Matt Bradford 1

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, 2011

Matt Bradford 2

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, 2011

Matt Bradford 3

21 cm Probes Galaxies at Reionization

CSO NSF visit October 13, 2011

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 emissionPop II stars

Pop III stars, less efficiency W-F coupling

Beforehand, spin temp in equilibrium with CMB.

All HI eventually destroyed

Matt Bradford 4

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. 2007. 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, 2011

PAPER: http://astro.berkeley.edu/~dbacker/eor/ MWA: http://www.mwatelescope.org/

Matt Bradford 5

Tomography in C+Y. Gong, A. Cooray, et al.

CSO NSF visit October 13, 2011

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/1107.3553v1

Matt Bradford 6

Tomography in C+

CSO NSF visit October 13, 2011

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.

Matt Bradford 7

Tomography in C+: Power SpectraY. Gong, A. Cooray, et al.

CSO NSF visit October 13, 2011

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/1107.3553v1

Matt Bradford 8

Cross correlation C+ with HIY. Gong, A. Cooray, et al.

CSO NSF visit October 13, 2011

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/1107.3553v1

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.