GPU-accelerated LISA parameter estimation with full time domain response

International audienceWe conduct the first full Bayesian inference analysis for LISA parameter estimation incorporating the effects of subdominant harmonics and spin-precession through a full time domain response. The substantial computational demands of using time domain waveforms for LISA are significantly mitigated by implementing a novel Python version of the IMRPhenomT family of waveform models and the LISA response with GPU acceleration. This time domain response alleviates the theoretical necessity of developing specific transfer functions to approximate the LISA response in the Fourier domain for each specific type of system and allows for the use of unequal arms configurations and realistic LISA orbits. Our analysis includes a series of zero-noise injections for a Massive Black Hole Binary with aligned and precessing spins. We investigate the impact of including subdominant harmonics, compare equal and unequal arm configurations, and analyze different Time-Delay-Interferometry (TDI) configurations. We utilize full and uniform priors, with a lower frequency cutoff of 0.1mHz, and a signal duration of approximately two months, sampled every 5 seconds. The sampler is initialized based on Fisher estimates. Our results demonstrate LISA capability to measure the two spin magnitudes and the primary spin tilt angle, alongside sky localization, with percent-level precision, while component masses are determined with sub-percent accuracy

The LOFAR Two-metre Sky Survey: Deep Fields Data Release 2. I. The ELAIS-N1 field

International audienceWe present the final 6'' resolution data release of the ELAIS-N1 field from the LOw-Frequency ARray (LOFAR) Two-metre Sky Survey Deep Fields project (LoTSS Deep). The 144MHz images are the most sensitive achieved to date at this frequency and were created from 290 TB of data obtained from 505 hrs on-source observations taken over 7.5 years. The data were processed following the strategies developed for previous LoTSS and LoTSS Deep data releases. The resulting images span 24.53 square degrees and, using a refined source detection approach, we identified 154,952 radio sources formed from 182,184 Gaussian components within this area. The maps reach a noise level of 10.7 $\mu$Jy/beam at 6'' resolution where approximately half of the noise is due to source confusion. In about 7.4% of the image our limited dynamic range around bright sources results in a further > 5% increase in the noise. The images have a flux density scale accuracy of about 9% and the standard deviation of offsets between our source positions and those from Pan-STARRS is 0.2'' in RA and Dec for high significance detections. We searched individual epoch images for variable sources, identifying 39 objects with considerable variation. We also searched for circularly polarised sources achieving three detections of previously known emitters (two stars and one pulsar) whilst constraining the typical polarisation fraction plus leakage to be less than 0.045%

Wandering and escaping: Recoiling massive black holes in cosmological simulations

International audienceAfter a merger of two massive black holes (MBHs), the remnant receives a gravitational wave (GW) recoil kick that can have a strong effect on its future evolution. The magnitude of the kick (vrecoil) depends on the mass ratio and the alignment of the spins and orbital angular momenta, and therefore on the previous evolution of the MBHs. We investigate the cosmic effect of GW recoil by running for the first time a high-resolution cosmological simulation including on-the-fly GW recoil that depends on the MBH spins (evolved through accretion and mergers), masses and dynamics which are also all evolved directly in the simulation. We also run a twin simulation without GW recoil. The simulations are zoom-in type of simulations run down to z = 4.4. We find that GW recoil reduces the growth of merger remnants, and can have a significant effect on the MBH-galaxy correlations and the merger rate. We find large recoil kicks across all galaxy masses in the simulation, up to a few 1011 M⊙. The effect of recoil can be significant even if the MBHs are embedded in a rotationally supported gaseous structure. We investigate the dynamics of recoiling MBHs and find that MBHs remain in the centre of the host galaxy for low vrecoil/vesc and escape rapidly for high vrecoil/vesc. Only if vrecoil is comparable to vesc the MBHs escape the central region of the galaxy but might remain as wandering MBHs until the end of the simulation. Recoiling MBHs are a significant fraction of the wandering MBH population. Although the dynamics of recoiling MBHs can be complex, some retain their initial radial orbits but are difficult to discern from other wandering MBHs on radial orbits. Others scatter with the halo substructure or circularise in the asymmetric potential. Our work highlights the importance of including GW recoil in cosmological simulation models

Pre-flight performance of the ion energy mass spectrum analyzer for the Martian Moons eXploration (MMX) mission

International audienceAbstract An ion energy mass spectrum analyzer was developed for the Martian Moons eXploration (MMX) mission to measure the three-dimensional velocity distribution function and mass profile of low-energy ions around the Mars-Moon system. The hemispheric field-of-view (FOV) is acquired by a pair of angular scanning deflectors, and the energy/charge and mass/charge are determined for each ion by an electrostatic analyzer and a linear-electric-field (LEF) time-of-flight (TOF) analyzer, respectively, with an enhanced mass resolution of $$m/\Delta m\sim 100$$ m / Δ m ∼ 100 . The ion analyzer, together with magnetometers, constitutes the mass spectrum analyzer (MSA), one of the scientific instruments on board the MMX spacecraft. This paper describes the instrumentation of the ion analyzer, and results of the performance tests of its flight model (FM)

Milestone in predicting core plasma turbulence: successful multi-channel validation of the gyrokinetic code GENE

International audienceAbstract On the basis of several recent breakthroughs in fusion research, many activities have been launched around the world to develop fusion power plants on the fastest possible time scale. In this context, high-fidelity simulations of the plasma behavior on large supercomputers provide one of the main pathways to accelerating progress by guiding crucial design decisions. When it comes to determining the energy confinement time of a magnetic confinement fusion device, which is a key quantity of interest, gyrokinetic turbulence simulations are considered the approach of choice – but the question, whether they are really able to reliably predict the plasma behavior is still open. The present study addresses this important issue by means of careful comparisons between state-of-the-art gyrokinetic turbulence simulations with the GENE code and experimental observations in the ASDEX Upgrade tokamak for an unprecedented number of simultaneous plasma observables

A new classification of ex-situ and in-situ Galactic globular clusters based on a method trained on Milky Way analogues in the TNG50 cosmological simulations

International audienceWe present a novel method combining existing cosmological simulations and orbital integration to study the hierarchical assembly of globular cluster (GC) populations in the Milky Way (MW). Our method models the growth and evolution of GC populations across various galactic environments as well as the dynamical friction and mass loss experienced by these objects. This allows us to track the trajectory of about 18,000 GCs over cosmic time in 198 MW-like galaxies from TNG50. This cosmological-scale tracking of the dynamics of in-situ and ex-situ GC populations with such a large statistical sample allows us to confirm the presence of an overlap between the two populations in MW-like galaxies, occurring below an energy threshold of $E 0.7 E_{\rm circ}(r_{\rm hm}^{*})$, and that the real challenge lies in distinguishing the two populations below this energy threshold. In this context, we provide new predictions regarding the origins of the MW GCs observed with Gaia, as well as a comparison with existing literature. Additionally, we highlight that even if ex-situ clusters share a common origin, they inevitably lose their dynamical coherence in the $E$-$L_{z}$ space within MW-like galaxies. We observe a dispersion of GC groups as a function of $E$ and $L_{z}$, primarily driven by the evolution of the galactic potential over time and by dynamical friction, respectively

First Searches for Dark Matter with the KM3NeT Neutrino Telescopes

International audienceIndirect dark matter detection methods are used to observe the products of dark matter annihilations or decays originating from astrophysical objects where large amounts of dark matter are thought to accumulate. With neutrino telescopes, an excess of neutrinos is searched for in nearby dark matter reservoirs, such as the Sun and the Galactic Centre, which could potentially produce a sizeable flux of Standard Model particles. The KM3NeT infrastructure, currently under construction, comprises the ARCA and ORCA undersea Čerenkov neutrino detectors located at two different sites in the Mediterranean Sea, offshore of Italy and France, respectively. The two detector configurations are optimised for the detection of neutrinos of different energies, enabling the search for dark matter particles with masses ranging from a few GeV/c$^2$ to hundreds of TeV/c$^2$. In this work, searches for dark matter annihilations in the Galactic Centre and the Sun with data samples taken with the first configurations of both detectors are presented. No significant excess over the expected background was found in either of the two analyses. Limits on the velocity-averaged self-annihilation cross section of dark matter particles are computed for five different primary annihilation channels in the Galactic Centre. For the Sun, limits on the spin-dependent and spin-independent scattering cross sections of dark matter with nucleons are given for three annihilation channels

Dark matter fraction derived from the M31 rotation curve

International audienceMass estimates of a spiral galaxy derived from its rotation curve must account for the galaxy's past accretion history. There are several lines of evidence indicating that M31 experienced a major merger 2 to 3 Gyr ago. Here, we have generated a dynamical model of M31 as a merger remnant that reproduces most of its properties, from the central bar to the outskirts. The model accounts for the past major merger, and reproduces the details of M31's rotation curve, including its 14 kpc bump and the observed increase of velocity beyond 25 kpc. Furthermore, we find non-equilibrium and oscillatory motions in the gas of the merger-remnant outskirts caused by material in a tidal tail returning to the merger remnant. A total dynamical M31 mass of 4.5 $\times 10^{11} M_{\odot}$ within 137 kpc has been obtained after scaling it to the observed HI rotation curve. Within this radial distance, 68% of the total dynamical mass is dark

Magnetosphere and Plasma Science with the Jupiter Icy Moons Explorer

International audienceThe Jupiter Icy Moons Explorer ( JUICE ) is a European Space Agency mission to explore Jupiter and its three icy Galilean moons: Europa, Ganymede, and Callisto. Numerous JUICE investigations concern the magnetised space environments containing low-density populations of charged particles that surround each of these bodies. In the case of both Jupiter and Ganymede, the magnetic field generated internally produces a surrounding volume of space known as a magnetosphere. All these regions are natural laboratories where we can test and further our understanding of how such systems work, and improved knowledge of the environments around the moons of interest is important for probing sub-surface oceans that may be habitable. Here we review the magnetosphere and plasma science that will be enabled by JUICE from arrival at Jupiter in July 2031. We focus on the specific topics where the mission will push forward the boundaries of our understanding through a combination of the spacecraft trajectory through the system and the measurements that will be made by its suite of scientific instruments. Advances during the initial orbits around Jupiter will include construction of a comprehensive picture of the poorly understood region of Jupiter’s magnetosphere where rigid plasma rotation with the planet breaks down, and new perspectives on how Jupiter’s magnetosphere interacts with both Europa and Callisto. The later orbits around Ganymede will dramatically improve knowledge of this moon’s smaller magnetosphere embedded within the larger magnetosphere of Jupiter. We conclude by outlining the high-level operational strategy that will support this broad science return

The Ganymede Laser Altimeter (GALA) on the Jupiter Icy moons Explorer (JUICE) Mission

International audienceThe Ganymede Laser Altimeter (GALA) on the Jupiter Icy Moons Explorer (JUICE) mission, is in charge of a comprehensive geodetic mapping of Europa, Ganymede, and Callisto on the basis of Laser range measurements. While multiple topographic profiles will be obtained for Europa and Callisto during flybys, GALA will provide a high-resolution global shape model of Ganymede while in orbit around this moon based on at least 600 million range measurements from altitudes of 500 km and 200 km above the surface. By measuring the diurnal tidal deformation of Ganymede, which crucially depends on the decoupling of the outer ice shell from the deeper interior by a liquid water ocean, GALA will obtain evidence for (or against) a subsurface ocean on Ganymede and will provide constraints on the ice shell thickness above the ocean. In combination with other instruments, it will characterize the morphology of surface units on Ganymede, Europa, and Callisto providing not only topography but also measurements of surface roughness on the scale of the laser footprint, i.e. at a scale of about 50 m from 500 km altitude, and albedo values at the laser wavelength of 1064 nm. GALA is a single-beam laser altimeter, operating at a nominal frequency of 30 Hz, with a capability of reaching up to 48 Hz. It uses a Nd:YAG laser to generate pulses with pulse lengths of 5.5 ± 2.5 ns. The return pulse is detected by an Avalanche Photo Diode (APD) with 100 MHz bandwidth and the signal is digitized at a sampling rate of 200 MHz providing range measurements with a sub-sample resolution of 0.1 m. Research institutes and industrial partners from Germany, Japan, Switzerland and Spain collaborated to build the instrument. JUICE, conducted under responsibility of the European Space Agency (ESA), was successfully launched in April 2023 and is scheduled for arrival at the Jupiter system in July 2031. The nominal science mission including multiple close flybys at Europa, Ganymede, and Callisto, as well as the final Ganymede orbit phase will last from 2031 to 2035. In May 2023 GALA has completed its Near-Earth Commissioning, showing full functionality of all units. Here we summarize the scientific objectives, instrument design and implementation, performance, and operational aspects of GALA