A New Population of High Redshift, Dusty Lyman-Alpha Emitters and Blobs Discovered by WISE

TL;DR

This paper introduces a novel method combining WISE infrared data and optical spectroscopy to identify rare, dusty high-redshift Lyman-alpha emitters and blobs, revealing their extreme luminosities and potential AGN-driven feedback processes.

Contribution

The study presents a new selection technique for dusty LAEs and LABs at high redshift, achieving high success rates and uncovering their properties and evolutionary implications.

Findings

Identified rare dusty LAEs and LABs with a 78% success rate.

Measured median redshifts of 2.3 for LAEs and 2.5 for LABs.

Found these galaxies have extreme infrared luminosities and warm colors, indicative of AGN activity.

Abstract

We report a new technique to select 1.6<z<4.6 dusty Lyman-alpha emitters (LAEs), over a third of which are `blobs' (LABs) with emission extended on scales of 30-100kpc. Combining data from the NASA Wide-field Infrared Survey Explorer (WISE) mission with optical spectroscopy from the W.M. Keck telescope, we present a color criteria that yields a 78% success rate in identifying rare, dusty LAEs of which at least 37% are LABs. The objects have a surface density of only ~0.1 per square degree, making them rare enough that they have been largely missed in narrow surveys. We measured spectroscopic redshifts for 92 of these WISE-selected, typically radio-quiet galaxies and find that the LAEs (LABs) have a median redshift of 2.3 (2.5). The WISE photometry coupled with data from Herschel reveals that these galaxies have extreme far-infrared luminosities (L_IR>10^{13-14}L_sun) and warm colors, typically larger than submillimeter-selected galaxies (SMGs) and dust-obscured galaxies (DOGs). These traits are commonly associated with the dust being energized by intense AGN activity. We hypothesize that the combination of spatially extended Lyman-alpha, large amounts of warm IR-luminous dust, and rarity (implying a short-lived phase) can be explained if the galaxies are undergoing strong `feedback' transforming them from an extreme dusty starburst to a QSO.