ORCID Profile
0000-0003-2065-5410
Current Organisation
Friedrich-Alexander-Universität Erlangen-Nürnberg
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Publisher: SPIE
Date: 16-12-2020
DOI: 10.1117/12.2561841
Publisher: IOP Publishing
Date: 12-2021
DOI: 10.1088/1748-0221/16/12/C12016
Abstract: Starburst galaxies (SBGs) and more in general star-forming galaxies represent a class of galaxies with a high star formation rate (up to 100 M ⊙ /year). Despite their low luminosity, they can be considered as guaranteed “factories” of high energy neutrinos, being “reservoirs” of accelerated cosmic rays and hosting a high density target gas in the central region. In this contribution we present a novel multimessenger study of these sources and the possibility of observing their neutrino signals with the KM3NeT/ARCA telescope. The differential sensitivity for different SBG scenarios is reported considering track-like neutrino events in the 100 GeV–100 PeV energy range.
Publisher: Springer Science and Business Media LLC
Date: 06-2019
Abstract: The ANTARES neutrino telescope has an energy threshold of a few tens of GeV. This allows to study the phenomenon of atmospheric muon neutrino disappearance due to neutrino oscillations. In a similar way, constraints on the 3+1 neutrino model, which foresees the existence of one sterile neutrino, can be inferred. Using data collected by the ANTARES neutrino telescope from 2007 to 2016, a new measurement of Δ m 32 2 and θ 23 has been performed — which is consistent with world best-fit values — and constraints on the 3+1 neutrino model have been derived.
Publisher: American Astronomical Society
Date: 18-01-2018
Publisher: SPIE-Intl Soc Optical Eng
Date: 23-12-2019
Publisher: American Physical Society (APS)
Date: 27-10-2020
Publisher: Elsevier BV
Date: 10-2022
Publisher: IOP Publishing
Date: 31-05-2018
Publisher: IOP Publishing
Date: 02-2023
DOI: 10.1088/1748-0221/18/02/T02001
Abstract: The optical data transport system of the KM3NeT neutrino telescope at the bottom of the Mediterranean Sea will provide more than 6000 optical modules in the detector arrays with a point-to-point optical connection to the control stations onshore. The ARCA and ORCA detectors of KM3NeT are being installed at a depth of about 3500 m and 2500 m, respectively and their distance to the control stations is about 100 kilometers and 40 kilometers. In particular, the two detectors are optimised for the detection of cosmic neutrinos with energies above about 1 TeV (ARCA) and for the detection of atmospheric neutrinos with energies in the range 1 GeV–1 TeV (ORCA). The expected maximum data rate is 200 Mbps per optical module. The implemented optical data transport system matches the layouts of the networks of electro-optical cables and junction boxes in the deep sea. For efficient use of the fibres in the system the technology of Dense Wavelength Division Multiplexing is applied. The performance of the optical system in terms of measured bit error rates, optical budget are presented. The next steps in the implementation of the system are also discussed.
Publisher: American Astronomical Society
Date: 14-10-2015
Publisher: Springer Science and Business Media LLC
Date: 05-09-2022
Publisher: American Astronomical Society
Date: 08-2022
Abstract: For several decades, the origin of ultra-high-energy cosmic rays (UHECRs) has been an unsolved question of high-energy astrophysics. One approach for solving this puzzle is to correlate UHECRs with high-energy neutrinos, since neutrinos are a direct probe of hadronic interactions of cosmic rays and are not deflected by magnetic fields. In this paper, we present three different approaches for correlating the arrival directions of neutrinos with the arrival directions of UHECRs. The neutrino data are provided by the IceCube Neutrino Observatory and ANTARES, while the UHECR data with energies above ∼50 EeV are provided by the Pierre Auger Observatory and the Telescope Array. All experiments provide increased statistics and improved reconstructions with respect to our previous results reported in 2015. The first analysis uses a high-statistics neutrino s le optimized for point-source searches to search for excesses of neutrino clustering in the vicinity of UHECR directions. The second analysis searches for an excess of UHECRs in the direction of the highest-energy neutrinos. The third analysis searches for an excess of pairs of UHECRs and highest-energy neutrinos on different angular scales. None of the analyses have found a significant excess, and previously reported overfluctuations are reduced in significance. Based on these results, we further constrain the neutrino flux spatially correlated with UHECRs.
Publisher: Springer Science and Business Media LLC
Date: 02-2020
Publisher: Elsevier BV
Date: 11-2017
Publisher: IOP Publishing
Date: 06-05-2014
Publisher: Springer Science and Business Media LLC
Date: 29-01-2016
Publisher: American Association for the Advancement of Science (AAAS)
Date: 28-11-2014
Abstract: Supermassive black holes with masses of millions to billions of solar masses are commonly found in the centers of galaxies. Astronomers seek to image jet formation using radio interferometry but still suffer from insufficient angular resolution. An alternative method to resolve small structures is to measure the time variability of their emission. Here we report on gamma-ray observations of the radio galaxy IC 310 obtained with the MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes, revealing variability with doubling time scales faster than 4.8 min. Causality constrains the size of the emission region to be smaller than 20% of the gravitational radius of its central black hole. We suggest that the emission is associated with pulsar-like particle acceleration by the electric field across a magnetospheric gap at the base of the radio jet.
Publisher: IOP Publishing
Date: 29-01-2021
Publisher: Elsevier BV
Date: 09-2019
Publisher: IOP Publishing
Date: 23-06-2016
Publisher: IOP Publishing
Date: 04-12-2015
Publisher: EDP Sciences
Date: 06-2014
Publisher: American Astronomical Society
Date: 12-07-2019
Publisher: SPIE-Intl Soc Optical Eng
Date: 07-01-2021
Publisher: Springer Science and Business Media LLC
Date: 05-2017
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-03-2021
Abstract: If a black hole interacts with a binary companion star, the system emits x-rays and can form a radio jet. The masses of black holes in these x-ray binaries are all lower than those detected using gravitational waves, challenging models of black hole formation from massive stars. Miller-Jones et al. used radio astrometry to refine the distance to Cygnus X-1, a well-studied x-ray binary. They found a larger distance than previous estimates, raising the mass of the black hole in the system to 21 solar masses. The results challenge the wind mass loss rates implemented in stellar evolution models. Science , this issue p. 1046
Publisher: EDP Sciences
Date: 07-2019
DOI: 10.1051/0004-6361/201935697
Abstract: Aims . In the framework of the multi-wavelength and very long baseline interferometry (VLBI) monitoring program TANAMI (Tracking Active Nuclei with Austral Milliarcsecond Interferometry), we study the evolution of the parsec-scale radio emission in radio galaxies in the southern hemisphere and their relationship to the γ -ray properties of the sources. Our study investigates systematically, for the first time, the relationship between the two energy regimes in radio galaxies. In this first paper, we focus on Fermi -LAT-detected sources. Methods . The TANAMI program monitors a large s le of radio-loud AGN at 8.4 GHz and 22.3 GHz with the Australian long baseline array (LBA) and associated telescopes in Antarctica, Chile, New Zealand and South Africa. We performed a kinematic analysis for five γ -ray detected radio galaxies using multi-epoch 8.4 GHz VLBI images, deriving limits on intrinsic jet parameters such as speed and viewing angle. We analyzed 103 months of Fermi -LAT data in order to study possible connections between the γ -ray properties and the pc-scale jets of Fermi -LAT-detected radio galaxies, both in terms of variability and average properties. We discuss the in idual source results and draw preliminary conclusions on s le properties including published VLBI results from the MOJAVE (Monitoring Of Jets in Active galactic nuclei with VLBA Experiments) survey, with a total of fifteen sources. Results . We find that the first γ -ray detection of Pictor A might be associated with the passage of a new VLBI component through the radio core, which appears to be a defining feature of high-energy emitting Fanaroff-Riley type II radio galaxies. We detect subluminal parsec-scale jet motions in the peculiar AGN PKS 0521−36, and we confirm the presence of fast γ -ray variability in the source down to timescales of six hours, which is not accompanied by variations in the VLBI jet. We robustly confirm the presence of significant superluminal motion, up to β app ∼ 3, in the jet of the TeV radio galaxy PKS 0625−35. Our VLBI results constrain the jet viewing angle to be θ 53°, allowing for the possibility of a closely aligned jet. Finally, by analyzing the first pc-scale multi-epoch images of the prototypical compact symmetric object (CSO) PKS 1718−649, we place an upper limit on the separation speed between the two mini-lobes. This in turn allows us to derive a lower limit on the age of the source. Conclusions. We can draw some preliminary conclusions on the relationship between pc-scale jets and γ -ray emission in radio galaxies, based on Fermi -LAT-detected sources with available multi-epoch VLBI measurements. We find that the VLBI core flux density correlates with the γ -ray flux, as seen in blazars. On the other hand, the γ -ray luminosity does not show any dependence on the core brightness temperature and core dominance, which are two common indicators of jet Doppler boosting. This seems to indicate that γ -ray emission in radio galaxies is not driven by orientation-dependent effects, as in blazars, in accordance with the unified model of jetted AGN.
Publisher: Springer Science and Business Media LLC
Date: 2017
Publisher: EDP Sciences
Date: 20-05-2011
Publisher: Springer Science and Business Media LLC
Date: 18-04-2016
DOI: 10.1038/NPHYS3715
Publisher: IOP Publishing
Date: 03-2021
DOI: 10.1088/1475-7516/2021/03/092
Abstract: The first gamma-ray burst detections by Imaging Atmospheric Cherenkov Telescopes have been recently announced: GRB 190114C, detected by MAGIC, GRB 180720B and GRB 190829A, observed by H.E.S.S. A dedicated search for neutrinos in space and time coincidence with the gamma-ray emission observed by IACTs has been performed using ANTARES data. The search covers both the prompt and afterglow phases, yielding no neutrinos in coincidence with the three GRBs studied. Upper limits on the energetics of the neutrino emission are inferred. The resulting upper limits are several orders of magnitude above the observed gamma-ray emission, and they do not allow to constrain the available models.
Publisher: EDP Sciences
Date: 04-2018
DOI: 10.1051/0004-6361/201833064
Abstract: PKS 1718−649 is one of the closest and most comprehensively studied candidates of a young active galactic nucleus (AGN) that is still embedded in its optical host galaxy. The compact radio structure, with a maximal extent of a few parsecs, makes it a member of the group of compact symmetric objects (CSO). Its environment imposes a turnover of the radio synchrotron spectrum towards lower frequencies, also classifying PKS 1718−649 as gigahertz-peaked radio spectrum (GPS) source. Its close proximity has allowed the first detection of extended X-ray emission in a GPS/CSO source with Chandra that is for the most part unrelated to nuclear feedback. However, not much is known about the nature of this emission. By co-adding all archival Chandra data and complementing these datasets with the large effective area of XMM-Newton , we are able to study the detailed physics of the environment of PKS 1718−649. Not only can we confirm that the bulk of the ≲kiloparsec-scale environment emits in the soft X-rays, but we also identify the emitting gas to form a hot, collisionally ionized medium. While the feedback of the central AGN still seems to be constrained to the inner few parsecs, we argue that supernovae are capable of producing the observed large-scale X-ray emission at a rate inferred from its estimated star formation rate.
Publisher: IOP Publishing
Date: 06-2022
DOI: 10.1088/1475-7516/2022/06/018
Abstract: Solar Atmospheric Neutrinos (SA ν s) are produced by the interaction of cosmic rays with the solar medium. The detection of SA ν s would provide useful information on the composition of primary cosmic rays as well as the solar density. These neutrinos represent an irreducible source of background for indirect searches for dark matter towards the Sun and the measurement of their flux would allow for a better assessment of the uncertainties related to these searches. In this paper we report on the analysis performed, based on an unbinned likelihood maximisation, to search for SA ν s with the ANTARES neutrino telescope. After analysing the data collected over 11 years, no evidence for a solar atmospheric neutrino signal has been found. An upper limit at 90% confidence level on the flux of solar atmospheric neutrinos has been obtained, equal to 7×10 -11 [ TeV -1 cm -2 s -1 ] at E ν = 1 TeV for the reference cosmic ray model assumed.
Publisher: IOP Publishing
Date: 08-10-2020
Publisher: EDP Sciences
Date: 30-01-2014
Publisher: Elsevier BV
Date: 2020
Publisher: IOP Publishing
Date: 24-02-2016
Publisher: EDP Sciences
Date: 09-2010
Publisher: Elsevier BV
Date: 06-2022
Publisher: Springer Science and Business Media LLC
Date: 07-2022
Abstract: Non-standard interactions of neutrinos arising in many theories beyond the Standard Model can significantly alter matter effects in atmospheric neutrino propagation through the Earth. In this paper, a search for deviations from the prediction of the standard 3-flavour atmospheric neutrino oscillations using the data taken by the ANTARES neutrino telescope is presented. Ten years of atmospheric neutrino data collected from 2007 to 2016, with reconstructed energies in the range from ∼16 GeV to 100 GeV, have been analysed. A log-likelihood ratio test of the dimensionless coefficients ε μτ and ε ττ − ε μμ does not provide clear evidence of deviations from standard interactions. For normal neutrino mass ordering, the combined fit of both coefficients yields a value 1.7 σ away from the null result. However, the 68% and 95% confidence level intervals for ε μτ and ε ττ − ε μμ , respectively, contain the null value. Best fit values, one standard deviation errors and bounds at the 90% confidence level for these coefficients are given for both normal and inverted mass orderings. The constraint on ε μτ is among the most stringent to date and it further restrains the strength of possible non-standard interactions in the μ − τ sector.
Publisher: Springer Science and Business Media LLC
Date: 05-2020
DOI: 10.1140/EPJC/S10052-020-8015-6
Abstract: An offline search for a neutrino counterpart to gravitational-wave (GW) events detected during the second observation run (O2) of Advanced-LIGO and Advanced-Virgo performed with ANTARES data is presented. In addition to the search for long tracks induced by $$\\nu _\\mu $$ ν μ ( $${\\overline{\\nu }}_{\\mu }$$ ν ¯ μ ) charged current interactions, a search for showering events induced by interactions of neutrinos of any flavour is conducted. The severe spatial and time coincidence provided by the gravitational-wave alert allows regions above the detector horizon to be probed, extending the ANTARES sensitivity over the entire sky. The results of this all-neutrino-flavour and all-sky time dependent analysis are presented. The search for prompt neutrino emission within ±500 s around the time of six GW events yields no neutrino counterparts. Upper limits on the neutrino spectral fluence and constraints on the isotropic energy radiated via high-energy neutrinos (from a few TeV to a few tens of PeV) are set for each GW event analysed.
Publisher: American Astronomical Society
Date: 04-12-2013
Publisher: EDP Sciences
Date: 09-2020
DOI: 10.1051/0004-6361/202038236
Abstract: Aims. This is the second paper in our series studying the evolution of parsec-scale radio emission in radio galaxies in the Southern Hemisphere. Following our study of the radio and high-energy properties of γ -ray-emitting sources, here we investigate the kinematic and spectral properties of the parsec-scale jets of radio galaxies that have not yet been detected by the Fermi Large Area Telescope ( Fermi -LAT) instrument on board NASA’s Fermi Gamma-ray Space Telescope. For many sources, these results represent the first milliarcsecond resolution information in the literature. These studies were conducted within the framework of the Tracking Active Nuclei with Austral Milliarcsecond Interferometry (TANAMI) monitoring program and in the context of high-energy γ -ray observations from Fermi -LAT. Methods. We took advantage of the regular 8.4 GHz and 22.3 GHz Very Long Baseline Interferometry (VLBI) observations provided by the TANAMI monitoring program, and explored the kinematic properties of six γ -ray-faint radio galaxies. We complemented this with ∼8.5 years of Fermi -LAT data, deriving updated upper limits on the γ -ray emission from this subs le of TANAMI radio galaxies. We included publicly available VLBI kinematics of γ -ray-quiet radio galaxies monitored by the MOJAVE program and performed a consistent Fermi -LAT analysis. We combined these results with those from our previous paper to construct the largest s le of radio galaxies with combined VLBI and γ -ray measurements to date. The connection between parsec-scale jet emission and high-energy properties in the misaligned jets of radio galaxies was explored. Results. For the first time, we report evidence of superluminal motion up to β app = 3.6 in the jet of the γ -ray-faint radio galaxy PKS 2153−69. We find a clear trend of higher apparent speed as a function of distance from the jet core, which indicates that the jet is still being accelerated on scales of tens of parsecs, or ∼10 5 R s , corresponding to the end of the collimation and acceleration zone in nearby radio galaxies. We find evidence of subluminal apparent motion in the jets of PKS 1258−321 and IC 4296, and no measurable apparent motion for PKS 1549−79, PKS 1733−565, and PKS 2027−308. For all these sources, TANAMI provides the first multi-epoch kinematic analysis on parsec scales. We then compare the VLBI properties of γ -ray-detected and undetected radio galaxies, and find that the two populations show a significantly different distribution of median core flux density, and, possibly, of median core brightness temperature. In terms of correlation between VLBI and γ -ray properties, we find a significant correlation between median core flux density and γ -ray flux, but no correlation with typical Doppler boosting indicators such as median core brightness temperature and core dominance. Conclusions. Our study suggests that high-energy emission from radio galaxies is related to parsec-scale radio emission from the inner jet, but is not driven by Doppler boosting effects, in contrast to the situation in their blazar counterparts. This implies that γ -ray loudness does not necessarily reflect a higher prevalence of boosting effects.
Publisher: American Astronomical Society
Date: 22-11-2016
Publisher: IOP Publishing
Date: 30-10-2015
Publisher: Elsevier BV
Date: 09-2019
Publisher: EDP Sciences
Date: 05-2021
DOI: 10.1051/0004-6361/202039378
Abstract: Context. On 2019 October 25, the Fermi -Large Area Telescope observed the first ever γ -ray flare from the radio-loud narrow-line Seyfert 1 galaxy PKS 2004−447 ( z = 0.24). Prior to this discovery, only four sources of this type had shown a flare at gigaelectronvolt energies. Aims. We report on follow-up observations in the radio, optical-UV, and X-ray bands that were performed by ATCA, the Neil Gehrels Swift Observatory, XMM-Newton , and NuSTAR , respectively, and analyse these multi-wavelength data with a one-zone leptonic model in order to understand the physical mechanisms that were responsible for the flare. Methods. We study the source’s variability across all energy bands and additionally produce γ -ray light curves with different time binnings to study the variability in γ -rays on short timescales during the flare. We examine the combined X-ray spectrum from 0.5 to 50 keV by describing the spectral shape with an absorbed power law. We analyse multi-wavelength datasets before, during, and after the flare and compare these with a low activity state of the source by modelling the respective spectral energy distributions (SEDs) with a one-zone synchrotron inverse Compton radiative model. Finally, we compare the variability and the SEDs to γ -ray flares previously observed from other γ -loud narrow-line Seyfert 1 galaxies. Results. At γ -ray energies (0.1−300 GeV) the flare reached a maximum flux of (1.3 ± 0.2) × 10 −6 ph cm −2 s −1 in daily binning and a total maximum flux of (2.7 ± 0.6) × 10 −6 ph cm −2 s −1 when a 3 h binning was used. With a photon index of Γ 0.1−300 GeV = 2.42 ± 0.09 during the flare, this corresponds to an isotropic γ -ray luminosity of (2.9 ± 0.8) × 10 47 erg s −1 . The γ -ray, X-ray, and optical-UV light curves that cover the end of September to the middle of November show significant variability, and we find indications for flux-doubling times of ∼2.2 h at γ -ray energies. The soft X-ray excess, which is observed for most narrow-line Seyfert 1 galaxies, is not visible in this source. During the flare, the SED exhibits large Compton dominance. While the increase in the optical-UV range can be explained by enhanced synchrotron emission, the elevated γ -ray flux can be accounted for by an increase in the bulk Lorentz factor of the jet, similar to that observed for other flaring γ -ray blazars.
Publisher: Springer Science and Business Media LLC
Date: 04-2022
DOI: 10.1140/EPJC/S10052-022-10137-Y
Abstract: The KM3NeT research infrastructure is unconstruction in the Mediterranean Sea. KM3NeT will study atmospheric and astrophysical neutrinos with two multi-purpose neutrino detectors, ARCA and ORCA, primarily aimed at GeV–PeV neutrinos. Thanks to the multi-photomultiplier tube design of the digital optical modules, KM3NeT is capable of detecting the neutrino burst from a Galactic or near-Galactic core-collapse supernova. This potential is already exploitable with the first detection units deployed in the sea. This paper describes the real-time implementation of the supernova neutrino search, operating on the two KM3NeT detectors since the first months of 2019. A quasi-online astronomy analysis is introduced to study the time profile of the detected neutrinos for especially significant events. The mechanism of generation and distribution of alerts, as well as the integration into the SNEWS and SNEWS 2.0 global alert systems, are described. The approach for the follow-up of external alerts with a search for a neutrino excess in the archival data is defined. Finally, an overview of the current detector capabilities and a report after the first two years of operation are given.
Publisher: EDP Sciences
Date: 30-03-2015
Publisher: EDP Sciences
Date: 04-05-2016
Publisher: American Physical Society (APS)
Date: 06-2020
Publisher: SPIE
Date: 15-12-2020
DOI: 10.1117/12.2562243
Publisher: SPIE
Date: 21-12-2020
DOI: 10.1117/12.2563050
Publisher: Elsevier BV
Date: 09-2014
Publisher: IOP Publishing
Date: 06-2022
DOI: 10.1088/1475-7516/2022/06/028
Abstract: Searches for dark matter (DM) have not provided any solid evidence for the existence of weakly interacting massive particles in the GeV-TeV mass range. Coincidentally, the scale of new physics is being pushed by collider searches well beyond the TeV domain. This situation strongly motivates the exploration of DM masses much larger than a TeV. Secluded scenarios contain a natural way around the unitarity bound on the DM mass, via the early matter domination induced by the mediator of its interactions with the Standard Model. High-energy neutrinos constitute one of the very few direct accesses to energy scales above a few TeV. An indirect search for secluded DM signals has been performed with the ANTARES neutrino telescope using data from 2007 to 2015. Upper limits on the DM annihilation cross section for DM masses up to 6 PeV are presented and discussed.
Publisher: Oxford University Press (OUP)
Date: 20-02-2012
Publisher: IOP Publishing
Date: 19-11-2020
Publisher: Springer Science and Business Media LLC
Date: 02-2014
Publisher: EDP Sciences
Date: 09-2014
Publisher: IOP Publishing
Date: 13-11-2013
Publisher: IOP Publishing
Date: 07-2022
DOI: 10.1088/1748-0221/17/07/P07038
Abstract: The optical module of the KM3NeT neutrino telescope is an innovative multi-faceted large area photodetection module. It contains 31 three-inch photomultiplier tubes in a single 0.44 m diameter pressure-resistant glass sphere. The module is a sensory device also comprising calibration instruments and electronics for power, readout and data acquisition. It is capped with a breakout-box with electronics for connection to an electro-optical cable for power and long-distance communication to the onshore control station. The design of the module was qualified for the first time in the deep sea in 2013. Since then, the technology has been further improved to meet requirements of scalability, cost-effectiveness and high reliability. The module features a sub-nanosecond timing accuracy and a dynamic range allowing the measurement of a single photon up to a cascade of thousands of photons, suited for the measurement of the Cherenkov radiation induced in water by secondary particles from interactions of neutrinos with energies in the range of GeV to PeV. A distributed production model has been implemented for the delivery of more than 6000 modules in the coming few years with an average production rate of more than 100 modules per month. In this paper a review is presented of the design of the multi-PMT KM3NeT optical module with a proven effective background suppression and signal recognition and sensitivity to the incoming direction of photons.
Publisher: EDP Sciences
Date: 28-06-2016
Publisher: Oxford University Press (OUP)
Date: 25-11-2020
Abstract: Addressing the origin of the astrophysical neutrino flux observed by IceCube is of paramount importance. Gamma-Ray Bursts (GRBs) are among the few astrophysical sources capable of achieving the required energy to contribute to such neutrino flux through pγ interactions. In this work, ANTARES data have been used to search for upward going muon neutrinos in spatial and temporal coincidence with 784 GRBs occurred from 2007 to 2017. For each GRB, the expected neutrino flux has been calculated in the framework of the internal shock model and the impact of the lack of knowledge on the majority of source redshifts and on other intrinsic parameters of the emission mechanism has been quantified. It is found that the model parameters that set the radial distance where shock collisions occur have the largest impact on neutrino flux expectations. In particular, the bulk Lorentz factor of the source ejecta and the minimum variability time-scale are found to contribute significantly to the GRB-neutrino flux uncertainty. For the selected sources, ANTARES data have been analysed by maximizing the discovery probability of the stacking s le through an extended maximum-likelihood strategy. Since no neutrino event passed the quality cuts set by the optimization procedure, 90 per cent confidence level upper limits (with their uncertainty) on the total expected diffuse neutrino flux have been derived, according to the model. The GRB contribution to the observed diffuse astrophysical neutrino flux around 100 TeV is constrained to be less than 10 per cent.
Publisher: Oxford University Press (OUP)
Date: 29-10-2020
Abstract: Cygnus X–1 is the first Galactic source confirmed to host an accreting black hole. It has been detected across the entire electromagnetic spectrum from radio to GeV gamma-rays. The source’s radio through mid-infrared radiation is thought to originate from the relativistic jets. The observed high degree of linear polarization in the MeV X-rays suggests that the relativistic jets dominate in this regime as well, whereas a hot accretion flow dominates the soft X-ray band. The origin of the GeV non-thermal emission is still debated, with both leptonic and hadronic scenarios deemed to be viable. In this work, we present results from a new semi-analytical, multizone jet model applied to the broad-band spectral energy distribution of Cygnus X–1 for both leptonic and hadronic scenarios. We try to break this degeneracy by fitting the first-ever high-quality, simultaneous multiwavelength data set obtained from the CHOCBOX c aign (Cygnus X–1 Hard state Observations of a Complete Binary Orbit in X-rays). Our model parametrizes dynamical properties, such as the jet velocity profile, the magnetic field, and the energy density. Moreover, the model combines these dynamical properties with a self-consistent radiative transfer calculation including secondary cascades, both of leptonic and hadronic origin. We conclude that sensitive TeV gamma-ray telescopes like Cherenkov Telescope Array (CTA) will definitively answer the question of whether hadronic processes occur inside the relativistic jets of Cygnus X–1.
Publisher: EDP Sciences
Date: 02-2018
DOI: 10.1051/0004-6361/201731455
Abstract: Context. TANAMI is a multiwavelength program monitoring active galactic nuclei (AGN) south of − 30° declination including high-resolution very long baseline interferometry (VLBI) imaging, radio, optical/UV, X-ray, and γ -ray studies. We have previously published first-epoch8.4 GHz VLBI images of the parsec-scale structure of the initial s le. In this paper, we present images of 39 additional sources. The full s le comprises most of the radio- and γ -ray brightest AGN in the southern quarter of the sky, overlapping with the region from which high-energy ( 100 TeV) neutrino events have been found. Aims. We characterize the parsec-scale radio properties of the jets and compare them with the quasi-simultaneous Fermi /LAT γ -ray data. Furthermore, we study the jet properties of sources which are in positional coincidence with high-energy neutrino events compared to the full s le. We test the positional agreement of high-energy neutrino events with various AGN s les. Methods. TANAMI VLBI observations at 8.4 GHz are made with southern hemisphere radio telescopes located in Australia, Antarctica, Chile, New Zealand, and South Africa. Results. Our observations yield the first images of many jets below − 30° declination at milliarcsecond resolution. We find that γ -ray loud TANAMI sources tend to be more compact on parsec-scales and have higher core brightness temperatures than γ -ray faint jets, indicating higher Doppler factors. No significant structural difference is found between sources in positional coincidence with high-energy neutrino events and other TANAMI jets. The 22 γ -ray brightest AGN in the TANAMI sky show only a weak positional agreement with high-energy neutrinos demonstrating that the 100 TeV IceCube signal is not simply dominated by a small number of the γ -ray brightest blazars. Instead, a larger number of sources have to contribute to the signal with each in idual source having only a small Poisson probability for producing an event in multi-year integrations of current neutrino detectors.
Publisher: Springer Science and Business Media LLC
Date: 10-2013
Publisher: American Astronomical Society
Date: 11-04-2014
Publisher: Oxford University Press (OUP)
Date: 31-12-2014
Publisher: Elsevier BV
Date: 05-2021
Publisher: EDP Sciences
Date: 04-2020
DOI: 10.1051/0004-6361/201834647
Abstract: We present the spectral and timing evolution of the persistent black hole X-ray binary GRS 1758−258 based on almost 12 years of observations using the Rossi X-ray Timing Explorer Proportional Counter Array. While the source was predominantly found in the hard state during this time, it entered the thermally dominated soft state seven times. In the soft state GRS 1758−258 shows a strong decline in flux above 3 keV rather than the pivoting flux around 10 keV more commonly shown by black hole transients. In its 3–20 keV hardness intensity diagram, GRS 1758−258 shows a hysteresis of hard and soft state fluxes typical for transient sources in outburst. The RXTE-PCA and RXTE-ASM long-term light curves do not show any orbital modulations in the range of 2–30 d. However, in the dynamic power spectra significant peaks drift between 18.47 and 18.04 d for the PCA data, while less significant signatures between 19 d and 20 d are seen for the ASM data as well as for the Swift /BAT data. We discuss different models for the hysteresis behavior during state transitions as well as possibilities for the origin of the long term variation in the context of a warped accretion disk.
Publisher: Springer Science and Business Media LLC
Date: 26-08-2011
Publisher: Elsevier BV
Date: 06-2020
Publisher: IOP Publishing
Date: 19-12-2016
Publisher: EDP Sciences
Date: 29-10-2013
Publisher: American Physical Society (APS)
Date: 28-12-2020
Publisher: Springer Science and Business Media LLC
Date: 10-2021
Abstract: KM3NeT/ORCA is a next-generation neutrino telescope optimised for atmospheric neutrino oscillations studies. In this paper, the sensitivity of ORCA to the presence of a light sterile neutrino in a 3+1 model is presented. After three years of data taking, ORCA will be able to probe the active-sterile mixing angles θ 14 , θ 24 , θ 34 and the effective angle θ μe , over a broad range of mass squared difference $$ \\Delta {m}_{41}^2 $$ ∆ m 41 2 ∼ [10 − 5 , 10] eV 2 , allowing to test the eV-mass sterile neutrino hypothesis as the origin of short baseline anomalies, as well as probing the hypothesis of a very light sterile neutrino, not yet constrained by cosmology. ORCA will be able to explore a relevant fraction of the parameter space not yet reached by present measurements.
Publisher: EDP Sciences
Date: 09-2015
Publisher: American Astronomical Society
Date: 04-2020
Publisher: American Astronomical Society
Date: 25-11-2019
Publisher: American Astronomical Society
Date: 30-01-2017
Publisher: IOP Publishing
Date: 11-11-2014
Publisher: Elsevier BV
Date: 11-2020
Publisher: Springer Science and Business Media LLC
Date: 03-2022
Abstract: This article presents the potential of a combined analysis of the JUNO and KM3NeT/ORCA experiments to determine the neutrino mass ordering. This combination is particularly interesting as it significantly boosts the potential of either detector, beyond simply adding their neutrino mass ordering sensitivities, by removing a degeneracy in the determination of ∆ $$ {m}_{31}^2 $$ m 31 2 between the two experiments when assuming the wrong ordering. The study is based on the latest projected performances for JUNO, and on simulation tools using a full Monte Carlo approach to the KM3NeT/ORCA response with a careful assessment of its energy systematics. From this analysis, a 5 σ determination of the neutrino mass ordering is expected after 6 years of joint data taking for any value of the oscillation parameters. This sensitivity would be achieved after only 2 years of joint data taking assuming the current global best-fit values for those parameters for normal ordering.
Publisher: EDP Sciences
Date: 04-2016
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jörn Wilms.