 Okay, I think we are live so welcome everybody to this Latin American webinar of physics is new. The webinar number 989 sorry so we are just one more to arrive to the 90th. The webinar. So today we have a very interesting talk. There's the speaker is Sylvia Manconi from the Institute of theoretical particle physics and cosmology from the university is from the. RWDH agent in Germany for the rain issue with fall issue technician how school they are. So Sylvia she obtained the PhD from the University of the study Torino and I NFN Torino. And now she's a postdoc there in the RWDH in in action. So she's working on various topics on theoretical astro particle physics, and she just got the PhD last year. And she's from Sardinia from where she did the bachelor studies in physics in the University of Canada. So the talk of Sylvia's, I mean the title of serious talk is insight on the local emission of cosmic race election and positive. So Sylvia welcome to the Latin American webinar. Thank you. Yes, thank you. Okay, so I will stop the video and share my screen. Exactly. Right, can you see the slides right now? Yes, we can. Okay, perfect. Okay, so thank you very much for the introduction for this nice opportunity. I will talk about some recent work we did in collaboration with Mattia di Mauro and Florence Adonato about insights we can have on the local emission of cosmic ray electrons and positrons. This is an overview of the talk. I will start with an introduction and then I will speak about some multi messenger constraints to the local emission of cosmic ray electrons and positrons. We were studying using the radio emission from supernova remnants or the emission in gamma rays from nearby parts of the universe. And then I will summarize. Let's start with the introduction. And I like to show to you the total flux of cosmic rays we receive at the earth to see where the electrons and positrons to which we will concentrate in this talk are related to the rest of the cosmic rays. As you can see here the total cosmic ray flux and this is the flux multiply normally to the second power of the energy as a function of the energy we detected here. And you see that the component we are talking about is just few percent of the total cosmic ray flux. Here you see the electrons and positrons and here the total electrons plus positron flux that is dominated by the electron component. Because even if they are subdominant in the cosmic ray total flux, they are a unique window to the acceleration of particles to the multi TV energies and to the properties of the local graphic environment. In fact, as we will see later on those particles since tougher the severe radiative losses have a typical propagation scale of few kiloparsecs. So they test the properties of local sources of cosmic rays. This is a view of the present situation of the observation for the total flux of electrons plus positrons, the positron flux, the positron fraction and the electron component. So you see that all those fluxes they have different spectral characteristics and those are a result of different mechanism and source classes we want to investigate. In particular, in the last 10 years, I would say the positron flux or the positron fraction has gained a lot of attention since we observed what we call a rise in the positron fraction. So the flux that is observed above about 10 GB here you see again this flux as a function of the energy is exceeding what we call the predicted secondary component. So what we expect for the antimatter production from the escalation of primary cosmic ray cosmic rays into the intercellar medium. So in order to explain these rays and then recently the AMS experiment reported also a sharp fall above about 300 GB. We need a new primary source of cosmic ray positrons so antimatter cosmic rays in addition to the secondaries in order to explain those data. So if we want to understand and model those fluxes, what are the ingredients we need to care about? We have different components in this modeling. First of all, we need to understand what are the cosmic ray sources, and in particular we need to understand what is the acceleration mechanism, what is the source distribution in the galaxy and what is the source spectrum that is produced from each sources. And then no matter what is the cosmic ray source, those particles propagate in the galaxy and in order to understand this process, we need to understand different inputs, in particular some astrophysics input such as for example the value of the magnetic field, the value of the diffusion coefficient and what is the matter and photon distribution in our galaxy. But we need also some basic physics input as for example we need to understand what are the cross sections of interaction of those particles with the intercellar medium or the electromagnetic energy losses. Once we model those two steps, then we are ready to compute what we call the propagated spectrum and to compare with the fluxes that we just seen that are detected by different experiment on satellites for example. So all this problem can be seen as a propagation equation in which we have a source there, in which we put all the information of the production of cosmic rays. Then we have a propagation operator that will have inside all the processes that happen during the propagation and our goal is to solve this problem to obtain the flux at the earth. This is a view of the galaxy as is seen for a cosmic ray physicist. So for us the galaxy is very well approximated by a cylinder in which the magnetic field are confined. Here you see this thick cylinder in which here there is the galactic center. We are here at 8 kPa from the center and the total radius of this cylinder is about 20 kPa. So here you see a thin cylinder instead that is the disk in which the gas and the stars and all the sources of cosmic rays are confined. Instead here you see the part in which the galactic magnetic field are confined. In this diffusion zone different processes are going on but if we want to analyze the electrons and pulse it turns out energy larger than 10 gV. We need to care in particular about energy losses by synchrotron emission in the galactic magnetic field and inverse Compton scattering on the different interstellar radiation fields. And then we need to care about the fact that the random scattering in the magnetic field irregularities is causing spatial diffusion on those charged particles. The solar modulation for us is subdominant in this energy range and this effect is coming from the solar wind that is depleting the total flux of the interstellar flux before those particles will reach our detectors. So the propagation equation can be written in this way for electrons and positrons in which you see the diffusion term and the energy loss term. So as for the diffusion in principle you can model it in a very complicated way taking into account the parallel and perpendicular component of this diffusion coefficient but for our purposes we will consider it as isotropic even if we will see in the following results that we have evidences that actually this diffusion coefficient is not isotropic at least nearby the sources. And here you see the energy loss term in which we have the synchrotron term as I was saying before and then the different photon fields that we need to compute the inverse Compton losses. We solve and I will discuss with you some result obtained solving this equation with semi-analytical methods in which we take into account both the vertical and radial border. Normally but there are on the market also very different numerical codes that solve numerically this problem taken into account also for example the spatial distribution of the energy losses. But for our purposes this is not making a lot of difference because in any case the typical propagation scale for this particle is pretty small and this is demonstrated by this quantity that is the typical propagation scale this lambda that is the integral of the diffusion coefficient divided by the energy loss term and I'm plotting this quantity here as a function of the energy that we detect at the earth for different energy starting energy at the source. And you see that for example if you concentrate on one cosmic ray electron that you receive a 100 GV but was produced at the source at one TV energies you see that the typical propagation scale so effectively the horizon of this particle is 4 kPa similarly for the same energies here. So since this we need to take into account and to remind that those particles probe a few kPa near the earth and so it's very important to model the local sources of cosmic ray electrons and positrons. So what are the different candidates in order to produce electrons and positrons in our local galaxy? We have supernova remnants that is a late stage of the evolution of massive stars in which a strong shock is propagating through the intercellar medium and possibly accelerated matter that is meeting in this shock. Then we have the pulsar manipulate that are believed to be accelerators or both electrons and positrons since electrons and positron pairs are produced in the very strong magnet field of these sources and we will see later on some more details about those two types of sources. But if we want to look near by the earth so now in this plot here you see we are sitting in the center this is the distance from us and we are plotting here the position of the supernova remnants that are dots and the pulsar manipulate that are stars that are found in the source catalogue around us. So you see that we don't have a long list of candidates and actually we will concentrate on those in particular those four sources of which I've wrote also the name. And in order to compute what is the flux of electrons and positrons we expect from these sources we need to model you remember the source there from the propagation equation and in this source then we have different entries in particular we need to model the energy spectrum we need to model the spatial distribution that for single sources is just we need to know the distance from the sources and then there is also the possibility that this emission has a time dependency so we need to learn about it and our focus during the rest of the talk will be to use radio and gamma reemission in order to get insights on the cosmic reemission from those candidate local sources and in particular about those four sources we see here. So let's keep going with the rest of the talking which I will show to you some recent results and let's start from local supernova remnant and radio constraints. So supernova remnant in general I believe to be the main sources of galactic cosmic rays both protons and electrons in particular and we have different evidences for the fact that the cosmic rays are accelerating in this system in particular we see a pion bump so the evidence that there are protons are accelerating around the sources in gamma rays but we see also the sources in radio emission and x-ray emission so we have the evidence that there are high energy electrons accelerating around. The injection spectrum is general model as a power law here we have an normalization and we believe that at some point this acceleration mechanism will have an exponential cut off. And as I was saying before we have a few very few observed supernova remnant can contribute significantly to the observed flux by just looking to the distance and the age of the sources that we have in the catalogs and from now on we will concentrate on the two sources we have a distances that are less than 0.5 kiloparsecs. So in this work we wanted to use the radio emission in order to constrain more the parameters for the source term in order to compute more carefully the contribution from those two sources and in particular we decided to analyze the full radio emission that is seen from these two sources and to fit this full radio spectrum in order to find regions in the parameter space for the source term. This is translated into the result that you see in the left plot here in which you see some contours for the total energy that is connected to the normalization of the spectrum and the spectral index and to relate the radio spectrum to those two parameters we use this formula in which you see also the distance and the magnetic field appears. So you see here that those two different bubbles have different contours. They are 1, 2 and 3 sigma contours from the fit to the radio data here for the VELA supernova and then here for the signals loop. You see that if we want to constrain the source term using those radio data we find very narrow ranges for the injection spectrum. Now if we let vary the normalization and the spectral index only in two regions and in particular we concentrate on the two sigma regions that are allowed by looking to the radio emission we end up with those propagation spectrum bands. So you see that now the contribution from VELA a signals loop is bounded in those two regions and depending on the particular 1, 2, 3 sigma that you consider here and considering two sigma flows from those two sources can reach the flux data that we have at the TV energy. This is the total electron plus positron spectrum but as we saw before this is dominated by the electron component. We went forward in that because in principle the radio emission that we see in supernova remnants is from low energy particles that are still trapped in the supernova render but the particles that we are more interested in actually are the ones that escaped already the system and they are traveling towards the earth. So we include these we try to include these in this model by looking to modeling that were available in the literature for the escape of electrons from supernova remnant. So now the quantities that will be fixed to radio data are only the normalization of the trapped electrons and then we compute the normalization spectral index of the escaped electron through the models that we found in the literature. So now we have two different sets of contours here again the one for the trapped cosmic rays and here the one that we can compute taking into account the modeling for the escape of those electrons. You see that apart from the difference in normalization because we have to divide some of those particles that are still trapped and the one that are that has been released we have also a general shift in the spectral index that is expected to be connected with escape mechanism. Now if we play the same game to compute what is the expected contribution of those two sources to add to the electrons plus positive flux we see that the band is a little bit lower and in particular there is a depletion of the cosmic ray flux that are low energies with respect to the plot that I was seeing I was showing to you before and this is the effect of the fact that those particles in this model are now trapped in the system and they have not escaped yet. So this is showing to us the importance of modeling the escape of electrons from nearby supernova remnant in order to understand their contribution to the GV and TV energies and more work has to be done in order to understand those processes in the future. But imagining that we want to consider if we can fit all the electrons plus positive spectrum by looking to the constraints of those nearby supernova remnants and by taking into account all the different other components that I didn't commentate before in the introduction we are demonstrating in this paper that actually we are able to reproduce the total electron plus positive flux with a nice chi-square and here I want just to comment a little bit on the other components that I'm not I'm not mentioning in the rest of the talk here you have the secondary emission that is in any case subdominant in all the range from the spallation of the cosmic ray protons and other cosmic rays into the interstellar medium then we have the contribution from far away supernova remnant the contribution from nearby supernova remnant that here is bounded from the radio data that we saw before and then the total contribution from the pulsar that we have in the catalogue. If we can then also check if the dipole anisotropy from those nearby sources is compatible or not the answer is yes and here I'm just plotting the comparison between the upper limits that have been released from the Fermilat experiment with respect to the expectation that we have in this particular model I'm not going to discuss more into the details this dipole anisotropy what we need to understand for this plot is just that we measure not only the cosmic ray flux we measure also the arrival direction of those charged particles at very high energies if we have a very bright dominant source we could expect that there is a dipole anisotropy in the observed flux. For electrons and positrons we don't see this in the experiment so we have upper limits that are those values as a function of the energy so we need to take into account also the fact if we want to produce a model that is compatible with all the observables and I inserted some more backup slides on this topic if you are interested. So this is just to demonstrate that it's possible to build a model that is compatible but with the data of electrons and positrons both in flux and dipole anisotropy but also with the multi-webland observation of few local sources Now let's move on to the other sources that we will discuss for the rest of the talk that are pulsars and the pulsar wind Nebolev So the engine of those sources is the central pulsar that is a fast rotating magnetized neutral star that is the final stage of the evolution of a very massive star In the eye magnetic field a wind of particles is extracted from the surface of the pulsars and electrons and positron pairs are produced by the magnetic cascade and this is a way of producing not only electrons so matter but also antimatter particles and in particular positrons In this way the pulsar spindle energy is transferred to electrons and positron pairs that are then accelerated to very high energies and also in this case we expected that the acceleration is ending up producing a power low but in principle with a different spectral index those electrons and positron pairs are possible released in the interstellar medium and they can reach our detectors and participate to the total electrons and positron flux we observe and the relativistic electrons and positron pairs have been seen shining from radio to gamma rays so we have a confirmation about the fact that this picture can make sense and again in order to compute what is that we observe at the earth we need to understand different parameters from these sources and in this case we need to know what is the conversion efficiency of those systems for the pulsar spindle energy that is transferred into electrons and positron pairs and also as before we need to know what is the spectral index of the electrons and positron distribution So as I was saying those electrons and positron pairs that have been accelerated they lose energy by inverse Compton scattering and synchrotron emission and they produce a cascade of photons in a broad range of frequency so the idea is that with modeling the intensity and distribution of the photomission we can learn about the properties of the accelerated electrons and positrons and this is a method that is traditionally applied to the pulsar and to the pulsar we enable emission but to the Arco minute Arco second scale emission that is seen and this is connected to physical distances from the central pulsar that is at most one percent what we will discuss later on is some emission that is extended few degrees scale so possibly physically tens of percent away from the source and these those are the emission that have been seen by Oak and then recently also by Fermilard data. Those two pulsars we will be protagonists for the rest of few slides and they are among the most studied nearby pulsar because they are nearby and they have been considered as the main candidate in order to produce the positron flux this positron excess that we want to interpret. We have different scales of the emission from those sources we have a pulsar that is point like we have then what we call pulsar we enable that is seen both in X-ray and the radio at the Arco minute and Arco second scale you see here the radio emission and here the X-ray from Chander in particular for the gaming pulsar we enable and for this source you see that we have this very peculiar morphology that is produced by the fact that this source is running in the intercellar medium with a very large proper motion and this was as the consequence of creating this both shock pulsar we enable and as we will see we'll create also consequences for the GV morphology. A couple of years ago in particular two years ago almost three the Oak experiment detected and reported a few degree extended gamma reemission from those two sources gaming and monogen at energy large and 5 TV and the Milagro experiment observed similar extended emission at a larger energy and this is the scale of the emission so here you see the moon to scale and here is what the Oak experiment is seen around those two nearby pulsar so is a few degree extended emission that is corresponding to 20% and remember that those two sources are far away 250% and 288% so this is a significant amount of their distance with respect to us so this has been recognized as the first evidence of electrons and positron that are not more trapped and confined into the pulsar we enable but are diffusing away from the pulsar and they produce this inverse component emission by scattering the CMB photons so of course we now believe that those electrons and positrons have been released into the intercellar and they can probably participate to the flux of cosmic rays we see so this is saying that we have a strong support for the idea that pulsar we enable can be in the positron sources so what we learn in particular from these Oak data we learn the fact that we need a continuous injection of electrons and positrons in order to have very high energy emission also after 300 kilo years after the death of this pulsar then we can compute what is the pulsar spindle energy that is converted into electrons and positrons because we see the amount of energy that is lost in gamma rays so we can compare with respect to what we expect from the pulsar spindle energy and we can compute the efficiency and then one of the most striking result was the fact that if you analyze the profile of the gamma ray emission as a function of the distance from the central position of the source you can compute how fast electrons and positrons diffuse away from the pulsar and if you compute this number you obtain a diffusion coefficient that is 500 times smaller with respect to the average value that we see in the galaxy by analyzing all the sources and all the cosmic rays that have been seen as the discovery about the fact that probably around in the vicinity and for a region that is at least 20 percent the properties of diffusion of cosmic ray electrons and positrons are different but we want to use those multi-messenger data in order to predict the positron flux that is from when we started and here I want to stress to you that using photons between 5 and 40 TV in order to predict what we are interested in so the positrons where the positron excess is seen is a strong extrapolation. In fact if you use only the odd results in order to calibrate the photon emission and nearest to the spectral energy distribution of the inverse quantum emission as a function of the energy here and the positron flux at the earth you understand that the gaming contribution to the positron flux in particular is not constrained and you can see here by looking to those two different lines with two different colors they are both compatible with what we see in the office experiment here but they end up with very different extrapolation in the Fermilat energy range and this has used consequences for the contribution to the positron flux because depending on the spectral index that for the blue is 2.3 and for the green is 2 we are compatible with the odd data and in fact in the region the very high energy region those two contributions they become again equal but for the contribution to the positron flux in this range they are pretty different so we cannot conclude yet if this source can or not contribute significantly to the positron flux so this is the idea we had to analyze the Fermilat data in this range in order to search for a counterpart of this gamma ray emission and possibly discriminate between the different spectral indexes for the accelerated positrons so we analyze it the Fermilat data in a very big region of interest because if you saw before the extension that is predicted the very high energies multi-TV energies at the GV the extension of this emission is predicted to increase even more and we model this energy dependence of the special morphology of this inverse Compton emission by creating different templates for a large range of different diffusion coefficient and then we test analyzing the data which of the model was best reproducing what we observe and here you see what I was mentioning before we looked at low energies and in particular this is for 10GV the morphology of the GV emission coming from the inverse Compton scattering is expected to be distorted from the effect of the proper motion and this effect is less important if you go to higher energies so we analyzed the Fermilat data and we found a detection for taking a halo in the Fermilat data and this detection is pretty significant and depending on the background emission modeling we have a diffusion coefficient that is ranging between compatible value with respect to the AUK experiment and the physical side of this emission is about 60% at 100GV and now so in this spectral energy distribution of the GEMINGA emission we have the AUK measurement and here we have the contribution that we are adding to the problem by adding the Fermilat data those are detection and those are upper limits so now you see that we can bound more the contribution of this source and the spectral energy distribution of this source as for the monogen source this is not detected in the Fermilat data but we found upper limit for this emission the fact that the proper motion is distorted in the morphology of this emission has been also taken into account and we found that actually by analyzing the data with a model in which the proper motion was included the data were best fit so the model fit the proper motion is preferred at least at 4 sigma and what we are seeing here is possibly the first time that we are detecting the proper motion of a pulsar and pulsar we enable only by looking to GEV gamma rays that is a sort of first time in gamma ray astronomy so now we want to compute what are the consequence of this observation for the cosmic positron flux and in order to take into account this now we update our diffusion model in particular we consider what we call a two zone diffusion model in which we put the slow diffusion just in the region in which we see the gamma rays this plot is called relic pulsar we enable and here you see we have the gamma rays and the fast diffusion in the rest of the galaxy this is in order to take into account both the evidence that we have from the gamma rays but also the fact that for the rest of the galaxy we don't have any other evidence for the fact that we have a slow diffusion also there and so if you compute what is the contribution to the positron flux now by taking into account also these two zone diffusion model for the gaming pulsar and for the monogen pulsar you end up with those contours by varying different parameters that are compatible with the gamma rays so the conclusion is that the gaming monogen can contribute at most few percent to the AMS positrons data and that along those two sources as constrained by now from AUK and Fermilab data they cannot contribute more than those few percent to the positron excess so now we are left with a different question first of all is this gamma ray halo that we are seeing both in gaming and then in AUK experiment also in the monogen pulsar this is a general properties of all the pulsars or it's just a peculiar property of these two sources that we have nearby and the second question that we'll discuss later on is the pulsar-enabler are still a viable interpretation for the positron flux or not since the two nearby ones cannot explain all the flux so let's start with the first question and before looking to the actual data something that we need to understanding is how the angular size of those object is changing with respect to the energy that the extension of gaming for example was larger at Fermilab energies and in particular for this experiment it's challenging to detect something that is more extended at let's say 10 degrees inside for the very high energy experiment such as as an AUK we have the opposite problem that we have a few degrees instantaneous fluid of use so it's challenging to detect something that is more extended for example so in this plot what we wanted to study was the evolution of this extension that we define as the angle that is containing the 68% of the gamma reflux at a particular energy value as a function of the distance and of the age of the pulsars and here you see the contours that are just computed for each point in this 2D plot and those they are green cross they are the position in which the pulsars from the catalogues are sitting so you see here that at 10 GB that is the plot in the left a source that is 100 kilo years all should be far at least 0.9 kiloparsec in order to be detected with an extension smaller than 2 degrees so that was kind of the region in which could be easy to detect a Fermilat extension while at one TV in principle and by looking to diffusion coefficient that are similar to the gaming values most of the pulsars in the catalogues would be good targets for inverse Compton gamma reflux because they are basically all in this range between 0 let's say in 5 degrees of extension what we did was to go into the catalogues and try to understand if we had already some observation of the sources in order to search for those alos and in particular we ranked all the pulsars that we have in the catalog according to the expected gamma reflux at 10 GB discovering that the majority of the first tranks in this method were already sources that have been detected by OK and S experiment so we decided to take the flux map that are available from the public S catalog and to extract the surface brightness above 1 TV so this is the flux as a function of the distance from the central position of the gamma rate peak let's say and here you see for example one example in which we extracted the data from this source and then we fit this brightness with a model of the inverse Compton scattering emission coming from those electrons and positive transplants being accelerated and for the majority of the case we have a situation like this in which this diffusion profile is best at describing the gamma rate data with respect to the Gaussian profile for example that is normally used in order to for example compute what is the extension of those sources so we have a size for a set of different sources and we test if the diffusion around those sources was again inhibited and the answer was yes so in the majority of the sources that we analysed we found a load diffusion zone and the value of this diffusion coefficient is similar to the value that was found for gaming and monogamy you see here those thieves points for different values of the age of the sources and we found that this diffusion coefficient is systematically lower by two orders of magnitude with respect to the galactic mean value we also report that there is not a clear trend with respect to the age and the inverse Compton TV also they show a typical size of about 35 bars as you can see here above one TV and what we are doing also analysed that is in progress is to look also from a set of sources to the formula data in order to do the same exercise we did for gaming and monogamy so let's go to the final question so what are the consequences of all this multi messenger observation of those pulsars for the positron flux so in principle those two sources are not the only pulsars in our galaxy and in fact in the past by taking into account parameters for the production of cosmic rays around those two sources and the rest of the sources in the galaxy so for example an efficiency of few percent for the conversion of the pulsar spin down in electrons and positron pairs and by taking into account all the distribution of pulsars in our galaxy so both as moot distribution or just the sources that we have in the catalogue it was demonstrated that actually you can fit the positron flux and the positron fraction so now we want to understand what is the effect of this new evidence of the low diffusion bubbles around the pulsars so we can still conclude that the positrons can be explained by the total contribution from galactic pulsar enabling the answer is yes and in this last paper that I wanted to discuss in this seminar we analyzed in particular what were the effects of these two zone phenomenological models to describe the propagation around those sources so by taking into account the fact that we analyzed a sample of pulsar venebula 30 more or less in the previous analysis we take those mean values as representative for the rest of the galactic pulsar and we try to understand what is the cumulative emission from those sources if we take into account for all of them these two zone diffusion models so this is for example the effect on the total contribution from the pulsars in the catalogue for the value of the diffusion coefficient at the fixed value for this radio of the bubble and this is the effect instead of the radius of the bubble so you see that the properties of this low diffusion zone in particular significantly affect the prediction for the positron flux at large energies so where exactly we have the positron excess so it's really fundamental to understand what are the properties of propagation around those sources in order to understand if we can explain or not the positron fluxes but assuming that the values that we are finding in those initial analysis of the pulsar venebula halo are representative for the rest of the galactic pulsars what we concluded and this is shown in those two plots that both if you consider the pulsars that we have in the catalogue or if you can consider the stimulated galactic pulsars and you put them in order to model the distribution of distances around the earth the cumulative positron emission can still explain the positron excess and I want to stress here that this is not a fit so here I'm not fitting the data but this is a prediction so I'm just taking the total contribution for the different pulsars in the catalogue or from the simulation and this ban is just the variation from different types of those simulation and I'm reaching the level of positron data of course more work needs to be done here in order to try to understand if we can by varying the single parameters of the most important sources we can still explain and fit better the positron flux and this is some further work we would like to do in the future so I'm going to my summaries I hope that I explained to you why cosmic ray electrons and positron fluxes are a unique window on local sources of electrons and positrons and how we can use multi-message analysis in order to reduce the uncertainties coming from the cosmic ray emission in supernova remnants and pulsar will enable and then we discussed how we can use the radio data to constrain the electrons emission from nearby supernova remnants and the take on message here is that we need to understand more the release mechanism in order to predict more with more detail the emission from nearby sources and then we discussed this very recent topic about the extended gamma ray alos around pulsar and pulsar will enable by looking to the detection of these alo also in Fermilat data and by looking to the constrain we can put on the interpretation of the positron flux also using the Fermilat data and then in the last part we saw how these TV alos that have been sometimes called in the literature are emerging as a general characteristic of the pulsars that we have in the galaxy and new and promising source classes can be seen in the future experiments such as CTA and the conclusion as far as the analysis that we have done is that in Fermilat remain the most promising candidate to spend the positon flux of the earth but now we have more insight into the cosmic reproduction and emission mechanism in these sources. Thank you. I finished. Thank you very much Silvia. It was very nice your talk. I like it a lot. Thank you. So for all the viewers that are following us in YouTube or you can start to write your questions in the chat in the YouTube system that we have in the stream and for those that are watching this video in the future with respect to the live transmission remember that you can subscribe to the YouTube channel and also to follow us in Twitter or following our WordPress page in which we have the summary of all these webinars so for the meanwhile the people is writing questions for Silvia and I'm going to start the question round with the people here in the session. If there is somebody here of the two guys otherwise I have this topic is one of the topics that I worked on with the PhD so I have many questions Go ahead. Let's start with some questions from YouTube. Sorry. On slide 14 you can go to slide 14. Can you explain why the modeling with trapping and why there are and gamma anti-correlated from Philip Merz. Yes, so you are asking why the total energy and the spectral index are anti-correlated. So this is connected probably to the escape mechanism that is modeled in this particular model we are taken into account so since there is this variation in spectral index probably you have also variation in the normalization of the spectrum that you have different slices let's say in the spectrum. This is my understanding. Okay, so we are going to let's wait for Philip. Any further comment? If I understood correctly. In the escape one, of course. Okay. It was clear after this. So let's see if we have more questions otherwise I have one. For instance, when you model the change between the diffusion term between the inside and outside in part of the galactic medium one in the other side that you were showing you use this particular parameterization do you expect that you have a sudden change between one side to another or do you expect some kind of smooth transition? Yeah, this is an important point. So we are using the most simple phenomenological equation in which there is a sharp cut, let's say, completely change with respect to this RB. But in the literature that has been studied and in particular in this reference in this preformo et al. they demonstrate that actually the way in which you change between the two different diffusion coefficient can have consequences on the form of the propagated cosmic rays. But for the moment we don't have any clue on how this transition can be described. So we need to understand better and we need to look to the gamma ray spectrum property in this range once we will have the precision to look there in order to understand this. But of course we don't expect that there is a sharp discontinuity, let's say. So but also I was wondering I mean you effectively you have one diffusion term on one side and the other but this diffusion term since we know or more or less is expected that depends between the intensity of the magnetic field or the amount of turbulence that the magnetic field exists. What do you think that could be the why is it changing because of the magnetic field dropping too fast or it is In general it was kind of expected that in the region around the pulsar venebula the magnetic field and the turbulence is not the same as the rest of the interstellar medium. The evidence here is that this effect is actually extending way larger with respect to the boundary of the pulsar venebula that we see for example in X-rays and there have been studies in the literature and they are again here linked in this slide in which they try to explain why there is this inhibited diffusion. So there can be some feedback of the cosmic rays that are confined there or some different turbulence but for the moment there is not yet a unique understanding of this. This is something that is needed in order to understand those observations surely. This is nice for the next another question I have. Do you have any prospects for future CTA that is going to be able to help with the gamma rays? We produced I have something in the backup so we produced a very simple prediction of the number of possibly yellow if we consider that all the pulsars in the catalogs they have this gamma ray yellow and this is the number that CTA can possible detect as a function of this value of the efficiency so you see that even for very small values of efficiency we expect to see a large number of those objects so of course we can help in understanding if these sources are really a general characteristics of all the pulsars or if they are just characteristics of particular pulsars that we are seeing for the moment. That would be awesome. Regarding also to the part, this is for the gamma ray but relating with the radio signal associated with the pulsars with Nebula or ALMA or SQA can help in the quest because which are the sources of data? Of course the detection of such a large extension in radio and X-ray is really challenging. We started to understand this and we realized that actually this extension is expected to be pretty large but probably if you combine the observation in the same ROI, in the same region of interest, similarly to what is done in order to study the diffuse emission of the galaxy for example, this can be possible I think but you need to provide really also a targeting analysis and method in order to understand this and I'm not an expert on X-ray and radio detectors and strategies of observation so I would be happy to speak with some experts in order to see if it's possible. And my last question in the slide I don't know if other people have questions there are. I like this slide especially the graph are very impressive and this wiggling of the flux is a kind of prediction either with the real data or with the simulated data but this wiggling is there no matter in the case of the simulated collected pulsars for all this sample has this kind of wiggling no this depends on the particular realisation so for example you see here right, this is a mean among 20 simulations if you simulate more or more or less you end up with the same band and you see here these bands but this is guided by very few sources but there are also some realisation in which you end up with a smooth profile and you can see it here so here of course we are considering all the sources with the same spectral index and with a distribution of efficiency but what you can do you can always play with the values of the particular sources that are contributing more and end up probably with a smooth so this is something that we want to explore in the future and it will be amazing to try to see the list of sources that are more let's say more dominant in the positron flux in gamma rays and x-rays in order to fix the parameters of those sources and then to see if they end up larger or lower with respect to the cosmic ray data but in principle I would say that the wiggles are a feature but can be also avoided if you fit the contribution of different sources. Yeah so I mean if you start I mean the same in a different way if AMS when it releases new data or whatever in the future it starts to appear this kind of wiggling in the electron plus positron flux or non-electron so it could be a good indication that these type of sources would be the right Yeah then of course you see on the plot on the right that the uncertainties in the prediction are for the moment larger with respect to the uncertainties in the data so we need to be careful also interpreting those so we can always find a model that is exactly fit in order to explain those features but in principle the theoretical uncertainties are larger here. Okay but the other point is I mean this is extra of the question many people when they are talking about in case of dark matter annihilation producing the electron that you cannot generate or you can generate a strong sharp cut in the in the flux but looking your plot in the left side it seems that your flux cannot be sharply down or something like that. Yeah this is connected as you see here but to the properties of this diffusion I think but also to the properties of the sources that contribute exactly in this range in which you see the cutoff because imagine that the sources that have are in this region they have a smaller efficiency or a different cutoff then you can probably recover this and then we are not yet sure what will happen at the multi TV so one prediction of this modeling and in particular of the continuous emission scenario is that at some point you will reach some flattening let's say from the continuous injection and this can be tested with future data of course but for the moment we have this evidence for a sharp cutoff that can be continually or can be just one cutoff on one source and then you can have other contribution. Let's see what data will say to us. Okay so those were my questions let's see if the it seems that in YouTube there are no more questions so I don't know the rest of the guys here in the in the audience if they want to ask otherwise we can there is a chat sorry let's see okay so if there are no more questions we can thank Silvia again it was a pleasure to have her here in the low physics with this nice talk and the rest of the audience you can tune up for the next webinar that in principle would be in the next two weeks so especially in this period that we have to stay at home so this is a good way to spread science and to keep the activities so for all the people that is following us and everything stay safe stay at home and see you in the next report. Thank you.