arXiv subjects

L. Rolland

Publications and source records attributed to L. Rolland.

7 recordsLinked to original sources

arXiv2022

ETpathfinder: a cryogenic testbed for interferometric gravitational-wave detectors

The third-generation of gravitational wave observatories, such as the Einstein Telescope (ET) and Cosmic Explorer (CE), aim for an improvement in sensitivity of at least a factor of ten over a wide frequency range compared to the current advanced detectors. In order to inform the design of the third-generation detectors and to develop and qualify their subsystems, dedicated test facilities are required. ETpathfinder prototype uses full interferometer configurations and aims to provide a high sensitivity facility in a similar environment as ET. Along with the interferometry at 1550 nm and silicon test masses, ETpathfinder will focus on cryogenic technologies, lasers and optics at 2090 nm and advanced quantum-noise reduction schemes. This paper analyses the underpinning noise contributions and combines them into full noise budgets of the two initially targeted configurations: 1) operating with 1550 nm laser light and at a temperature of 18 K and 2) operating at 2090 nm wavelength and a temperature of 123 K.

astro-ph.IM↗

arXiv2021

The Advanced Virgo Photon Calibrators

As the sensitivities of LIGO, Virgo and KAGRA detectors improve, calibration of the interferometers output is becoming more and more important and may impact scientific results. For the observing run O3, Virgo used for the first time photon calibrators (PCal) to calibrate the interferometer, using radiation pressure of a modulated auxiliary laser beam impinging on the Advanced Virgo end mirrors. Those optical devices, also used in LIGO, are now the calibration reference for the global gravitational wave detectors network. The intercalibration of LIGO and Virgo PCals, based on the same absolute reference called the Gold Standard, has allowed to remove a systematic bias of 3.92% that would have been present in Virgo calibration using the PCal. The uncertainty budget on the PCal-induced displacement of the end mirrors (NE and WE) of Advanced Virgo has been estimated to be 1.36% for O3a and 1.40% on NE PCal (resp. 1.74% on WE PCal) for O3b. This uncertainty is the limiting one for the global calibration of Advanced Virgo. It is expected to be reduced below 1% for the next observing runs.

astro-ph.IM↗

arXiv2018

First Tests of a Newtonian Calibrator on an Interferometric Gravitational Wave Detector

The ongoing improvements of the advanced gravitational wave (GW) detectors are setting challenging requirements on instrument calibration. We report tests of a calibration technique, based on the well-known gravitation force, which has been applied for the first time on a large interferometer. The results obtained with Advanced Virgo are in good agreement with the predictions and with the usual calibration method. This technique is expected to lead to accurate absolute calibration at the sub-percent level in the coming years, matching the needs of the blooming GW science.

gr-qc↗

arXiv2018

The Nice Cube (Nice3) nanosatellite project

CubeSats are tiny satellites with increasing capabilities. They have been used for more than a decade by universities to train students on space technologies, in a hands-on project aiming at building, launching and operating a real satellite. Still today, one shortcoming of CubeSats is their poor ability to transmit large amounts of data to the ground. A possible way to overcome this limitation relies on optical communications. Universite Cote d'Azur is studying the feasibility of a student's CubeSat whose main goal is to transmit data with an optical link to the ground at the moderate rate of 1 kb/s (or better). In this paper, we will present the current state of the project and its future developments.

astro-ph.IM↗

arXiv2011

A Multi-Wavelength Study of the Unidentified TeV Gamma-ray Source HESS J1626-490

HESS J1626-490, so far only detected with the H.E.S.S. array of imaging atmospheric Cherenkov telescopes, could not be unambiguously identified with any source seen at lower energies. Therefore, we analyzed data from an archival XMM-Newton observation, pointed towards HESS J1626-490, to classify detected point-like and extended X-ray sources according to their spectral properties. None of the detected X-ray point sources fulfills the energetic requirements to be considered as the synchrotron radiation (SR) counterpart to the VHE source assuming an Inverse Compton (IC) emission scenario. Furthermore, we did not detect any diffuse X-ray excess emission originating from the region around HESS J1626-490 above the Galactic Background. The derived upper limit for the total X-ray flux disfavors a purely leptonic emission scenario for HESS J1626-490. To characterize the Interstellar Medium surrounding HESS J1626-490 we analyzed ^{12}CO(J=1-0) molecular line data from the Nanten Galactic plane survey and HI data from the Southern Galactic Plane Survey (SGPS). We found a good morphological match between molecular and atomic gas in the -27 km/s to -18 km/s line-of-sight velocity range and HESS J1626-490. The cloud has a mass of 1.8x10^4 M_sun and is located at a mean kinematic distance of d = 1.8 kpc. Furthermore, we found a density depression in the HI gas at a similar distance which is spatially consistent with the SNR G335.2+00.1. Therefore, the most likely origin of the VHE gamma-ray emission observed with H.E.S.S. is the hadronic interaction of cosmic rays with a moderately dense molecular cloud, which we detected with Nanten. The application of a detailed hadronic model for cosmic ray transport and interaction shows that the cosmic rays could originate from the nearby SNR G335.2+00.1.

astro-ph.HE↗

arXiv2010

A multi-wavelength study of the unidentified TeV gamma-ray source HESS J1626-490

HESS J1626-490, so far only detected with the H.E.S.S. array of imaging atmospheric Cherenkov telescopes, could not be unambiguously identified with any source seen at lower energies. Therefore, we analyzed data from an archival XMM-Newton observation, pointed towards HESS J1626-490, to classify detected X-ray point-sources according to their spectral properties and their near-infrared counterparts from the 2MASS catalog. Furthermore, we characterized in detail the diffuse X-ray emission from a region compatible with the extended VHE signal. To characterize the Interstellar Medium surrounding HESS J1626-490 we analyzed $^{12}$CO(J=1-0) molecular line data from the NANTEN Galactic plane survey, HI data from the Southern Galactic Plane Survey and Spitzer data from the GLIMPSE and MIPSGAL surveys. None of the detected X-ray point sources fulfills the energetic requirements to be considered as the synchrotron radiation (SR) counterpart to the VHE source assuming an Inverse Compton (IC) emission scenario. We did not detect any diffuse X-ray excess emission originating from the region around HESS J1626-490 above the Galactic Background and the derived upper limit for the total X-ray flux disfavors a purely leptonic emission scenario for HESS J1626-490. We found a good morphological match between molecular and atomic gas in the -27km/s to -18km/s line-of-sight velocity range and HESS J1626-490. The cloud has a mass of 1.8$times 10^4$M$_{odot}$ and is located at a mean kinematic distance of $d$ = 1.8 kpc. Furthermore, we found a density depression in the HI gas at a similar distance which is spatially consistent with the SNR G335.2+00.1. We discuss various scenarios for the VHE emission, including the CO molecular cloud being a passive target for cosmic ray protons accelerated by the nearby SNR G335.2+00.1.

astro-ph.HE↗

arXiv2007

Search for a Dark Matter annihilation signal from the Sagittarius dwarf galaxy with H.E.S.S

Dwarf Spheroidal galaxies are amongst the best targets to search for a Dark Matter annihilation signal. The annihilation of WIMPs in the center of Sagittarius dwarf spheroidal (Sgr dSph) galaxy would produce high energy gamma-rays in the final state. Observations carried out with the H.E.S.S. array of Imaging Atmospheric Cherenkov telescopes are presented. A careful modelling of the Dark Matter halo profile of Sgr dwarf was performed using latest measurements on its structural parameters. Constraints on the velocity-weighted cross section of Dark Matter particles are derived in the framework of Supersymmetric and Kaluza-Klein models.

astro-ph↗