The Hobby-Eberly Telescope Dark Energy Experiment Survey (HETDEX) Active Galactic Nuclei Catalog: the Fourth Data Release

TL;DR

This paper presents the fourth data release of the HETDEX AGN catalog, containing nearly 16,000 spectroscopically confirmed AGN across a wide redshift range, derived from an untargeted spectroscopic survey covering 62.9 square degrees.

Contribution

The catalog includes a large, unbiased sample of AGN with no imaging pre-selection, including low-luminosity and narrow-line AGN, expanding the available data for AGN studies.

Findings

Catalog contains 15,940 AGN with redshifts from 0.1 to 4.6.

66% of AGN have redshifts confirmed by line pairs or SDSS matches.

39% of confirmed AGN show extended emission-line regions.

Abstract

We present the Active Galactic Nuclei (AGN) catalog from the fourth data release (HDR4) of the Hobby-Eberly Telescope Dark Energy Experiment Survey (HETDEX). HETDEX is an untargeted spectroscopic survey. HDR4 contains 345,874 Integral Field Unit (IFU) observations from January 2017 to August 2023 covering an effective area of 62.9 deg2. With no imaging pre-selection, our spectroscopic confirmed AGN sample includes low-luminosity AGN, narrow-line AGN, and/or red AGN down to g~25. This catalog has 15,940 AGN across the redshifts of z=0.1~4.6, giving a raw AGN number density of 253.4 deg-2. Among them, 10,499 (66%) have redshifts either confirmed by line pairs or matched to the Sloan Digital Sky Survey Quasar Catalog. For the remaining 5,441 AGN, 2,083 are single broad line AGN candidates, while the remaining 3,358 are single intermediate broad line (full width at half maximum, FWHM ~ 1200 km s-1) AGN candidates. A total of 4,060 (39%) of the 10,499 redshift-confirmed AGN have emission-line regions $3\sigma$ more extended than the image quality which could be strong outflows blowing into the outskirts of the host galaxies or ionized intergalactic medium.