An international collaboration led by a team from the Astrophysics Department/AIM Laboratory of IRFU has predicted and characterised the expected signature of internal magnetic fields in stars through their seismology - called asteroseismology. This study demonstrates that thanks to the very precise data from the Kepler (NASA), TESS (NASA) and soon PLATO (ESA) satellites, we are potentially able to detect magnetic fields in the cores of red giant stars (which are the descendants of low-mass stars such as our Sun and intermediate masses below ~8 solar masses). The results are published in two papers in the journal Astronomy & Astrophysics.
An international team including researchers from the Astrophysics Department (DAp) of CEA/Irfu, working in particular at the laboratory for the Dynamics of Stars, (Exo) planets and their Environment (LDE3), has been able to demonstrate that stars rotate faster than expected as they get older. Using asteroseismological techniques - the study of stars through the characterization of their oscillation modes by seismic methods - researchers were able to analyze for the first time a complete sample of 91 stars brooding ages 1 to 13 billion years. These data confirm that the oldest stars slow down their rotation less effectively. This discovery sheds new light on the evolution of star rotation and should make it possible to more accurately calculate the age of stars. These results are published in the journal Nature Astronomy on April 22, 2021.
The search for double beta decay without neutrino emission (0νββ) is one of the major challenges of contemporary physics, because its observation would make a clear statement about the nature of the neutrino itself and potentially on the origin of the matter/antimatter asymmetry of our universe. The CUPID collaboration, in which several researchers from IRFU and IN2P3 are involved, is actively researching this process using scintillating bolometers as detectors. In June 2020, the CUPID-Mo demonstrator experiment, which is located at the Modane underground laboratory, demonstrated the excellent potential of this detection method with only 2.264 kg of 100Mo and one year of data collection. In the coming years, the objective of the CUPID collaboration is to design one of the most sensitive experiments ever built by increasing the total mass of 100Mo to 250 kg. Three articles have just been published on the technological and methodological choices needed for this change of scale, while maintaining the required performances of the final experiment.
The ancients understood that heroes, like Orion with Sirius, need their faithful companion. IRFU engineers and physicists and their collaborators are no exception to the rule and have just completed the development of a modern Sirius, a key element of the super spectrometer separator (S3) under construction at GANIL. The tests having been successful and the system has been moved to GANIL for its final installation.
In Greek mythology, Sirius, Orion's faithful four-legged companion, an outstanding hunter, was transformed into a constellation and placed at his side. This famous canid also gave its name to the brightest star in the night sky. IRFU physicists have just honoured him in their own way, this time in the world of detectors.
The 2021 MERAC Prize for the Best Early Career Researcher in Theoretical Astrophysics is awarded to Dr Antoine Strugarek (CEA Saclay, France) for ground- breaking contributions in stellar astrophysics, including dynamo theory, predictions of solar flares and pioneering work on star-exoplanet interactions. The prize from the MERAC foundation (Mobilization for European Research in Astrophysics and Cosmology) is awarded each year by the European Society of Astronomy (ESA).
An X-ray camera, intended to equip the Sino-French SVOM satellite, has just been assembled and delivered by scientists and technicians from the Institute for Research on the Fundamental Laws of the Universe (CEA/Irfu). This high-tech prototype will capture high-energy photons (X-rays) emitted during the explosion of massive stars or the fusion of dense stars. The camera, particularly compact and innovative, integrates in a very limited volume, a complete detection chain, an active thermal control and a filter wheel. It will be placed at the focus of a telescope 1.15 m long to form the MXT (Microchannel X-ray Telescope). With a field of view of 1 square degree, for only 35 kg of mass, the MXT telescope, equipped with an original "faceted" optics inspired by lobster eyes, will make it possible to locate the position of the most powerful cosmic explosions in the Universe with a precision better than 2 arcmin. After various tests, including a calibration campaign in Germany, the assembly will be shipped to China in November 2021 to be integrated into the SVOM satellite, which is scheduled for launch at the end of 2022.
The muon spectrometer of the ATLAS experiment has been an important contribution of IRFU since the design, and IRFU is still in charge of the alignment today. The spectrometer plays a key role in the reconstruction of high-energy muons, the detection of which is crucial for the search of phenomena beyond the Standard Model. The spectrometer consists of about 1200 muon chambers that form a gigantic edifice 44 m long and 24 m in diameter. Despite these imposing proportions, the relative positions of the chambers must be known with an accuracy of the order of 50 μm in order to achieve the optimum performance of the spectrometer. To this end, a network of optical lines is used to continuously monitor the positions of the chambers relative to each other, as well as their deformations. An elaborate procedure for reconstructing the 56,000 parameters determining the alignment (for the central part) has been developed by a team at IRFU in order to obtain the precision required for the reconstruction of high-energy muons. This method, adopted by the ATLAS collaboration, is presented for the first time in an ATLAS note.
The high luminosity phase of the LHC (HL-LHC) should enable the collection of a dataset unprecedented in the history of particle physics. In order to record these data, the Atlas detector will undergo a major upgrade. IRFU, via the Paris-Cluster in synergy with two other laboratories in Ile de France, is committed to the construction of a part of the internal tracker. The year 2021 is brilliantly starting for the Paris-Cluster, which has just passed an important milestone in this endeavour: the first phase of the assembly and testing processes developed by our teams has been validated by the Atlas collaboration.
Nearly 200 researchers were involved in collecting, processing and assembling images of half the sky to prepare for the start of observations by DESI, the Dark Energy Spectroscopic Instrument, which aims to solve the mystery of dark energy.
In order for DESI to begin its 5-year mission (2021-2026) to produce the largest 3D sky map ever made, researchers first needed a gigantic 2D map of the Universe. Based on 200,000 images from 1405 nights of observations on three telescopes and several years of satellite data, this 2D map is the largest ever produced, based on the area of sky covered, the depth of the imagery and the more than one billion images of galaxies it contains.
Imaging planets that could potentially sustain life around nearby stars has become a possibility thanks to advances reported by an international team of astronomers in the journal Nature Communications. Using a newly developed system for mid-infrared exoplanet imaging in combination with a very long observation time, they achieved the capability of directly imaging planets about three times the size of Earth within the habitable zones of nearby stars. This experiment, called NEAR (Near Earths in the AlphaCen Region), was performed using VISIR, a mid-infrared instrument built by the Astrophysical Department of CEA-IRFU. The VISIR camera has been adapted to a 8m large telescope VLT UT4 (Yepun) in Chile, with a specific star-light blocking device and a a built-in adaptive optics sytems to correct for the atmospheric turbulence. A potential Neptune-to Saturn-sized planet orbiting Alpha Centauri may have been pinpointed but still requires further confirmation.
See the video : Breakthrough Watch/NEAR
Since the interferometers of the LIGO-Virgo collaboration detected gravitational waves from the merging of two black holes, black hole binaries have been among the celestial objects that most interrogate scientists. A team of astronomers, including researchers from the Astrophysics Department / AIM Laboratory of CEA Paris-Saclay and the APC laboratory (University of Paris), have determined, using more than 60,000 digital simulations of stellar evolution, the characteristics of the progenitors at the origin of mergers of black hole binaries of mass less than 10 solar masses. According to this study, a phase in the evolution of the binary system known as the common envelope phase plays an essential role in the process eventually leading, or not, to the merger of the two black holes. This work is presented in an article to appear in the journal Astronomy & Astrophysics.