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SUMMARY:New Puzzles in Galaxy Formation: From the Cosmic Web to the Origin
  of the Hubble Sequence - Viraj Pandya (Columbia University)
DTSTART:20241010T150000Z
DTEND:20241010T160000Z
UID:TALK221917@talks.cam.ac.uk
CONTACT:107123
DESCRIPTION:I will present surprising observational results on the 3D shap
 es and large-scale alignments of high-redshift galaxies from JWST. I will 
 show that there are many more linear\, elongated dwarf galaxies than there
  are round\, circular dwarf galaxies seen in projection at high redshift (
 z>1). This puzzle was first hinted at with HST ~30 years ago but has defie
 d a clear explanation since. After ruling out a detection bias against fai
 nt\, face-on disks with JWST\, I will explore a variety of solutions. One 
 reasonable interpretation is that\, unlike in the local Universe\, the maj
 ority of high-redshift dwarf galaxies (including Milky Way progenitors at 
 z~3) may be significantly flattened along two axes like prolate (cigar-sha
 ped) or triaxial (surfboard-shaped) ellipsoids. This preferential elongati
 on is naturally expected from the tidal field of the filamentary cosmic we
 b\, in which case we should also see strong intrinsic alignments. I will p
 resent evidence for such alignments when averaging over the orientations o
 f background galaxies in a "blank" JWST deep field. We cannot yet rule out
  a lensing origin for the alignments and I will discuss implications for u
 pcoming weak lensing searches with Roman and Euclid. If confirmed\, this n
 ew dominant class of early elongated protogalaxies may hold unique clues a
 bout the origin of the Hubble Sequence and the emergence of early cosmic w
 eb filaments. Finally\, I will also summarize how this seemingly niche puz
 zle bridges together many different areas of astrophysics and cosmology (i
 ncluding Galactic archaeology\, dynamics and dark matter phenomenology)\, 
 unlocks fresh science cases for the upcoming era of Extremely Large Telesc
 opes\, and requires a mixture of theory\, observations\, statistics and AI
 /ML to fully understand.
LOCATION:Hoyle Lecture Theatre\, Institute of Astronomy
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