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Cake Talk: Thomas Greve and Seiji Fujimoto @ Zoom
Jun 24 @ 16:00 – 17:00
When: This Thursday @ 1600 CET
Duration: 1 hour (2 x 20 minute talks + questions)

Thomas Greve:

Galaxy Clusters – Emergence and Prominence
Galaxy clusters are the most massive gravitationally-bound objects in the Universe. Their alluring beauty so prominently on display in the present-day Universe, mega-parsec-sized structures containing up to thousands of galaxies residing in massive dark matter halos, belies what is likely a complex and prolonged formation history. In this caketalk I will discuss what we know and don’t know about how galaxy overdensities associated with protoclusters formed and evolved with cosmic time.  I will also discuss what role accreting supermassive black holes, so-called active galactic nuclei (AGN), might have had in the buildup of protoclusters.  I will present result from the RAGERS, SPT, and COSMOS2020 surveys – surveys that we are either leading or are deeply involved in at DAWN.
Seiji Fujimoto: 

ALMA Lensing Cluster Survey: A Sub-kpc View of [CII] emission from a Sub-L* Galaxy in the epoch of reionization

I present bright [CII] 158 μm line detections from a strongly magnified and multiply-imaged (μ20160) sub-L (MUV = 19.75) Lyman-break galaxy (LBG) at z=6.0719 +/- 0.0004 from the ALMA Lensing Cluster Survey (ALCS). Owing to the uniquely deep and wide survey volume being explored by ALCS, we successfully detect emission lines at 268.7 GHz at ≥ 8σ exactly at positions of two multiple images of the LBG behind a massive galaxy cluster. Our lens models, updated with the latest spectroscopy from VLT/MUSE, indicate that a sub region of the LBG crosses the caustic and is lensed into a long (6) arc with a local magnification of μ160, for which the [CII] line is also significantly detected. The source-plane reconstruction resolves the interstellar medium (ISM) structure, showing that the [CII] line is co-spatial with the rest-frame UV continuum at the scale of 300 pc. The [CII] line properties suggest that the LBG is a rotation-dominated system whose velocity gradient explains a slight difference of redshifts between the whole LBG and its sub region. The star formation rate (SFR)-L[CII] relations from the sub to the whole regions of the LBG are consistent with those of local galaxies. We evaluate the lower limit of the faint-end of the [CII] luminosity function at z=6, and find that it is consistent with predictions from semi-analytical models and from a SFR function at z=6 converted with the local SFR-L[CII] relation. These results imply that the local SFR-L[CII] relation is universal for a wide range of scales including the spatially resolved ISM, the whole region of the galaxy, and the cosmic scale, even in the epoch of reionization. I will also present JWST observations for this unique lensed system, which has been approved in cycle 1. I will also introduce our DAWN-IRES summer project working with Hollis at the end of the talk.
Cake Talk: Laia Barrufet and Andrea Weibel (U. of Geneva)
Aug 11 @ 14:00 – 15:00
Laia Barrufet (University of Geneva) – Unveiling the Nature of Infrared Bright, Optically Dark Galaxies with Early JWST Data
Abstract: Over the last few years, both ALMA and Spitzer/IRAC observations have revealed a population of likely massive galaxies at z>3. However, due to the very limited photometry for individual galaxies, the true nature of these so-called HST-dark galaxies has remained elusive. In this talk, I will present the results of 33 HST-dark sources selected based on their red colours across 1.6 to 4.4 micron with NIRCam imaging from the Early Release Science Program CEERS. These galaxies are generally heavily dust-obscured, massive, star-forming sources at z~2-8. Our analysis shows the unique power of JWST to reveal this previously missing galaxy population and to provide a complete census of galaxies at z=2-8 based on rest-frame optical imaging.
Andrea Weibel (University of Geneva) – Is There Spectroscopic Evidence for Ongoing Quenching in SDSS Green Valley Galaxies?
DAWN-IRES presentations @ Room 01.2.I.158
Aug 16 @ 14:00 – 15:15
  • 2:00-2:15: Lauren
    • [CII] as a Tracer of HI Gas in High-z Galaxies
  • 2:15-2:30: Eric
    • [CII] as a tracer of molecular and atomic gas
  • 2:30-2:45: Allan
    • Analyzing ALESS73.1 in CO and [CI]
  • 2:45-3:00: Rebeca
    • Star Formation Efficiency with FLARES
  • 3:00-3:15: Hanga
    • Searching through MOSFIRE Archival Data
Cake talk: Marshall Perrin
Sep 20 @ 15:30 – 16:30

JWST: from First Photons to First Science

After decades of development by a globe-spanning international team, JWST is now providing an unprecedented view of the cosmos. In this talk I will describe our experience thus far operating this new great observatory: from mission design history and development, to prelaunch preparations, to launch and commissioning, and now into the first of many years of mission operations at the Earth-Sun L2 point.  I will provide a first-hand look at the processes and teamwork we used to deploy the observatory and align its segmented mirror system, and discuss some of the surprises (both challenges and good news) encountered during commissioning.  Even early during telescope commissioning, this observatory’s tremendous power and sensitivity were already apparent with spectacular images and spectra. Now during science operations, we continue to learn more about observatory hardware performance; this is still early days in our adventure with JWST. I will close with a look at (a small fraction of) some of the early science results with JWST, with particular attention to our early observations of nearby exoplanetary systems.