Search

Experiments during recent years with SEVAN detectors on mountain tops in Armenia, Slovakia, and Bulgaria reveal the broad potential of SEVAN detectors; The SEVAN detector on Lomnicky Stit (Slovakia) measured the largest thunderstorm ground enhancements (TGE), with particle fluxes exceeding the background 100-times. With muon and gamma ray fluxes, the maximum values of the potential difference in thunderclouds were measured, equal to 350 MV at Mt. Aragats, and 500 MV at the sharp peak of Lomnicky Stit. In Nov 2019, SEVAN detectors were installed at DESY (Hamburg and Zeuthen sites). Fluxes of electrons, photons, and muons and weather parameters are continuously monitored at all sites (at different latitudes, longitudes, and altitudes). To fully exploit the scientific potential of the SEVAN detectors, in 2023 is planned to install a new detector in the Umwelt-Forschungs-Station (UFS, Schneefernerhaus, 2650 m asl) near the top of the Zugspitze (2962 m), a site with a long history of atmospheric research. The new SEVAN module will be compact (SEVAN-light), and will enable the energy spectra measurements in the range from 0.3 to 50 MeV, allowing unambiguously separating Radon progeny gamma radiation from runaway electron-photon avalanches.

Proceeding from a stormy day of 22 September 2022, when 7 thunderstorm ground enhancements occurred (TGEs, 3 of them very large), we perform an analysis of the most important conditions, on which depend the origination of the large particle fluxes in the thunderous atmosphere. Among these conditions are the near-surface electric field (NSEF), graupel fall, and lightning activity. We estimate the intensity of the largest particle flux of 1,25 mln gamma rays hitting each square meter of surface on Aragats with energy spectra extended up to 70 MeV. Only one TGE from 7 meets the conditions to recover the electron energy spectrum; the fraction of electrons with energies above 10 MeV relative to the gamma ray flux reaches 45%. By carefully examining the graupel fall, we demonstrate that the lower dipole, which accelerates electrons, is formed by the main negative and lower positively charged regions. The lower dipole decays with a graupel fall that coincides with TGE terminations (usually by a lightning flash).

Stellar counter-rotation in disk galaxies directly relates to the complex phenomenon of the disk mass assembly believed to be driven by external processes, such as accretion and mergers. The detailed study of such systems makes it possible to reveal the source of external accretion and establish the details of this process. In this paper, we investigate the galaxy PGC 66551 (MaNGA ID~1-179561) which hosts two large-scale counter-rotating stellar disks suspected in the SDSS MaNGA data and then confirmed using deep follow-up spectroscopy with the 10-m Southern African Large Telescope. We measured properties of ionized gas and stellar populations of both counter-rotating disks in PGC 66551. We found that the counter-rotating disk is compact, contains young stars with subsolar metallicity, and has a stellar mass $5\times10^{9}$ M$_\odot$ which amounts to $\approx$20\% of the galaxy's total. Surprisingly, the main 8 Gyr old disk has a significantly lower metallicity -0.8 dex than other counter-rotating galaxies. We developed a simple analytic model for the metal enrichment history, which we applied to PGC 66551 and constrained the parameters of the galactic outflow wind and estimated the metallicity of the infalling gas that formed the counter-rotating disk to be $-0.9 ... -0.5$ dex. Our interpretation prefers a merger with gas-rich satellite over cold accretion from a cosmic filament as a source of gas, which then formed the counter-rotating disk in PGC 66551., 18 pages, 10 figure, submitted to ApJ

This dataset contains measured data corresponding to the eruption of the Hunga Tonga - Hunga Ha’apai volcano on January 15, 2022. Time series of lightning stroke rates and atmospheric electric potential gradient (PG) data were converted to 1-minute time resolution. The sampling rate of Schumann resonance (SR) records is specified below. Lightning_GLD360_global_except_HT-HH_15January2022.txt This file contains lightning stroke rates detected by Vaisala’s GLD360 lightning detection network on January 15, 2022 globally, except for the area (latitude [-22.5,-18.5] degrees North and longitude [-177.4,-173.4] degrees East). Data in column ‘Datetime’ has the format YYYY-MM-DD hh:mm:ss, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 ss is the zero added second 00,01,...,59 Data in column ‘lightning strokes per minute‘ contains the number of detected lightning strokes in the corresponding minute. Reference: Said et al., 2010 Lightning_GLD360_near_HT-HH_15January2022.txt This file contains lightning stroke rates detected by Vaisala’s GLD360 lightning detection network on January 15, 2022 within the area (latitude [-22.5,-18.5] degrees North and longitude [-177.4,-173.4] degrees East). Data format is the same as in the file GLD360_global_except_HT-HH_15January2022.txt Reference: Said et al., 2010 Lightning_WWLLN_global_except_HT-HH_15January2022.txt This file contains lightning stroke rates detected by World Wide Lightning Location Network (WWLLN) on January 15, 2022 globally, except for the area (latitude [-22.5,-18.5] degrees North and longitude [-177.4,-173.4] degrees East). Data format is the same as in the file GLD360_global_except_HT-HH_15January2022.txt Reference: Rodger et al., 2006; Hutchins et al., 2012; Holzworth et al., 2019 Lightning_WWLLN_near_HT-HH_15January2022.txt This file contains lightning stroke rates detected by World Wide Lightning Location Network (WWLLN) on January 15, 2022 within the area (latitude [-22.5,-18.5] degrees North and longitude [-177.4,-173.4] degrees East). Data format is the same as in the file GLD360_global_except_HT-HH_15January2022.txt Reference: Rodger et al., 2006; Hutchins et al., 2012; Holzworth et al., 2019 PG_EVO_14-16January2022.txt This file contains PG data from University of Évora campus, Évora, Portugal (38°34'03.2"N 7°54'41.1"W). Data in column ‘day + time’ has the format YYYY.MM.DD h:mm, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 h is the hour 0,1,...,23 mm is the zero added minute 00,01,..., 59 Data in column ‘PotG_Avg (V/m)’ is the mean PG value in the corresponding minute. Data in column ‘PotG_Med (V/m)’ is the median PG value in the corresponding minute. Reference: Silva et al., 2014; Conceição et al., 2018 PG_KSC_TongaMedians_2022-01-14.txt PG_KSC_TongaMedians_2022-01-15.txt PG_KSC_TongaMedians_2022-01-16.txt These files contain atmospheric electric potential gradient (PG) data from the Kennedy Space Center, Florida, USA (28°30' N, 80°35' W). Data in column ‘Date’ has the format YYYY-MM-DD, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 Data in column ‘Time’ has the format hh:mm, where hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 Data in column ‘MeanPG1’ is the mean PG value from one subgroup of measuring locations in the corresponding minute. Data in column ‘MeanPG2’ is the mean PG value from another subgroup of measuring locations in the corresponding minute. Data in column ‘MedianPG_overall_accepted’ is the median PG value from quality-checked measuring locations in the corresponding minute. Reference: Lucas et al., 2017; Wilson & Cummins, 2021 PG_LAL_14January2022.txt PG_LAL_15January2022.txt PG_LAL_16January2022.txt These files contain atmospheric electric potential gradient (PG) data from the Los Alamos National Laboratory (35°52' N 106°19' W). Data in column ‘Datetime’ has the format YYYY-MM-DD hh:mm:ss, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 ss is the zero added second 00,01,...,59 Data in column ‘PG [V/m]’ is the mean PG value in the corresponding minute. PG_NCK_14-16January2022.txt This file contains atmospheric electric potential gradient (PG) data from the Széchenyi István Geophysical Observatory, Hungary (47°37'54.8"N 16°43'04.6"E). Data in column ‘Datetime’ has the format YYYY-MM-DD hh:mm:ss, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 ss is the zero added second 00,01,...,59 Data in column ‘PG [V/m]’ is the mean PG value in the corresponding minute. Reference: Sátori et al., 2013; Bór et al., 2020 PG_SWI_14January2022.txt PG_SWI_15January2022.txt PG_SWI_16January2022.txt These files contain atmospheric electric potential gradient (PG) data Geophysical Observatory in Świder, Poland (52°07' N, 21°14' E). Data in column ‘SAMPLE’ is the minute of the day 0,1,...,1439 Data in column ‘Ez(V/m)’ is the mean PG value in the corresponding minute. Reference: Kubicki et al., 2016 PG_YER_14-16January2022.txt This file contains atmospheric electric potential gradient (PG) data from Yerevan Institute of Physics, Yerevan, Armenia (40°12' N, 44°29' E). Data in column ‘Datetime’ has the format YYYY-MM-DD hh:mm:ss, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 ss is the zero added second 00,01,...,59 Data in column ‘PG [kV/m]’ is the mean PG value in the corresponding minute. Reference: Chilingaryan et al., 2010; Mkrtchyan et al., 2020 SR_ALB.zip This file contains Schumann resonance (SR) data from Alberta station (51o53’ N, 111o28’ W) of the Heartmath Institute. SR_BAI.zip This file contains SR data from Baisogala station (55o37’ N, 23o42’ E) of the Heartmath Institute. SR_BOU.zip This file contains SR data from Boulder Creek station (37o11’ N, 122o7’ W) of the Heartmath Institute. SR_HLU.zip This file contains SR data from Hluhluwe station (28o3’ S, 32o19’ E) of the Heartmath Institute. SR_NOR.zip This file contains SR data from Northland station (35o6’ S, 173o29’ E) of the Heartmath Institute. In each of these archives, there are data files with names XXX_220115_hh00_OK.txt, where XXX is the name of the archive. It also identifies the recording station. 220115 is the date of recording, 2022, January, 15 hh is the zero added hour 00,01,...,23 00 is the minute (always zero) These files contain Schumann resonance data from the hour identified by the ‘hh’ value. In these files, data in column ‘Time’ has the format YYYY/MM/DD hh:mm:ss.micros, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 ss is the zero added second 00,01,...,59 micros is the zero added microsecond 000000,000001,...,999999 Data in column ‘HNS’ contains bandpass filtered (2-45 Hz) time series in pT corresponding to the north-south magnetic field component (sampling frequency: 130.2083 Hz). Due to the filtering, Nan values appear at the beginning and end of each file. Data in column ‘HEW’ contains bandpass filtered (2-45 Hz) time series in pT corresponding to the east-west magnetic field component (sampling frequency: 130.2083 Hz). Due to the filtering, Nan values appear at the beginning and end of each file. Reference: https://www.heartmath.org/gci/ SR/NOR_raw.zip This file contains unfiltered SR data from Northland station (35o6’ S, 173o29’ E) of the Heartmath Institute. In this archive, there are data files with names NOR_220115_hh00_OK.txt, where NOR identifies the recording station. 220115 is the date of recording, 2022, January, 15 hh is the zero added hour 00,01,...,23 00 is the minute (always zero) These files contain Schumann resonance data from the hour identified by the ‘hh’ value. In these files, data in column ‘Time’ has the format YYYY/MM/DD hh:mm:ss.micros, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 ss is the zero added second 00,01,...,59 micros is the zero added microsecond 000000,000001,...,999999 Data in column ‘HNS’ contains raw measured time series in pT corresponding to the north-south magnetic field component (sampling frequency: 130.2083 Hz). Data in column ‘HEW’ contains raw measured time series in pT corresponding to the east-west magnetic field component (sampling frequency: 130.2083 Hz). Reference: https://www.heartmath.org/gci/ SR_NCK.zip This file contains Schumann resonance data from the Széchenyi István Geophysical Observatory, Hungary (47°37'54.8"N 16°43'04.6"E). In this archive, there are data files with names NCK_220115_hh00_OK.txt, where NCK is the name of the archive. It also identifies the recording station. 220115 is the date of recording, 2022, January, 15 hh is the zero added hour 00,01,...,23 00 is the minute (always zero) These files contain Schumann resonance data from the hour identified by the ‘hh’ value. In these files, data in column ‘Time’ has the format YYYY/MM/DD hh:mm:ss.micros, where YYYY is the 4-digit year MM is the zero added month 01,02,...,12 DD is the zero added day 01,02,...,31 hh is the zero added hour 00,01,...,23 mm is the zero added minute 00,01,..., 59 ss is the zero added second 00,01,...,59 micros is the zero added microsecond 000000,000001,...,999999 Data in column ‘EZ’ contains raw measured time series in digital units corresponding to the vertical electric field component (sampling frequency: 500 Hz). Data in column ‘HNS’ contains raw measured time series in digital units corresponding to the north-south magnetic component (sampling frequency: 500 Hz). Data in column ‘HEW’ contains raw measured time series in digital units corresponding to the north-south magnetic component (sampling frequency: 500 Hz). Reference: Sátori et al., 2013; Bór et al., 2020 Acknowledgements HGS acknowledges the support given by Samuel Bárias with the maintenance of the Évora's JCI sensor and data recording. PG values recorded at Yerevan station, Armenia were extracted from the database of Cosmic Ray Division of Yerevan Physics Institute via ADEI multivariate visualization and correlation analysis platform. The authors wish to thank the World Wide Lightning Location Network (http://wwlln.net), a collaboration among over 50 universities and institutions, for providing the lightning location data used in this study. This contribution was supported by the National Research, Development, and Innovation Office, Hungary-NKFIH, project number NKFIH-K138824. This contribution was also financed by the Institute of Geophysics of the Polish Academy of Sciences with a subsidy from the Ministry of Education and Science. The research leading to these results has also benefited from data from the Institute of Earth Sciences (Évora Pole) - ICT under project (UID/GEO/04683/2013) with the reference POCI-01-0145-FEDER-007690. References: Bór, J., Sátori, G., Barta, V., Szabóné-André, K., Szendrői, J., Wesztergom, V., et al. (2020). Measurements of atmospheric electricity in the Széchenyi István Geophysical Observatory, Hungary. History of Geo- and Space Sciences, 11, 53–70. https://doi.org/10.5194/hgss-11-53-2020 Chilingaryan, S., Beglarian, A., Kopmann, A., & Vöcking, S. (2010). Advanced data extraction infrastructure: Web based system for management of time series data. Journal of Physics: Conference Series, 219, 042034. https://doi.org/10.1088/1742-6596/219/4/042034 Conceição, R., Silva, H.G., Bennett, A., Salgado, R., Bortoli, D., Costa, M.J., et al. (2018). High-Frequency Response of the Atmospheric Electric Potential Gradient Under Strong and Dry Boundary-Layer Convection. Boundary-Layer Meteorology, 166, 69–81. https://doi.org/10.1007/s10546-017-0298-2 Holzworth, R.H., McCarthy, M.P., Brundell, J.B., Jacobson, A.R., & Rodger, C.J. (2019). Global Distribution of Superbolts. Journal of Geophysical Research: Atmospheres, 124(17-18), 9996–10005. https://doi.org/10.1029/2019JD030975 Hutchins, M.L., Holzworth, R.H., Brundell, J.B., & Rodger, C.J. (2012). Relative detection efficiency of the World Wide Lightning Location Network. Radio Science, 47(6), RS6005. https://doi.org/10.1029/2012RS005049 Kubicki, M., Odzimek, A., & Neska, M. (2016). Relationship of ground-level aerosol concentration and atmospheric electric field at three observation sites in the Arctic, Antarctic and Europe. Atmospheric Research, 178–179, 329–346. https://doi.org/10.1016/j.atmosres.2016.03.029 Lucas, G.M., Thayer, J.P., & Deierling, W. (2017). Statistical analysis of spatial and temporal variations in atmospheric electric fields from a regional array of field mills. Journal of Geophysical Research: Atmospheres, 122(2), 1158–1174. https://doi.org/10.1002/2016JD025944 Mkrtchyan, H., Karapetyan, G., & Aslanyan, D. (2020). Atmospheric electric field variations during fair weather and thunderstorms at different altitudes. Journal of Atmospheric and Solar-Terrestrial Physics, 211, 105452. https://doi.org/10.1016/j.jastp.2020.105452 Rodger, C.J., Werner, S., Brundell, J.B., Lay, E.H., Thomson, N.R., Holzworth, R.H., & Dowden, R.L. (2006). Detection efficiency of the VLF World-Wide Lightning Location Network (WWLLN): initial case study. Annales Geophysicae, 24(12), 3197–3214. https://doi.org/10.5194/angeo-24-3197-2006 Said, R.K., Inan, U.S., & Cummins, K.L. (2010). Long-range lightning geolocation using a VLF radio atmospheric waveform bank. Journal of Geophysical Research: Atmospheres, 115(D23), D23108. https://doi.org/10.1029/2010JD013863 Sátori, G., Rycroft, M., Bencze, P., Märcz, F., Bór, J., Barta, V., et al. (2013). An Overview of Thunderstorm-Related Research on the Atmospheric Electric Field, Schumann Resonances, Sprites, and the Ionosphere at Sopron, Hungary. Surveys in Geophysics, 34, 255–292. https://doi.org/10.1007/s10712-013-9222-6 Silva, H.G., Conceição, R., Melgão, M., Nicoll, K., Mendes, P.B., Tlemçani, M., et al. (2014). Atmospheric electric field measurements in urban environment and the pollutant aerosol weekly dependence. Environmental Research Letters, 9(11), 114025. https://doi.org/10.1088/1748-9326/9/11/114025 Wilson, J.G., & Cummins, K.L. (2021). Thunderstorm and fair-weather quasi-static electric fields over land and ocean. Atmospheric Research, 257, 105618. https://doi.org/10.1016/j.atmosres.2021.105618

Context. The BL Lac object 1ES 0647+250 is one of the few distant γ-ray emitting blazars detected at very high energies (VHEs; ≳100 GeV) during a non-flaring state. It was detected with the MAGIC telescopes during a period of low activity in the years 2009−2011 as well as during three flaring activities in the years 2014, 2019, and 2020, with the highest VHE flux in the last epoch. An extensive multi-instrument data set was collected as part of several coordinated observing campaigns over these years. Aims. We aim to characterise the long-term multi-band flux variability of 1ES 0647+250, as well as its broadband spectral energy distribution (SED) during four distinct activity states selected in four different epochs, in order to constrain the physical parameters of the blazar emission region under certain assumptions. Methods. We evaluated the variability and correlation of the emission in the different energy bands with the fractional variability and the Z-transformed discrete correlation function, as well as its spectral evolution in X-rays and γ rays. Owing to the controversy in the redshift measurements of 1ES 0647+250 reported in the literature, we also estimated its distance in an indirect manner through a comparison of the GeV and TeV spectra from simultaneous observations with Fermi-LAT and MAGIC during the strongest flaring activity detected to date. Moreover, we interpret the SEDs from the four distinct activity states within the framework of one-component and two-component leptonic models, proposing specific scenarios that are able to reproduce the available multi-instrument data. Results. We find significant long-term variability, especially in X-rays and VHE γ rays. Furthermore, significant (3−4σ) correlations were found between the radio, optical, and high-energy (HE) γ-ray fluxes, with the radio emission delayed by about ∼400 days with respect to the optical and γ-ray bands. The spectral analysis reveals a harder-when-brighter trend during the non-flaring state in the X-ray domain. However, no clear patterns were observed for either the enhanced states or the HE (30 MeV < E < 100 GeV) and VHE γ-ray emission of the source. The indirect estimation of the redshift yielded a value of z = 0.45 ± 0.05, which is compatible with some of the values reported in the literature. The SEDs related to the low-activity state and the three flaring states of 1ES 0647+250 can be described reasonably well with the both one-component and two-component leptonic scenarios. However, the long-term correlations indicate the need for an additional radio-producing region located about 3.6 pc downstream from the gamma-ray producing region., Astronomy & Astrophysics, 670, ISSN:0004-6361, ISSN:1432-0746

4MOST-ChANGES will target a legacy sample of active galactic nuclei (AGN), based on optical continuum variability and spectral energy distribution (SED) selection from several existing sur- veys, and ultimately complemented by Rubin LSST to: 1) constrain the low-MBH, low-L/LEdd end of the accretion and black hole (BH) density functions to z ~ 1, and, by extension, BH seed models; 2) investigate correlations among AGN (MBH, L/LEdd, ultraviolet slope, outflows, variability) and host properties (stellar age, metallicity, kinematics); 3) confirm/characterise rare BH subsamples (extreme variability, tidal disruption events, lensed, intervening absorption line systems) for detailed multi-wavelength follow-up studies., Published in The Messenger vol. 190, pp. 34-37, March 2023.

Line-like features in TeV $\gamma$-rays constitute a ''smoking gun'' for TeV-scale particle dark matter and new physics. Probing the Galactic Center region with ground-based Cherenkov telescopes enables the search for TeV spectral features in immediate association with a dense dark matter reservoir at a sensitivity out of reach for satellite $\gamma$-ray detectors, and direct detection and collider experiments. We report on 223 hours of observations of the Galactic Center region with the MAGIC stereoscopic telescope system reaching $\gamma$-ray energies up to 100 TeV. We improved the sensitivity to spectral lines at high energies using large-zenith-angle observations and a novel background modeling method within a maximum-likelihood analysis in the energy domain. No line-like spectral feature is found in our analysis. Therefore, we constrain the cross section for dark matter annihilation into two photons to $\langle \sigma v \rangle \lesssim 5 \times 10^{-28}\,\mathrm{cm^3\,s^{-1}}$ at 1 TeV and $\langle \sigma v \rangle \lesssim 1 \times 10^{-25}\,\mathrm{cm^3\,s^{-1}}$ at 100 TeV, achieving the best limits to date for a dark matter mass above 20 TeV and a cuspy dark matter profile at the Galactic Center. Finally, we use the derived limits for both cuspy and cored dark matter profiles to constrain supersymmetric wino models., Comment: Accepted in Phys. Rev. Lett., includes Supplemental materials. 9+4 pages, 3+3 figures, 3 tables. Corresponding authors: T. Inada, D. Kerszberg, M. H\"utten

The astrophysical journal / Supplement series 266(2), 37 (2023). doi:10.3847/1538-4365/acc181, We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) $γ$-rays. A significant correlation (>3σ) between X-rays and VHE $γ$-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy γ-rays and radio, with the radio lagging by more than 100 days, placing the γ-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE $γ$-rays from mid-2017 to mid-2019 with a stable VHE flux (>0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2 $γ$r long low state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED toward the low state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock., Published by Institute of Physics Publ., London

Astronomy and astrophysics 670, A8 (2023). doi:10.1051/0004-6361/202038748, Context. Diffusive shock acceleration (DSA) is the most promising mechanism that accelerates Galactic cosmic rays (CRs) in the shocks of supernova remnants (SNRs). It is based on particles scattering caused by turbulence ahead and behind the shock. The turbulence upstream is supposedly generated by the CRs, but this process is not well understood. The dominant mechanism may depend on the evolutionary state of the shock and can be studied via the CRs escaping upstream into the interstellar medium (ISM).Aims. Previous observations of the γ Cygni SNR showed a difference in morphology between GeV and TeV energies. Since this SNR has the right age and is at the evolutionary stage for a significant fraction of CRs to escape, our aim is to understand γ-ray emission in the vicinity of the γ Cygni SNR.Methods. We observed the region of the γ Cygni SNR with the MAGIC Imaging Atmospheric Cherenkov telescopes between 2015 May and 2017 September recording 87 h of good-quality data. Additionally, we analysed Fermi-LAT data to study the energy dependence of the morphology as well as the energy spectrum in the GeV to TeV range. The energy spectra and morphology were compared against theoretical predictions, which include a detailed derivation of the CR escape process and their γ-ray generation.Results. The MAGIC and Fermi-LAT data allowed us to identify three emission regions that can be associated with the SNR and that dominate at different energies. Our hadronic emission model accounts well for the morphology and energy spectrum of all source components. It constrains the time-dependence of the maximum energy of the CRs at the shock, the time-dependence of the level of turbulence, and the diffusion coefficient immediately outside the SNR shock. While in agreement with the standard picture of DSA, the time-dependence of the maximum energy was found to be steeper than predicted, and the level of turbulence was found to change over the lifetime of the SNR.Key words: acceleration of particles / cosmic rays / gamma rays: general / gamma rays: ISM / ISM: clouds / ISM: supernova remnants★ Corresponding authors; e-mail: contact.magic@mpp.mpg.de, Published by EDP Sciences, Les Ulis

Context. Diffusive shock acceleration (DSA) is the most promising mechanism that accelerates Galactic cosmic rays (CRs) in the shocks of supernova remnants (SNRs). It is based on particles scattering caused by turbulence ahead and behind the shock. The turbulence upstream is supposedly generated by the CRs, but this process is not well understood. The dominant mechanism may depend on the evolutionary state of the shock and can be studied via the CRs escaping upstream into the interstellar medium (ISM). Aims. Previous observations of the γ Cygni SNR showed a difference in morphology between GeV and TeV energies. Since this SNR has the right age and is at the evolutionary stage for a significant fraction of CRs to escape, our aim is to understand γ-ray emission in the vicinity of the γ Cygni SNR. Methods. We observed the region of the γ Cygni SNR with the MAGIC Imaging Atmospheric Cherenkov telescopes between 2015 May and 2017 September recording 87 h of good-quality data. Additionally, we analysed Fermi-LAT data to study the energy dependence of the morphology as well as the energy spectrum in the GeV to TeV range. The energy spectra and morphology were compared against theoretical predictions, which include a detailed derivation of the CR escape process and their γ-ray generation. Results. The MAGIC and Fermi-LAT data allowed us to identify three emission regions that can be associated with the SNR and that dominate at different energies. Our hadronic emission model accounts well for the morphology and energy spectrum of all source components. It constrains the time-dependence of the maximum energy of the CRs at the shock, the time-dependence of the level of turbulence, and the diffusion coefficient immediately outside the SNR shock. While in agreement with the standard picture of DSA, the time-dependence of the maximum energy was found to be steeper than predicted, and the level of turbulence was found to change over the lifetime of the SNR.

Astronomy and astrophysics 670, A145 (2023). doi:10.1051/0004-6361/202244126, Context. Extended and delayed emission around distant TeV sources induced by the effects of propagation of γ ray s through the intergalactic medium can be used for the measurement of the intergalactic magnetic field (IGMF).Aims. We search for delayed GeV emission from the hard-spectrum TeV γ-ray emitting blazar 1ES 0229+200, with the goal of detecting or constraining the IGMF-dependent secondary flux generated during the propagation of TeV γ rays through the intergalactic medium.Methods. We analysed the most recent MAGIC observations over a 5 year time span, and complemented them with historic data of the H.E.S.S. and VERITAS telescopes, along with a 12-year-long exposure of the Fermi/LAT telescope. We used them to trace source evolution in the GeV–TeV band over a decade and a half. We used Monte Carlo simulations to predict the delayed secondary γ-ray flux, modulated by the source variability, as revealed by TeV-band observations. We then compared these predictions for various assumed IGMF strengths to all available measurements of the γ-ray flux evolution.Results. We find that the source flux in the energy range above 200 GeV experiences variations around its average on the 14-year time span of observations. No evidence for the flux variability is found in the 1 − 100 GeV energy range accessible to Fermi/LAT. The non-detection of variability due to delayed emission from electromagnetic cascade developing in the intergalactic medium imposes a lower bound of B > 1.8 × 10´$^{−17}$ G for the long-correlation-length IGMF and B > 10$^{−14}$ G for an IGMF of cosmological origin. Though weaker than the one previously derived from the analysis of Fermi/LAT data, this bound is more robust, being based on a conservative intrinsic source spectrum estimate and accounting for the details of source variability in the TeV energy band. We discuss implications of this bound for cosmological magnetic fields that might explain the baryon asymmetry of the Universe., Published by EDP Sciences, Les Ulis

Emission lines with a double-peak (DP) shape, detected in the centre of galaxies, have been extensively used in the past to identify peculiar kinematics such as dual active galactic nuclei, outflows or mergers. From a large DP galaxy sample, a connection to minor merger galaxies with ongoing star formation was suggested. To gain a better understanding of different mechanisms creating a DP signature, we here explore synthetic SDSS spectroscopic observations computed from disc models and simulations. We show how a DP signature is connected to the central part of the rotation curve of galaxies, which is mostly shaped by the stellar bulge. We, furthermore, find that bars can create strong DP emission-line signatures when viewed along their major axis. Major mergers can form a central rotating disc in late post-coalescence merger stages (1\,Gyr after the final coalescence), which creates a DP signature. Minor mergers tend to show a DP feature with no correlation to the galaxy inclination within 350\,Myr after the final coalescence. Comparisons of these scenarii with observations disfavour major mergers, since these show predominantly elliptical and only a few S0 morphologies. Furthermore, at such a late merger stage the enhanced star formation is most likely faded. Bars and minor mergers, on the other hand, can be compared quite well with the observations. Both observations coincide with increased star formation found in observations, and minor mergers in particular do not show any dependency with the observation direction. However, observations resolving the galaxy kinematics spatially are needed to distinguish between the discussed possibilities. More insight into the origin of DP will be gained by a broader comparison with cosmological simulations. The understanding of the DP origin can provide important tools to study the mass growth of galaxies in future high redshift surveys., 22 pages, 19 figures, article accepted to A&A

Rare giant low surface brightness galaxies (gLSBGs) act as a stress test for the current galaxy formation paradigm. To answer the question `How rare are they?' we estimate their volume density in the local Universe. A visual inspection of 120~sq.~deg. covered by deep Subaru Hyper Suprime-Cam data was performed independently by four team members. We detected 42 giant disky systems (30 of them isolated) at $z\leq0.1$ with either $g$-band 27.7~mag~arcsec$^{-2}$ isophotal radius or four disc scalelengths $4h \geq 50$~kpc, 37 of which (including 25 isolated) had low central surface brightness ($μ_{0,g}\ge 22.7$ mag~arcsec$^{-2}$). This corresponds to volume densities of 4.70$\times 10^{-5}$ Mpc$^{-3}$ for all galaxies with giant extended discs and 4.04$\times 10^{-5}$ Mpc$^{-3}$ for gLSBGs, which converts to $\sim $12,700 such galaxies in the entire sky out to $z, 5 pages, 2 tables, 5 figures, accepted for publication in MNRAS Letters

Full list of authors: Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A.; Artero, M.; Asano, K.; Babić, A.; Baquero, A.; Barres de Almeida, U.; Barrio, J. A.; Batković, I.; Becerra González, J.; Bednarek, W.; Bellizzi, L.; Bernardini, E.; Bernardos, M.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Blanch, O.; Bošnjak, Ž.; Busetto, G.; Carosi, R.; Ceribella, G.; Cerruti, M.; Chai, Y.; Chilingarian, A.; Cikota, S.; Colak, S. M.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Amico, G.; D'Elia, V.; da Vela, P.; Dazzi, F.; de Angelis, A.; de Lotto, B.; Delfino, M.; Delgado, J.; Delgado Mendez, C.; Depaoli, D.; di Pierro, F.; di Venere, L.; Do Souto Espiñeira, E.; Dominis Prester, D.; Donini, A.; Doro, M.; Fallah Ramazani, V.; Fattorini, A.; Ferrara, G.; Fonseca, M. V.; Font, L.; Fruck, C.; Fukami, S.; García López, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giglietto, N.; Giordano, F.; Gliwny, P.; Godinović, N.; Green, J. G.; Green, D.; Hadasch, D.; Hahn, A.; Heckmann, L.; Herrera, J.; Hoang, J.; Hrupec, D.; Hütten, M.; Inada, T.; Inoue, S.; Ishio, K.; Iwamura, Y.; Jiménez, I.; Jormanainen, J.; Jouvin, L.; Kajiwara, Y.; Karjalainen, M.; Kerszberg, D.; Kobayashi, Y.; Kubo, H.; Kushida, J.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; López-Coto, R.; López-Moya, M.; López-Oramas, A.; Loporchio, S.; Machado de Oliveira Fraga, B.; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menchiari, S.; Mender, S.; Mićanović, S.; Miceli, D.; Miener, T.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Morcuende, D.; Moreno, V.; Moretti, E.; Neustroev, V.; Nigro, C.; Nilsson, K.; Nishijima, K.; Noda, K.; Nozaki, S.; Ohtani, Y.; Oka, T.; Otero-Santos, J.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pavletić, L.; Peñil, P.; Perennes, C.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Priyadarshi, C.; Puljak, I.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Sakurai, S.; Satalecka, K.; Saturni, F. G.; Schmidt, K.; Schweizer, T.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Spolon, A.; Stamerra, A.; Strom, D.; Strzys, M.; Suda, Y.; Surić, T.; Takahashi, M.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M.; Tosti, L.; Truzzi, S.; Tutone, A.; Ubach, S.; van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Ventura, S.; Verguilov, V.; Vigorito, C. F.; Vitale, V.; Vovk, I.; Will, M.; Wunderlich, C.; Zarić, D.; Baack, D.; Balbo, M.; Biederbeck, N.; Biland, A.; Bretz, T.; Buss, J.; Dorner, D.; Eisenberger, L.; Elsaesser, D.; Hildebrand, D.; Iotov, R.; Mannheim, K.; Neise, D.; Noethe, M.; Paravac, A.; Rhode, W.; Schleicher, B.; Sliusar, V.; Walter, R.; D'Ammando, F.; Horan, D.; Lien, A. Y.; Baloković, M.; Madejski, G. M.; Perri, M.; Verrecchia, F.; Leto, C.; Lähteenmäki, A.; Tornikoski, M.; Ramakrishnan, V.; Järvelä, E.; Vera, R. J. C.; Chamani, W.; Villata, M.; Raiteri, C. M.; Gupta, A. C.; Pandey, A.; Fuentes, A.; Agudo, I.; Casadio, C.; Semkov, E.; Ibryamov, S.; Marchini, A.; Bachev, R.; Strigachev, A.; Ovcharov, E.; Bozhilov, V.; Valcheva, A.; Zaharieva, E.; Damljanovic, G.; Vince, O.; Larionov, V. M.; Borman, G. A.; Grishina, T. S.; Hagen-Thorn, V. A.; Kopatskaya, E. N.; Larionova, E. G.; Larionova, L. V.; Morozova, D. A.; Nikiforova, A. A.; Savchenko, S. S.; Troitskiy, I. S.; Troitskaya, Y. V.; Vasilyev, A. A.; Merkulova, O. A.; Chen, W. P; Samal, M.; Lin, H. C.; Moody, J. W.; Sadun, A. C.; Jorstad, S. G.; Marscher, A. P.; Weaver, Z. R.; Feige, M.; Kania, J.; Kopp, M.; Kunkel, L.; Reinhart, D.; Scherbantin, A.; Schneider, L.; Lorey, C.; Acosta-Pulido, J. A.; Carnerero, M. I.; Carosati, D.; Kurtanidze, S. O.; Kurtanidze, O. M.; Nikolashvili, M. G.; Chigladze, R. A.; Ivanidze, R. Z.; Kimeridze, G. N.; Sigua, L. A.; Joner, M. D.; Spencer, M.; Giroletti, M.; Marchili, N.; Righini, S.; Rizzi, N.; Bonnoli, G.; MAGIC Collaboration; Fact Collaboration.-- This is an Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited., Aims. We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with a special focus on the multi-band flux correlations. Methods. The dataset has been collected through an extensive multi-wavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina, and Metsahovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. Results. The very-high-energy (VHE; E 100 GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow dierent patterns, partly due to substantial changes in the Compton dominance for a few days without a simultaneous increase in the X-ray flux (i.e., orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. The peak frequency of the synchrotron bump varies by two orders of magnitude throughout the campaign. Our multi-band correlation study also hints at an anti-correlation between UV-optical and X-ray at a significance higher than 3. A VHE flare observed on MJD 57788 (2017 February 4) shows gamma-ray variability on multi-hour timescales, with a factor ten increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario.We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors, from 0 min = 2104 to 0 max = 6105. © 2021 Georg Thieme Verlag. All rights reserved., The MAGIC Collaboration would like to thank the Instituto de Astrofísica de Canarias for the excellent working conditions at the Observatorio del Roque de los Muchachos in La Palma. The financial support of the German BMBF, MPG and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish Ministerio de Ciencia e Innovación (MICINN) (FPA2017-87859-P, FPA2017-85668-P, FPA2017-82729-C6-5-R, FPA2017-90566-REDC, PID2019-104114RB-C31, PID2019-104114RB-C32, PID2019-105510GB-C31,PID2019-107847RB-C41, PID2019-107847RB-C42, PID2019-107847RB-C44, PID2019-107988GB-C22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1-268/16.12.2019 and the Academy of Finland grant nr. 320045 is gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia “Severo Ochoa” SEV-2016-0588, SEV-2017-0709 and CEX2019-000920-S, and “María de Maeztu” CEX2019-000918-M, the Unidad de Excelencia “María de Maeztu” MDM-2015-0509-18-2 and the “la Caixa” Foundation (fellowship LCF/BQ/PI18/11630012) and by the CERCA program of the Generalitat de Catalunya; by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02; by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3; the Polish National Research Centre grant UMO-2016/22/M/ST9/00382; and by the Brazilian MCTIC, CNPq and FAPERJ. The important contributions from ETH Zurich grants ETH-10.08-2 and ETH-27.12-1 as well as the funding by the Swiss SNF and the German BMBF (Verbundforschung Astro- und Astroteilchenphysik) and HAP (Helmoltz Alliance for Astroparticle Physics) are gratefully acknowledged. Part of this work is supported by Deutsche Forschungsgemeinschaft (DFG) within the Collaborative Research Center SFB 876 “Providing Information by Resource-Constrained Analysis”, project C3. We are thankful for the very valuable contributions from E. Lorenz, D. Renker and G. Viertel during the early phase of the project. We thank the Instituto de Astrofísica de Canarias for allowing us to operate the telescope at the Observatorio del Roque de los Muchachos in La Palma, the Max-Planck-Institut für Physik for providing us with the mount of the former HEGRA CT3 telescope, and the MAGIC collaboration for their support. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l’Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d’Études Spatiales in France. This work performed in part under DOE Contract DE-AC02-76SF00515. This work made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC; Italy) and the California Institute of Technology (USA). This research has also made use of the XRT Data Analysis Software (XRTDAS) developed under the responsibility of the ASI Science Data Center (ASDC), Italy. A.A.E and D.P acknowledge support from the Deutsche Forschungs gemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy – EXC-2094 – 390783311. M. B. acknowledges support from the YCAA Prize Postdoctoral Fellowship and from the Black Hole Initiative at Harvard University, which is funded in part by the Gordon and Betty Moore Foundation (grant GBMF8273) and in part by the John Templeton Foundation. This publication makes use of data obtained at the Metsähovi Radio Observatory, operated by Aalto University in Finland. This research has made use of data from the OVRO 40-m monitoring program (Richards et al. 2011) which is supported in part by NASA grants NNX08AW31G, NNX11A043G, and NNX14AQ89G and NSF grants AST-0808050 and AST-1109911. I.A. acknowledges financial support from the Spanish “Ministerio de Ciencia e Innovación” (MCINN) through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía-CSIC (SEV-2017-0709). Acquisition and reduction of the MAPCAT data was supported in part by MICINN through grants AYA2016-80889-P and PID2019-107847RB-C44. The MAPCAT observations were carried out at the German-Spanish Calar Alto Observatory, which is jointly operated by Junta de Andalucía and Consejo Superior de Investigaciones Científicas. C.C. acknowledges support from the European Research Council (ERC) under the European Union Horizon 2020 research and innovation program under the grant agreement No 771282. This research was partially supported by the Bulgarian National Science Fund of the Ministry of Education and Science under grants KP-06-H28/3 (2018), KP-06-H38/4 (2019) and KP-06-KITAJ/2 (2020). We acknowledge support by Bulgarian National Science Fund under grant DN18-10/2017 and National RI Roadmap Projects DO1-277/16.12.2019 and DO1-268/16.12.2019 of the Ministry of Education and Science of the Republic of Bulgaria. This research was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia (contract No 451-03-68/2020-14/200002). G.D. acknowledges observing grant support from the Institute of Astronomy and Rozhen NAO BAS through the bilateral joint research project “Gaia Celestial Reference Frame (CRF) and fast variable astronomical objects” (2020–2022, head – G. Damljanovic). The BU group was supported in part by NASA Fermi guest investigator program grants 80NSSC19K1505 and 80NSSC20K1566. This study was based in part on observations conducted using the 1.8 m Perkins Telescope Observatory (PTO) in Arizona, which is owned and operated by Boston University. This article is partly based on observations made with the LCOGT Telescopes, one of whose nodes is located at the Observatorios de Canarias del IAC on the island of Tenerife in the Observatorio del Teide. This article is also based partly on data obtained with the STELLA robotic telescopes in Tenerife, an AIP facility jointly operated by AIP and IAC. The Abastumani team acknowledges financial support by the Shota Rustaveli National Science Foundation under contract FR-19-6174. Based on observations with the Medicina telescope operated by INAF – Istituto di Radioastronomia.

Full list of authors: Acciari, V. A.; Ansoldi, S.; Antonelli, L. A.; Arbet Engels, A. ; Artero, M.; Asano, K.; Baack, D.; Babić, A.; Baquero, A.; Barres de Almeida, U.; Barrio, J. A.; Batković, I.; Becerra González, J.; Bednarek, W.; Bellizzi, L.; Bernardini, E.; Bernardos, M.; Berti, A.; Besenrieder, J.; Bhattacharyya, W.; Bigongiari, C.; Biland, A.; Blanch, O.; Bošnjak, Ž.; Busetto, G.; Carosi, R.; Ceribella, G.; Cerruti, M.; Chai, Y.; Chilingarian, A.; Cikota, S.; Colak, S. M.; Colombo, E.; Contreras, J. L.; Cortina, J.; Covino, S.; D'Amico, G.; D'Elia, V.; da Vela, P.; Dazzi, F.; de Angelis, A.; de Lotto, B.; Delfino, M.; Delgado, J.; Delgado Mendez, C.; Depaoli, D.; Pierro, F. Di; Venere, L. Di; Do Souto Espiñeira, E.; Dominis Prester, D.; Donini, A.; Dorner, D.; Doro, M.; Elsaesser, D.; Fallah Ramazani, V.; Fattorini, A.; Ferrara, G.; Fonseca, M. V.; Font, L.; Fruck, C.; Fukami, S.; García López, R. J.; Garczarczyk, M.; Gasparyan, S.; Gaug, M.; Giglietto, N.; Giordano, F.; Gliwny, P.; Godinović, N.; Green, J. G.; Green, D.; Hadasch, D.; Hahn, A.; Heckmann, L.; Herrera, J.; Hoang, J.; Hrupec, D.; Hütten, M.; Inada, T.; Inoue, S.; Ishio, K.; Iwamura, Y.; Jiménez, I.; Jormanainen, J.; Jouvin, L.; Kajiwara, Y.; Karjalainen, M.; Kerszberg, D.; Kobayashi, Y.; Kubo, H.; Kushida, J.; Lamastra, A.; Lelas, D.; Leone, F.; Lindfors, E.; Lombardi, S.; Longo, F.; López-Coto, R.; López-Moya, M.; López-Oramas, A.; Loporchio, S.; Machado de Oliveira Fraga, B.; Maggio, C.; Majumdar, P.; Makariev, M.; Mallamaci, M.; Maneva, G.; Manganaro, M.; Mannheim, K.; Maraschi, L.; Mariotti, M.; Martínez, M.; Mazin, D.; Menchiari, S.; Mender, S.; Mićanović, S.; Miceli, D.; Miener, T.; Minev, M.; Miranda, J. M.; Mirzoyan, R.; Molina, E.; Moralejo, A.; Morcuende, D.; Moreno, V.; Moretti, E.; Neustroev, V.; Nigro, C.; Nilsson, K.; Nishijima, K.; Noda, K.; Nozaki, S.; Ohtani, Y.; Oka, T.; Otero-Santos, J.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Pavletić, L.; Peñil, P.; Perennes, C.; Persic, M.; Prada Moroni, P. G.; Prandini, E.; Priyadarshi, C.; Puljak, I.; Rhode, W.; Ribó, M.; Rico, J.; Righi, C.; Rugliancich, A.; Saha, L.; Sahakyan, N.; Saito, T.; Sakurai, S.; Satalecka, K.; Saturni, F. G.; Schleicher, B.; Schmidt, K.; Schweizer, T.; Sitarek, J.; Šnidarić, I.; Sobczynska, D.; Spolon, A.; Stamerra, A.; Strom, D.; Strzys, M.; Suda, Y.; Surić, T.; Takahashi, M.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Teshima, M.; Tosti, L.; Truzzi, S.; Tutone, A.; Ubach, S.; van Scherpenberg, J.; Vanzo, G.; Vazquez Acosta, M.; Ventura, S.; Verguilov, V.; Vigorito, C. F.; Vitale, V.; Vovk, I.; Will, M.; Wunderlich, C.; Zarić, D.; Bissaldi, E.; Bonnoli, G.; Cutini, S.; D'Ammando, F.; Nabizadeh, A.; Marchini, A.; Orienti, M.; MAGIC Collaboration., We report here on the first multiwavelength (MWL) campaign on the blazar TXS 1515-273, undertaken in 2019 and extending from radio to very-high-energy gamma-rays (VHE). Up until now, this blazar had not been the subject of any detailed MWL observations. It has a rather hard photon index at GeV energies and was considered a candidate extreme high-synchrotron-peaked source. MAGIC observations resulted in the first-time detection of the source in VHE with a statistical significance of 7.6σ. The average integral VHE flux of the source is 6 ± 1 per cent of the Crab nebula flux above 400 GeV. X-ray coverage was provided by Swift-XRT, XMM-Newton, and NuSTAR. The long continuous X-ray observations were separated by ∼9 h, both showing clear hour scale flares. In the XMM-Newton data, both the rise and decay time-scales are longer in the soft X-ray than in the hard X-ray band, indicating the presence of a particle cooling regime. The X-ray variability time-scales were used to constrain the size of the emission region and the strength of the magnetic field. The data allowed us to determine the synchrotron peak frequency and classify the source as a flaring high, but not extreme synchrotron-peaked object. Considering the constraints and variability patterns from the X-ray data, we model the broad-band spectral energy distribution. We applied a simple one-zone model, which could not reproduce the radio emission and the shape of the optical emission, and a two-component leptonic model with two interacting components, enabling us to reproduce the emission from radio to VHE band. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society., The financial support of the German BMBF, MPG, and HGF; the Italian INFN and INAF; the Swiss National Fund SNF; the ERDF under the Spanish Ministerio de Ciencia e Innovacion (MICINN) (FPA201787859-P, FPA2017-85668-P, FPA2017-82729-C6-5-R, FPA201790566-REDC, PID2019-104114RB-C31, PID2019-104114RB-C32, PID2019-105510GB-C31, PID2019-107847RB-C41, PID2019107847RB-C42, PID2019-107847RB-C44, PID2019-107988GBC22); the Indian Department of Atomic Energy; the Japanese ICRR, the University of Tokyo, JSPS, and MEXT; the Bulgarian Ministry of Education and Science, National RI Roadmap Project DO1268/16.12.2019 and the Academy of Finland grant nr. 317637 and 320045 are gratefully acknowledged. This work was also supported by the Spanish Centro de Excelencia `Severo Ochoa' SEV-20160588, SEV-2017-0709 and CEX2019-000920-S, and `Maria de Maeztu' CEX2019-000918-M, the Unidad de Excelencia `Maria de Maeztu' MDM-2015-0509-18-2 and the `la Caixa' Foundation (fellowshipLCF/BQ/PI18/11630012), by the Croatian Science Foundation (HrZZ) Project IP-2016-06-9782 and the University of Rijeka Project 13.12.1.3.02, by the DFG Collaborative Research Centers SFB823/C4 and SFB876/C3, the Polish National Research Centre grant UMO-2016/22/M/ST9/00382 and by the Brazilian MCTIC, CNPq, and FAPERJ. The Fermi-LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, theCommissariat à l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucleaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase from the following agencies is also gratefully acknowledged: the Istituto Nazionale di Astrofisica in Italy and the Centre National d'Etudes Spatiales in France.