ANTARES Telescope Research Articles

Follow-up of high energy neutrinos detected by the ANTARES telescope

The ANTARES telescope is well suited to detect neutrinos produced in astrophysical transient sources as it can observe a full hemisphere of the sky with a high duty cycle. Potential neutrino sources are gamma-ray bursts, core-collapse supernovae and flaring active galactic nuclei. To enhance the sensitivity of ANTARES to such sources, a detection method based on follow-up observations from the neutrino direction has been developed. This program, denoted as TAToO, includes a network of robotic optical telescopes (TAROT, Zadko and MASTER) and the Swift-XRT telescope which are triggered when an “interesting” neutrino is detected by ANTARES. A follow-up of special events, such as neutrino doublets in time/space coincidence or single neutrino having a very high energy or in the specific directions of local galaxies, significantly improves the perspective for the detection of transient sources. As images can be taken within 20 seconds after the neutrino trigger and as observations are also made up to two months after the alert, the search for fast transient sources such as gamma-ray burst afterglows or slowly rising sources such as core-collapse supernovae becomes possible. Recently, the follow-up has been extended with a search for correlations between neutrinos and individual high energy photons detected by Fermi-LAT. The analysis of follow-up observations, as well as the search for ν/γ correlations have been done and the results covering optical, X-ray and gamma-ray data, will be presented.

A search for time dependent neutrino emission from microquasars with the ANTARES telescope

Results are presented on a search for neutrino emission from a sample of six microquasars, based on the data collected by the ANTARES neutrino telescope between 2007 and 2010. By means of appropriate time cuts, the neutrino search has been restricted to the periods when the acceleration of relativistic jets was taking place at the microquasars under study. The time cuts have been chosen using the information from the X-ray telescopes RXTE/ASM and Swift/BAT, and, in one case, the gamma-ray telescope Fermi/LAT. No statistically significant excess has been observed, thus upper limits on the neutrino fluences have been derived and compared to the predictions by models. Constraints have been put on the ratio of proton to electron luminosity in the jets.

A search for neutrino emission from the Fermi bubbles with the ANTARES telescope

Analysis of the Fermi-LAT data has revealed two extended structures above and below the Galactic Centre emitting gamma rays with a hard spectrum, the so-called Fermi bubbles. Hadronic models attempting to explain the origin of the Fermi bubbles predict the emission of high-energy neutrinos and gamma rays with similar fluxes. The ANTARES detector, a neutrino telescope located in the Mediterranean Sea, has a good visibility to the Fermi bubble regions. Using data collected from 2008 to 2011 no statistically significant excess of events is observed and therefore upper limits on the neutrino flux in TeV range from the Fermi bubbles are derived for various assumed energy cutoffs of the source.

NEUTRINOS AS COSMIC MESSENGERS IN THE ERA OF ICECUBE, ANTARES AND KM3NET

Using neutrinos as cosmic messengers for observation of non-thermal processes in the Universe is a highly attractive and promising vision, which has been pursued in various neutrino telescope projects for more than two decades. Recent results from ground-based TeV gamma-ray observatories and refinements of model calculations of the expected neutrino fluxes indicate that Gigaton target volumes will be necessary to establish neutrino astronomy. A first neutrino telescope of that size, IceCube, is operational at the South Pole. Based on experience with the smaller first-generation ANTARES telescope in the Mediterranean Sea, the multi-Gigaton KM3NeT device is in preparation. These neutrino telescopes are presented, and some selected results and the expected KM3NeT performance are discussed.

Transient point source analyses in the ANTARES neutrino telescope

The ANTARES telescope, with a duty cycle close to unity and a full hemisphere of the sky at all the times visible, is well suited to detect neutrinos produced in astrophysical transient sources. Assuming a known neutrino production period, the background and the sensitivity can be drastically improved by selecting a narrow time window around it. GRBs, μ-quasars and AGNs are particularly attractive potential neutrino point sources since neutrinos and gamma-rays may be produced in hadronic interactions with the surrounding medium as they are the most likely sources of the observed ultra high energy cosmic rays. A strong correlation between the gamma-ray and the neutrino fluxes is expected in this scenario.ANTARES data has been analyzed in various transient source analyses with the goal of detecting cosmic neutrinos from GRBs, μ-quasars and AGNs. The sensitivity of a standard time-integrated point source search can be improved by a factor 2–3 by looking for neutrinos only during the most probable emission time. This information can be provided by the different satellite telescope types on the X-rays and γ-rays wavelengths. The results of these different analyses will be presented.

Measurement of the atmospheric ν μ energy spectrum from 100 GeV to 200 TeV with the ANTARES telescope

Atmospheric neutrinos are produced during cascades initiated by the interaction of primary cosmic rays with air nuclei. In this paper, a measurement of the atmospheric \nu_\mu + \bar{\nu}_\mu energy spectrum in the energy range 0.1 - 200 TeV is presented, using data collected by the ANTARES underwater neutrino telescope from 2008 to 2011. Overall, the measured flux is ~25% higher than predicted by the conventional neutrino flux, and compatible with the measurements reported in ice. The flux is compatible with a single power-law dependence with spectral index \gamma_{meas}=3.58\pm 0.12. With the present statistics the contribution of prompt neutrinos cannot be established.

SEARCH FOR A CORRELATION BETWEEN ANTARES NEUTRINOS AND PIERRE AUGER OBSERVATORY UHECRs ARRIVAL DIRECTIONS

This paper presents a search for correlation in the arrival directions of 2190 neutrino candidate events detected in 2007-2008 by the ANTARES telescope, and 69 ultra-high energy cosmic rays (UHECRs) observed by the Pierre Auger Observatory between January 1st 2004 and December 31st 2009. No significant correlation was found. The corresponding 90% C.L. upper limit on the neutrino flux from each observed UHECR direction (assuming an equal flux from all of them and for $E^{-2}$ energy spectrum) is 4.99$\times10{^{-8}}$ GeV cm$^{-2}$ s$^{-1}$.

Time integrated search for point sources of cosmic neutrinos with the ANTARES telescope

Results of a time-integrated search for astrophysical high-energy neutrinos are presented using data collected from January 2007 to December 2010 with the ANTARES neutrino telescope. An unbinned likelihood ratio method is used to search for signal events. The final sample consists of 3058 events. Simulations estimate 84% to be neutrinos, while the rest are mis-reconstructed atmospheric muons. A full sky survey as well as a search on a pre-defined list of candidate objects was performed. No evidence for a signal is found and neutrino flux upper limits have been obtained. The neutrino flux sensitivity is 2.6×10−8(E/GeV)−2GeV−1s−1cm−2 for the part of the sky that is always visible (declination ≤−48°) which corresponds to almost a factor 3 better than the previous search.

Upper Limit on the Diffuse νμ Flux with the ANTARES Telescope

A search for very-high energy cosmic muon neutrinos from unresolved sources is presented using data collected by the ANTARES neutrino telescope. Data corresponding to 334 days of equivalent live time show that the observed number of events is compatible with the expected number of background events. A 90% c.l. upper limit on the diffuse νμ flux is set at E2Φ90%=5.3×10−8 GeV cm−2 s−1 sr−1 in the energy range 20 TeV – 2.5 PeV.

Search for neutrino emission from gamma-ray flaring blazars with the ANTARES telescope

The ANTARES telescope is well-suited to detect neutrinos produced in astrophysical transient sources as it can observe a full hemisphere of the sky at all times with a high duty cycle. Radio-loud active galactic nuclei with jets pointing almost directly towards the observer, the so-called blazars, are particularly attractive potential neutrino point sources. The all-sky monitor LAT on board the Fermi satellite probes the variability of any given gamma-ray bright blazar in the sky on time scales of hours to months. Assuming hadronic models, a strong correlation between the gamma-ray and the neutrino fluxes is expected. Selecting a narrow time window on the assumed neutrino production period can significantly reduce the background.An unbinned method based on the minimization of a likelihood ratio was applied to a subsample of data collected in 2008 (61days live time). By searching for neutrinos during the high state periods of the AGN light curve, the sensitivity to these sources was improved by about a factor of two with respect to a standard time-integrated point source search. First results on the search for neutrinos associated with ten bright and variable Fermi sources are presented.

SEARCH FOR NEUTRINO EMISSION FROM GAMMA-RAY SOURCES WITH THE ANTARES TELESCOPE

ANTARES is the first undersea neutrino detector ever built and presently the neutrino telescope with the largest effective area operating in the Northern Hemisphere. A three-dimensional array of photomultiplier tubes detects the Cherenkov light induced by the muons produced in the interaction of high energy neutrinos with the matter surrounding the detector. The detection of astronomical neutrino sources is one of the main goals of ANTARES. The search for point-like neutrino sources with the ANTARES telescope is described and the preliminary results obtained with data collected from 2007 to 2010 are shown. No cosmic neutrino source has been observed and neutrino flux upper limits have been calculated for the most promising source candidates.

Search for neutrinos from transient sources with the ANTARES telescope and optical follow-up observations

The ANTARES telescope is well suited to detect neutrinos produced in astrophysical transient sources as it can observe a full hemisphere of the sky at all the times with a duty cycle close to unity and an angular resolution better than 0.5°. Potential sources include gamma-ray bursts (GRBs), core collapse supernovae (SNe), and flaring active galactic nuclei (AGNs). To enhance the sensitivity of ANTARES to such sources, a new detection method based on coincident observations of neutrinos and optical signals has been developed. A fast online muon track reconstruction is used to trigger a network of small automatic optical telescopes. Such alerts are generated one or two times per month for special events such as two or more neutrinos coincident in time and direction or single neutrinos of very high energy. Since February 2009, ANTARES has sent 37 alert triggers to the TAROT and ROTSE telescope networks, 27 of them have been followed. First results on the optical images analysis to search for GRBs are presented.

The ANTARES telescope neutrino alert system

The ANTARES telescope has the capability to detect neutrinos produced in astrophysical transient sources. Potential sources include gamma-ray bursts, core collapse supernovae, and flaring active galactic nuclei. To enhance the sensitivity of ANTARES to such sources, a new detection method based on coincident observations of neutrinos and optical signals has been developed. A fast online muon track reconstruction is used to trigger a network of small automatic optical telescopes. Such alerts are generated for special events, such as two or more neutrinos, coincident in time and direction, or single neutrinos of very high energy.

Search for neutrinos from transient sources with the ANTARES telescope and optical follow-up observations (TAToO)

The ANTARES telescope has the opportunity to detect transient neutrino sources, such as gamma-ray bursts, core-collapse supernovae, flares of active galactic nuclei. In order to enhance the sensitivity to these sources, we have developed a new detection method based on the follow-up by optical telescopes of “golden” neutrino events, such as neutrino doublets coincident in time and space or single neutrinos of very high energy. The ANTARES collaboration has therefore implemented a very fast on-line reconstruction with a good angular resolution. These characteristics allow us to trigger an optical telescope network. Since February 2009, ANTARES is sending alert triggers once or twice per month to the two 25 cm robotic telescope of TAROT. This optical follow-up of such special events would not only give access to the nature of the sources, but also would improve the sensitivity to transient neutrino sources.

On the detection of the Moon shadow with the ANTARES neutrino telescope

We discuss the possibility of detecting the Moon shadow with the ANTARES neutrino telescope. A detailed Monte Carlo simulation was conducted in order to calculate the expected significance for the measurement. Simulation results show that the ANTARES telescope will be able to observe the effect in a couple of years. Results of the simulation study will be presented and discussed.

A photonic readout and data acquisition system for deep-sea neutrino telescopes

In the context of the KM3NeT Design Study and building on the experience with the data acquisition system of the ANTARES telescope, an alternative readout and DAQ architecture has been developed for deep-sea neutrino telescopes. The system relies on sensor technology using photonic readout and a 10 Gb/s optical network for data acquisition and communication. Compared to ANTARES, more functionality has been migrated to the shore, thus allowing for timely deployment of the telescope components and easy access to the system during the long lifetime of neutrino telescopes. Also the reconfiguration of the DAQ system is located on shore. Timing calibration is an integral part of the network architecture providing an event timing integrity with less than 1 ns. Although developed for use in the deep-sea, the concept of the system can be used in other applications, e.g. in the LHC experiments.

A sensor architecture for neutrino telescopes

In the Mediterranean Sea the ANTARES telescope is operating since 2006. Building on the success of this telescope and on the experiences of the DUMAND, IceCube, NEMO and NESTOR projects, a design for a new generation deep-sea neutrino telescope has been developed, which relies on the paradigm of the neutrino telescope as a giant sensor. Slender flexible strings with optical sensors form the basic building blocks for the telescope. The sensor concept has been implemented using photonic technologies for readout, data acquisition and communication, which allow for migration of functionalities from the deep-sea to the shore. This is one of the detector designs options developed during the EU funded KM3NeT Design Study. We will present its concept and implications for the detector as a whole.

Study on the possible detection of Gamma Ray Bursts with the ANTARES neutrino telescope

The ANTARES telescope, currently in construction, is aiming to detect high energy neutrinos. Data from the first line of the detector, which became operational recently, demonstrates that the nominal time and space resolutions are achieved. Various models predict the emission of high energy neutrinos from astrophysical sources such as Supernova Remnants, Microquasars, Active Galactic Nuclei and Gamma Ray Bursts. With the custom designed data acquisition system of this detector, in combination with the existing satellite alert systems, the ANTARES telescope has an increased sensitivity for neutrinos from Gamma Ray Bursts compared to conventional time independent sources.

The ANTARES telescope turns its gaze to the sky

The ANTARES telescope turns its gaze to the sky

Detecting High-Energy Neutrinos from Microquasars with the ANTARES Telescope

The ANTARES project aims at the construction of a neutrino telescope 2500m below the surface of the Mediterranean sea, close to the southern French coast. The apparatus will consist of a 3D array of photomultiplier tubes, which detects the Cherenkov light emitted by upward going neutrino-induced muons. High-energy neutrinos may be produced in powerful cosmic accelerators, such as, gamma-ray bursters, active galactic nuclei, supernova remnants, and microquasars. We have estimated the event rate in ANTARES of neutrinos coming from these sources, and particularly for a microquasar model, and found that for some of these sources the detection rate can be up to several events per year.