 Hello everyone. So first let me thank the organizers of this webinar series for their invitation. In this talk, I will first present some space mission and especially focus on its core program which is devoted to gamma robust. And then I will try to discuss possible interesting synergies with the Cherenkov telescope array observatory. So I will start with a very brief introduction to gamma robust. So gamma robust appear in two main classes, according to their duration, short gamma reverse of the duration of typically 0.1 seconds and long gamma reverse several times or hundreds of seconds and probably the same physics at work with two different classes of progenitors. And observation shows that there are two main episodes of emission, the prompt gamma reverse, which is a short lived and is observed mainly in sub gamma rays, but thanks to Fermilat we know that there is high energy mission, and there are also a few cases of prompt detection in optical with robotic telescopes. And then multi wavelengths afterglow which is a fastly decaying and shows a complex temporal behavior with also some led variability and change of temporal slopes. This afterglow is observed from radio to x-rays, very commonly. And again Fermilat has shown that there is a high energy mission with a so called long lasting emission in Fermilat and very recently as everyone knows there were a few detection by S and magic. On the theoretical point of view, we know thanks to optical afterglow and the spectroscopy of the optical afterglows that can reverse occur in distant galaxies at cosmological distance. Meaning that they are extremely bright intrinsically and the combination of this huge radiated energy with a short time scale variability which is observed in the light curve. Associat gamma reverse to cataclysmic event leading to the formation of a stellar mass compact object, a black hole, or possibly a magnetar. And so a long gamma reverse are associated to the collapse of an assistar, some assistars, there are probably some diversity in the population, and short gamma reverse are very probably associated to a binary neutron star merger. There is one famous association. The gamma radiation cannot be produced by the source, the central engine itself, due because it's opaque. And so first the energy is injected in a relativistic jet by a mechanism which still needs to be clearly identified. And then at a certain radius, which is called the photosphere radius, the jet becomes transparent for its own radiation and the observed emission can be produced. So due to the high variability in the prompt light curve, we know that the gamma reverse itself must be produced by internal dissipation in the jet itself. There are several possible mechanisms. And then the afterglow is a signature of the deceleration of this jet by the ambient medium. So, now that I have tried to introduce very, very briefly this general context, I will move to the presentation of Zvom. So, Zvom is a Chinese French mission. I have listed here the laboratories which are involved. And I should mention that on the French side, we have also associate partners in Mexico for robotic telescope in the visible, and in UK and Germany for the X-ray on board Zvom. So, Zvom stands for space-based multiband astronomical variable objects monitor. It should be launched mid-2023 for a duration of five years plus possible extension. And it offers a very broad set of instruments. So first, there is a spacecraft with two wide field instruments, Eclare and GRM in gamma rays, and two narrow field instruments, MXT in X-rays and VT invisible. And there are some rapid slowing capabilities, especially in the context of gamma reverse to follow an alert and through the spacecraft to point the narrow field instruments. There is a VHF alert network which allows to transmit a sub-sample of data in near real time. And of course, we have selected the relevant data to be able to produce near real-time alerts following a gamma robust. And of course, then the full set of data is transmitted more regularly with another channel. And in addition to the spacecraft, we have also our own ground segment for a rapid follow up with several robotic telescopes of different sizes. I will show that in a few minutes. An important property of zoom is an early anti-solar pointing, which will optimize the rapid follow up of gamma robust, and especially the rapid follow up on ground in the visible or near infrared where of course you need to wait for the night. So the core program of zoom is devoted to gamma robust. It will represent typically 25% of the observing time of zoom alerts and follow up. But of course gamma reverse at the highest priority so the other observation program will be interrupted when we detect a gamma. And so the best to present the various instruments of the zone is to show what kind of gamma robust sample we expect to detect. So the idea is that it starts with a first instrument which is a eclair. It's a French coded mask telescope operating in soft gamma rays from four to 150 kb. And which is responsible for the trigger, the localization, and then the measurement in combination with another instrument of the light curve and spectrum of the prompt emission. So we have simulated many gamma reverse from current and past mission with eclair. So, for instance, on the plot on the right here, you have a plane with on the x axis, the direction of gamma robust, and on the y axis, the peak and the spectrum properties of the gamma reverse is it a soft event, a hard event. And we are simulated many, many events from the various catalogs that you can read here. And the color code is for the detection efficiency by eclair, assuming a random position in the field of view. And from that, we show that eclair is sensitive to all known classes of gamma robust, of course, classical long gamma robust, but also less known population of soft gamma robust, low luminosity gamma robust, extra rich gamma robust, extra flashes. And eclair is also sensitive to short gamma robust, but with the more moderate efficiencies due to the spectrum range of the instrument. And thanks to the field of view, which is about two steradian, we expect from 40 to 80 gamma reverse per year and of course there are large uncertainties due to the low energy threshold of eclair which will probe less known populations. So, the advantage of using a coded mass telescope is that we will be able immediately after the trigger to have a localization accuracy, better than 12 minutes. And it will be transmitted in every time thanks to our VHF network. This is a second gamma ray instrument called GRM, which is a Chinese instrument and which will extend the spectral range for the observation of the prompt emission to five MED, which is a good advantage because our purpose is really to build a sample of gamma robust, where we can correctly characterize all important aspects of the phenomenon the prompt emissions you have to go and of course measure the distance. So the GRM will help. And you see the comparison of the field of view of the three detectors at GRM with the eclair field of view on the on the on the on the right. And of course, the sub sample of gamma robust seen by the two instruments will of course be our best sample. GRM itself will also detect other gamma robust, which are outside the field of view of eclair, but then the localization is not so good it's a few degrees of this in the sky. And by combining eclair and GRM we can improve our sensitivity to short gamma robust, which is of course an important goal in the context of multi messenger. So, to finish with the prompt emission, we have also another Chinese instrument called GWAC, which operates in the visible with a very large field of view it's a set of robotic cameras, and it follows eclair field of view and then we expect to have either an upper limit or a detection of the prompt optical 10% of cases, and as this prompt that you can mission has not been explored so much. There are only a few cases of detection. It is, it's potentially very interesting to extend the spectral range where we cover as the prompt emission. I show here an example of spectrum that we have simulated, taking a family burst and simulating it in both in eclair and GRM, and we show that combining both instruments, we can really well recover the spectral, the spectral shape of the event. Even taking into account complex multi component spectra as as obtained in some bright GBM burst. So we will really be able to characterize correctly the prompt emission. So, then for the if is a signal is strong enough so that we are quite confident in the localization. There will be a few requests for the spacecraft. And then we can focus on this sample of camera burst where a clue will occur, because this will be the most interesting sample with afterglow observation. So typically, from, I mean, about 90% of the previous sample. So, the first narrow field instrument is an x ray telescope and x t, which results from a collaboration between France, UK and Germany. And we show that with the sensitivity of an x t, which is a little less than the sensitivity of XRT on both swift. On the other hand, with a large larger field of view covering very well. We will detect the extra afterglow in 90% of cases after the through, and then be able to provide a much better localization, typically less than 13 act second. So you can see here as an example of the simulation of a swift XRT afterglow in the mixed in continuity with the detection of the prompt emission by a clear and German. That is that with a low energy threshold of a clear, we could see the beginning of the afterglow in some cases. Then we have also on board Chinese telescope operating in the visible with two filters in which will allow also some early diagnostic about dust or irate shift. And then we have several ground based telescopes. So in addition to GWACs that I have already mentioned, which has not a very deep limit magnitude, we have larger telescopes and French telescopes a French one is called Colibri and is prepared in collaboration with Mexico. And we, we, our goal is to have a fast follow up and to be able to provide a photometric redshift in as many cases as possible. And in the I should mention that the French ground follow up telescope has a near infrared channel, which of course helps quickly for this redshift measurement. And so combining these telescopes, our system and the anti solar pointing strategy, and taking into account the fact that we are currently having some agreement with several other teams having their own telescopes for follow up. We expect to improve the fraction of Camaribus with a redshift measurement and our goal is to reach two thirds of our sample. So I can summarize by saying that if we compare to current observation with swift and Fermi, we do not expect a sample as large as what is currently done, but we expect a sample where all properties of the event are correctly measured. So compared to swift, for instance, we have a better coverage, a much better coverage of the prompt emission and compared to Fermi we have of course the capability of localization and afterglow follow up. And we will try to improve the redshift measurement. Even with swift it's still only a little less than one third of Camaribus which have a measured redshift. And in addition, we open this new window with at low energy with this low energy threshold at 40. And so of course we will address all the other topics of Camaribus science today. I will now, if you want, focus on some aspects, which have maybe some connection with Cherenkov telescope array to discuss some possible synergies. So for instance, I will skip the interesting topic of Camaribus as a tool to study the distance universe because on the point of view of Cherenkov telescopes. So I received Camaribus, which are the most interesting events. So I will say a little more, a little more words about two other samples short gamma robust, and also all the diversity of long gamma robust including soft events in the local universe. So let's start with short gamma robust, which are associated to binary neutron star measures. And of course, a major, a major target in the present context, especially with the coming runs of Lego will go. And the idea is that the situation is quite complex today, because we know that these events, especially on the point of view of emission from the relative stick ejection ejecta have a strong dependency on the viewing angle. And we have clearly two kinds of events, typically, typically nearby events detected by gravitational waves, which are usually seen off axis. And where we are limited by the gamma race sensitivity for instance 17 or 17 was only at the detect detection threshold of firm. And we have on axis events where we can detect the short gamma reverse even at high distance, but for the moment, the horizon and gravitational was do not reach hybrid shift. We will probably have to wait for the search generation of detectors to really reach hybrid shift, even if we second generation detectors at final sensitivity. So we can still expect to have both population verging. And so clearly observing bright short gamma reverse in association with gravitational wave is really a difficult goal and should not be too optimistic for this point. But still, if it's possible, of course, large field of view of a clear is very well adapted for that and off tier and of course, and then for the off axis short gamma reverse. You will see that the discussion is more or less the same as detecting fend event in the local universe. So I will join the both discussion in two slides. So just to say that of course we will have a sample of short gamma reverse maybe without gravitational was but it's still very interesting to probe this, this is a population, and especially to try to really characterize it well because for instance, as shown that some short gamma reverse are followed by an X, an X retail. And this is very interesting to try to understand the post merger evolution. And clearly, with the combination of girm and eclair with a low energy threshold of eclair, we are well adapted to probe this phenomenon. So here I show an example of a short gamma reverse with a soft tail simulated again by eclair and girm. And you see that we measure well the spectrum of the initial spike, which is the short gamma reverse itself, and also the properties of the of the X retail. So, we hope to have a to extend the sample of a short gamma reverse to reason with a tail, which is not so large currently. And then, as I said, the, the, the four TV low energy threshold of eclair is also very well adapted to study all the city of the gamma reverse population. So short and long, of course, but also the diversity of the long population with a very complex phenomenology, low luminosity burst, X reflashes, X ray rich gamma reverse, and try to build again a sample with a full set of observation from the prompt to the afterglow and the redshift. So, the plot I have already shown, which is on the top right clearly shows that we are sensitive to this low epic population. And it's difficult to predict rights because this population currently is not very well known we don't have a limited function, for instance, but we have made some simulation taking, taking a sample of about 34 local gamma reverse. And you see long gamma reverse, but also some short gamma reverse. And in the long gamma sample, we have all classes of gamma of a long gamma reverse. And we have simulated them in eclair and you see the result on the top on the bottom right, sorry, within the X axis, the distance of these events or other redshift, and on the Y axis, the signal to the ratio in eclair. But most of them are detected. It includes, for instance, for short gamma reverse 17 or 17 so it shows us good sensitivity to nearby of axis short gamma reverse. And it also includes all the diversity of long gamma reverse, for instance, for the experts to recognize 980425, which is the first gamma reverse with an associated supernova, and which was a low luminosity of gamma reverse. And then what is interesting is that thanks to instruments and rapid follow up we will, we should be able to give that early times an estimate of the redshift and say that we have a nearby event and try to trigger a deep follow up. So, we can try to do it with our own instruments, for instance, here I show that with the limit magnitude in airbound of the visible telescope and also of ground follow up telescopes. So, we are sensitive to a killer novel like the one observed in 17 or 17 up to a redshift which is comparable with the horizon of, of, of Lego vehicle in 04. And we are so sensitive to bright see supernovae like the one in association with 8090. And up to that equals 0.3 event to a little fanter one see supernovae, which means that we will use our sample we will also be able to investigate this complex question of the supernova long gamma reverse association, because there are already a few cases of long gamma reverse in the nearby universe of the supernova, but also without a supernova, which is of course very interesting to understand the projector and the, and the initial event triggering the gamma reverse. And as I said, our goal is to provide all the information in early alerts to favor a deep follow up, especially for instance in radio, which will allow the calorimetry energy to measure the energetics of the event. And maybe in some cases via bi, which is very important to better constrained the jet geometry and the viewing angle. Okay, so with all the samples, of course, the idea is to probe the physics of these relativistic jets, the physics of particle acceleration, relative processes. And this is of course where some interesting synergies exist with the chairing of the copyright. Before discussing this synergies I will just show two slides to just mention the fact that in addition to the normal mode of gamma reverse observations that I have just described, starting with a trigger by a clear and all these follow up observation. We will also react to external alerts with of course a longer delay. And this is of course interesting in the multi wavelengths, the multi messenger context. So we will react in particular to gravitational wave alerts and to neutrino alerts. The idea is that with large field of view instruments, we can of course, search for associated camera recorder parts. And we can even do that offline with a better sensitivity than with onboard algorithm. And what what what we can also do is to through our spacecraft, use a neuro field instruments and search for X ray or visible counterparts of typically to search for instance for a Kiloneva or an afterglow following a gravitational wave alert or for an afterglow following a high energy neutrino alert. So in the case of high energy neutrino with an error box of a square degree. NXT as a field of view which is very well adapted. In the case of gravitational waves or box actually much larger and then we are forced to use a complex tiling strategy to explore. And we are trying currently to optimize this strategy, taking into account the expected properties of alerts during both four and five. And of course we will also use our own robotic telescope for the follow up. Either to explore large error box but probably more to try to characterize proposed candidates by other instruments, thanks to our good photometric and even spectroscopic capabilities. Okay, so now I move to the second part of my talk and I will come back on some aspects of what they've discussed and show some synergies with the Jacob telescope array observatory. So, as I said, there are two main phases of emission in gamma in gamma robust the prompt emission with the afterglow. And in both cases, we expect a very high energy emission. So let's start with the prompt emission which is for the moment is less understood component. There are many models in many of them. The observes TV and TV emission comes from synchrotron emission from non some electrons. There are some problems with the scenario and clearly having a broader spectral coverage of the prompt emission should help for for better understanding the scenario. But on the other hand, there are also arguments to say that such an emission in optical is the regime above the photosphere exists, because for instance in some cases we see a variable energy mission in the last. The question of the energy and very high energy emission in this prompt phase is quite complex because there are possible limitations. What you expect is of course synchrotron self content emission, but then it can be shown that we are usually quite deep in the climate in a regime which can of course limit strongly the US content emission. And in addition, there is the limitation due to the per production. So if we have a very high energy we are energy depends on the line sector, we expect a cutoff due to the production of pairs by gamma gamma. So, the idea is that if we can measure correctly as a spectrum at high and very energy, we will learn a lot about both aspects I just mentioned. There is no very high energy detection, and there are a few cases of high energy detection with with a lot where the origin of the mission is not always very clear due to the time resolution but there are a few cases where there is clearly sometimes get by everything and so it's probably an internal origin. So here I show an example of a bright gamma reverse observed by Fermilat, where there is clearly a prompt additional component I energy detected by the lot. And here I show a refined analysis in three different bins of this component done in collaboration with my colleagues in Montpellier at LEPM. And here you see clearly that we, we start to constrain the shape of this additional component with a possible cutoff. So if we analyze this cutoff as due to per production, we can put very interesting constraints on the ejecta on for instance the Lorentz factor of the ejecta or the radius of emission. And what we find are typical values, which we are compatible with the most standard scenario where the mission is produced by internal dissipation shocks or connection above the photosphere. But of course, as the shape is not so well constrained. We can also consider other scenarios where what we see is not a cutoff but more the natural curvature of SSC component. And then of course the question which is important and where the answer is not known is what is in this case, the maximum energy of the mission does it reach a very high energy range. And in some scenarios, it can reach 10 GB or even above. And here I show an example, which are synthetic spectra produced by Jelika Boschnak and myself in the context of the internal shock scenario, which is one of the most discussed scenarios for the origin of the promotion. So we explore a very broad space parameter space, and you see that in many cases, we have a component, which is not often, which is not always bright that is bright in some cases, which extend well above 100 MV and even well above 10 GB so it starts to be for the Chinese telescope array. And I know that Jelika Boschnak is correctly participating in a working group to try to simulate that more precisely in the CTA. Another interesting aspect where there could be a synergy between Zvom and CTA is the fact that there is at least one case where we know that the prompt optical energy emission was really variable. This is a naked burst. And then probably it has an internal origin like the soft gamma rays. And in this case, there are many possibilities but in some scenarios. These prompt optical could be associated to light internal shocks, whereas the synchro tropics in optical rather than in soft gamma rays so you are more easily in the Thompson regime for invest content. So it could be a very interesting to have simultaneously high and very high energy constraints to check such scenario because it's very possible to have a very high energy emission in this case. Of course, there is also the very important discussion of possible ironic contribution because if electrons are accelerated. Even maybe more easily. And then of course, the synergy is not only with the CTA but also with high energy neutrino experiment. I think constraints by the three instruments would be very important for probing such scenarios. So here I have tried to summarize on this summary what can what Zvom can bring and what CTA can bring. So of course for this part, the fast reaction time and the high sensitivity of CTA are the two main assets. And it has been discussed in several papers. I will emphasize the fact that it's very interesting that Zvom is probing the diversity of long gamma reverse in the nearby universe, because for instance, high energy neutrino emission is favored in some scenarios for low energy to be possible to process scenario. And of course, the sample is very interesting for for the CTA more generally because in the nearby in the universe you don't suffer from the extension by the extra galactic background light. And I have mentioned the fact that our constraints on the prompt of the commission can be very relevant to discuss also the very high energy. And of course the afterglow the situation is a little more clear because we have now detections. So a few detections since 2018. So, as you know, it gives some strong in indicate evidence for again the presence, the second possibly SSC component in the afterglow spectrum. And what is interesting is that for instance if you take the example of 1901 14 C. It shows that when you have such a nice data set, including very high energy, very high energy coverage. It allows a very detailed modeling and much better constraints on the afterglow models. And there are the magic collaboration has produced a very nice multi wavelength feet in collaboration with other groups. What is also interesting is that even if there are nice feats. And there is also some current debate in the community about the result of the feats and the way to model this emission. So, of course, we wait for for more events and it will trigger more activity but the idea is that, in principle, this is the best sample to really probe the physics of the acceleration of particles at the forward shock, in the external medium. And I would like also to mention this second case 19 or a 29 a, because what is very interesting this case. This is the fact that the TV mission is detected, but this is not at all a bright gamma robust. And it is observed at a very low rate shift, and it is a low limit of the gamma robust. So already with with very few events we have at TV, we are starting to probe the diversity of this long gamma robust population. So here I really think that some could play a role because it will be very sensitive to this population. There are multi wavelength feats which have been produced. And then it shows that such events are very relevant to probe the physics of particle acceleration in the forward shot, and maybe even in the river shock propagating in the ejecta itself. So, I will finish by your last point to try to keep time for questions and discussion. This is a question of the very high energy emission from short gamma robust. As you know, there is an upper limit for 17 or 17. And on the theoretical point of view. It was not expected to detect the event because it can be shown that the combination of the fact that it's really of axis, and that we are very deep in the climate in a regime shows that the expected flux was very low. Let me show here an example of a simulation which has been done by my PhD student Clement Pelloy. So taking into the full physics of the afterglow including inverse content inclination regime and the full physics of structure jets, which have been revealed by the observation of 17 or 17. And we show that we were two orders of magnitude below the limit by S at the peak. And the same event is observed a little less of axis, typically 10 degrees, we can reach the limit by S. Of course, the peak is much earlier in this case, five days. And what is interesting is that with the sensitivity of CTA it should probably be detectable up to 100 megaparsec or even at a distance. So you see that I should have mentioned that really a tiny China plus, of course, the limit on the acceleration of electrons, limit strongly the emission at high of axis angle and it's much better here. And then there is also a very interesting fact, this is that in the case of 17 or 17, the external density is supposed to be quite low, typically 10 to minus three particles per cubic centimeter. But we know that the afterglow is much brighter if the density is larger. And we know that short gamma-ray burst show afterglow fits, which are better reproduced with high density. We also know that short when the host galaxies detected, which is not so fun. All gamma-ray, all short gamma-ray burst do not show large offset compared to the galaxies, some have a smaller set, so should be associated with denser region. So we can see what becomes a very high energy emission of the afterglow for short gamma-ray burst with a denser environment. So here it's always 17 or 17, but I increase the density of the external medium. And you see that with one particle per cubic centimeter, we reach the current sensitivity. So it's a very interesting channel, because I have also mentioned that some short gamma-ray burst afterglows favor the high density. But more generally, in the discussion about the formation of binary nuisance term merger, there are many discussions about the possibility of having a fast merging channel. This is, for instance, motivated by the early enrichment in air process elements observed in metal pour stars. And so the idea is that this population, if it exists, could be a very important part of the sample of joint gravitational web and electromagnetic detection, and maybe the best one to detect at very high energy. So here again, I have tried to summarize on this slide what some can bring for this sample and what CTA can bring. So again, for the afterglow, the rapid reaction time of CTA is also an advantage, because I didn't have time to mention that, but there are also a lot of theoretical questions about the transition from the prompt to the afterglow emission. And more generally, of course, with the sensitivity of CTA, we should extend the sample of very high energy afterglows and explore the diversity. And again, I know that there is a working group in CTA trying to predict some rates for that. And so I will conclude by saying that we can be quite optimistic about the future and the fact that in 20 after the second part of 2023 or 2024. I really expect some common events detected both by SOM and the CTA. And here, I show a figure provided by Frédéric Piron, where there is a spectrum of 1901-14C observed from low to very high energy. And with the indicated spectral range of SOM instruments and of Fermilat and of the CTA. And of course such an event would be of first interest. And I mentioned also some references if you are interested to learn more about SOM. And I thank you for your attention and I will be happy to discuss and answer questions. Thank you.