BEGIN:VCALENDAR VERSION:2.0 PRODID:-//IAP calendar product//iap.fr// CALSCALE:GREGORIAN X-WR-CALNAME:IAP Journal Club: Galaxies BEGIN:VTIMEZONE TZID:Europe/Paris BEGIN:STANDARD DTSTART:19961027T030000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZNAME:CET TZOFFSETFROM:+0200 TZOFFSETTO:+0100 END:STANDARD BEGIN:DAYLIGHT DTSTART:19810329T020000 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3 TZNAME:CEST TZOFFSETFROM:+0100 TZOFFSETTO:+0200 END:DAYLIGHT END:VTIMEZONE BEGIN:VEVENT SUMMARY:Assembly theory of the Milky Way galaxy DTSTART;TZID=Europe/Paris:20260430T113000 DTEND;TZID=Europe/Paris:20260430T123000 DTSTAMP:20260430T112100Z UID:2026-04-3011:30:00+00:09"AssemblytheoryoftheMilkyWaygalaxy"_I0ryD1oCDf ZZHVEmh7rm DESCRIPTION:Sergey Khoperskov\nAstroph. Inst. Potsdam (AIP)\, Potsdam\, Al lemagne\n\n\nAbstract: How did the Milky Way assemble its present-day disc \, bar\, and bulge\, and what imprint did that history leave on the chemo- dynamical structure we observe today? In this talk\, I present a complete picture of the Galaxy’s assembly based on a novel orbit-superposition re construction of the Milky Way constrained by APOGEE DR17. The method first establishes that orbit-based modelling can recover the stellar density\, kinematics\, and chemical-abundance structure of the Galaxy despite the in complete spatial coverage of the Galactic surveys\, and then uses this fra mework to infer the large-scale organisation of the disc and bulge as well as the spatially resolved star-formation history of the disc. The emergin g picture is that of a Galaxy shaped by coupled secular evolution and long -term inside-out growth: the disc exhibits coherent chrono-chemo-kinematic structure\, including azimuthal metallicity variations in the 6–8 kpc r egion that peak along the bar major axis\, while the inner radial metallic ity profile is flattened by an old\, metal-poor\, high-a population that c ontributes a substantial fraction of the stellar mass (~40%). In the bulge \, chemically distinct components map onto the X-shaped and boxy structure s\, and the absence of a single universal metallicity gradient supports a bulge built primarily out of disc material through bar-driven evolution. F inally\, the reconstructed star-formation history implies that the Milky W ay was a compact system at early times\, experienced its main star-formati on peak 9-10 Gyr ago\, and subsequently grew to its present size through i nside-out disc formation\, with a later episode establishing the outer\, m etal-poor low-a disc. Together\, these results outline a physically connec ted assembly narrative for the Milky Way\, linking present-day orbital str ucture to the Galaxy’s formation history.\n LOCATION:Salle Entresol Daniel Chalonge END:VEVENT BEGIN:VEVENT SUMMARY:Breaking Early-Universe Galaxies Apart & Putting Them Back Togethe r Again DTSTART;TZID=Europe/Paris:20260507T113000 DTEND;TZID=Europe/Paris:20260507T123000 DTSTAMP:20260507T112100Z UID:2026-05-0711:30:00+00:09"BreakingEarly-UniverseGalaxiesApart&PuttingTh emBackTogetherAgain"_dc1ipPHPPjC8rBREJzwc DESCRIPTION:Dr. Taylor Hutchison and Dr. Gourav Khullar\n\nAbstract: T his talk will lay out the landscape of spectroscopic studies of lensed gal axies in the JWST era\, with complementary foci across two talks. \n\n\n Across cosmic time\, star-forming clumps have served as one of the most fundamental building blocks of galaxies. While mapping galaxy formation me chanisms to higher redshift systems is challenging given cosmic scales and sizes\, the marriage of gravitational lensing and space-based telescopes enables us to zoom into sub-kpc regions of individual galaxies at high red shifts\, to investigate the variation and magnitude of ISM conditions and more directly locate where star-forming clumps are situated (& where they are not) at scales similar to local studies (~10-100pc). NASA/ESO/CSA’s JWST observatory has shepherded a new era of spatially-resolved spectrosco py that has truly revolutionized the study of star forming and quenched cl umps in distant galaxies. Specifically\, JWST’s ability to detect contin uum in individual high-redshift clumps provides unprecedented constraints on clump ages and masses when combined with JWST and archival HST imaging. Drs Hutchison (NASA Goddard) & Khullar (Univ. of Washington) will share e xciting spatially-resolved science currently being done with JWST – show ing results from highly-magnified clumpy galaxies across the peak of cosmi c star-formation up to the tail end of the reionization era.\n LOCATION:Salle Entresol Daniel Chalonge END:VEVENT BEGIN:VEVENT SUMMARY:The Ashes of the First Stars: A Transition at z ~ 9 DTSTART;TZID=Europe/Paris:20260518T113000 DTEND;TZID=Europe/Paris:20260518T123000 DTSTAMP:20260518T112100Z UID:2026-05-1811:30:00+00:09"TheAshesoftheFirstStars:ATransitionatz~9"_cTJ mfwpPD0gaeaZhrzss DESCRIPTION:Denis Burgarella\nLab. Astroph. Marseille (LAM)\, Marseille\, France\n\n\nAbstract: Recent observations with JWST and ALMA reveal a sudd en break in the dust content of galaxies at z~9. Dust attenuation and dust -to-stellar mass ratios drop sharply\, implying that early galaxies contai n far less dust than expected. Why does dust seemingly disappear so early? I argue that we are not seeing a lack of dust production\, but a regime w here dust is rapidly destroyed. In this picture\, grains formed in superno vae are efficiently processed by reverse shocks\, leaving behind intrinsic ally dust-poor\, metal-poor systems. This naturally produces a population of galaxies with extremely low dust attenuation (GELDAs)\, where the trans parency is driven by a true deficit of surviving grains\, not by outflows or geometry. When implemented in galaxy models\, this mechanism suppresses the brightest systems and reconciles theory with JWST observation\, witho ut invoking extreme star formation or dust-free galaxies. If correct\, the break at z~9 marks a transition: we may be witnessing galaxies whose dust is shaped\, and largely destroyed\, by the first generations of supernova e\, potentially carrying the imprint of Population III stars. I will concl ude by presenting the PRIMA project\, and its main characteristics\, highl ighting how it will probe the origin and evolution of dust in galaxies.\n LOCATION:Salle Entresol Daniel Chalonge END:VEVENT BEGIN:VEVENT SUMMARY:The Ashes of the First Stars: A Transition at z ~ 9 DTSTART;TZID=Europe/Paris:20260518T113000 DTEND;TZID=Europe/Paris:20260518T123000 DTSTAMP:20260518T112100Z UID:2026-05-1811:30:00+00:09"TheAshesoftheFirstStars:ATransitionatz~9"_OzR gNrvNv6y1xVrFAywB DESCRIPTION:Denis Burgarella\nLab. Astroph. Marseille (LAM)\, Marseille\, France\n\n\nAbstract: Recent observations with JWST and ALMA reveal a sudd en break in the dust content of galaxies at z~9. Dust attenuation and dust -to-stellar mass ratios drop sharply\, implying that early galaxies contai n far less dust than expected. Why does dust seemingly disappear so early? \n\nI argue that we are not seeing a lack of dust production\, but a regim e where dust is rapidly destroyed. In this picture\, grains formed in supe rnovae are efficiently processed by reverse shocks\, leaving behind intrin sically dust-poor\, metal-poor systems. This naturally produces a populati on of galaxies with extremely low dust attenuation (GELDAs)\, where the tr ansparency is driven by a true deficit of surviving grains\, not by outflo ws or geometry. When implemented in galaxy models\, this mechanism suppres ses the brightest systems and reconciles theory with JWST observation\, wi thout invoking extreme star formation or dust-free galaxies. If correct\, the break at z~9 marks a transition: we may be witnessing galaxies whose d ust is shaped\, and largely destroyed\, by the first generations of supern ovae\, potentially carrying the imprint of Population III stars.\n\nI will conclude by presenting the PRIMA project\, and its main characteristics\, highlighting how it will probe the origin and evolution of dust in galaxi es.\n LOCATION:Salle Entresol Daniel Chalonge END:VEVENT END:VCALENDAR