Radio Detection of 18 Rass BL Lac Objects

TL;DR

This study reports the radio detection of 18 BL Lac objects from a large sky survey, identifying typical and unusual sources, and suggests the RASS may contain around 2000 BL Lac objects based on their distribution.

Contribution

First radio detection of 18 BL Lac objects from a comprehensive sky survey, including identification of a candidate radio-quiet BL Lac and an extreme HBL.

Findings

All detected objects are above 1 mJy in radio emission.

The Log(N)-Log(S) relation aligns with other samples.

Estimated ~2000 BL Lac objects in the RASS survey.

Abstract

We present the radio detection of 18 BL Lac objects from our survey of over 575 square degrees of sky. These 18 objects are located within 20 arcsec of the X-ray position, of which 11 have a measured red-shift. All candidates are radio emitters above ~1 mJy and fall within the range of existing samples on the two colour, alpha_ro vs alpha_ox, diagram with a transitional population of three (3) evident. Two unusual sources have been identified, a candidate radio quiet BL Lac, RX J0140.9-4130, and an extreme HBL, RX J0109.9-4020, with Log(nu_peak)~19.2. The BL Lac Log(N)-Log(S) relation is consistent with other samples and indicates the ROSAT All Sky Survey (RASS) could contain (2000+-400) BL Lac objects.