Calendar

Speaker: Quentin Changeat (UCL)

Title: Atmospheric retrievals in the era of next generation telescopes.

Abstract: With the recent launch of the NASA/ESA/CSA-JWST telescope and the upcoming ESA-Ariel, we are now entering a new era of exoplanet characterisation. These next-generation telescopes will revolutionise our understanding of exoplanet atmospheres, but the analysis of their observations will be very challenging.

Prova tesi di Edoardo Alaimo (UNIPA), seminario in modalita` ibrida

Google meet: https://meet.google.com/sxz-cctp-tsc

Titolo: CHARACTERISATION AND MODELLING OF THE UV-VIS-IR TRANSMISSION OF MULTILAYER THIN FILM FILTERS FOR APPLICATIONS IN HIGH HIGH ENERGY ASTROPHYSICS
Abstract: TBD

Seminario in forma ibrida

Indirizzo Google meet: https://meet.google.com/sxz-cctp-tsc

Speaker: R. Giuffrida (UNIPA)
Titolo: The supernova remnant SN 1006 as a Galactic particle accelerator
Abstract:
The origin of cosmic-rays is an open issue of high-energy astrophysics. Supernova remnants are expected to be the main source of Galactic cosmic rays up to energies of about 3 PeV, provided that they transfer a significant fraction of their kinetic energy to the particles (∼ 10%). In particular, the loss of such a large fraction of energy is predicted to alter the shock dynamics by enhancing the shock compression ratio above the canonical value of 4 (shock modification). The bilateral supernova remnant SN 1006 is an ideal target to study shock modification because of its evolution in a fairly uniform environment. SN 1006 shows bright synchrotron X-ray emission from ultrarelativistic electrons accelerated at the shock front in its northeastern and southwestern limbs. If efficient hadron acceleration occurs in these regions, we should observe shock modification therein. We performed a spatially resolved spectral analysis of Chandra and XMM-Newton observations of SN 1006 by selecting narrow regions between the shock front and the contact discontinuity and measuring the density of the X-ray emitting plasma. Our results show an increase of the compression ratio from the characteristic value of 4, in thermal limb, up to ∼ 7 in nonthermal limbs, i.e. in regions where the ambient magnetic field is almost parallel to the shock velocity. We conclude that an efficient particle acceleration causes shock modification in quasi-parallel shocks in SN 1006. By comparing our results with state-of-the-art models, we find that SN 1006 is transferring a significant fraction of its kinetic energy to hadrons. The inferred values of compression ratios and cosmic ray slopes are consistent with those expected for modified shocks when the effects of the postcursor are included.