Car* Tutt*

ieri pomeriggio, 17 novembre, ci siamo sentiti con molti di voi per continuare la discussione iniziata il giorno prima sui temi del PRIN CTA/SKA di prossima (?) uscita. Invio pero' questa pseudo-minuta (vedi sotto) anche a molte persone che non c'erano ma so essere interessate.  

Erano presenti:

Covino, Amati, Brocato, Piro, Pastorello, Benetti, Tomasella, Ghirlanda, Campana,
Tavecchio, Vercellone, Donnarumma, Casella, Panessa, Possenti, Romano, Masetti, Pian

Durante la telecon abbiamo discusso idee, temi (iniziando da quelli che non avevano trovato spazio il giorno prima e cioe supernovae e transienti galattiche
di ogni tipo), strategie, approcci concettuali e metodologici. Piu o meno tutti sono intervenuti e tutti abbiamo cercato di definire quanto meglio possibile il fuoco della proposta e gli obiettivi. Molte classi di sorgenti sono emerse, ma forse la lista non e' completa e comunque non si e' parlato di tutto quello che si puo' fare con ogni singola classe, e siamo rimasti d'accordo che il prossimo passo e' infatti quello di definire veri e propri Working Groups che forniscano il contributo di ogni classe al quadro generale finale.  

Piuttosto che elencare qui la lunga serie di interventi che hanno avuto luogo e di disperdere cosi il senso della discussione, ho cercato di compendiare un po' il risultato in sezioni di sequenza logica (che scrivo in inglese perche' mi e' piu semplice e cosi serve anche come guida per quando poi si scrivera' il proposal vero e proprio) che riassumono l'essenza del dibattito e vanno un po' oltre il "constructive brain-storming" che abbiamo avuto, anche a beneficio di chi non c'era.  Fate girare i vostri commenti.
Grazie, a presto, elena


Generic title: Relativistic, explosive and aperiodic transient sources


Introduction: 
Variability on all scales is at the forefront of modern astrophysical research. The numerous wide-field surveys accomplished in the last 10 years at many wavelengths and with various cadences have given impulse to systematic MWL studies of a range of transient sources at galactic and extragalactic distances.  In this context, the 2 largest infrastructural facilities INAF has committed to fund and foster, CTA and SKA, will determine, starting in about a decade from now, a transformational progress.  Within the broad variety of transient sources, those powered by strong gravity and accretion pose the biggest challenge: extreme temperatures, densities, magnetic fields, and rotation can generate dramatic manifestations like thermal runaways, explosions, particles acceleration to moderate-to-ultra-relativistic regimes, and spacetime perturbation.  These in turn produce variable MWL and non-electromagnetic displays that represent our investigation tool.  With this proposal, we want to get prepared for the coming era, and thus set up strategies, observing programs and theoretical scenarios that we will use  when the new facilities will be available.


Scientific Objectives: 
We intend to explore quantitatively the variable sources of explosive nature and those of aperiodic behavior, namely "one-off" transients, or erratically alternating between quiescence (in which they are nearly undetected) and dramatic outbursts, with different time scales, depending on source type.  Moreover, we will investigate the substantial fraction of gamma-ray transients detected by Fermi and the current Cherenkov telescopes that are unidentified: while many of them presumably correspond to known types of sources, a number may be related to events that are now being characterized thanks to new  sophisticated instruments and techniques (fast radio bursts, EM counterparts of GWs), and some may still remain unclassified until the CTA era.  We will not be concerned in this proposal with blazar flares, that will be the subject of a separate proposal.  

Our effort aims at tackling some basic problems with the presently available information and to formulate a strategy for CTA and SKA.
An incomplete list of outstanding questions in high energy astrophysics and time domain astronomy appears to be:

* what are the conditions for the formation of relativistic shocks, that are responsible for particle acceleration in jets over an extremely wide range of 
central compact object (neutron star, stellar BH, SMBH)

* how does rotation of the inner engine influence jet formation and acceleration

* how does the formation and evolution of single or binary compact stars or binary SMBHs influence the close surrounding medium

* what is the precise interplay between accretion, ejection and  explosion (or outburst) in a variety of sources with and without a relativistic jet, or in a spherical or asymmetric geometry

* how does the information  carried by multi-messenger signals couple to EM
observations

* ENERGY CONVERSION AND EFFICIENCY


Methods:
SKA and CTA, together with sophisticated optical, NIR and X-ray facilities in the future, will cover the entire EM spectrum with large sensitivity and will thus grant access to the whole EM information with unprecedented depth for all sources under study.  In the meantime, several precursors (ASTRI for TeV energies, Meerkat, ASKAP for radio wavelengths) will come online that will allow a gradual transition to the quality step that will be generated by CTA and SKA.  We would like to prepare for these successive phases by identifying science cases and tailoring the approach to the specific physical problems.  The investigation will take place on both observational and theoretical fronts and will see the CTA and SKA communities work together at every step.  In most cases it will also involve international collaborators via direct exchange of data or expertise or via implementation of formal MoUs (e.g. GWs, FRBs).  The preparatory work we intend to accomplish on each designated transient class is detailed in the working packages listed below (TB filled with details by each group):

GWs (GRAWITA)
GRBs (Brera, IASFBO, IAPS...)
TDEs (Brera...)
core-collapse supernovae (Padova, IASFBO...)
supernovae Ia: very deep and unprecedented radio constraints or even detection?
UHE neutrino counterparts (IASFBO, Torino...)
FRBs (Cagliari, IASFBO, IRA...)
SFXTs (Brera....)
XRBs/microquasars (OA-Roma...)
transitional PSRs (Cagliari...)
novae (IASFBO, Padova, Napoli....)
galactic (NS, BH) transients (IASFBO, IAPS...)
magnetars/SGRs/AXPs? (IASFMI...)
unidentified gamma-ray transients (Torino, IASFBO...)


Expected Results:
Describe here the results we intend to achieve with the WPs. 
We will have at least 2 levels: 
1) a "mid-term" phase which will last about 2 years, i.e. until the end of this PRIN, when we will have to assess the results in each individual WP, define the limits of the research based on state-of-the-art instruments and theory, and estimate quantitatively the level of improvement we expect from CTA and SKA.
2) a "long-term" phase, during which we will work with the precursors data on the themes developed during the PRIN, put them in closer perspective toward CTA and SKA, and redress our progress estimates. This phase will end with the advent of CTA and SKA, when we will finally be able to work with those data.

In this section we may discuss also the archiving of big amounts of information that this preparatory work will require and the future archival needs for CTA and SKA and coordinated/simultaneous observations at other wavelengths.  We can also 
predict the implementation of some products like improved or new pipelines or 
routines, improved or new codes for data analysis and interpretation (model codes, simulations...).