Calendar

Giu
9
gio
Seminario: Julien Gressot (Université de Neuchâtel, Switzerland)
Giu 9@15:00–16:30

SPEAKER: Julien Gressot, Doctorant FNS – Histoire des techniques et de l’innovation, Institut d’histoire
AFFILIATION: Université de Neuchâtel (Switzerland)
TITLE: The Photographic Zenith tube (PZT) of the Neuchâtel Observatory: Achievement of time determination or failure of innovation?
ABSTRACT: Throughout its existence, the Neuchâtel Observatory has sought to be at the forefront of astronomical time determination. In the mid-20th century, a technological innovation began to spread in observatories with PZTs (Photographic Zenith Tube). The Neuchâtel Observatory was one of the first to obtain this instrument, the purpose of which was to eliminate the human factor by automating the time determination and certain other instrumental errors. PZTs were presented as the most accurate instruments of their time, but their development was soon halted. In this paper, we will examine the technical evolution of PZTs, the reasons why they became the must-have instrument, and the explanations for their rapid abandonment.

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

Giu
14
mar
Riunione con IEMEST
Giu 14@16:00–18:30
Giu
20
lun
UCL-OAPa @ Aula
Giu 20@9:00–14:00
Giu
21
mar
Seminario: Quentin Changeat (UCL) ore 15
Giu 21@15:00–16:30

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.

In this presentation, state-of-the-art techniques, which were thoroughly tested to analyse exo-atmospheric data from HST and Spitzer, will be presented. We will also explore some of their limitations, as well as the challenges associated with their application to next-generation telescopes.
Giu
22
mer
UCL-OAPa
Giu 22@14:00–22:00
Lug
7
gio
Visita IEMEST
Lug 7@11:00–14:00

Ref. Laura Daricello

Lug
25
lun
Seminario: prova tesi Edoardo Alaimo (UNIPA)
Lug 25@15:00–16:30

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

Set
6
mar
Seminario: R. Giuffrida (UNIPA)
Set 6@15:00–16:30

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.

Set
7
mer
Telecon Sara, Loredana, Jesus, Paolo (remoto)
Set 7@11:30–12:30
Set
14
mer
Seminario: Vincenzo Sapienza (UNIPA)
Set 14@15:00–16:30

Seminario in forma ibrida

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

Speaker: Vincenzo Sapienza (UNIPA)

Titolo: A spatially resolved study of hard X-ray emission in Kepler’s SNR: indications of different regimes of particle acceleration

Abstract:
L’emissione di Sincrotrone nei raggi X proveniente da resti di supernova (SNR) giovani è un potente strumento diagnostico per studiare la popolazione di elettroni altamente energetici accelerati al fronte di shock oltre che per studiare il processo di accelerazione stesso.
In questo lavoro abbiamo eseguito un’analisi spettrale spazialmente risolta di osservazioni NuSTAR e XMM-Newton del giovane SNR di Keplero, con lo scopo di studiare in dettaglio la sua emissione non termica nei raggi X duri.
Gli spettri sono stato analizzati adottando un modello di radiazione di sincrotrone in un regime in cui l’energia massima degli elettroni è limitata dalle perdite radiative, in modo da vincolare la dipendenza dell’energia di cutoff del sincrotrone dalla velocità del fronte di shock.
Abbiamo identificato due diversi regimi di accelerazione di particelle.
A nord, dove lo shock sta interagendo con un mezzo circumstellare denso, abbiamo trovato una accelerazione più efficiente che a sud, dove la velocità del fronte di shock è più alta e non ci sono segni di interazione tra shock e un mezzo circumstellare denso.
I nostri risultati suggeriscono un’efficienza maggiore in regioni dove l’interazione tra shock e mezzo circumstellare genera un campo magnetico turbolento ed amplificato.
Combinando lo spettro nei raggi X duri con osservazioni radio e gamma del SNR di Keplero, abbiamo modellato la distribuzione dell’energia spettrale (SED). Alla luce dei nostri risultati proponiamo che l’emissione gamma osservata sia principalmente adronica (associata a protoni ultrarelativistici), e che origini dalla parte nord del resto.