High-Redshift Galaxies: A brief summary Brant Robertson (Caltech) on behalf of David Law (UCLA), Bahram Mobasher (UCR), and Brian Siana (Caltech/Incoming CGE)
Observable Cosmological History t~3.7x10 5 yr t~10 8 yr t~4.8x10 8 yr t~1.2x10 9 yr t~2.2x10 9 yr t~1.37x10 10 yr Recombination Dark Ages Neutral IGM First Stars Form First Galaxies Form Ionized Bubbles Overlap Reionization IGM Mostly Ionized Modern Galaxies Form Today z~1100 z~30 z~10 z~5 z~3 z~0 Robertson et al., Nature, 468, 49 (2010d)
Global History of Galaxy Formation SFR Density Ionized Hydrogen Filling Factor Stellar Mass Density Electron Scattering Optical Depth Robertson et al., Nature, 468, 49 (2010d)
Integrate ionizing photon production rate SFR Density Ionized Hydrogen Filling Factor Integrate star formation rate Integrate ionized path length Stellar Mass Density Electron Scattering Optical Depth
Galaxy formation at z~2-4 t~3.7x10 5 yr t~10 8 yr t~4.8x10 8 yr t~1.2x10 9 yr t~2.2x10 9 yr t~1.37x10 10 yr Recombination Dark Ages Neutral IGM First Stars Form First Galaxies Form Ionized Bubbles Overlap Reionization IGM Mostly Ionized Modern Galaxies Form Today z~1100 z~30 z~10 z~5 z~3 z~0 Reference: David Law
Galaxies at z~2-4: What do we know? A WFC3 Gallery at z~2-4 Local structures largely in place by z~1. z>1 galaxies small (~2 kpc), irregular morphology Outflow features in star-forming galaxies (Steidel et al. 2010) High SFR (~30 Msun/yr) typical, high gas fraction, high vdisp, outflows ubiquitous Understand global properties well: clustering, mass distribution, SFR, etc. Reference: David Law
Galaxies at z~2-4: What we donʼt know. Left: FUV stacked continuum image of z~2 SF galaxies. Right: Continuum-subtracted, stacked Lya emission image. Boxes ~150kpc to a side (Steidel et al. 2011). BPT diagram illustrating the effect of faint AGN on galaxy properties derived from unresolved data (red points: Wright et al. 2010). Reference: David Law How did galaxies accrete their gas? Generally see gas outflows, not inflows. What is the contribution of galaxies to the IGM? What is the prevalence of mergers? What regulates star formation? What do z~2-4 galaxies evolve into at z~0?
Early build up of stellar mass at z~5 t~3.7x10 5 yr t~10 8 yr t~4.8x10 8 yr t~1.2x10 9 yr t~2.2x10 9 yr t~1.37x10 10 yr Recombination Dark Ages Neutral IGM First Stars Form First Galaxies Form Ionized Bubbles Overlap Reionization IGM Mostly Ionized Modern Galaxies Form Today z~1100 z~30 z~10 z~5 z~3 z~0 Reference: Bahram Mobasher
Evolution of High-z Stellar Mass Density Adapted from Yan et al. (2006) Spitzer IRAC detections of restframe optical breaks nominally indicate substantial stellar masses in z~5-6 galaxies. Yan et al. (2006) Mobasher et al. Eyles et al. (2006) Stark et al. (2006) Important constraint on the integrated star formation history of the universe / galaxy formation in general. Reference: Bahram Mobasher
z = 5.1! E B-V = 0.0! age = 0.9 Gyr!! = 0.1 Gyr! M * = 4 10 11 M o! z = 5.0! E B-V = 0.0! age = 0.8 Gyr!! = 0.2 Gyr! M * = 5 10 10 M o! From Bahram Mobasher Richard et al. (2011) - Abell 383 from CLASH Richard et al. (2011) zspec~6.027 zform~18 Mstar~6e9 Msun
What about nebular emission contamination? See Matt Schenkerʼs Poster! Rest-frame optical emission lines can mimic breaks! Richard et al. (2011) zspec~6.027 zform~18 Mstar~6e9 Msun
Observational probes of high-z galaxies t~3.7x10 5 yr t~10 8 yr t~4.8x10 8 yr t~1.2x10 9 yr t~2.2x10 9 yr t~1.37x10 10 yr Recombination Dark Ages Neutral IGM First Stars Form First Galaxies Form Ionized Bubbles Overlap Reionization IGM Mostly Ionized Modern Galaxies Form Today z~1100 z~30 z~10 z~5 z~3 z~0 Reference: Brian Siana
Photometric and Spectroscopic Probes z 2.3 Lyα 2.30 Redshift 0.4 0.35 Abell 1689 CII 0.8 μm Strong lensing [OII] CIV λ OIII] Spectroscopy from space [OIII] + H" 0.82 1.65 Wavelength [um] H! CIII] Keck/LRIS 6hr Spectrum HST WISP SURVEY WISP PI: M. Malkan 1.65 μm Size - TMT / JWST (AO/HST via lensing) Metallicity - MOSFIRE / JWST Nebular line contribution to photometry UV spectral slope Black Hole vs. Stellar Growth - MOSFIRE / TMT Inflow / Outflow - KCWI / MOSFIRE / TME Ionizing Emission - HST/MOSFIRE Keck/DEIMOS Stark et al. (2011) Reference: Brian Siana
Did Star-Forming Galaxies Reionize the Universe? Total SFRD @ z > 6 - MOSFIRE/TMT/ JWST intrinsic LyC production - LRIS/ MOSFIRE/HST the LyC escape fraction - LRIS / HST Robertson et al. (2010d) Ionizing (LyC) Non-Ionizing Starburst99? HST F336W HST F814W Siana et al. (2011, in prep) Nestor, Shapley et al. (2011) Reference: Brian Siana
Dropout Galaxies at z~7 ~0.9 microns ~1.0 microns ~1.2 microns ~1.6 microns
z>7 Galaxy! Hubble UDF
Robertson et al., Nature, 468, 49 (2010d) Did Star-Forming Galaxies Reionize the Universe? Likely, but future data are required.
James Webb Space Telescope: 2015-2017? JWST Segment Test NASA/MSFC - XRCF CGE
James Webb Space Telescope Overview NIRCam: 0.6-5 μm imager 18x1.3m (6.5m) Au-plated Be Mirrors Credit: Lockheed Martin ~10x sensitivity of HST/WFC3 Primary mirror unfolds in orbit Imaging and Spectroscopic capability Credit: Science and Technology Facilities Council Mid-Infrared Instrument: 5-28.3 μm CGE NIRSpec: IR Multi-object Spectrograph Microshutter arrays enable 100x multiplexing
CGE
Fast Facts 30 meter, filled aperture, 492-segment primary mirror Three-mirror telescope f/1 primary Field of view 20 arcminute Wavelength 0.31 28 µm Fully integrated adaptive optics Seeing-limited mode 14-200 times the sensitivity of current telescopes (D 2 - D 4 gain) 3-5 times the resolution of James Webb Space Telescope 61 CGE
Looking forward with TMT and other next generation facilities. Nebular emission from HDF-BX1564 as simulated with Keck (left, confirmed by OSIRIS observations) and TMT (right). TMT significantly increases sensitivity to low surface brightness regions and individual star forming clumps (Law et al. 2009). Need to tie global properties with spatially resolved information to constrain details of SF and feedback. Can we constraint the SF histories (rising/flat/falling) of z>2 galaxies? TMT will reveal low-sb features and resolve individual super-star clusters. Will map kinematics, abundance gradients, and constrain central AGN in typical-brightness galaxies. Need deep observations of IGM surrounding galaxies to constrain gas-phase abundances and inflows/outflows. ALMA will map sites of current star formation. Need good theories of SF and dynamics in gas-dominated systems. Reference: David Law
Bahramʼs Questions: How many more high-z candidates are we going to discover with no hope of spectroscopic confirmation in our lifetime? Where does the search for the highest redshift galaxies lead to? How long more of our life are we going to spend looking at 9 arcmin 2 of the sky (the HUDF)? We don t know much about the nature of high-z galaxies because they are too faint to study and don t know much about details of nearby galaxies because we spend all our time looking for high-z galaxies Bahramʼs Suggestions: Need ambitious spectroscopic campaign to take ultra-deep exposures on z > 6 candidates. Concentrate on the bright-end of galaxy LF Perform wide-area surveys using new and unconventional broad-band filters at ~1 micron Do an entirely new field- no GOODS, no HUDF WFC3 grism observations? Reference: Bahram Mobasher