S. Escoffier | Aix-Marseille University (original) (raw)

Papers by S. Escoffier

Cornell University - arXiv, Sep 30, 2013

We study the comoving relative velocities, v12, of model isolated galaxy pairs at z = 0.5. For th... more We study the comoving relative velocities, v12, of model isolated galaxy pairs at z = 0.5. For this purpose, we use the predictions from the galform semi-analytical model of galaxy formation and evolution based on a Λ cold dark matter cosmology consistent with the results from WMAP7. In real space, we find that isolated pairs of galaxies are predicted to form an angle t with the line-of-sight that is uniformly distributed as expected if the Universe is homogeneous and isotropic. We also find that isolated pairs of galaxies separated by a comoving distance between 1 and 3 h −1 Mpc are predicted to have v12 ∼ 0. For galaxies in this regime, the distribution of the angle t is predicted to change minimally from real to redshift space, with a change smaller than 5% in sin 2 t. However, the distances defining the comoving regime strongly depends on the applied isolation criteria.

A time integrated search for point sources of cosmic neutrinos was performed using the data colle... more A time integrated search for point sources of cosmic neutrinos was performed using the data collected from January 2007 to November 2012 by the ANTARES neutrino telescope. This dataset includes a total of 5921 events obtained during the effective livetime of 1338 days.

We briefly present observations of nonthermal continuum (NTC) radiations obtained close to the so... more We briefly present observations of nonthermal continuum (NTC) radiations obtained close to the sources at the plasmapause by the Whisper instruments on Cluster. The examples considered illustrate the variety of the characteristics of the NTC such as the overall bandwidth of the emissions. The omnipresent multiple narrow bandwidth components are further evidence that the emissions could be generated from multiple, closely spaced, short scale regions (a few 10 km).

Astronomy and Computing, 2019

The aim of this study is to distinguish genuine cosmic voids, found in a galaxy catalog by the vo... more The aim of this study is to distinguish genuine cosmic voids, found in a galaxy catalog by the void finder ZOBOV-VIDE, from under-dense regions in a Poisson distribution of objects. For this purpose, we perform two multivariate analyses using the following physical void characteristics: volume, redshift, density contrast, minimum density, contrast significance and number of member galaxies of the void. The multivariate analyses are trained on a catalog of voids obtained from a random Poisson distribution of points, used as background, and a catalog of voids identified in a mock galaxy catalog, used as signal. The classifications are then applied to voids extracted from the Data Release 12 sample of Luminous Red Galaxies in the redshift range 0.45 ≤ z ≤ 0.7 from the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (SDSS BOSS DR12 CMASS). Our results show that the resulting void catalog is nearly free of contamination by Poisson noise. We also study the effect of tracer sparsity and bias on the classification efficiencies.

The Astrophysical Journal Supplement Series, 2018

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July ... more The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.

Intense and localized burst of electrostatic emissions have been observed by the Whisper instrume... more Intense and localized burst of electrostatic emissions have been observed by the Whisper instrument on Cluster at frequency close to the electron plasma frequency, in the magnetopause boundary layer. The good time resolution of Whisper when in burst mode telemetry as well as the combination of the observations performed by the four Cluster spacecraft at short separation distance (~100 km) have allowed to determine in one case the dimension of these structure, typically a few tens of kilometers, close to the electron scale. We browse Whisper data in search for such events and present here some examples of their observations. We present the main characteristics of the spectra and power profile of the emissions.

Ocean Science Discussions, 2010

Reply referee 2 (P. Rhines) We thank the referee for the comments raised. Reading through the com... more Reply referee 2 (P. Rhines) We thank the referee for the comments raised. Reading through the comments we realized that our writing-up was terse in places. We should have elaborated on the error analysis of vertical current measurement and we should have stressed that our observations are from multiple independent variables, not just vertical current observations. Furthermore, the observations are not "permanent" or "constant with time" but show considerable variability with time, notably a typical 20 days periodicity. All the independent observations merely support each-other. The revised manuscript has been modified accordingly.

Journal of High Energy Astrophysics, 2014

Results are presented on a search for neutrino emission from a sample of six microquasars, based ... more 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. Since none of the searches has produced a statistically significant signal, upper limits on the neutrino fluences are derived and compared to the predictions from theoretical models.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Te... more The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Telescope in the Mediterranean Sea. The main purpose of the detector is to perform neutrino astronomy and the apparatus also offers facilities for marine and Earth sciences. This paper describes the design, the construction and the installation of the telescope in the deep sea, offshore from Toulon in France. An illustration of the detector performance is given.

This paper has been withdrawn due a problem with the estimation of background.

The Astronomical Journal, 2011

Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of ... more Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS Data Release 8 (DR8), which was made public in January 2011 and includes SDSS-I and SDSS-II images and spectra reprocessed with the latest pipelines and calibrations produced for the SDSS-III investigations. This paper presents an overview of the four surveys that comprise SDSS-III. The Baryon Oscillation Spectroscopic Survey (BOSS) will measure redshifts of 1.5 million massive galaxies and Lyα forest spectra of 150,000 quasars, using the baryon acoustic oscillation feature of large scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z < 0.7 and at z ≈ 2.5. SEGUE-2, an already completed SDSS-III survey that is the continuation of the SDSS-II Sloan Extension for Galactic Understanding and Exploration (SEGUE),

Physics Letters B, 2011

A search for a diffuse flux of astrophysical muon neutrinos, using data collected by the ANTARES ... more A search for a diffuse flux of astrophysical muon neutrinos, using data collected by the ANTARES neutrino telescope is presented. A (0.83 × 2π) sr sky was monitored for a total of 334 days of equivalent live time. The searched signal corresponds to an excess of events, produced by astrophysical sources, over the expected atmospheric neutrino background. The observed number of events is found compatible with the background expectation. Assuming an E −2 flux spectrum, a 90% c.l. upper limit on the diffuse ν µ flux of E 2 Φ 90% = 5.3 × 10 −8 GeV cm −2 s −1 sr −1 in the energy range 20 TeV-2.5 PeV is obtained. Other signal models with different energy spectra are also tested and some rejected.

Physical Review C, 2004

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarize... more We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from protons. Significant contributions to this asymmetry could arise from the contributions of strange form factors in the nucleon. The measured asymmetry is A = −15.05 ± 0.98(stat) ± 0.56(syst) ppm at the kinematic point θ lab = 12.3 • and Q 2 = 0.477 (GeV/c) 2. Based on these data as well as data on electromagnetic form factors, we extract the linear combination of strange form factors G s E + 0.392G s M = 0.014 ± 0.020 ± 0.010 where the first error arises from this experiment and the second arises from the electromagnetic form factor data. This paper provides a full description of the special experimental techniques employed for precisely measuring the small asymmetry, including the first use of a strained GaAs crystal and a laser-Compton polarimeter in a fixed target parity-violation experiment.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described ... more The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described in this article aims at the investigation of techniques for acoustic detection of neutrinos in the deep sea. It is integrated into the ANTARES neutrino telescope in the Mediterranean Sea. Its acoustic sensors, installed at water depths between 2050 and 2300 m, employ piezo-electric elements for the broad-band recording of signals with frequencies ranging up to 125 kHz. The typical sensitivity of the sensors is around −145 dB re 1V/µPa (including preamplifier). Completed in May 2008, AMADEUS consists of six "acoustic clusters", each comprising six acoustic sensors that are arranged at distances of roughly 1 m from each other. Two vertical mechanical structures (so-called lines) of the ANTARES detector host three acoustic clusters each. Spacings between the clusters range from 14.5 to 340 m. Each cluster contains custom-designed electronics boards to amplify and digitise the acoustic signals from the sensors. An onshore computer cluster is used to process and filter the data stream and store the selected events. The daily volume of recorded data is about 10 GB. The system is operating continuously and automatically, requiring only little human intervention. AMADEUS allows for extensive studies of both transient signals and ambient noise in the deep sea, as well as signal correlations on several length scales and localisation of acoustic point sources. Thus the system is excellently suited to assess the background conditions for the measurement of the bipolar pulses expected to originate from neutrino interactions.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

Completed in May 2008, the ANTARES neutrino telescope is located 40 km off the coast of Toulon, a... more Completed in May 2008, the ANTARES neutrino telescope is located 40 km off the coast of Toulon, at a depth of about 2500 m. The telescope consists of 12 detector lines housing a total of 884 optical modules. Each line is anchored to the seabed and pulled taught by the buoyancy of the individual optical modules and a top buoy. Due to the fluid nature of the seawater detecting medium and the flexible nature of the detector lines, the optical modules of the ANTARES telescope can suffer from deviations of up to several meters from the vertical and as such, real time positioning is needed. Real time positioning of the ANTARES telescope is achieved by a combination of an acoustic positioning system and a lattice of tiltmeters and compasses. These independent and complementary systems are used to compute a global fit to each individual detector line, allowing us to construct a 3 dimensional picture of the ANTARES neutrino telescope with an accuracy of less than 10 cm. In this paper we describe the positioning system of the ANTARES neutrino telescope and discuss its performance during the first year of 12 line data taking.

The Astrophysical Journal, 2011

Results are presented of a search for cosmic sources of high energy neutrinos with the ANTARES ne... more Results are presented of a search for cosmic sources of high energy neutrinos with the ANTARES neutrino telescope. The data were collected during 2007 and 2008 using detector configurations containing between 5 and 12 detection lines. The integrated live time of the analyzed data is 304 days. Muon tracks are reconstructed using a likelihood-based algorithm. Studies of the detector timing indicate a median angular resolution of 0.5 ± 0.1 degrees. The neutrino flux sensitivity is 7.5 × 10 −8 (E ν /GeV) −2 GeV −1 s −1 cm −2 for the part of the sky The Netherlands

Deep Sea Research Part I: Oceanographic Research Papers, 2011

An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site of the ANTARES neutri... more An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site of the ANTARES neutrino telescope near Toulon, France, thus providing a unique opportunity to compare high-resolution acoustic and optical observations between 70 and 170 m above the sea bed at 2475 m. The ADCP measured downward vertical currents of magnitudes up to 0.03 m s-1 in late winter and early spring 2006. In the same period, observations were made of enhanced levels of acoustic reflection, interpreted as suspended particles including zooplankton, by a factor of about 10 and of horizontal currents reaching 0.35 m s-1. These observations coincided with high light levels detected by the telescope, interpreted as increased bioluminescence. During winter 2006 deep dense-water formation occurred in the Ligurian subbasin, thus providing a possible explanation for these observations. However, the 10-20 days quasi-periodic episodes of high levels of acoustic reflection, light and large vertical currents continuing into the summer are not direct evidence of this process. It is hypothesized that the main process allowing for suspended material to be moved vertically later in the year is local advection, linked with topographic boundary current instabilities along the rim of the 'Northern Current'.

The Astrophysical Journal Supplement Series, 2012

The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon... more The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z ∼ 0.52), 102,100 new quasar spectra (median z ∼ 2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T eff < 5000 K and in metallicity estimates for stars with [Fe/H] > -0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SEGUE-2. The astrometry error introduced in ...

Cornell University - arXiv, Sep 30, 2013

We study the comoving relative velocities, v12, of model isolated galaxy pairs at z = 0.5. For th... more We study the comoving relative velocities, v12, of model isolated galaxy pairs at z = 0.5. For this purpose, we use the predictions from the galform semi-analytical model of galaxy formation and evolution based on a Λ cold dark matter cosmology consistent with the results from WMAP7. In real space, we find that isolated pairs of galaxies are predicted to form an angle t with the line-of-sight that is uniformly distributed as expected if the Universe is homogeneous and isotropic. We also find that isolated pairs of galaxies separated by a comoving distance between 1 and 3 h −1 Mpc are predicted to have v12 ∼ 0. For galaxies in this regime, the distribution of the angle t is predicted to change minimally from real to redshift space, with a change smaller than 5% in sin 2 t. However, the distances defining the comoving regime strongly depends on the applied isolation criteria.

A time integrated search for point sources of cosmic neutrinos was performed using the data colle... more A time integrated search for point sources of cosmic neutrinos was performed using the data collected from January 2007 to November 2012 by the ANTARES neutrino telescope. This dataset includes a total of 5921 events obtained during the effective livetime of 1338 days.

We briefly present observations of nonthermal continuum (NTC) radiations obtained close to the so... more We briefly present observations of nonthermal continuum (NTC) radiations obtained close to the sources at the plasmapause by the Whisper instruments on Cluster. The examples considered illustrate the variety of the characteristics of the NTC such as the overall bandwidth of the emissions. The omnipresent multiple narrow bandwidth components are further evidence that the emissions could be generated from multiple, closely spaced, short scale regions (a few 10 km).

Astronomy and Computing, 2019

The aim of this study is to distinguish genuine cosmic voids, found in a galaxy catalog by the vo... more The aim of this study is to distinguish genuine cosmic voids, found in a galaxy catalog by the void finder ZOBOV-VIDE, from under-dense regions in a Poisson distribution of objects. For this purpose, we perform two multivariate analyses using the following physical void characteristics: volume, redshift, density contrast, minimum density, contrast significance and number of member galaxies of the void. The multivariate analyses are trained on a catalog of voids obtained from a random Poisson distribution of points, used as background, and a catalog of voids identified in a mock galaxy catalog, used as signal. The classifications are then applied to voids extracted from the Data Release 12 sample of Luminous Red Galaxies in the redshift range 0.45 ≤ z ≤ 0.7 from the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (SDSS BOSS DR12 CMASS). Our results show that the resulting void catalog is nearly free of contamination by Poisson noise. We also study the effect of tracer sparsity and bias on the classification efficiencies.

The Astrophysical Journal Supplement Series, 2018

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July ... more The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.

Intense and localized burst of electrostatic emissions have been observed by the Whisper instrume... more Intense and localized burst of electrostatic emissions have been observed by the Whisper instrument on Cluster at frequency close to the electron plasma frequency, in the magnetopause boundary layer. The good time resolution of Whisper when in burst mode telemetry as well as the combination of the observations performed by the four Cluster spacecraft at short separation distance (~100 km) have allowed to determine in one case the dimension of these structure, typically a few tens of kilometers, close to the electron scale. We browse Whisper data in search for such events and present here some examples of their observations. We present the main characteristics of the spectra and power profile of the emissions.

Ocean Science Discussions, 2010

Reply referee 2 (P. Rhines) We thank the referee for the comments raised. Reading through the com... more Reply referee 2 (P. Rhines) We thank the referee for the comments raised. Reading through the comments we realized that our writing-up was terse in places. We should have elaborated on the error analysis of vertical current measurement and we should have stressed that our observations are from multiple independent variables, not just vertical current observations. Furthermore, the observations are not "permanent" or "constant with time" but show considerable variability with time, notably a typical 20 days periodicity. All the independent observations merely support each-other. The revised manuscript has been modified accordingly.

Journal of High Energy Astrophysics, 2014

Results are presented on a search for neutrino emission from a sample of six microquasars, based ... more 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. Since none of the searches has produced a statistically significant signal, upper limits on the neutrino fluences are derived and compared to the predictions from theoretical models.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Te... more The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Telescope in the Mediterranean Sea. The main purpose of the detector is to perform neutrino astronomy and the apparatus also offers facilities for marine and Earth sciences. This paper describes the design, the construction and the installation of the telescope in the deep sea, offshore from Toulon in France. An illustration of the detector performance is given.

This paper has been withdrawn due a problem with the estimation of background.

The Astronomical Journal, 2011

Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of ... more Building on the legacy of the Sloan Digital Sky Survey (SDSS-I and II), SDSS-III is a program of four spectroscopic surveys on three scientific themes: dark energy and cosmological parameters, the history and structure of the Milky Way, and the population of giant planets around other stars. In keeping with SDSS tradition, SDSS-III will provide regular public releases of all its data, beginning with SDSS Data Release 8 (DR8), which was made public in January 2011 and includes SDSS-I and SDSS-II images and spectra reprocessed with the latest pipelines and calibrations produced for the SDSS-III investigations. This paper presents an overview of the four surveys that comprise SDSS-III. The Baryon Oscillation Spectroscopic Survey (BOSS) will measure redshifts of 1.5 million massive galaxies and Lyα forest spectra of 150,000 quasars, using the baryon acoustic oscillation feature of large scale structure to obtain percent-level determinations of the distance scale and Hubble expansion rate at z < 0.7 and at z ≈ 2.5. SEGUE-2, an already completed SDSS-III survey that is the continuation of the SDSS-II Sloan Extension for Galactic Understanding and Exploration (SEGUE),

Physics Letters B, 2011

A search for a diffuse flux of astrophysical muon neutrinos, using data collected by the ANTARES ... more A search for a diffuse flux of astrophysical muon neutrinos, using data collected by the ANTARES neutrino telescope is presented. A (0.83 × 2π) sr sky was monitored for a total of 334 days of equivalent live time. The searched signal corresponds to an excess of events, produced by astrophysical sources, over the expected atmospheric neutrino background. The observed number of events is found compatible with the background expectation. Assuming an E −2 flux spectrum, a 90% c.l. upper limit on the diffuse ν µ flux of E 2 Φ 90% = 5.3 × 10 −8 GeV cm −2 s −1 sr −1 in the energy range 20 TeV-2.5 PeV is obtained. Other signal models with different energy spectra are also tested and some rejected.

Physical Review C, 2004

We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarize... more We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from protons. Significant contributions to this asymmetry could arise from the contributions of strange form factors in the nucleon. The measured asymmetry is A = −15.05 ± 0.98(stat) ± 0.56(syst) ppm at the kinematic point θ lab = 12.3 • and Q 2 = 0.477 (GeV/c) 2. Based on these data as well as data on electromagnetic form factors, we extract the linear combination of strange form factors G s E + 0.392G s M = 0.014 ± 0.020 ± 0.010 where the first error arises from this experiment and the second arises from the electromagnetic form factor data. This paper provides a full description of the special experimental techniques employed for precisely measuring the small asymmetry, including the first use of a strained GaAs crystal and a laser-Compton polarimeter in a fixed target parity-violation experiment.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2011

The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described ... more The AMADEUS (ANTARES Modules for the Acoustic Detection Under the Sea) system which is described in this article aims at the investigation of techniques for acoustic detection of neutrinos in the deep sea. It is integrated into the ANTARES neutrino telescope in the Mediterranean Sea. Its acoustic sensors, installed at water depths between 2050 and 2300 m, employ piezo-electric elements for the broad-band recording of signals with frequencies ranging up to 125 kHz. The typical sensitivity of the sensors is around −145 dB re 1V/µPa (including preamplifier). Completed in May 2008, AMADEUS consists of six "acoustic clusters", each comprising six acoustic sensors that are arranged at distances of roughly 1 m from each other. Two vertical mechanical structures (so-called lines) of the ANTARES detector host three acoustic clusters each. Spacings between the clusters range from 14.5 to 340 m. Each cluster contains custom-designed electronics boards to amplify and digitise the acoustic signals from the sensors. An onshore computer cluster is used to process and filter the data stream and store the selected events. The daily volume of recorded data is about 10 GB. The system is operating continuously and automatically, requiring only little human intervention. AMADEUS allows for extensive studies of both transient signals and ambient noise in the deep sea, as well as signal correlations on several length scales and localisation of acoustic point sources. Thus the system is excellently suited to assess the background conditions for the measurement of the bipolar pulses expected to originate from neutrino interactions.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2009

Completed in May 2008, the ANTARES neutrino telescope is located 40 km off the coast of Toulon, a... more Completed in May 2008, the ANTARES neutrino telescope is located 40 km off the coast of Toulon, at a depth of about 2500 m. The telescope consists of 12 detector lines housing a total of 884 optical modules. Each line is anchored to the seabed and pulled taught by the buoyancy of the individual optical modules and a top buoy. Due to the fluid nature of the seawater detecting medium and the flexible nature of the detector lines, the optical modules of the ANTARES telescope can suffer from deviations of up to several meters from the vertical and as such, real time positioning is needed. Real time positioning of the ANTARES telescope is achieved by a combination of an acoustic positioning system and a lattice of tiltmeters and compasses. These independent and complementary systems are used to compute a global fit to each individual detector line, allowing us to construct a 3 dimensional picture of the ANTARES neutrino telescope with an accuracy of less than 10 cm. In this paper we describe the positioning system of the ANTARES neutrino telescope and discuss its performance during the first year of 12 line data taking.

The Astrophysical Journal, 2011

Results are presented of a search for cosmic sources of high energy neutrinos with the ANTARES ne... more Results are presented of a search for cosmic sources of high energy neutrinos with the ANTARES neutrino telescope. The data were collected during 2007 and 2008 using detector configurations containing between 5 and 12 detection lines. The integrated live time of the analyzed data is 304 days. Muon tracks are reconstructed using a likelihood-based algorithm. Studies of the detector timing indicate a median angular resolution of 0.5 ± 0.1 degrees. The neutrino flux sensitivity is 7.5 × 10 −8 (E ν /GeV) −2 GeV −1 s −1 cm −2 for the part of the sky The Netherlands

Deep Sea Research Part I: Oceanographic Research Papers, 2011

An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site of the ANTARES neutri... more An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site of the ANTARES neutrino telescope near Toulon, France, thus providing a unique opportunity to compare high-resolution acoustic and optical observations between 70 and 170 m above the sea bed at 2475 m. The ADCP measured downward vertical currents of magnitudes up to 0.03 m s-1 in late winter and early spring 2006. In the same period, observations were made of enhanced levels of acoustic reflection, interpreted as suspended particles including zooplankton, by a factor of about 10 and of horizontal currents reaching 0.35 m s-1. These observations coincided with high light levels detected by the telescope, interpreted as increased bioluminescence. During winter 2006 deep dense-water formation occurred in the Ligurian subbasin, thus providing a possible explanation for these observations. However, the 10-20 days quasi-periodic episodes of high levels of acoustic reflection, light and large vertical currents continuing into the summer are not direct evidence of this process. It is hypothesized that the main process allowing for suspended material to be moved vertically later in the year is local advection, linked with topographic boundary current instabilities along the rim of the 'Northern Current'.

The Astrophysical Journal Supplement Series, 2012

The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon... more The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z ∼ 0.52), 102,100 new quasar spectra (median z ∼ 2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T eff < 5000 K and in metallicity estimates for stars with [Fe/H] > -0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SEGUE-2. The astrometry error introduced in ...