Physics & Astronomy ETDs

Publication Date



The Arecibo L-Band Feed Array Zone of Avoidance (ALFA ZOA) Survey detects galaxies behind the Milky Way by 21cm emission from neutral hydrogen gas (HI). The goal of ALFA ZOA is to detect nearby galaxies that have an impact on the peculiar velocity of the Local Group and to compare large scale structure across the ZOA to predicted structure from density reconstruction maps. ALFA ZOA is conducted in two phases: shallow and deep. Observations for the Shallow survey are finished and 45% of the survey has been cataloged with 280 detections found at a sensitivity of 5.4 mJy at 9 km/s channel resolution. The survey is complete above integrated flux 2.2 Jy km/s and has a positional accuracy of 26 arcseconds. First results from the Deep survey find 61 galaxies within a 15 square degree area. The Deep survey reaches its expected sensitivity of 1 mJy at 9 km/s channel resolution, and is shown to be complete above integrated flux 0.5 Jy km/s, detecting galaxies out to a recessional velocity of nearly 19,000 km/s. ALFA ZOA finds 3 out of 7 predicted, major large scale structures to have been misplaced in density reconstruction maps from the literature. No new Local Group galaxies are found, but three galaxy groups are discovered within 20 Mpc and one may have the mass and distance to recover the mass density dipole vector. ALFA ZOA increases the number of galaxies cataloged in the area by 100%, and the number with known redshift by over 800%.

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Level of Degree


Department Name

Physics & Astronomy

First Committee Member (Chair)

Rand, RIchard

Second Committee Member

Pihlstrom, Ylva

Third Committee Member

Westpfahl, Dave

Fourth Committee Member

Minchin, Robert

Project Sponsors

New Mexico Space Grant Cornell University Arecibo Observatory National Astronomy and Ionosphere Center





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