Epoch of Reionization Tomography with the CSO Wide-field C+ spectral mapping and correlation with HI Matt Bradford CSO NSF visit: October 12, 2011 CSO NSF visit October 13, Matt Bradford

Epoch of Reionization  First UV sources turn on and reionize the HI.  Quasars + WMAP => redshift ~20 to 6 (0.3-1 Gyr after the Big Bang)  Details not clear. Ionizing sources? Pop III stars and/or AGN, Pop II stars. In terms of galaxy counts, reionization dominated by sources at the low-luminosity end of the distribution, at or below threshold in current or JWST surveys. CSO NSF visit October 13, 2011Matt Bradford 2

21 cm Probes Galaxies at Reionization CSO NSF visit October 13, 2011Matt Bradford 3 Shapiro et al., 2008 Wouthuysen-Field effect: HI is coupled to matter temperature via absorption of UV photons early in reionization. Shows absorption against CMB. Furlanetto et al. 2006: Mean 21 cm signal against CMB through reionization. As reionization proceeds, X-rays heat IGM, bring HI into emission Pop II stars Pop III stars, less efficiency W-F coupling Beforehand, spin temp in equilibrium with CMB. All HI eventually destroyed

But mean absolute spectrum is hard to measure -> look at fluctuations Reionization maps in HI, 94 comoving Mpc across at z=7.7. McQuinn et al Ionized (white) and neutral (black) gas via 21 cm. Patch sizes related to ionizing source sizes (large or small galaxies). CSO NSF visit October 13, 2011Matt Bradford 4 PAPER: r/ MWA:

Tomography in C+ Y. Gong, A. Cooray, et al. CSO NSF visit October 13, 2011Matt Bradford 5 First-principles calculation of mean intensity of C+ as a function of redshift under various assumptions, including painting on to numerical sims (DeLucia and Blaizot (2007). Matches with simple scalings form star formation history estimates. arxiv.org/ v1

Tomography in C+ CSO NSF visit October 13, 2011Matt Bradford 6 Background-limited sensitivity relative to the mean intensity. This gets much harder at earlier times. Power spectrum measurement requires only fractional SNR in each spatial- spectral bin (voxel) Lower-redshift measurement in 650, 850 micron windows a first step.

Tomography in C+: Power Spectra Y. Gong, A. Cooray, et al. CSO NSF visit October 13, 2011Matt Bradford 7 The aggregate glow of undetected small galaxies. Shot-noise dominates, but clustering enters at low k. Error bars based on Z-Spec like instrument scaled up to 64 spatial pixels, and R=700 with 312 spectral pixels -> 20,000 total detectors.  Need integral field on- chip spectrometers. Assume mapping 16 square degrees with 4000 hours total. Basic sensitivity independent of aperture; for z=7, SNR per spectral / spatial voxel is ~5e-3 in 1 h arxiv.org/ v1

Cross correlation C+ with HI Y. Gong, A. Cooray, et al. CSO NSF visit October 13, 2011Matt Bradford 8 Basic C+ sensitivity independent of aperture, but would like to probe angular scales which show inversion of correlation with HI.  Large scales: HI anticorrelated with galaxies which produce reionizing photons.  Anti-correlation disappears on scales of the ionizing bubble size. arxiv.org/ v1  10m aperture for C+ is well-suited to comparison with 21-cm experiments.  a potential long-term future CSO experiment: automated, low overhead, if the instrumentation can be developed.