim of POEMMA is the observation of Ultra High Energy COsmic Rays (UHECRs) in order to elucidate their nature and origins and to discover $\gtrsim$ 20 PeV very high energy neutrinos that originate from transient and steady astrophysical sources. EUSO-SPB2 was launched from Wānaka New Zealand on May 13th, 2023 as a NASA Balloon Program Office test flight. The mission goals included making the first near-space altitude observations of the fluorescence emission from UHECR-induced extensive air showers (EASs) and making the first direct Cherenkov light emission from PeV cosmic rays traversing Earth's atmosphere. In addition, a Target of Opportunity program was developed for selecting and scheduling observations of potential neutrino sources as they passed just below the Earth's limb. Although a leaky balloon forced termination over the Pacific Ocean after 37 hours, data was collected to demonstrate the successful commissioning and operation of the instruments. This paper includes a description of the payload and the key instruments, pre-flight instrument characterizations in the lab and in the desert, flight operations and examples of the data collected. The flight was too short to catch a UHECR event via fluorescence, however about 10 candidate EAS events from cosmic rays were recorded via Cherenkov light.

astro-ph.HE↗

arXiv2024

The Camera and Readout for the Trinity Demonstrator and the EUSO-SPB2 Cherenkov Telescope

We developed a modular silicon photomultiplier camera to detect Earth-skimming PeV to EeV tau neutrinos with the imaging atmospheric Cherenkov technique. We built two cameras, a 256-pixel camera with S14161-6050HS SiPMs for the Trinity Demonstrator located on Frisco Peak, Utah, and a 512-pixel camera with S14521-6050AN SiPMs for the EUSO-SPB2 Cherenkov Telescope. The front-end electronics are based on the eMUSIC ASIC, and the camera signals are sampled and digitized with the 100MS/s and 12-bit AGET system. Both cameras are liquid-cooled. We detail the camera concept and the results from characterizing the SiPMs, bench testing, and calibrating the two cameras.

astro-ph.IM↗

arXiv2021

Overview of Cherenkov Telescope on-board EUSO-SPB2 for the Detection of Very-High-Energy Neutrinos

We present the status of the development of a Cherenkov telescope to be flown on a long-duration balloon flight, the Extreme Universe Space Observatory Super Pressure Balloon 2 (EUSO-SPB2). EUSO-SPB2 is an approved NASA balloon mission that is planned to fly in 2023 and is a precursor of the Probe of Extreme Multi-Messenger Astrophysics (POEMMA), a candidate for an Astrophysics probe-class mission. The purpose of the Cherenkov telescope on-board EUSOSPB2 is to classify known and unknown sources of backgrounds for future space-based neutrino detectors. Furthermore, we will use the Earth-skimming technique to search for Very-High-Energy (VHE) tau neutrinos below the limb (E > 10 PeV) and observe air showers from cosmic rays above the limb. The 0.785 m^2 Cherenkov telescope is equipped with a 512-pixel SiPM camera covering a 12.8° x 6.4° (Horizontal x Vertical) field of view. The camera signals are digitized with a 100 MS/s readout system. In this paper, we discuss the status of the telescope development, the camera integration, and simulation studies of the camera response.

astro-ph.IM↗

arXiv2021

Robust constraints on Lorentz Invariance Violation from H.E.S.S., MAGIC and VERITAS data combination

Gamma-Ray bursts, flaring active galactic nuclei and pulsars are distant and energetic astrophysical sources, detected up to tens of TeV with Imaging Atmospheric Cherenkov Telescopes (IACTs). Due to their high variability, they are the most suitable sources for energy-dependent time-delay searches related to Lorentz Invariance Violation (LIV) predicted by some Quantum Gravity (QG) models. However, these studies require large datasets. A working group between the three major IACTs ground experiments - H.E.S.S., MAGIC and VERITAS - has been formed to address this issue and combine for the first time all the relevant data collected by the three experiments in a joint analysis. This proceeding will review the new standard combination method. The likelihood technique used to deal with data from different source types and instruments will be presented, as well as the way systematic uncertainties are taken into account. The method has been developed and tested using simulations based on published source observations from the three experiments. From these simulations, the performance of the method will be assessed and new light will be shed on time delays dependencies with redshift.

astro-ph.HE↗

arXiv2021

Prospects for macroscopic dark matter detection at space-based and suborbital experiments

We compare two different formalisms for modeling the energy deposition of macroscopically sized/massive quark nuggets (a.k.a. macros) in the Earth's atmosphere. We show that for a reference mass of 1 g, there is a discrepancy in the macro luminosity of about 14 orders of magnitude between the predictions of the two formalisms. Armed with our finding we estimate the sensitivity for macro detection at space-based (Mini-EUSO and POEMMA) and suborbital (EUSO-SPB2) experiments.

hep-ph↗

arXiv2019

Development of a Cherenkov Telescope for the Detection of Ultrahigh Energy Neutrinos with EUSO-SPB2 and POEMMA

The detection of astrophysical neutrinos by IceCube and the potential to constrain source models of ultra-high energy cosmic rays provide the motivation to develop instruments for the observation of neutrinos above $10^7$ GeV. Among the different techniques to detect ultra-high energy neutrinos is the Earth-skimming technique. It makes use of the fact that the tau produced in a tau neutrino interaction inside the Earth can emerge from the ground and initiate an upward-going particle shower in the atmosphere. The particle shower and thus the neutrino can be reconstructed by measuring the Cherenkov and radio emission from the shower particles. In this presentation, we discuss our ongoing development of a Cherenkov telescope for the detection of tau neutrinos, which is to be deployed on the Extreme Universe Space Observatory Super Pressure Balloon 2 (EUSO-SPB2) and is a precursor experiment for the proposed Probe of Extreme Multi-Messenger Astrophysics (POEMMA) mission. POEMMA aims at the detection of ultrahigh energy cosmic rays and ultrahigh energy neutrinos from low earth orbit. The 1 m$^2$ Cherenkov telescope for EUSO-SPB2 will use silicon photomultipliers coupled to a 100 MS/s readout based on the ASIC for General Electronics for TPC`s (AGET) switch capacitor ring sampler. We present the optics, results from our studies to qualify the readout concept and the design of the mechanical integration of the photon detectors and the readout into the telescope.

astro-ph.IM↗

arXiv2019

Trinity: An Air-Shower Imaging System for the Detection of Ultrahigh Energy Neutrinos

Efforts to detect ultrahigh energy neutrinos are driven by several objectives: What is the origin of astrophysical neutrinos detected with IceCube? What are the sources of ultrahigh energy cosmic rays? Do the ANITA detected events point to new physics? Shedding light on these questions requires instruments that can detect neutrinos above $10^7$ GeV with sufficient sensitivity - a daunting task. While most ultrahigh energy neutrino experiments are based on the detection of a radio signature from shower particles following a neutrino interaction, we believe that the detection of Cherenkov and fluorescence light from shower particles is an attractive alternative. Imaging air showers with Cherenkov and fluorescence light is a technique that is successfully used in several ultrahigh energy cosmic ray and very-high energy gamma-ray experiments. We performed a case study of an air-shower imaging system for the detection of earth-skimming tau neutrinos. The detector configuration we consider consists of an imaging system that is located on top of a mountain and is pointed at the horizon. From the results of this study we conclude that a sensitivity of $3\cdot10^{-9}$ GeV cm$^{-2}$s$^{-1}$sr$^{-1}$ can be achieved at $2\cdot10^8$ GeV with a relatively small and modular system after three years of observation. In this presentation we discuss key findings of our study and how they translate into design requirements for an imaging system we dub Trinity.

astro-ph.IM↗

arXiv2019

Trinity: An Air-Shower Imaging Instrument to detect Ultrahigh Energy Neutrinos

Trinity is a proposed air-shower imaging system optimized for the detection of earth-skimming ultrahigh energy tau neutrinos with energies between $10^7$ GeV and $10^{10}$ GeV. Trinity will pursue three major scientific objectives. 1) It will narrow in on possible source classes responsible for the astrophysical neutrino flux measured by IceCube. 2) It will help find the sources of ultrahigh-energy cosmic rays (UHECR) and understand the composition of UHECR. 3) It will test fundamental neutrino physics at the highest energies. Trinity uses the imaging technique, which is well established and successfully used by the very high-energy gamma-ray community (CTA, H.E.S.S., MAGIC, and VERITAS) and the UHECR community (Telescope Array, Pierre Auger)

astro-ph.IM↗

arXiv2017

First combined studies on Lorentz Invariance Violation from observations of astrophysical sources

Imaging Atmospheric Cherenkov Telescopes study the highest energy (up to tens of TeV) photon emission coming from nearby and distant astrophysical sources, thus providing valuable results from searches for Lorentz Invariance Violation (LIV) effects. Highly variable, energetic and distant sources such as Pulsars and AGNs are the best targets for the Time-of-Flight LIV studies. However, the limited number of observations of AGN flares or of high-energy pulsed emission greatly restricts the potential of such studies, especially any potential LIV effects as a function of redshift. To address these issues, an inter-experiment working group has been established by the three major collaborations taking data with Imaging Atmospheric Cherenkov Telescopes (H.E.S.S., MAGIC and VERITAS) with the aim to increase sensitivity to any effects of LIV, together with an improved control of systematic uncertainties, by sharing data samples and developing joint analysis methods. This will allow an increase in the number of available sources and to perform a sensitive search for redshift dependencies. This presentation reviews the first combined maximum likelihood method analyses using simu- lations of published source observations done in the past with H.E.S.S., MAGIC and VERITAS. The results from analyses based on combined maximum likelihood methods, the strategies to deal with data from different types of sources and instruments, as well as future plans will be presented.

astro-ph.HE↗

arXiv2013

Gamma-Ray Burst Science in the Era of the Cherenkov Telescope Array

We outline the science prospects for gamma-ray bursts (GRBs) with the Cherenkov Telescope Array (CTA), the next-generation ground-based gamma-ray observatory operating at energies above few tens of GeV. With its low energy threshold, large effective area and rapid slewing capabilities, CTA will be able to measure the spectra and variability of GRBs at multi-GeV energies with unprecedented photon statistics, and thereby break new ground in elucidating the physics of GRBs, which is still poorly understood. Such measurements will also provide crucial diagnostics of ultra-high-energy cosmic ray and neutrino production in GRBs, advance observational cosmology by probing the high-redshift extragalactic background light and intergalactic magnetic fields, and contribute to fundamental physics by testing Lorentz invariance violation with high precision. Aiming to quantify these goals, we present some simulated observations of GRB spectra and light curves, together with estimates of their detection rates with CTA. Although the expected detection rate is modest, of order a few GRBs per year, hundreds or more high-energy photons per burst may be attainable once they are detected. We also address various issues related to following up alerts from satellites and other facilities with CTA, as well as follow-up observations at other wavelengths. The possibility of discovering and observing GRBs from their onset including short GRBs during a wide-field survey mode is also briefly discussed.

astro-ph.HE↗

arXiv2012

Prospects of performing Lorentz invariance tests with VHE emission from pulsars

Gamma-ray observations provide sensitive tests of Lorentz invariance violation (LIV). At present the most sensitive tests come from observations of transient events, gamma-ray bursts and flaring AGN. Disadvantages of transients are that an independent confirmation by a different experiment is often not possible and that limits cannot be improved with a longer exposure. Pulsars do not have these disadvantages. Testing Lorentz invariance with pulsars was not considered seriously so far because limits were not competitive. The VERITAS collaboration has recently reported the detection of pulsed emission from the Crab pulsar above 100 GeV. This measurement can be used to constrain LIV effects with a sensitivity that is competitive with some of the best available limits. In view of this unexpected result we discuss what the prospects are of doing LIV tests with very-high energy gamma-ray emission from pulsars.

astro-ph.HE↗

arXiv2011

First Detection of a Pulsar above 100 GeV

We present the detection of pulsed gamma-ray emission from the Crab Pulsar above 100 GeV with the VERITAS array of atmospheric Cherenkov telescopes. Gamma-ray emission at theses energies is not expected in present pulsar models. We find that the photon spectrum of pulsed emission between 100 MeV and 400 GeV can be described by a broken power law, and that it is statistically preferred over a power law with an exponential cut-off. In the VERITAS energy range the spectrum can be described with a simple power law with a spectral index of -3.8 and a flux normalization at 150 GeV that is equivalent to 1 % of the Crab Nebula gamma-ray flux. The detection of pulsed emission above 100 GeV and the absence of an exponential cutoff rules out curvature radiation as the primary gamma-ray-producing mechanism. The pulse profile exhibits the characteristic two pulses of the Crab Pulsar at phases 0.0 and 0.4, albeit 2-3 times narrower than below 10 GeV. The narrowing can be interpreted as a tapered particle acceleration region in the magnetosphere. Our findings require that the emission region of the observed gamma rays be beyond 10 stellar radii from the neutron star.

astro-ph.HE↗

arXiv2011

The Upgrade of VERITAS with High Efficiency Photomultipliers

We are in the process of upgrading the VERITAS array of Cherenkov telescopes with new, high efficiency photomultipliers (PMT) that will considerably lower the energy threshold of the instrument and improve the overall sensitivity. The upgrade will be finished in Summer 2012 when the PMTs will be installed in the existing cameras. We discuss the performance of the new photon detectors and the status of the project.

astro-ph.IM↗

arXiv2011

Catching GRBs with atmospheric Cherenkov telescopes

Fermi has shown GRBs to be a source of >10 GeV photons. We present an estimate of the detection rate of GRBs with a next generation Cherenkov telescope. Our predictions are based on the observed properties of GRBs detected by Fermi, combined with the spectral properties and redshift determinations for the bursts population by instruments operating at lower energies. While detection of VHE emission from GRBs has eluded ground-based instruments thus far, our results suggest that ground-based detection may be within reach of the proposed Cherenkov Telescope Array (CTA), albeit with a low rate, 0.25 - 0.5/yr. Such a detection would help constrain the emission mechanism of gamma-ray emission from GRBs. Photons at these energies from distant GRBs are affected by the UV-optical background light, and a ground-based detection could also provide a valuable probe of the Extragalactic Background Light (EBL) in place at high redshift.

astro-ph.HE↗

arXiv2009

Upgrade of the VERITAS Cherenkov Telescope Array

The VERITAS Cherenkov telescope array has been fully operational since Fall 2007 and has fulfilled or outperformed its design specifications. We are preparing an upgrade program with the goal to lower the energy threshold and improve the sensitivity of VERITAS at all accessible energies. In the baseline program of the upgrade we will relocate one of the four telescopes, replace the photo-sensors by higher efficiency photomultipliers and install a new trigger system. In the enhanced program of the upgrade we foresee, in addition, the construction of a fifth telescope and installation of an active mirror alignment system.

astro-ph.IM↗

arXiv2007

Observation of the Crab Nebula with the MAGIC telescope

We report about very high energy (VHE) gamma-ray observations of the Crab Nebula with the MAGIC telescope. The gamma-ray flux from the nebula was measured between 60 GeV and 9 TeV. The energy spectrum can be described with a curved power law dF/dE=f_0 (E/300GeV)^(a+b log10(E/300GeV)) with a flux normalization f_0 of (6.0+-0.2stat)*10^-10 cm^-2 s^-1 TeV^-1, a=-2.31+-0.06stat and b=-0.26+-0.07stat. The position of the IC-peak is determined at 77+-47 GeV. Within the observation time and the experimental resolution of the telescope, the gamma-ray emission is steady and pointlike. The emission's center of gravity coincides with the position of the pulsar. Pulsed gamma-ray emission from the pulsar could not be detected. We constrain the cutoff energy of the spectrum to be less than ~30 GeV, assuming that the differential energy spectrum has an exponential cutoff. For a super-exponential shape, the cutoff energy can be as high as ~60GeV.

astro-ph↗