Do BL Lac objects and FR I radio galaxies inhabit the same galaxy environment?. (22nd March 2019)

• Record Type: Journal Article
• Authors: Sandrinelli, A; Falomo, R; Treves, A
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 485:Number 1(2019)
• Page Start: L89
• Page End: L92
• Publication Date: 2019-03-22
• Subjects: galaxies: active -- BL Lacertae objects: general -- galaxies: clusters: general -- radio continuum: galaxies; Astronomy -- Research -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnrasl/slz033
• Languages: English
• ISSNs: 1745-3933

Abstract

ABSTRACT: We investigate the environments of galaxies around BL Lacertae (BL Lac) objects and Fanaroff–Riley class I (FR I) radio galaxies, the alleged parent populations of misaligned sources. We compare the environment of a sample of 50 BL Lac objects at 0.1 < z < 0.33 with that of a sample of 90 FR I galaxies at 0.1 < z < 0.15. The galaxy environment is studied by using Sloan Digital Sky Survey Data Release 14 images in the i band. We find that the galaxy excess density within 0.5 Mpc around FR I radio galaxies is a factor of ∼2 larger than that around BL Lacs. This implies a reconsideration of the parent population of BL Lac objects.