A Proposed VLA Band - 190 MHz Pathfinder Study for the EOR L A Proposed VLA Band - 190 MHz Pathfinder Study for the EOR L. Greenhill (CfA) Basic Goals Detection of HI shells around “EOR quasars” Exploration of line brightness fluctuations over ~10(°)2 Explore noise-limited deep imaging Befriend galactic foregrounds Status Funding approved by Smithsonian (October 1) US$110K Leverages previous investments in the VLA Now under peer review by NRAO Technical/management review to begin Dec. 04 Proposed tracks in late 2005, early 2007. Permanent addition to the VLA. Legacy science.

Key VLA/VHF Science Questions What are the shapes/sizes of the HII regions? How anisotropic is the ionizing radiation? When did the quasars form after recombination? What is the nature of the IGM at z~6.3? When did Tspin exceed TCMB? What is the reionization history? Constrain the neutral fraction at z~ 6.3 Pathfinder program w/r to foreground elimination and assessment of gross signal strength (case A/B). Co-Is: Blundell, Loeb, Zaldarriaga (CfA), Carilli, Perley (NRAO), Furlanetto (CalTech)

(more likely) Weak Signal Case Strong Signal Case and (more likely) Weak Signal Case

How Strong is Strong - How Weak is Weak? 295 mK (Wyithe & Loeb) Initial target list: 3 SDSS quasars (z=6.2-6.4) that show a “depth effect” to the Lya absorption (Fan et al.). The HI lines will lie at 192-196 MHz.

The Sky at 408 MHz Tsky = 14-16 K (408 MHz) => ~110 K (194 MHz) Haslam et al. 1982 Adapted by Emerson Tsky = 14-16 K (408 MHz) => ~110 K (194 MHz)

Placement of Proposed VHF Receivers Although Ae(327 MHz) ~ 0.40, Ae(VHF) ~ 0.50 !

Schematic Layout for VHF Rx Test of strong signal case and technical demo 50h per source in 2005. The proposed VHF system is opti-mized for sensitivity more so than existing 4m and 0.9 m systems.

Radio Spectrum Allocation

RFI at the VLA Site Clear sky TV Carrier Lightning Monitoring continues. Winter observing

Timeline Oct. 04 - Observing proposal Jan. 05 - First prototype delivered Mar. 05 - Four prototypes deployed Jun. 05 - 14 Rx delivered Jul. 05 - 14 Rx delivered Late 05 - 1st D-config. and 1st “useful” data Early 07 - 2nd D-config.

System Specifications Dipole - parabolic dish hybrid Eases calibration Bandwidth - 186 - 202 MHz (1.6 m) Primary beam - 4.3° Synthesized beam - 5-15´ (D-config.) Tsys ~ 180 K Ae ~ 0.5 ( ~6600 m2) Sensitivity ~ 10 mK in 50h Crossed dipole system l/3 from focus Invisibility