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Cake talk by Sam Cutler (University of Massachusetts Amherst)
Feb 11 @ 15:00 – 15:30


Diagnosing DASH: A Morphological Catalog for the COSMOS-DASH Survey


COSMOS-DASH is a 0.5 square degree survey of the COSMOS field, obtained utilizing the novel “Drift And SHift” (DASH) observing technique for HST-WFC3 imaging. While DASH observations are significantly more efficient than standard HST imaging, they also are shallower and have an unusual data reduction, both of which may impact morphology measurements for fainter galaxies. In this talk I will present the F160W morphological catalog for for 51,534 galaxies in the COSMOS-DASH survey. Using morphological measurements from GALFIT, we recover consistent results with those from the deeper 3D-HST morphological catalogs out to z=2 and logM~10. I will also discuss the parameter space where morphological fits of DASH galaxies are robustly recovered. At logM<10.5, we find a flattening of the quiescent size-mass relation, implying the sizes of low mass quiescent galaxies are more similar to star-forming galaxies with a similar redshift and mass. Trends with axis-ratio and environment also suggest that low mass galaxies that quench in low density environments may retain morphologies comparable to similar mass star-forming galaxies.
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.
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