arXiv subjects

Florent Robinet

Publications and source records attributed to Florent Robinet.

9 recordsLinked to original sources

arXiv2026

The IRT Telescope on board the THESEUS mission

We present the Infra-Red Telescope (IRT), which is part of the payload of the THESEUS mission, one on the three phase A candidate missions for the M7 slot of ESA (launch date 2037). The IRT is a 0.7 m class telescope with an off-axis Korsch optical design, with imaging capabilities in the 0.7-1.8 microns range over a 15 x 15 arc min field of view. The IRT also provides slit-less low resolution spectroscopy (R~400) over a limited field of view of 2 x 2 arc min, in the 0.8-1.6 microns range. The goal of the IRT is to identify the near infrared counterparts to the Gamma-Ray Bursts (GRBs) detected by the two other telescopes on board THESEUS (the XGIS and the SXI), and to measure on board its photometric redshift in near real-time. The position and the redshift will be transmitted immediately to ground to allow for deeper follow-up by the large telescopes (ELT, VLT, ...). If the source is bright enough, spectroscopy will be performed to characterize the GRB environment.

astro-ph.IM↗

arXiv2022

Analysis methods to localize and characterize X-ray sources with the Micro-channel X-ray Telescope on board the SVOM satellite

SVOM is a Sino-French space mission targeting high-energy transient astrophysical objects such as gamma-ray bursts. The soft X-ray part of the spectrum is covered by the Micro-channel X-ray Telescope (MXT) which is a narrow field telescope designed to precisely localize X-ray sources. This paper presents the method implemented on-board to characterize and localize X-ray sources with the MXT. A specific localization method was developed to accommodate the optical system of the MXT, which is based on "Lobster-Eye" grazing incidence micro-pore optics. For the first time, the algorithm takes advantage of cross-correlation techniques to achieve a localization accuracy down to 2 arcmin with less than 200 photons, which guarantees a rapid follow-up for most of the gamma-ray bursts that SVOM will observe. In this paper, we also study the limitations of the algorithm and characterize its performance.

astro-ph.HE↗

arXiv2020

DQSEGDB: A time-interval database for storing gravitational wave observatory metadata

The Data Quality Segment Database (DQSEGDB) software is a database service, backend API, frontend graphical web interface, and client package used by the Laser Interferometer Gravitational-Wave Observatory (LIGO), Virgo, GEO600 and the Kamioka Gravitational wave detector for storing and accessing metadata describing the status of their detectors. The DQSEGDB has been used in the analysis of all published detections of gravitational waves in the advanced detector era. The DQSEGDB currently stores roughly 600 million metadata entries and responds to roughly 600,000 queries per day with an average response time of 0.223 ms.

astro-ph.IM↗

arXiv2020

Omicron: a tool to characterize transient noise in gravitational-wave detectors

The Omicron software is a tool developed to perform a multi-resolution time-frequency analysis of data from gravitational-wave detectors: the LIGO, Virgo, and KAGRA detectors. Omicron generates spectrograms from whitened data streams, offering a visual representation of transient detector noises and gravitational-wave events. In addition, these events can be parameterized with an optimized resolution. They can be written to disk to conduct offline noise characterization and gravitational-wave event validation studies. Omicron is optimized to process, in parallel, thousands of data streams recorded by gravitational-wave detectors. The Omicron software plays an important role in vetting gravitational-wave detection candidates and characterization of transient noise.

astro-ph.IM↗

arXiv2017

An information-theoretic approach to the gravitational-wave burst detection problem

The observational era of gravitational-wave astronomy began in the Fall of 2015 with the detection of GW150914. One potential type of detectable gravitational wave is short-duration gravitational-wave bursts, whose waveforms can be difficult to predict. We present the framework for a new detection algorithm for such burst events -- \textit{oLIB} -- that can be used in low-latency to identify gravitational-wave transients independently of other search algorithms. This algorithm consists of 1) an excess-power event generator based on the Q-transform -- \textit{Omicron} --, 2) coincidence of these events across a detector network, and 3) an analysis of the coincident events using a Markov chain Monte Carlo Bayesian evidence calculator -- \textit{LALInferenceBurst}. These steps compress the full data streams into a set of Bayes factors for each event; through this process, we use elements from information theory to minimize the amount of information regarding the signal-versus-noise hypothesis that is lost. We optimally extract this information using a likelihood-ratio test to estimate a detection significance for each event. Using representative archival LIGO data, we show that the algorithm can detect gravitational-wave burst events of astrophysical strength in realistic instrumental noise across different burst waveform morphologies. We also demonstrate that the combination of Bayes factors by means of a likelihood-ratio test can improve the detection efficiency of a gravitational-wave burst search. Finally, we show that oLIB's performance is robust against the choice of gravitational-wave populations used to model the likelihood-ratio test likelihoods.

gr-qc↗

arXiv2017

Searches for continuous gravitational waves from Scorpius X-1 and XTE J1751-305 in LIGO's sixth science run

Scorpius X-1 (Sco X-1) and X-ray transient (XTE) J1751-305 are Low-Mass X-ray Binaries (LMXBs) that may emit continuous gravitational waves detectable in the band of ground-based interferometric observatories. Neutron stars in LMXBs could reach a torque-balance steady-state equilibrium in which angular momentum addition from infalling matter from the binary companion is balanced by angular momentum loss, conceivably due to gravitational-wave emission. Torque-balance predicts a scale for detectable gravitational-wave strain based on observed X-ray flux. This paper describes a search for Sco X-1 and XTE J1751-305 in LIGO Science Run 6 data using the TwoSpect algorithm, based on searching for orbital modulations in the frequency domain. While no detections are claimed, upper limits on continuous gravitational-wave emission from Sco X-1 are obtained, spanning gravitational-wave frequencies from 40 to 2040 Hz and projected semi-major axes from 0.90 to 1.98 light-seconds. These upper limits are injection validated, equal any previous set in initial LIGO data, and extend over a broader parameter range. At optimal strain sensitivity, achieved at 165 Hz, the 95% confidence level random-polarization upper limit on dimensionless strain $h_0$ is approximately $1.8 \times 10^{-24}$. Closest approach to the torque-balance limit, within a factor of 27, is also at 165 Hz. These are the first upper limits known to date on $r$-mode emission from this XTE source. Upper limits are set in particular narrow frequency bands of interest for J1751-305. The TwoSpect method will be used in upcoming searches of Advanced LIGO and Virgo data.

gr-qc↗

arXiv2016

Globally coherent short duration magnetic field transients and their effect on ground based gravitational-wave detectors

It has been recognized that the magnetic fields from the Schumann resonances could affect the search for a stochastic gravitational-wave background by LIGO and Virgo. Presented here are the observations of short duration magnetic field transients that are coincident in the magnetometers at the LIGO and Virgo sites. Data from low-noise magnetometers in Poland and Colorado, USA, are also used and show short duration magnetic transients of global extent. We measure at least 2.3 coincident (between Poland and Colorado) magnetic transient events per day where one of the pulses exceeds 200 pT. Given the recently measured values of the magnetic coupling to differential arm motion for Advanced LIGO, there would be a few events per day that would appear simultaneously at the gravitational-wave detector sites and could move the test masses of order $10^{-18}$ m. We confirm that in the advanced detector era short duration transient gravitational-wave searches must account for correlated magnetic field noise in the global detector network.

astro-ph.IM↗

arXiv2015

Improved constraint on the primordial gravitational-wave density using recent cosmological data and its impact on cosmic string models

The production of a primordial stochastic gravitational-wave background by processes occuring in the early Universe is expected in a broad range of models. Observing this background would open a unique window onto the Universe's evolutionary history. Probes like the Cosmic Microwave Background (CMB) or the Baryon Acoustic Oscillations (BAO) can be used to set upper limits on the stochastic gravitational-wave background energy density $Ω_{GW}$ for frequencies above $10^{-15}$ Hz. We perform a profile likelihood analysis of the Planck CMB temperature anisotropies and gravitational lensing data combined with WMAP low-$\ell$ polarization, BAO, South Pole Telescope and Atacama Cosmology Telescope data. We find that $Ω_{GW}h_{0}^{2} < 3.8 \times 10^{-6}$ at 95\% confidence level for adiabatic initial conditions which improves over the previous limit by a factor 2.3. Assuming that the primordial gravitational waves have been produced by a network of cosmic strings, we have derived exclusion limits in the cosmic string parameter space. If the size of the loops is determined by gravitational back-reaction, string tension values greater than $\sim 4 \times 10^{-9}$ are excluded for a reconnection probability of $10^{-3}$.

astro-ph.CO↗

arXiv2009

On the background estimation by time slides in a network of gravitational wave detectors

Time shifting the outputs of Gravitational Wave detectors operating in coincidence is a convenient way to estimate the background in a search for short duration signals. However this procedure is limited as increasing indefinitely the number of time shifts does not provide better estimates. We show that the false alarm rate estimation error saturates with the number of time shifts. In particular, for detectors with very different trigger rates this error saturates at a large value. Explicit computations are done for 2 detectors, and for 3 detectors where the detection statistic relies on the logical ``OR'' of the coincidences of the 3 couples in the network.

gr-qc↗