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Science/Instrument (DAp)

INTEGRAL : 20 ans dans l'espace pour une aventure de plus de 35 ans

Philippe LAURENT, Aymeric SAUVAGEON et Jérôme RODRIGUEZ

Abstract: The INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) has been launch on October 17th, 2002 from Baikonour (Kasakstan). Since then it has remained on its high-eccentricity elliptical orbit (about 3 days) performing 2568 revolutions (as of Nov. 8th, 2022) around the Earth for around 530 megaseconds of scientific observations. This medium sized mission caries two main instruments operating in the spectral domain of hard X-rays/Soft Gamma-rays (20keV-10 MeV), whose optics is based on the concept of coded masks: one is dedicated to fine spectral analysis with moderate imaging capabilities (SPI) the other is dedicated to fine(-ish) imaging with moderate spectral capabilities (IBIS). These 20 years in space are the results of at least 15 years of project development before INTEGRAL could unveil the mystery of the high-energy sky.

The DAp has been deeply involved in this long-term adventure from the very beginning of the mission concept development (large involvement in both instruments, ISGRI and SPI, participation to the data centre, development of the s/w analysis, monitoring of the camera) to the current analysis of real time and archival data, with a large number of published papers in all fields allowed by the instrumental capabilities and even beyond.

We will, in this seminary, summarised these 35 years+ by presenting various aspects of the project/mission, focusing especially on those where the involvement of the DAp has been crucial. This will start with an overall overview of the mission history, the main instrumental characteristics and scientific goals at launch, followed by a focus on the ISGRI camera, the 20-250 keV detector layer of the IBIS telescope, which is followed-up at DAp every days. ISGRI has been developed at IRFU and obtained most of the INTEGRAL results. We will conclude with a quick and obviously biased overview of some scientific results obtained over these 20 years.

The talks will be given by Philippe Laurent, Aymeric Sauvageon, and Jérôme Rodriguez humbly on behalf of many, many former and current colleagues and presented in French with slides in English.

Anaëlle Maury (DAp)

Magnetic fields from star-forming cores to protostellar disks : a review of major contributions from the MagneticYSOs project

Abstract: Wherever we have the means of observing them, magnetic fields are detected across the full spectrum of astrophysical environments, from our own Earth, to stars, and cosmological structures. Magnetic fields are also present at all scales and evolutionary stages of star-forming structures. They have long been suspected to play a key role in shaping the typical outcome of the star formation process, such as stellar mass, spin, and multiplicity, or even the fate of stars towards their ultimate stages.

In this talk, I will provide a global outlook on the progresses made in the recent years to characterize the role of magnetic fields during the embedded phases of the star formation process.

Thanks to the development of observational capabilities and the parallel progress in numerical models capturing most of the important physics at work during star formation, the MagneticYSOs team successfully confronted detailed predictions of magnetized models to observational properties of the youngest protostars.

I will present the physical processes and observational methods allowing to trace the magnetic field in embedded protostars, and review the main steps, success and limitations in comparing real observations to synthetic observations from the non-ideal MHD models.

I will show how our work has shed light on the physical conditions required to ensure an efficient magnetic field coupling, and present unexpected results regarding the two main agents responsible for the coupling in star-forming cores: dust grains and ionized gas.

Following this Ariane thread, I will argue our observational and theoretical findings support a novel scenario where the angular momentum problem for star formation may be actually “solved” not by the formation of large protoplanetary disks but by the combination of 1) lack of organized rotation motions at large envelope radii, 2) the inefficient angular momentum transport due to magnetic braking in the inner envelope (and angular momentum removed through rotating outflows generated by the presence of the magnetic field), and 3) a local origin of the angular momentum incorporated in the star–disk system.

Antonio Garcia Muñoz (DAp)

Exoplanet atmospheres : An anticipated revolution

Abstract: The launch of the JWST less than a year ago is expected to set a turning point in exoplanet science, which is progressively transitioning from detection and population statistics to in-detail characterization of the exoplanets' atmospheres. In this talk, I will present an admittedly biased perspective of what this may represent for our understanding of exoplanets, and how ongoing theoretical work and future telescopes may build upon JWST's legacy.