BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Census of Northern Local Group Dwarf Galaxies using UNIONS DTSTART;VALUE=DATE-TIME:20230322T093700Z DTEND;VALUE=DATE-TIME:20230322T093900Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-261@meetings.aip.de DESCRIPTION:Speakers: Simon Smith (University of Victoria)\nDwarf galaxies play a key role in probing the dynamics of the Milky Way\, the history of star formation in the Local Group\, and the accretion and retention of ga s in dark matter halos at the smallest scales of galaxy formation. In this work\, we use the Ultraviolet Near-Infrared Optical Northern Survey (UNIO NS)\, the deepest\, widest photometric survey ever carried out in the nort hern hemisphere\, to complete a systematic analysis of 3600 sq. deg. of sk y in search of new dwarf galaxies within 1 Mpc of the Milky Way. This sear ch aims to detect Milky Way satellites\, M31 satellites\, and nearby\, iso lated dwarf galaxies using a matched-filter algorithm. To date\, all previ ously known dwarf galaxies in the survey footprint have been recovered\, e ach with high statistical significance. We present the discovery of a new Milky Way dwarf galaxy candidate\, a new\, faint star cluster\, and report on the follow-up of numerous high confidence candidate detections. The en d goal of this work will be to assess the completeness of the Milky Way sa tellite population as a function of position\, luminosity\, mass\, and siz e. UNIONS imaging\, when completed\, is the approximate depth of the LSST after a year of operation\, and our studies of the northern hemisphere pro vide a complementary approach and foretaste of what will come in the era o f Rubin.\n\nhttps://meetings.aip.de/event/20/contributions/261/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/261/ END:VEVENT BEGIN:VEVENT SUMMARY:Tidally perturbed 'feeble giant' dwarf galaxies DTSTART;VALUE=DATE-TIME:20230322T093500Z DTEND;VALUE=DATE-TIME:20230322T093700Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-254@meetings.aip.de DESCRIPTION:Speakers: Alexandra Borukhovetskaya (University of Victoria)\n The unusually low velocity dispersion and large sizes of `feeble giant' ga laxies\, such as Crater II or Antlia II\, pose a challenge to our understa nding of dwarf galaxies in the Lambda Cold Dark Matter (LCDM) cosmogony. T heir low velocity dispersions suggest either a dark halo mass much lower t han the minimum expected from hydrogen cooling limit arguments\, or one th at is in the late stages of extreme tidal stripping. The tidal interpretat ion has been favoured in recent work and is supported by the small pericen tric distances consistent with available kinematic estimates from Gaia. We use N-body simulations to examine this interpretation in detail\, assumin g a Navarro-Frenk-White (NFW) profile for the Crater II and Antlia II prog enitor halos. Our main finding is that\, although the low velocity dispers ions can indeed result from the effect of tides\, the large sizes of feebl e giants are inconsistent with this hypothesis. This is because galaxies s tripped in mass to match the observed velocity dispersions are also reduce d to sizes much smaller than the observed half-light radii of Crater II an d Antlia II. Unless their sizes has been substantially overestimated\, rec onciling systems like these (including Andromeda XXV and XIX) with LCDM re quires that either (i) they are not bound and near equilibrium (unlikely\, given their crossing times are shorter than the time elapsed since perice ntre)\, or that (ii) their progenitor halos deviate from the assumed NFW p rofile. The latter alternative may signal that baryons can affect the inne r halo cusp even in extremely faint dwarfs or\, more intriguingly\, may si gnal effects associated with the intimate nature of the dark matter\, such as finite self-interactions\, or other such deviations from the canonical LCDM paradigm.\n\nhttps://meetings.aip.de/event/20/contributions/254/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/254/ END:VEVENT BEGIN:VEVENT SUMMARY:Small-scale stellar haloes: detecting extended substructure in the outskirts of Milky Way dwarf galaxy satellites DTSTART;VALUE=DATE-TIME:20230322T104500Z DTEND;VALUE=DATE-TIME:20230322T110000Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-198@meetings.aip.de DESCRIPTION:Speakers: Jaclyn Jensen (University of Victoria)\nDwarf galaxi es are valuable laboratories for dynamical studies related to dark matter and galaxy evolution\, yet it is currently unknown just how extended their stellar components are. Each satellite orbiting within the Milky Way’s (MW’s) gravitational potential may undergo tidal stripping by the host g alaxy\, or alternatively\, may themselves have accreted yet smaller system s whose debris settles into the satellite’s own stellar halo. Both proce sses could mean that significant populations of member stars are found far from the center of the dwarf. Stars in the outskirts of these systems are especially valuable – and rare – tracers of the dwarf’s dynamics in low acceleration regimes\, and they give insight into the dwarf’s evolu tionary history. In this work\, we examine the MW’s ~60 dwarf satellites to search for these rare\, distant member stars. Using Gaia eDR3 and a ma ximum likelihood approach allowing for multi-component extended substructu res\, we find 9 dwarfs that exhibit a secondary\, lower-density\, outer pr ofile\, that we argue is indicative of an extended stellar halo and/or tid al disruption. Our method shows excellent consistency with spectroscopical ly confirmed members from the literature and requires no radial velocity i nformation. For each dwarf galaxy\, we derive a sample of high-confidence members which will prove useful for studying even the faintest MW dwarfs. We also briefly discuss a current spectroscopic follow-up campaign for the most radially distant outskirt members\, which will feature the newly com missioned Gemini High-resolution Optical SpecTrograph (GHOST). Already\, i nitial spectra obtained during GHOST commissioning has proven useful for c omprehensive chemodynamics of these Galactic building blocks.\n\nhttps://m eetings.aip.de/event/20/contributions/198/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/198/ END:VEVENT BEGIN:VEVENT SUMMARY:Dynamical evolution of the sub-galactic dark matter halos and the effect of the cusp-to-core transformation DTSTART;VALUE=DATE-TIME:20230322T093300Z DTEND;VALUE=DATE-TIME:20230322T093500Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-266@meetings.aip.de DESCRIPTION:Speakers: Yuka Kaneda (University of Tsukuba)\nIn the hierarch ical clustering scenario based on the $\\Lambda$ cold dark matter ($\\Lamb da$CDM) model\, sub-galactic dark matter halos (subhalos) are of crucial i mportance in building up the larger structures via merging processes. More over\, dwarf galaxies around the Milky Way (MW) are ideal sites for studyi ng the nature of dark matter since they are dark-matter-dominated systems. \n\nWe investigate the mass evolution histories and the evolutional track s on the $r_\\mathrm{max}$-$V_\\mathrm{max}$ plane of the subhalos associa ted with MW-sized host halos based on the ultra-high resolution cosmologic al $N$-body simulation\, Phi-4096 by Ishiyama et al. (2021)\, where $V_\\m athrm{max}$ and $r_\\mathrm{max}$ denote the maximum circular velocity and the radii where the circular velocity becomes $V_\\mathrm{max}$\, respect ively. We report that the evolutional tracks of dwarf-galaxy-mass halos sh ow an interesting feature compared to the ones of massive halos shown in t he literature. The mass evolution of subhalos clearly shows two phases: th e accretion phase and the stripping phase. First\, more than 90% of our sa mple subhalos increase their masses gradually until the redshift $z=1-2$ ( accretion phase)\, and then the masses decrease due to the tidal stripping driven by the host halo (stripping phase). Thus\, we show quantitatively that tidal stripping plays an essential role in the dynamical evolution of subhalos.\n\nIn addition\, the mass density profile of subhalos has a lon g-standing disagreement between the observations and the predictions by th e pure CDM simulations\, known as the cusp-core problem. Standing on a hyp othesis that DM halos are formed primarily with central cusps and then som e dynamical processes lead them to form cores\, we provide a ‘core-to-cu sp transformation model’ that reverts the properties of cored profile to ones of the cusp profile. In constructing a model\, some appropriate cond itions are imposed about how the transition should occur\, and detailed ph ysical processes are not considered here. The reverted observational prope rties\, including $r_\\mathrm{max}$ and $V_\\mathrm{max}$\, show excellent agreement with the theoretical prediction from the cosmological $N$-body simulation. This result supports the description that the CDM creates init ial cusps in the centre of DM halos\, and some dynamical process gives ris e to the cusp-to-core transformation.\n\nhttps://meetings.aip.de/event/20/ contributions/266/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/266/ END:VEVENT BEGIN:VEVENT SUMMARY:The Cosmic Hunt for Members in the Outskirts of Ultra Faint Dwarf Galaxies: Ursa Major I\, Coma Berenices\, and Boötes I DTSTART;VALUE=DATE-TIME:20230322T093100Z DTEND;VALUE=DATE-TIME:20230322T093300Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-264@meetings.aip.de DESCRIPTION:Speakers: Fletcher Waller (University of Victoria)\nThe chemic al abundance patterns exhibited by stars in Ultra-Faint Dwarf (UFD) galaxi es can provide a wealth of information about the evolutionary history of U FDs\, including what dynamical history the stars in a UFD may have experie nced. Of particular interest are stars in the outer regions of UFDs becaus e they may hold evidence of tidal stripping\, mergers\, or other mechanism s\; and because of the localized nature of enrichment events in UFDs\, it is important to use every available star in analyses of UFD histories. I p resent detailed abundances from high-resolution spectroscopy with Gemini/G RACES for five new stars in three UFDs\, Coma Berenices (Com Ber)\, Ursa M ajor I (UMaI)\, and Boötes I (BooI)\, where four of our five stars are at distances greater than two half-light radii. The chemistries for all thre e galaxies are consistent with the outermost stars forming in the central regions\, then moving to their current locations through dynamical mechani sms. In BooI\, the lower metallicity and lack of strong carbon enrichment of its outermost stars could also be evidence of a dwarf galaxy merger. Th e abundance ratios and chemical patterns of the stars in Com Ber are consi stent with contributions from SN Ia (including an unusually high Ni value) \, which is unexpected for its star formation history and in conflict with previous suggestions that this system evolved chemically from a single co re collapse supernova event. We look forward to the new GHOST (Gemini High -resolution Optical SpecTrograph)\, which will make these types of chemica l abundance-quality observations possible for many more stars in UFDs.\n\n https://meetings.aip.de/event/20/contributions/264/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/264/ END:VEVENT BEGIN:VEVENT SUMMARY:Dynamical modelling of cosmologically simulated Dwarf galaxy DTSTART;VALUE=DATE-TIME:20230322T115000Z DTEND;VALUE=DATE-TIME:20230322T115200Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-265@meetings.aip.de DESCRIPTION:Speakers: Amrit Sedain (University of Potsdam)\nProlate rotati on in galaxies (rotation around the major axis) is a rare phenomenon in th e Universe. The effect has been exclusively attributed to past major merge rs and thus studies of prolate-rotating systems can help us better underst and the hierarchical process of galaxy evolution. Dynamical studies of suc h galaxies is important to find their gravitational potential profile\, to tal mass\, and dark matter fraction. Recently\, it has been shown from cos mological simulation that it is possible to form a prolate-rotating dwarf galaxy following a dwarf-dwarf merger event. The simulation also shows tha t the unusual prolate rotation can be time enduring. In this particular ex ample the galaxy started rotating around its major axis about 7.4 Gyr ago and it is still continuing at the present time. In this project\, we use m ock observations of the hydrodynamically simulated galaxy to fit various s tages of its evolution with Jeans dynamical models. The Jeans model succes sfully fits the early oblate state and also for late prolate stage of simu lated galaxy\, prior the major merger event\, recovering the anisotropy\, mass density distribution\, velocity dispersion\, and rotation of the simu lated galaxy. This master thesis project is an important connecting link b etween cosmological simulations and real observational data\, as many prol ate rotation galaxies are being discovered.\n\nhttps://meetings.aip.de/eve nt/20/contributions/265/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/265/ END:VEVENT BEGIN:VEVENT SUMMARY:The Formation of Planes of Satellite Galaxies in the Local Group DTSTART;VALUE=DATE-TIME:20230322T114800Z DTEND;VALUE=DATE-TIME:20230322T115000Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-263@meetings.aip.de DESCRIPTION:Speakers: Janvi Madhani ()\nNumerous observations in recent ye ars have shown that the satellite galaxies orbiting our local galaxies ten d to align their orbits in one or two thin planes around the host galaxy. This has been observed in local galaxies\, Andromeda and Centaurus A\, and our own Milky Way. Numerical simulations in a cosmological context find t hese planes to be rare or short-lived leading to tension between observati on and theory. This leads to considerable debate on whether observations a re compatible with the standard\, Lambda Cold Dark Matter\, model of cosmo logy. We argue that on large scales\, these simulations did not sufficient ly resolve the nearby large-scale structure\, cosmic filaments\, which we believe to be responsible for the anisotropic infall of satellites forming planar alignments\, and on smaller scales\, they did not sufficiently res olve dwarf satellite galaxies. We use the high precision\, hydrodynamic\, cosmological zoom simulation\, New Horizon\, which has both the large volu me\, (16 Mpc)$^3$ and the small-scale resolution\, ~ 35 pc\, required to s tudy the interplay between cosmic web dynamics and the formation\, funneli ng\, and eventually the anisotropic distribution of satellites around loca l galaxies. Our results indicate that these planes exist in New Horizon in ~ 30% of Milky Way-type systems. The identified planes are comparable to observation in both physical extent and kinematic coherence. We also find that the distribution of dwarf satellites within their host dark matter ha loes is more anisotropic than previously understood.\n\nhttps://meetings.a ip.de/event/20/contributions/263/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/263/ END:VEVENT BEGIN:VEVENT SUMMARY:The origin of stellar ellipticity in tidally isolated ultra-faint dwarfs DTSTART;VALUE=DATE-TIME:20230322T114600Z DTEND;VALUE=DATE-TIME:20230322T114800Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-257@meetings.aip.de DESCRIPTION:Speakers: Alex Goater (University of Surrey)\nUltra-faint dwar f galaxies (UFDs) are often found in large numbers in close proximity to t he Milky Way and other massive spiral galaxies. As such\, their projected stellar ellipticity and extended light distributions are often thought to owe to tidal forces. I discuss the projected stellar ellipticities and fai nt stellar outskirts of isolated ultra-faints\, drawn from the `Engineerin g Dwarfs at Galaxy Formation’s Edge’ (EDGE) cosmological simulation su ite. I find that\, in spite of their tidal isolation\, the simulated dwarf s exhibit a wide range of projected ellipticities ($0.03 \n\nhttps://meeti ngs.aip.de/event/20/contributions/257/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/257/ END:VEVENT BEGIN:VEVENT SUMMARY:Revealing mass distributions of dwarf spheroidal galaxies in the S ubaru-PFS era DTSTART;VALUE=DATE-TIME:20230322T103000Z DTEND;VALUE=DATE-TIME:20230322T104500Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-204@meetings.aip.de DESCRIPTION:Speakers: Kohei Hayashi (NIT\, Ichinoseki college)\nThe dwarf spheroidal galaxies (dSphs) in the Local Group are excellent test beds for probing the properties of dark matter and its role in galaxy formation.\n These galaxies are sufficiently close that it is possible to measure line- of-sight velocities for large samples of resolved stars. This kinematic in formation enables us to study the structural properties of their dark matt er halos.\nHowever\, there are non-negligible uncertainties in the determi nation of the mass profiles of dark matter. \nIn particular\, this study h as been hampered by the well-known degeneracy between dark matter mass den sity and the anisotropy of the stellar velocity dispersion tensor\, which can lead to erroneous mass estimates.\nThe information encoded in the shap e of the line-of-sight velocity distribution (LOSVD) is potentially a stro ng tool to break this degeneracy\, but this requires sufficiently large ki nematic samples over the full radial extent of dSphs and identification of foreground contamination. \nThe combination of the 1.25 deg^2 field and 2394 fibers of the Subaru Prime Focus Spectrograph (PFS)\, plus pre-imagin g with Hyper Suprime Cam\, will allow us to make significant progress in t his undertaking. Furthermore\, the unique capability of PFS will permit us to revisit the core/cusp problem.\nIn this talk\, I will discuss the feas ibility and future prospects for this dark matter study with Subaru-PFS su rvey using mock stellar samples.\n\nhttps://meetings.aip.de/event/20/contr ibutions/204/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/204/ END:VEVENT BEGIN:VEVENT SUMMARY:Quenching and ram pressure in simulated low-mass Local Group galax ies DTSTART;VALUE=DATE-TIME:20230322T114400Z DTEND;VALUE=DATE-TIME:20230322T114600Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-262@meetings.aip.de DESCRIPTION:Speakers: Jenna Samuel (UT Austin)\nLow-mass or dwarf galaxies are particularly compelling laboratories for star formation quenching bec ause they are highly susceptible to quenching effects from both internal s tellar feedback and external environment. We explore the role of ram press ure in the environmental regulation of gas content and quenching of low-ma ss galaxies in zoom-in hydrodynamic simulations of Milky Way (MW) mass hos ts. The quiescent fraction of low-mass galaxies increases as their stellar mass decreases and as their distance to a MW-mass host decreases\, simila r to the Local Group. In addition\, the location of a satellite at quenchi ng (in a MW halo\, in a low-mass group\, or in isolation) and the timing o f quenching with respect to different events like infall or pericenter pas sage depend on the mass of the satellite galaxy. In particular\, we find t hat MW satellites can be efficiently quenched before infall into a MW halo by pre-processing in low-mass groups\, where they experience ram pressure comparable to that in a MW halo. Interestingly\, the density of halo gas near paired Local Group-like hosts is enhanced at small angles/latitudes o ff the host galaxy disk versus directly above or below the disk. Prelimina ry results indicate that both observed and simulated satellites within the se low-latitude regions at z=0 may be preferentially quenched\, similar to recently reported anisotropic quenching in massive galaxy clusters at low redshift. In addition\, we briefly discuss morphological changes to low-m ass galaxies induced by the Local Group environment\, such as the formatio n of ultra diffuse galaxies via tidal shocks.\n\nhttps://meetings.aip.de/e vent/20/contributions/262/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/262/ END:VEVENT BEGIN:VEVENT SUMMARY:Environmental secular evolution of satellite galaxies DTSTART;VALUE=DATE-TIME:20230322T114200Z DTEND;VALUE=DATE-TIME:20230322T114400Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-259@meetings.aip.de DESCRIPTION:Speakers: Matias Blaña (Instituto of Astrophysics\, Pontifici a Universidad Católica de Chile)\nIn this talk I will present our results on environmental secular evolution processes that affect satellite galaxi es as they enter their hosts. \nOur approaches consist of global statistic al analysis of satellites\, and the modelling of detailed observations. Fo r the latter approach we study distant gas rich dwarf satellites like Leo T and Phoenix\, which are entering the Milky Way. Both satellites present non-equilibrium offsets between their gaseous and stellar distributions\, with Leo T also showing an offset between its younger and older stellar po pulations. Using hydrodynamical simulations that include the Milky Way cor onal wind\, we find that cored dark matter density models can better repro duce the estimated timescales of the offsets in Leo T.\nFrom the global ap proach we present our latest analysis of the Milky Way and the Andromeda s atellite galaxies\, finding a transition radius at R*~0.4-0.6Rvir that del imits an inner satellite population with stellar densities that correlate with the tidal field of their hosts\, and an outer less processed populati on. Furthermore\, we find that this transition radius is also present in s atellites of the Fornax and Virgo galaxy clusters\, as well as in their co smological galaxy simulation counterparts.\n\nhttps://meetings.aip.de/even t/20/contributions/259/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/259/ END:VEVENT BEGIN:VEVENT SUMMARY:Does the presence of old globular clusters in low-mass galaxies di sprove modified gravity? DTSTART;VALUE=DATE-TIME:20230322T114000Z DTEND;VALUE=DATE-TIME:20230322T114200Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-255@meetings.aip.de DESCRIPTION:Speakers: Michal Bilek ()\nThe discussion "dark matter vs. mod ified gravity" has not been resolved yet. It was proposed that dynamical f riction could be used to discriminate between the two alternatives. Analyt ic calculations indicate that\, with modified gravity\, globular clusters (GCs) of low-mass galaxies experience much stronger dynamical friction tha n in the equivalent system with Newtonian gravity and dark matter. As a re sult\, in modified gravity the dynamical friction should have already forc ed the old GCs of low mass galaxies to settle in the centers of the galaxi es. This is not observed. I will report on our efforts to verify the analy tic results by self-consistent simulations with the MOND gravity. We publi shed already that the core stalling mechanism\, that was not considered in the analytic calculations\, prevents GC to settle in centers of ultra-dif fuse galaxies. In our ongoing work\, we investigate GCs of isolated dwarf galaxies. It seems so far that GCs of these galaxies survive if the do not move within the galaxy disk\, or if they counterrotate with respect of th e galaxy disk. In the simulations done so far\, supernova explosions influ ence the orbits of GCs only at low numerical resolution.\n\nhttps://meetin gs.aip.de/event/20/contributions/255/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/255/ END:VEVENT BEGIN:VEVENT SUMMARY:Kinematical asymmetry in the dwarf irregular galaxy WLM and a pert urbed halo potential DTSTART;VALUE=DATE-TIME:20230322T092900Z DTEND;VALUE=DATE-TIME:20230322T093100Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-256@meetings.aip.de DESCRIPTION:Speakers: Maryam Khademi (IPM \, Institute for Research in Fun damental Sciences (IPM)\, School of Astronomy)\nTo investigate the dynamic al nature of the kinematic asymmetry in the isolated gas-rich dwarf irregu lar galaxy W LM in the Local Group\, we first examine whether an m = 1 per turbation in the halo potential could be a mechanism creating such kinemat ical asymmetry. \nBy fitting a theoretical rotational velocity associated with an m = 1 perturbation in the halo potential model to the observed dat a\, we show that such a lopsided halo potential model can explain the asym metry in the kinematic data reasonably well.\nIn addition\, we study the k inematical classification of the velocity field of WLM with various method s\, and based on a kinemetry analysis\, we find that it is possible for WL M to lie in the transition region\, where the disk and merger coexist. Thu s\, a merger may indeed be one of the possible origins of the dark matter halo lopsidedness for this isolated galaxy.\n\nhttps://meetings.aip.de/eve nt/20/contributions/256/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/256/ END:VEVENT BEGIN:VEVENT SUMMARY:Stellar metallicities in the extremely low mass galaxy Leo P DTSTART;VALUE=DATE-TIME:20230322T092700Z DTEND;VALUE=DATE-TIME:20230322T092900Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-236@meetings.aip.de DESCRIPTION:Speakers: Heitor Ernandes (Lund Observatory)\nLeo P is a poorl y studied near-primordial isolated dwarf irregular galaxy at a distance of ∼ 1.6 Mpc\, with an extremely low mass of ∼ 105M⊙.\nFrom Hubble Spa ce Telescope and Arecibo Legacy Fast observations\, its characteristics sh ow the same behaviour as expected in a low-luminosity dSph Milky Way satel lite. It was defined as the “quintessential system to test theories of h ow the smallest structures in our universe survive and grow.”\nObservati ons suggest an ongoing star formation in its prominent H II region. This f eature also gives estimations of the oxygen abundance which is around 3% o f solar. It makes it one of the most metal-poor galaxies known in the loca l Universe.\nIn this work\, we present the first estimated spectroscopic m etallicities of evolved cool stars in Leo P. We use MUSE data to extract a nd analyse the spectra of 16 red giant branch stars. In order to derive th e metallicity of Leo P we apply literature calibrations for our equivalent widths measurements of the Ca II triplet lines.\nWe will also present ten tative luminosity- and stellar mass-metallicity relations compared to othe r low-metallicity galaxies (e.g. I Zw 18\, DDO 68\, and SBS 0335-052W) to check the previously detected offset of these other galaxies\, with respec t to Leo P\, in these relations.\n\nhttps://meetings.aip.de/event/20/contr ibutions/236/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/236/ END:VEVENT BEGIN:VEVENT SUMMARY:3D Velocities of Local Group dwarf galaxies combining HST and Gaia DTSTART;VALUE=DATE-TIME:20230322T092500Z DTEND;VALUE=DATE-TIME:20230322T092700Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-224@meetings.aip.de DESCRIPTION:Speakers: Paul Bennet (Space Telescope Science Institute)\nGai a has revolutionized our understanding of the Milky Way (MW) and its satel lite system. However\, the proper motions (PMs) of dwarf galaxies outside the MW system remain out of reach by Gaia and will remain so even with fut ure data releases. This is problematic\, as it means that our understandin g of systems outside the MW will be limited and we may be basing much of o ur cosmological modeling on the MW alone\, which may be atypical. This lim itation can be overcome through the use data from the Hubble Space Telesco pe\, either obtained at two different epochs\, or at one past epoch and co mbined with more recent Gaia positions. I will present new PMs obtained in this manner for a sample of distant dwarf galaxies in the Local Group (LG )\, expanding the number of systems for which we have full position-veloci ty information. These can be used to calculate the implied orbits. I will discuss how this information allows new science with the LG dwarfs and th eir hosts\, linking the star formation and orbital histories of dwarfs to determine when specific dwarfs quenched and whether they are first-infal l or ‘backsplash’ galaxies and how we can use this to determine host p roperties such as halo mass and the extent of the hot gas halo.\n\nhttps:/ /meetings.aip.de/event/20/contributions/224/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/224/ END:VEVENT BEGIN:VEVENT SUMMARY:Leo T Dissected with the MUSE-Faint Survey DTSTART;VALUE=DATE-TIME:20230322T091000Z DTEND;VALUE=DATE-TIME:20230322T092500Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-203@meetings.aip.de DESCRIPTION:Speakers: Daniel Vaz (Instituto de Astrofísica e Ciências do Espaço)\nPrevious studies of Ultra-Faint Dwarfs (UFDs) show that their d ynamical mass-to–light ratios are the highest values measured in any typ e of galaxy\, implying relatively pure dark-matter halos with minimal bary onic content. Furthermore\, UFDs have the lowest metallicities\, oldest ag es\, smallest sizes\, and simplest assembly histories of all galaxies. Und erstanding the nature of these galaxies would improve immensely the knowle dge of the galaxy formation process and help to unravel the nature of dark matter.\n\nThe Leo T UFD is one of the lowest mass galaxies known to cont ain neutral gas and to be also extremely dark-matter dominated. Previous s tudies have shown signs of recent star formation in the galaxy\, making it one of the very faintest galaxies to show this. It is\, therefore\, an in teresting laboratory for studies of gas and star formation at the limit of where galaxies are found to have rejuvenating episodes of star formation. \n\nIn this contribution I will discuss a novel study of Leo T that we hav e done using data from the MUSE integral field spectrograph. The high sens itivity of MUSE allowed us to obtain velocity measurements for stars as fa int as magnitude ~24\, which allowed us to increase the number of Leo T st ars observed spectroscopically from 19 to 75.\nCombining the MUSE data wit h photometric data from HST\, we have studied the age and metallicity of t hese stars and identified two populations\, all consistent with similar me tallicity. Within the young population sample we discovered three emission line Be stars - a first for ultra-faint dwarfs.\nWhile looking for differ ences in the dynamics of young and old stars\, we find that they have diff erent kinematics\, with the young population having a velocity dispersion consistent with the kinematics of the cold component of the neutral gas. \ nIn this contribution I will discuss these results and their implications for the origin and evolution of Leo T.\n\nhttps://meetings.aip.de/event/20 /contributions/203/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/203/ END:VEVENT BEGIN:VEVENT SUMMARY:High resolution spectroscopy of stars in the outskirts of the Tuca na II ultra-faint dwarf galaxy DTSTART;VALUE=DATE-TIME:20230322T085500Z DTEND;VALUE=DATE-TIME:20230322T091000Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-202@meetings.aip.de DESCRIPTION:Speakers: Anirudh Chiti (University of Chicago)\nWe present ki nematics and detailed chemical abundances of stars in the outskirts (out t o ~8 half-light radii) of the Tucana II ultra-faint dwarf galaxy ( 10^7 so lar masses out to 1 kpc). Our results suggest that key factors (e.g.\, mos t metal-poor stars\, evidence of extended halos) in understanding the earl y evolution and dynamical state of these relic galaxies lie in their outsk irts and may have been missed by previous observational work. We demonstra te that detailed spectroscopic studies of individual stars in such low sur face brightness features are now possible.\n\nhttps://meetings.aip.de/even t/20/contributions/202/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/202/ END:VEVENT BEGIN:VEVENT SUMMARY:The Dark Matter Density Profiles of Antlia B DTSTART;VALUE=DATE-TIME:20230322T084000Z DTEND;VALUE=DATE-TIME:20230322T085500Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-201@meetings.aip.de DESCRIPTION:Speakers: Mariana P. Júlio (AIP)\nOne particularly promising way to understand the nature of dark matter is to study the so-called core -cusp problem. Many solutions have been investigated to solve it and one p ossibility is that the nature of the dark matter itself is different from the successful $\\Lambda$-Cold Dark Matter model. To reduce the impact of baryonic physics which obscures our ability to constrain dark matter\, we need to study the most dark matter dominated systems known\, ultra-faint d warfs. \nHere we present the first spectroscopic observations of the Antli a B\, a distant (d ∼ 1.35 Mpc) ultra-faint dwarf ($M_V = -9.4$\, M$_\\st ar ∼ 8\\times 10^5$M$_\\odot$ )\, from MUSE-Faint – a survey of ultra- faint dwarfs with the Multi Unit Spectroscopic Explorer. We measure line-o f-sight velocities of 127 member stars\, and combine these with GravSphere \, a Jeans modelling code\, to place constraints on dark matter and derive the first dark matter density profile for this object.\n In particular we present constraints on the nature of self-interacting dark matter (SIDM) that is based on the assumption that the dark matter particles can scatter with one another\, being able to transport heat through the dark matter h alo\, altering the halo structure – and\, possibly\, producing a constan t-density core in the heart of the halo\; and scalar field dark matter (SF DM) that is a Bose-Einstein condensate and a quantum superfluid and can su ppress structure formation when there is a strong repulsive self-interacti on. These are to our knowledge the first constraints on SFDM using ultra-f aint dwarf galaxies and we show that we can rule out SFDM as an explanatio n for the cores in the larger dwarf galaxies in the Local Group. We also s how that if Antlia B has a core produced by SFDM\, the characteristic leng th scale of the repulsive self-interaction has to be smaller than $R_{\\te xt{TF}} \\approx 0.37$ kpc.\n\nhttps://meetings.aip.de/event/20/contributi ons/201/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/201/ END:VEVENT BEGIN:VEVENT SUMMARY:An aMUSEing view of the dwarf irregular galaxy IC 1613 DTSTART;VALUE=DATE-TIME:20230322T082500Z DTEND;VALUE=DATE-TIME:20230322T084000Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-199@meetings.aip.de DESCRIPTION:Speakers: Salvatore Taibi (Leibniz-Institute for Astrophysics Potsdam)\nAnalysing the stellar kinematic properties of a dwarf galaxy mak es it possible to investigate which internal mechanisms have shaped its ev olution. Isolated dwarf galaxies with an extended star formation history\, in particular\, offer the opportunity to study not only star formation pr ocesses at low-mass and low-metallicity scales\, but also to understand ho w internal kinematic properties evolve thanks to the possibility of a comb ined comparison of gas kinematics with that of young and old stars. \n\nIn this context\, we have analysed a new spectroscopic dataset of the isolat ed gas-rich dwarf galaxy IC 1613 taken with the integral-field-unit MUSE i nstrument mounted on the Very Large Telescope (VLT)\, capable of combining high spatial resolution to a wide spectral coverage (4750 − 9300 AA) wi th a resolving power of R = 1500 − 3000. Thanks to this revolutionary in strument\, we obtained a large dataset of ~2000 sources extracted from 3 p ointings\, of which we could reliably perform spectral classification and radial velocity determination for more than 800 stars. We were also able t o obtain metallicities from Ca II triplet lines for a selected subsample o f ~300 red giant branch stars. This dataset is the largest currently colle cted for an isolated dwarf galaxy in the Local Group. \n\nFrom the spectra l classification we found giant stars of all stellar types\, with a large predominance of red giant branch stars\, as to be expected. We were also a ble to identify a sample of C-star candidates\, useful for determining the spectroscopic C/M ratio\, and hot emission line stars as an additional ki nematic tracer for young stars.\nThe preliminary kinematic analysis has le d to a systemic velocity and a velocity dispersion both in agreement with previous literature values. We also found with high statistical significan ce a linear rotation signal along the optical major axis of the galaxy\, w hich is a novelty. Stars follow the velocity field of the neutral HI compo nent\, although they start to decouple from the gas motion around the half -light radius. When subdivided according to age\, young and old stars seem to follow similar kinematic trends\, although the statistics for young st ars drop dramatically in the outermost pointings. \nFinally\, chemical ana lysis resulted in an average [Fe/H] that was slightly higher than literatu re values\, but within the rms dispersion of the stellar luminosity-metall icity relation. We found no evidence of a radial metallicity gradient\, co mpatible with results from other similarly luminous dwarf galaxies.\n\nReg ardless of results actually obtained\, we want to show the vast research p ossibilities that MUSE offers in the field of resolved stellar populations in nearby dwarf galaxies\, whose surface we have only scratched.\n\nhttps ://meetings.aip.de/event/20/contributions/199/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/199/ END:VEVENT BEGIN:VEVENT SUMMARY:Understanding the formation of the extremely diffuse Andromeda XIX dwarf galaxy DTSTART;VALUE=DATE-TIME:20230322T080000Z DTEND;VALUE=DATE-TIME:20230322T082500Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-177@meetings.aip.de DESCRIPTION:Speakers: Michelle Collins (University of Surrey)\nAndromeda ( And) XIX is a unique dwarf galaxy in the M31 system. Its large half-light radius (in excess of 3 kpc) and low surface brightness (29.3 magnitudes pe r square arcsecond) make it one of the most diffuse galaxies in the known Universe. In addition to its extreme structural properties\, its dynamics also suggest that it sits in a low density dark matter halo that may have been shaped by tidal forces. To understand how such a galaxy could form\, we acquired deep HST imaging to resolve stars in this system down to its o ldest main sequence turn-off. These allow us to measure a detailed star fo rmation history for And XIX for the first time. In this talk\, I will pres ent our findings from these data in concert with chemodynamical observatio ns. These will allow me to confront various theories for the formation of And XIX and discuss how such galaxies may form.\n\nhttps://meetings.aip.de /event/20/contributions/177/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/177/ END:VEVENT BEGIN:VEVENT SUMMARY:Kinematics of The Tidally Disrupting Dwarf Galaxy Antlia II DTSTART;VALUE=DATE-TIME:20230321T163500Z DTEND;VALUE=DATE-TIME:20230321T165000Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-197@meetings.aip.de DESCRIPTION:Speakers: Alexander Ji ()\nThe Milky Way satellite dwarf galax y Antlia II is one of the lowest surface brightness galaxies known. It has a size comparable to the Large Magellanic Cloud\, but only 10^6 solar mas ses of stars. We present kinematic and chemical measurements from the Sout hern Stellar Stream Spectroscopic Survey using the AAT/2dF\, which clearly demonstrate that Antlia II is tidally disrupting. The orbit and velocity gradient also clearly shows that the Milky Way has moved in response to th e Large Magellanic Cloud. However\, Antlia II currently lies on the galaxy mass-metallicity relation\, suggesting that it has not lost too much stel lar mass. These measurements constrain the density profile of Antlia II an d generally illustrate the importance of full dynamic models when interpre ting the masses of local group galaxies.\n\nhttps://meetings.aip.de/event/ 20/contributions/197/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/197/ END:VEVENT BEGIN:VEVENT SUMMARY:On the many observational challenges to estimating the masses of d warf galaxies DTSTART;VALUE=DATE-TIME:20230321T155500Z DTEND;VALUE=DATE-TIME:20230321T163500Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-293@meetings.aip.de DESCRIPTION:Speakers: Alan McConnachie (NRC Herzberg)\nI will briefly summ arise the key methods for the determination of the dynamical mass and mass profiles of dwarf galaxies. I will then discuss in detail the observatio nal challenges associated with making the necessary measurements and obtai ning the necessary data\, with a focus on the systematic\, technical\, and physical limitations of the measurement. I will review the implications o f these limitations for the science we want to do\, and I will summarise f uture prospects for overcoming these challenges.\n\nhttps://meetings.aip.d e/event/20/contributions/293/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/293/ END:VEVENT BEGIN:VEVENT SUMMARY:Lopsidedness in Andromeda's satellite galaxy distribution: A renew ed tension with CDM simulations DTSTART;VALUE=DATE-TIME:20230322T112500Z DTEND;VALUE=DATE-TIME:20230322T114000Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-196@meetings.aip.de DESCRIPTION:Speakers: Kosuke Jamie Kanehisa (Leibniz-Institut für Astroph ysik Potsdam)\nDwarf satellite galaxies around Andromeda (M31) and the Mil ky Way form thin\, coherently rotating planes argued to be in tension with expectations from the cold-dark-matter (CDM) model of cosmology. For M31\ , this disagreement is compounded by a prominent asymmetry in its satellit e distribution\; over 80% of its dwarfs lie in the hemisphere facing the M ilky Way. To a degree\, lopsided dwarf galaxy systems appear to be ubiquit ous in the local Universe and may reflect an underlying asymmetry in their hosts' dark matter halo morphology - in turn carrying implications for ha lo mass estimates derived from satellite dynamics. Adopting a recently pub lished set of homogeneous\, RR Lyrae-based distances to the M31 satellites \, we discovered that the existing asymmetry is strengthened. 34 out of 35 satellites are contained within a cone with an opening angle of 202 degre es (or 213 degrees facing the Milky Way)\, while the luminous dwarf M110 d ominates the nearly hemispheric void on the other side. We further studied the rarity of similarly asymmetric dwarf galaxy distributions in several state-of-the-art cosmological simulations. Even when accounting for the lo ok-elsewhere effect in selecting a preferred opening angle\, less than 0.4 % of M31 analogs host satellite systems that match or exceed the observed asymmetry. The significance of the M31 satellites' observed asymmetry towa rds the Milky Way in CDM simulations now rivals that of M31's plane-of-sat ellites\, cementing the Andromeda system as a striking outlier from cosmol ogical expectations.\n\nhttps://meetings.aip.de/event/20/contributions/196 / LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/196/ END:VEVENT BEGIN:VEVENT SUMMARY:Gaia EDR3 proper motions\, energies\, angular momenta of Milky Way dwarfs: a recent infall to the Milky Way halo DTSTART;VALUE=DATE-TIME:20230322T110000Z DTEND;VALUE=DATE-TIME:20230322T112500Z DTSTAMP;VALUE=DATE-TIME:20240704T115708Z UID:indico-contribution-55-174@meetings.aip.de DESCRIPTION:Speakers: Yanbin Yang (CNRS France / Paris Observatory)\nGaia EDR3 has provided proper motions of Milky Way (MW) dwarf galaxies with an unprecedented accuracy\, which allows us to investigate their orbital prop erties. We found that the total energy and angular momentum of MW dwarfs a re much larger than that of MW K-giant stars\, Sagittarius stream stars an d globular clusters. It suggests that many MW dwarfs have recently infall into the Milky Way halo. We also confirmed that Milky Way dwarfs lie prefe rentially near their pericenters and many of them belong to a vast polar s tructure perpendicular to the Milky Way disk\, which suggests that Milky W ay dwarfs do not behave like satellite systems derived from LCDM cosmologi cal simulations. These new results require revisiting the origin of MW dwa rf galaxies\, e.g.\, if they came recently\, they were likely to have expe rienced gas removal due to the ram pressure induced by MW’s hot gas\, an d to be affected by MW tides. We will discuss the consequences of these pr ocesses on their mass estimation.\n\nhttps://meetings.aip.de/event/20/cont ributions/174/ LOCATION:Haus H\, Telegrafenberg URL:https://meetings.aip.de/event/20/contributions/174/ END:VEVENT END:VCALENDAR