Anders, F.

Antoja, T.

Balbinot, E.

Carballo-Bello, J. A.

Carrasco, J. M.

Castro-Ginard, A.

Helmi, A.

Jordi, C.

Mateu, C.

Ramos, P.

English

University of Groningen

   University of GroningenThe Sagittarius stream with Gaia dataAntoja, T.; Ramos, P.; Mateu, C.; Helmi, A.; Castro-Ginard, A.; Anders, F.; Jordi, C.; Carballo-Bello, J. A.; Balbinot, E.; Carrasco, J. M.IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2020Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Antoja, T., Ramos, P., Mateu, C., Helmi, A., Castro-Ginard, A., Anders, F., Jordi, C., Carballo-Bello, J. A.,Balbinot, E., & Carrasco, J. M. (2020). The Sagittarius stream with Gaia data. Paper presented at EA XIV.0Reunión Científica . https://ui.adsabs.harvard.edu/abs/2020sea..confE.117ACopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 19-11-2022XIV.0 Reunión Científica                                                                                                     13-15 julio 2020Teresa Antoja, P. Ramos, C. Mateu, A. Helmi, A. Castro-Ginard, F. Anders, C. Jordi, J. A. Carballo-Bello, E. Balbinot, J.M. CarrascoThe Sagittarius stream with Gaia dataThe in-fall of the Sagittarius Dwarf Spheroidal (Sgr) has possibly been responsible of important perturbations on the Milky Way (MW) disk. Yet, with only some thousand of line-of-sight velocities and very few astrometric measurements, there are still many open questions regarding its orbit and stellar content, which hinders our ability to constrain its effects on the MW. We present the largest sample of Sagittarius dwarf and stream stars available to date, obtained entirely by searching in the Gaia DR2 propermotions. Thanks to a smart use of the Gaia Archive combined with the Wavelet Transform to detect substructure, we have unveiled the stream and its proper motion in an almost 360º of its path on the sky, being the more extended and continuous proper motion sequence ever measured for a stream. We have also obtained a sample of RR Lyrae in the stream for which we gain access to the distances and, therefore, to the tangential velocities for the first time. We show the main kinematic and population characteristics of the stream derived in our study. A first comparison with one of the most successful models of the stream shows significant kinematical differences with the data. Our data will allow us to study the detailed the populations of Sgr, obtain the best possible fit to the MW potential from its orbit and, in turn, constrain its impact on our Galaxy.https://services.fqa.ub.edu/sagittariusXIV.0 Reunión Científica                                                                                                     13-15 julio 2020Context- The Sagittarius (Sgr) dwarf galaxy (Ibata+94) is the closest dwarf galaxy to the Sun not fully disrupted yet- A large fraction of its stars have left the progenitor and form a prominent stellar stream that fills the whole sky(Mateo et al., 1996; Totten & Irwin, 1998; Majewski et al., 2003)- Such a nearby massive satellite can perturb significantly the disc, but disentangling its effects from others(Galactic bar, transient arms, dark matter sub-halos) requires a detailed knowledge of its orbit and bound mass- Current models cannot reproduce the kinematics (radial velocity) of the stream nor some of its features like astream bifurcation (Belokurov et al., 2006; Koposov et al., 2012)- Only few proper motions had been measured for this system with the Hubble space telescope (Sohn et al., 2015).No purely Gaia study had been yet performedWe present the studies:- An all-sky proper-motion map of the Sagittarius stream using Gaia DR2, A&A, 635, L3, 2020Antoja, T.; Ramos, P.; Mateu, C.; Helmi, A.; Anders, F.; Jordi, C.; Carballo-Bello, J. A.- Full 5D characterisation of the Sagittarius stream with Gaia DR2 RR Lyrae A&A, 638, A104, 2020Ramos, P.; Mateu, C.; Antoja, T.; Helmi, A.; Castro-Ginard, A.; Balbinot, E.; Carrasco, J. M.XIV.0 Reunión Científica                                                                                                     13-15 julio 2020Data and MethodsKinematic 4D sample:- We select distant Gaia stars with parallax-parallax_error < 0.1 mas & bp_rp > 0.2 mag- We download the proper motion histogram at each sky region (HEALpix) from the Gaia Archive and apply the Wavelet Transformation to detect significant over-densities in proper motion- We select the kinematic structure created by the Sgr stream in the skyRR Lyrae 5D sample:- We use the Gaia catalogue of RR Lyrae stars (Holl et al., 2018; Clementini et al., 2019, Sesar et al., 2017) that have propermotions in Gaia- We present two samples selected in proper motion and distance: 1) Strip: more complete sample, but more contaminated, byselecting stars closer than 20º to the orbital plane, 2) nGC3: a purer sample, at the cost of completeness, by applying the PoleCount method (Abedi et al., 2014)Sagittarius stream in our detectionin the coordinatesof its orbital planeSagittarius dwarfLeading armTrailing arm Bifurcation in the leading armXIV.0 Reunión Científica                                                                                                     13-15 julio 2020Results: 4D sample (~200k stars in the dwarf + ~100k in the stream)2) We study the variations in the CMD along the stream. To zero-order, the position inthis diagram is dominated by the distance gradient, but we have now enough data tostudy in detail the population mix at different positions1) We measure the proper motion along the full first turn of the Sgr stream for the firsttime (blue and red dots). We note significant differences with the Law & Majewski 2010model (dashed)3) The distribution of apparent magnitudes as a function of angulardistance of our sample is dominated by the Red Clump, which revealsthe distance gradient of the streamXIV.0 Reunión Científica                                                                                                     13-15 julio 20201) By combining positions and proper motions we have, for the first time, quantified the tangential velocity trends along Sgr. Wereport significant deviations from the Law&Majewsky2010 model in distance and velocities, and no measurable metallicity gradientResults: 5D sample (~11k RR Lyrae)2) We detect the bifurcation at the leading arm also in this sample ofold stars, with no significant separation between the two branches indistance or proper motionsXIV.0 Reunión Científica                                                                                                     13-15 julio 2020Conclusions and prospects1. This work is the first look into the proper motions of the stream across the whole skythanks to Gaia2. We have compiled the largest sample of candidate stars of the Sgr stream: ~300 000stars of mixed populations and ~11 000 of RR Lyrae stars3. Even the most successful model for the Sgr orbit (Law&Majewski 2010) cannotreproduce the measured proper motion, tangential velocity nor distance trends4. We detect the bifurcation in the leading arm for all the samples, indicating that is notsensible to the age of the stars. There is no significant phase-space difference betweenbranches5. The new observational constrains provided will allow for a precise determination of the Sgr in-fall history using its full 6D phase-space information and for a much better measurement of the Milky Way potential6. It is also now possible to study the differences in population along the stream and relate this to a particular mass-loss and starformation history7. With the improved proper motions of EDR3 the sample size will grow and the uncertainties reduce, allowing for a betterdetermination of the trends and a rigorous comparison between the young and old stars in the stream

The Sagittarius stream with Gaia data

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The Sagittarius stream with Gaia data

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