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Rebecca Bowler - Bright galaxies in the first billion years (Diagram…
Rebecca Bowler - Bright galaxies in the first billion years
Probes of high redshift universe
Quasars
Sub-mm galaxies
Gamma-ray bursts
Normal galaxies
Neutral hydrogen?
Select galaxies at high redshift using the lyman-break
Finding the highest redshift requires the best data
Ultra deep fields, GOODS, CANDELS, frontier fields, optical (ACS), and near infra red (WFC3) data
Unrivaled depths, exceeding 30th magnitude
Use ground based telescopes to do wide, smaller limiting magnitude of 25
HST can reveal sizes/morphologies that are elusive in ground-based data
AMA provides unique view of FIR dust and line emission
Optical and near-infrared sectroscopy can reveal rest-UV emission lines
Luminosity functions at high-redshifts
lots of data because of hubble
Typical High z galaxies
very small (r<1kpc)
Not that dusty
Extreme SF conditions, low-Z high-U, alpha enhanced
Brightest galaxies
Brightest SF galaxies at z~7 are composed of multiple clumps under HST resolution
Mergers? Clumpy disks? JWST will tell
Dust continuum emission and FIR lines
ALMA provides unique view of dust emission
Detected in 10 minute
consistent with brightest galaxies being dustier
Potential offset to UV
New deeper data (2 hrs per source)
Why are luminosity functions at high z important
Faint galaxies re-ionised the universe (probably)
Integral gives you the sfr density at very early times
Shape tells you about SF efficiency, quenching, lensing, dust... or a mixture of these
Diagram
Number density of bright LBG unchanged from z~5 to 9
Strongest evolution around knee
At z=4 start to see impact of AGN
Double power law
Evolution in bright-end slope and M* reproduces observations
Schechter function does not reproduce bright data at z>5
With DPL formalism we see bright-end becoming shallower and M* evolving
Indicating a lack of quenching in these bright objects at <1 Gyr, before onset of BH feedback
Or is it indicating a lack of dust obscuration at z>5? Schtechter shape is due to dust in majority of simulations
Future
1000s of bright z>7 LBGs from Euclid and WFIRST
More direct measurements of dust to test this hypothesis
Morphology of star-formation/black hole activity and dust obscuration
JWST
LSST
Probing the Epoch of reionization with 21cm
21cm emission signal will have strong foregrounds
By cross-correlating with gaaxy samples the signal can be recovered
requires large numbers on deg scale
possible with combination of SKA LSST and Euclid