Alessandro Sozzetti
Toward DR4: Preparing for Gaia?s First Exoplanet Catalog˙(which data products will be released, reliability, non detections)

Good morning, everyone.
Many thanks, first of all to the organizing committee for inviting me here. In particular, Ilaria who is here, and Carl, who, as everyone knows, we don't have time, but because along with many other JPL colleagues, it was badly affected by the tragic events in California.
I I'm also very happy to be here because it's a little bit of a closing, a circle, a kind of event.
Last time I attended the exopag, it was Long Beach, CA 6th of January.
2015.
And I gave it talk essentially along the lines of the ones that were just delivered by Joanna and Tom talking about the guy to come in just about a year time for since then from then and today I am happy to announce.
That we are almost done.
In three days time, we will get the last data points with the Gaia spacecraft.
This will be more than a little more than a 11 year journey since take off in December 2013 and it's definitely.
Spectacular. Let's say generally that we have all witnessed for those who have been involved directly in the in the.
And the guy mission, the end of the data taking is not the end of the story. We have, at least on the order of another five years to go before we can claim that the mission is really accomplished.
There's two major data releases to come.
And the I'm here to briefly outline what you should be expecting from the one that is coming up, maybe in a 1 1/2 year or so now, which is the relevance for.
Before I before lying.
But you should be expecting. Let me go through quickly.
The lessons learned with data Release 3, which is the first one for which we started obtaining significant results.
On companions orbiting the stars.
Observer the guy.
Race 3 provided 2 main avenues of investigations to to understand, detect, and characterize planetary mass companions in particular.
The first is not Gaia only approach.
It leverages the availability of.
Two distant things in in time astronautic catalogues.
The guy who produced one and he parked US1 to identify astronautic accelerations in the Pakistan's indicative, the presence of a companion.
Uh, this type of scientific investigations?
Do not.
Use Gaia data only and so I will not be focusing those after the few words that I that I spent, but I will essentially spend my time on the what we have learned, what we have done and the things that we have understood better.
As far as Gaia Dr. 3 Orbital Solutions are concerned.
In this plot you see a summary of the less a bit less than 2000 orbitals, solutions that were published with GALILE 3 asometry.
For which we had a sense of a likely substella companion being responsible for the variations in astronomy, so that was affected.
The overwhelming majority of these.
Of these companions orbit lava stars.
This is essentially by design. Because of the still limited.
Quality of of the somatic measurements. Essentially only the very lowest mass companions around the lowest masters.
Were more readily accessible.
A small number of of these ones that are primarily dominated by a population of potentially.
Objects planetary masses down the to the 20 or less juvenile mass range.
This small sample that amounts to something like 72.
Became the very first exoplanet least produced by Gaia Dr. Three. This was not even.
Initially forecast as a potential delivery for for the first data release.
Eventually, we still want to this initial list contain.
A set of columns.
That particularly indicated whether the Gaia.
Source will be orbiting companion with a solution potentially corresponding to a planet was a candidate was a confirmed planet was a false positive.
Very first lesson that we learned and that has already been mentioned yesterday in by looking at the very small orbit sizes used by potentially a very low mass companions in in gyrosometry.
Told us about the story of the astrophysical force positives that eventually end up marrying as well.
The the data set of of Gaia astronomy, just like the transits and just like the Avi's astronomy has their own dedicated specific false positives.
These are specific configurations in which a very small orbes size is due not to the presence of a very low mass companion, but instead by quasi equal mass, binary and particular binary system with a mass ratio identical to the essentially to the fluctuation.
The way to uncover these is so much to essentially is blind.
It will just give you a small orbit size and you have to do something else.
Either look carefully at the possible location on the HL diagram of the of these objects to verify potential clear location well above the sequence. The indicative of a clear binary status or performance stats resolution in order to figure out whether the object is is double lined.
The these 70 something candidates have become the objective of the first program.
So follow up either to vet them, so establish whether they are likely candidates as likely planets, or indeed spectroscopic binaries.
And and or eventually follow them up to refine the orbital elements of the of the of the solutions provided initially by Guy.
And the the main.
Thing that we have learned.
Essentially, in three years time of of follow up is that on the order of 50% of these solutions indeed.
Are correspond to binary stars in the Lorna Star regime because as I mentioned, this is essentially.
A sample that is entirely dominated by candidates around and dwarves.
This is what we have learned.
So how can we do better in in guy ADR 4? As I mentioned, you should not expect this to be published before the the end of the first half of 2026. So from January, June, June 2626 onwards you should be expecting today the.
Arrival of the idea for.
And the numbers are going to increase exponentially.
I make no exact statement today on how many planets you should be expecting, or Canada plans you should be expecting, but certainly the win.
The the community.
Has probably also been.
A bit intrigued by the fact that the the way the three published orbits, Orbital Solutions included.
Specific.
A combination of of of elements, the tilings configuration that does not correspond directly to the standard template orbital elements that one is used to when one looks at of the solutions.
One had to essentially rederive them from scratch, from the from the provided orbit, publishing in the Gaia di Archive.
So one thing that we will do forget will be to actually publish both the fictit elements in the tennis configuration.
As well as the.
Rederived camp elements.
Along with all the COVID and along with those prescription that captures the residual jitter in the astronautic time series.
There will also be potentially very useful metric that essentially measures the likelihood of false positive or the likelihood of the the companion being a planet, which will be hopefully very useful for prioritization of follow up work afterwards.
For the first time, we are hoping to be able to identify in the data. Also some multiple companions, maybe 2-3.
I would say not. This may come in in favours of fully fledged 2 capillary orbital solutions and those will be published. But there is also chance that we may be publishing configurations where there is a fully capable orbit and there is an additional long term trend and A/C.
In the data indicated.
Long period additional body in the system.
There will also be a lot of acceleration solutions that will be published that depending on the size and significance of the acceleration terms, may point to the presence of a very long period may potentially plant a companion.
This will not be directly part of the exoplanet catalogue that will be assembled, because again, there will be a significant degeneracy and only follow up work will be able to establish.
That not even not even his candidate.
So they can be indicated.
Last obviously particularly relevant aspect of the delivery of Guardia for as far as suppliers are concerned is that all the somatic time series will be delivered.
This will be typically very large samples of order of 600 individual CCT observations for for typical target observed by Gaia on the order of 70 times.
Across the 5 1/2 years duration of the survey, data that we will be using.
And mind you, the focus is on the 1st automatic catalogs catalog FUNGALIA.
But there will also be a lot of transit candidates and potential.
Significant size of how Jupiter candidates affected by the runner velocities patron.
The way we will organize the the table of exoplanet candidates.
The first significant catalog from from Gaia will be similar to what we have seen from the very first rough small sampled exoplanet list.
So you should expect that it will.
There will not be a single table that captures all the relevant information.
This will be difficult in my opinion for the.
Deepak Consortium to produce because it would end up duplicating elements of information that already appear in other tables, so there will be.
An initial.
Let's say dissemination of relevant information.
So the overall solutions may be in one place.
Information on the on the Central star and the masses of the companions in in the second table and there will be a table that contains instead the I DS and the information on the likelihood of the planet being real or false positive.
It will naturally be, you know, be nicer to put everything together in a structured way.
So there are.
There is ongoing interaction both with the teams and another plan of archive and also the the iris equivalent, the external, so that eventually the the catalogue can be ingested, including all the relevant parameter information.
And the expectation is that we end up populating this regime of planetary masses and orbital periods with GAL 4.
My hope is that, at least for a subset of these objects, we will be able to break the 100 microsecond obesise regime and detect orbits that are significantly below this. This value, which would be in my opinion.
Particularly spectacular achievement by.
My guy.
As a calendar, we'll be out as as we've seen as already has told us, there will be a need for significant follow up work.
This will come likely in two flavours.
It will be certainly dominated by spectroscopic follow up.
I'm hoping that will also be some interesting data that will allow high contrast imaging follow up for direct detection of some of some of the of some of the candidates.
The.
The way we are, we are from the R3 is such that there will be additional information and Deepak will already be doing some work internally to prioritize the candidate list so that we that we get already through the metrics that I mentioned, a sense of the candid.
Being likely false positive or really likely plan, but nevertheless there will be a lot of work to do.
The spars investigations more or less independent.
Out both in Europe and in the US to follow up the small sample of candidates in output from Guy Dr. Three is something that we'll probably have to go in more coordinated way.
Once we really get close to delivery and we have essentially well understood the the size of the of the of the sample that will populate the catalogue, it is very possible that it may be useful to start coordination.
Umm, efforts on both sides of the Atlantic so that effectual, the effectiveness of these follow up efforts is maximized.
And to conclude, in a minute we have mentioned southwall all over the place throughout the meeting.
Kenya help HW at all.
The in the talk by Julia Decker yesterday pointed out the need to understand the outer regions of the planetary systems.
To screen for obtain bodies that may dynamically impact.
The presence and the existence, survival and poverty's and long term properties of habitable planets.
In that may be around the given star. In this sense, the screening for Jupiter size post is still something that has not been done successfully at all.
Even the longest term, the velocity surveys suffer from from this problem.
And we can maybe count the order of half of the targets.
That are in the 1st Tier 1.
Best sample for AW for which there is sufficient sensitivity and it has been established more or less clearly that there is a potential Jupiter mass companion.
On a five year Sobutal configuration, order is now.
So definitely more work has to be done.
Gaia in this respect.
On the face of the visual manager distribution of the of the tier, one simple targets may raise some eyebrows.
Is it going to make it to say something significant because this tablet targets us extremely bright, typically on the 5th magnitude, and there is this tail of supervised objects out to alpha sensor A and B.
And it is well known, as you've seen, the graph on the right that the Gaia performance idea for level is estimated now.
Ends up not getting better. The brighter as soon as you hit the six nitroso.
So eventually gets worse because of the difficulty in calibrating so few stars at the at the same level as the large stellar sample. At the same time, magnitudes there will be dedicated efforts that will try to.
Deliver.
Recently, good astronomy, or the very brightest stars.
For the intermediate bright, still very bright, we are expecting to deliver 7 millisecond precision.
It is still unclear whether time series of the VITER stars will come out for Idea 4.
Certainly anything will be fully released by Guardian 5, but there are my it is my opinion that you should expect something.
Very useful to be delivered by Gaia as far as knowledge of outer Jovian mass or Super Jovian mass companions.
Orbiting all the stars in the Tier 1 sample of astrology.
I can stop here and take any questions.
Thank you.
We have time for one very quick question.
Think you'll be able to help characterize the the main broad peak of giant planets at about 1 AU?
Think Rachel Fernandez published some on that.
Goes down.
Yes, I I showed the box of expected primary impact of the idea four in terms of optimized and that's exactly the region of the of the potential geek in the in the current state of giant planets.
At approximately 3 astronomical units or so. So guys certainly will impact and will help refining any occurrence weight calculations as far as the specific interval of octahedral and planetary masses is concerned.
Dependence on stellar mass. indeed.
Alright, let's thank the speaker one more time.