1. The case of AT2022wtn : a tidal disruption event in an interacting galaxyF. Onori, M. Nicholl, P. Ramsden, S. McGee, R. Roy, Wei Li, I. Arcavi, Mateusz Bronikowski, E. Concepcion, Tanja Petrushevska, 2025, original scientific article Abstract: Abstract
We present the results from our multi-wavelength monitoring campaign of the transient AT 2022wtn, discovered by the Zwicky Transient Facility in the nucleus of SDSS J232323.79+104107.7, the less massive galaxy in an active merging pair with a mass ratio of ∼10:1. AT 2022wtn shows spectroscopic and photometric properties consistent with a X-ray faint N-strong TDE-H+He with a number of peculiarities. Specifically, a 30-days long plateau at maximum luminosity, a corresponding dip in temperature and the development of a double-horned N iii+He ii line profile. Strong and time-evolving velocity offsets in the TDE broad emission lines and the detection of a transient radio emission, indicate the presence of outflows. Overall, the observed properties are consistent with the full disruption of a low-mass star by a ∼106M⊙ SMBH followed by an efficient disk formation and the launch of a quasi-spherical reprocessing envelope of fast expanding outflowing material. The observed differences between the He ii and the Hydrogen and N iii lines can be explained either with a spatial separation of the lines emitting region or with a late-time reveal of shocks from the returning debris streams, as the photosphere recedes. Finally, we present an extensive analysis of the hosting environment and discuss the implications for the discovery of two TDEs in interacting galaxy pairs, finding indication for an over-representation of TDEs in these systems. The AT 2022wtn host galaxy properties suggest that it is in the early stages of the merger, therefore we may be witnessing the initial enhanced rate of TDEs in interacting galaxies before the post-starburst phase.
Keywords: tidal disruption event, astronomy, AT2022wtn
Published in RUNG: 20.05.2025; Views: 398; Downloads: 5
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2. Searches for UHE neutrinos and upward-going showers at the Pierre Auger ObservatoryJaime Alvarez-Muňiz, Andrej Filipčič, Jon Paul Lundquist, Shima Ujjani Shivashankara, Samo Stanič, Serguei Vorobiov, Danilo Zavrtanik, Marko Zavrtanik, 2025, published scientific conference contribution Abstract: The Pierre Auger Observatory, as a key actor in multi-messenger astronomy, is playing a crucial role in searching for and following-up cosmic phenomena across different channels. Data from the Observatory have been utilized for nearly 20 years to search for showers induced by Ultra-High-Energy (UHE) neutrinos with energies exceeding 0.1 EeV. Neutrino-induced showers at high zenith angles are likely to develop deep in the atmosphere, resulting in a significant electromagnetic component that distinguishes them from the cosmic-ray background. This enables the identification of candidate events from both neutrinos interacting in the atmosphere and Earth-skimming τ neutrinos. Searches have been conducted for both diffuse and point sources using data collected by the Surface Detector, a large array of over 1660 water-Cherenkov stations spread over an area of 3000 square km. Additionally, the Fluorescence Detector consisting of 27 telescopes has been employed to search for upward-developing air showers, as predicted by several interpretations of the 'anomalous' events detected by the ANITA detector. In this contribution, we summarize the main results obtained in these searches and discuss their astrophysical implications.
Keywords: ulti-messenger astronomy, ultra-high-energy neutrino search, down-going neutrinos, Earth-skimming τ neutrinos, search for upward-developing air showers, ANITA detector, Pierre Auger Observatory
Published in RUNG: 24.03.2025; Views: 638; Downloads: 7
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3. LensWatch. II. improved photometry and time-delay constraints on the strongly lensed type Ia supernova 2022qmx ("SN Zwicky") with Hubble Space Telescope template observationsC. Larison, Justin Pierel, M. J. B. Newman, S. W. Jha, D. Gilman, E. E. Hayes, A. Agrawal, N. Arendse, Mateusz Bronikowski, Tanja Petrushevska, 2025, original scientific article Abstract: Abstract
Strongly lensed supernovae (SNe) are a rare class of transient that can offer tight cosmological constraints that are complementary to methods from other astronomical events. We present a follow-up study of one recently discovered strongly lensed SN, the quadruply imaged type Ia SN 2022qmx (aka “SN Zwicky”), at z = 0.3544. We measure updated, template-subtracted photometry for SN Zwicky and derive improved time delays and magnifications. This is possible because SNe are transient, fading away after reaching their peak brightness. Specifically, we measure point-spread-function photometry for all four images of SN Zwicky in three Hubble Space Telescope WFC3/UVIS passbands (F475W, F625W, and F814W) and one WFC3/IR passband (F160W), with template images taken ∼11 months after the epoch in which the SN images appear. We find consistency to within 2σ between lens-model-predicted time delays (≲1 day) and measured time delays with HST colors (≲2 days), including the uncertainty from chromatic microlensing that may arise from stars in the lensing galaxy. The standardizable nature of SNe Ia allows us to estimate absolute magnifications for the four images, with images A and C being elevated in magnification compared to lens model predictions by about 6σ and 3σ, respectively, confirming previous work. We show that millilensing or differential dust extinction is unable to explain these discrepancies, and we find evidence for the existence of microlensing in images A, C, and potentially D that may contribute to the anomalous magnification.
Keywords: supernova, strong lensing, astronomy
Published in RUNG: 10.03.2025; Views: 810; Downloads: 9
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4. The diversity of strongly interacting Type IIn supernovaeI. Salmaso, E. Cappellaro, L. Tartaglia, J. P. Anderson, S. Benetti, Mateusz Bronikowski, Y.-Z. Cai, P. Charalampopoulos, W. T. Chen, E. Concepcion, Tanja Petrushevska, 2025, original scientific article Abstract: Context. At late stages, massive stars experience strong mass-loss rates, losing their external layers and thus producing a dense H-rich circumstellar medium (CSM). After the explosion of a massive star, the collision and continued interaction of the supernova (SN) ejecta with the CSM power the SN light curve through the conversion of kinetic energy into radiation. When the interaction is strong, the light curve shows a broad peak and high luminosity that lasts for several months. For these SNe, the spectral evolution is also slower compared to non-interacting SNe. Notably, energetic shocks between the ejecta and the CSM create the ideal conditions for particle acceleration and the production of high-energy (HE) neutrinos above 1 TeV.
Aims. We study four strongly interacting Type IIn SNe, 2021acya, 2021adxl, 2022qml, and 2022wed, in order to highlight their peculiar characteristics, derive the kinetic energy of their explosion and the characteristics of the CSM, infer clues on the possible progenitors and their environment, and relate them to the production of HE neutrinos.
Methods. We analysed spectro-photometric data of a sample of interacting SNe to determine their common characteristics and derive the physical properties (radii and masses) of the CSM and the ejecta kinetic energies and compare them to HE neutrino production models.
Results. The SNe analysed in this sample exploded in dwarf star-forming galaxies, and they are consistent with energetic explosions and strong interaction with the surrounding CSM. For SNe 2021acya and 2022wed, we find high CSM masses and mass-loss rates, linking them to very massive progenitors. For SN 2021adxl, the spectral analysis and less extreme CSM mass suggest a stripped-envelope massive star as a possible progenitor. SN 2022qml is marginally consistent with being a Type Ia thermonuclear explosion embedded in a dense CSM. The mass-loss rates for all the SNe are consistent with the expulsion of several solar masses of material during eruptive episodes in the last few decades before the explosion. Finally, we find that the SNe in our sample are marginally consistent with HE neutrino production.
Keywords: astronomy, neutrinos, supernovae
Published in RUNG: 04.03.2025; Views: 789; Downloads: 8
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5. Existing open data practices in high energy astro- and particle physics : lecture at the Mini workshop on Open Science, 6. 11. 2024, AjdovščinaSerguei Vorobiov, 2024, unpublished conference contribution Abstract: In this presentation, the existing open data practices in high energy astro-, particle and astroparticle physics are presented. Open data has become fundamental in astrophysics, particle, and astroparticle physics, enhancing collaboration, reproducibility, and transparency, while accelerating innovation. A recent shift toward openness, marked by data-sharing initiatives and accessible resources, is driving breakthroughs like the multi-messenger observation of GW170817, a neutron star merger detected in both gravitational waves and gamma rays, and the identification of blazar TXS 0506+056 as a high-energy neutrino source.
Across these fields, robust efforts are underway to develop and implement FAIR-compliant data policies, with a wide array of supportive tools, standards, protocols, and software already in use (Virtual Observatory in astrophysics, CERN’s Open Data Portal in particle physics, ...).
The challenges of astroparticle physics data, often more complex than traditional astrophysics
or particle physics data, call for additional coordination and technical advancements to meet
FAIR principles effectively. Machine learning also plays a transformative role in these domains, enhancing the analysis of both proprietary and open data to reveal new insights and optimize
research methodologies.
Keywords: open data, FAIR data, astrophysics, high-energy particle physics, astroparticle physics, multi-messenger astronomy
Published in RUNG: 06.01.2025; Views: 1002; Downloads: 2
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6. Performance of the INFN Camera calibration device of the first Large Size Telescope in the Cherenkov Telescope ArrayM. Palatiello, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: On October 10th 2018 started the commissioning of the first Large Size Telescope (LST)
prototype at the Cherenkov Telescope Array (CTA) northern site at the Observatorio del Roque de los Muchachos, Canary Island of La Palma (Spain). For a precise event energy reconstruction, an LST camera requires a uniform and constant calibration over a large dynamic range, up to 10[sup]4 photo-electrons (p.e.), for each camera photomultiplier tube (PMT). This paper describes the performance of the LST-1 camera calibration system (named CaliBox) in the first commissioning period and provides preliminary results of measurements of the light flat field.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, CTAO North, Observatorio del Roque de los Muchachos, Large-Size Telescopes (LSTs)
Published in RUNG: 14.11.2024; Views: 1193; Downloads: 8
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7. The calibration of the first Large-Sized Telescope of the Cherenkov Telescope ArrayS. Sakurai, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: The Cherenkov Telescope Array (CTA) represents the next generation of very high-energy gamma-ray observatory, which will provide broad coverage of gamma rays from 20 GeV to 300 TeV with unprecedented sensitivity. CTA will employ three different sizes of telescopes, and the Large-Sized Telescopes (LSTs) of 23-m diameter dish will provide the sensitivity in the lowest energies down to 20 GeV. The first LST prototype has been inaugurated in October 2018 at La Palma (Canary Islands, Spain) and has entered the commissioning phase. The camera of the LST consists of 265 PMT modules. Each module is equipped with seven high-quantum-efficiency Photomultiplier Tubes (PMTs), a slow control board, and a readout board. Ensuring high uniformity and precise characterization of the camera is the key aspects leading to the best performance and low systematic uncertainty of the LST cameras. Therefore, prior to the installation on site, we performed a quality check of all PMT modules. Moreover, the absolute calibration of light throughput is essential to reconstruct the amount of light received by the telescope. The amount of light is affected by the atmosphere, by the telescope optical system and camera, and can be calibrated using the ring-shaped images produced by cosmic-ray muons. In this contribution, we will show the results of off-site quality control of PMT modules and on-site calibration using muon rings. We will also highlight the status of the development of Silicon Photomultiplier modules that could be considered as a replacement of PMT modules for further improvement of the camera.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, Large-Sized Telescopes (LSTs), LST-1 calibration, Photomultiplier Tubes (PMTs)
Published in RUNG: 14.11.2024; Views: 1135; Downloads: 8
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8. The Cherenkov transparency coefficient for the atmospheric monitoring and array calibration at the Cherenkov Telescope Array SouthStanislav Stefanik, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: Reconstruction of energies of very-high-energy γ–rays observed by imaging atmospheric Cherenkov telescopes is affected by changes in the atmospheric conditions and the performance of telescope components. Reliable calibration schemes aimed at these effects are necessary for the forthcoming Cherenkov Telescope Array (CTA) to achieve its goals on the maximally allowed systematic uncertainty of the global energy scale. A possible means of estimating the atmospheric attenuation of Cherenkov light is the method of the Cherenkov transparency coefficient (CTC). The CTC is calculated using the telescope detection rates, dominated by the steady cosmic ray background, while properly correcting for the hardware and observational conditions.
The coefficient can also be used to relatively calibrate the optical throughput of telescopes on the assumption of homogeneous atmospheric transparency above the array. Using Monte Carlo simulations, we investigate here the potential of the CTC method for the atmospheric monitoring and telescope cross-calibration at the CTA array in the southern hemisphere. We focus on the feasibility of the method for the array of telescopes of three sizes in different observation configurations and under various levels of atmospheric attenuation.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, imaging atmospheric Cherenkov telescopes (IACTs), atmospheric monitoring, IACT calibration
Published in RUNG: 14.11.2024; Views: 1095; Downloads: 5
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9. Using muon rings for the optical throughput calibration of the Cherenkov Telescope ArrayMarkus Gaug, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: Muon ring images observed with Imaging Atmospheric Cherenkov Telescopes (IACTs) provide a powerful means to calibrate the optical throughput of IACTs and monitor their optical point spread function. We investigate whether muons ring images can be used as the primary optical throughput calibration method for the telescopes of the future Cherenkov Telescope Array (CTA) and find several additional systematic effects in comparison to previous works. To ensure that the method achieves the accuracy required by CTA, these systematic effects need to be taken into account and minor modifications to the hardware and analysis are necessary. We derive analytic estimates for the expected muon data rates to be used for optical throughput calibration, monitoring of the optical point spread function, with achievable statistical and systematic uncertainties, and explore the potential of muon ring images as a secondary method of camera pixel flat-fielding.
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, Imaging Atmospheric Cherenkov Telescopes, IACT optical throughput calibration, IACT camera pixel flat-fielding, IACT optical point spread function (PSF), muon ring images
Published in RUNG: 13.11.2024; Views: 1043; Downloads: 8
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10. Status and performance results from NectarCAM : a camera for CTA medium sized telescopesThomas Tavernier, Christopher Eckner, Gašper Kukec Mezek, Samo Stanič, Serguei Vorobiov, Lili Yang, Gabrijela Zaharijas, Danilo Zavrtanik, Marko Zavrtanik, Lukas Zehrer, 2019, published scientific conference contribution Abstract: The Cherenkov Telescope Array (CTA) will be the first ground-based observatory for gamma-ray astronomy. With more than a hundred of 4th generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) distributed in two large arrays, CTA will reach unprecedented sensitivity, angular resolution, and spectral coverage. Three classes of IACTs – 40 Medium-Sized Telescopes (MSTs), 8 Large-Sized Telescopes (LSTs) and 70 Small-Sized Telescopes (SSTs) – are required to cover the full CTA energy range (20 GeV to 300 TeV).
NectarCAM is a Cherenkov camera which is designed to equip medium sized telescopes of CTA, covering the central energy range from 100 GeV to 30 TeV, with a field of view of 8 degrees. It is based on a modular design with data channels using the NECTAr chip, which is equipped with both GHz sampling Switched Capacitor Array and 12-bit Analog to Digital Converter (ADC). The camera will comprise 265 modules, each consisting of 7 photomultiplier Tubes (PMTs) and a Front-End Board performing the data capture, sending the data over the Ethernet after the trigger decision at rates up to 10 kHz.
This contribution provides an overview of the status of the first NectarCAM camera currently under integration in CEA Paris-Saclay (France). Furthermore, we will discuss the calibration strategies and present performance results from the CEA Paris-Saclay test bench and from the first data taken under a real sky on the prototype of medium sized telescope (MST) structure in Adlershof (Germany).
Keywords: very-high-energy gamma-ray astronomy, Cherenkov Telescope Array (CTA) Observatory, Imaging Atmospheric Cherenkov Telescopes, medium-sized telescopes, NectarCAM IACT camera
Published in RUNG: 13.11.2024; Views: 1123; Downloads: 7
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