Open Access2QZJ 215454.3−305654: a radio‐quiet BL Lacertae object or lineless quasi‐stellar object?
Author(s) -
Londish D.,
Heidt J.,
Boyle B. J.,
Croom S. M.,
KedzioraChudczer L.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07980.x
Subject(s) - physics , bl lac object , astrophysics , redshift , astronomy , quasar , flux (metallurgy) , emission spectrum , active galactic nucleus , wavelength , galaxy , spectral line , blazar , optics , gamma ray , materials science , metallurgy
High signal‐to‐noise ratio spectroscopy has established a redshift of z = 0.494 for the source 2QZJ 215454.3−305654, originally selected from the 2dF/6dF QSO Redshift Surveys as one of 45 candidate BL Lacertae (BL Lac) objects displaying a featureless continuum at optical wavelengths. Radio observations using the Australia Telescope Compact Array at 1.4 GHz place a 3σ upper limit on the radio flux density of the object of ∼0.14 mJy. The radio‐to‐optical flux ratio of this object is thus more than seven times lower than the lowest such ratio observed in BL Lac objects. While the optical properties of 2QZJ 215454.3−305654 are consistent with a BL Lac identification, the lack of radio and/or X‐ray emission is not. It is uncertain whether this object is an active galactic nucleus dominated by optical continuum emission from an accretion disc, or is similar to a BL Lac object with optical non‐thermal emission from a relativistic jet.