A Successful Broad-band Survey for Giant Lya Nebulae I: Survey Design and Candidate Selection

TL;DR

This paper introduces a broad-band survey method for detecting giant Lya nebulae at redshifts 2-3, covering the largest volume to date, and presents a candidate sample from the NDWFS Bootes field.

Contribution

It develops a new systematic broad-band survey technique for giant Lya nebulae and applies it to the largest volume search to date.

Findings

Identified 79 Lya nebula candidates including one known source.

Designed a survey covering 9.4 square degrees with a volume of ~10^8 h^-3_70 Mpc^3.

Established a new method for efficient detection of rare high-redshift nebulae.

Abstract

Giant Lya nebulae (or Lya "blobs") are likely sites of ongoing massive galaxy formation, but the rarity of these powerful sources has made it difficult to form a coherent picture of their properties, ionization mechanisms, and space density. Systematic narrow-band Lya nebula surveys are ongoing, but the small redshift range covered and the observational expense limit the comoving volume that can be probed by even the largest of these surveys and pose a significant problem when searching for such rare sources. We have developed a systematic search technique designed to find large Lya nebulae at 2<z<3 within deep broad-band imaging and have carried out a survey of the 9.4 square degree NOAO Deep Wide-Field Survey (NDWFS) Bootes field. With a total survey comoving volume of ~10^8 h^-3_70 Mpc^3, this is the largest volume survey for Lya nebulae ever undertaken. In this first paper in the series, we present the details of the survey design and a systematically-selected sample of 79 candidates, which includes one previously discovered Lya nebula.