Volume 547, November 2012
|Number of page(s)||6|
|Published online||19 October 2012|
Redshift constraints for RGB 0136+391 and PKS 0735+178 from deep optical imaging⋆
Finnish Centre for Astronomy with ESO (FINCA), University of
2 Nordic Optical Telescope, Apartado 474, 38700 Santa Cruz de La Palma, Spain
3 Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611-2055, USA
4 Tuorla Observatory, Department of Physics and Astronomy, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
Received: 20 June 2012
Accepted: 13 September 2012
We present the results of deep I-band imaging of two BL Lacerate objects, RGB 0136+391 and PKS 0735+178, during an epoch when the optical nucleus was in a faint state in both targets. In PKS 0735+178 we find a significant excess over a point source, which, if fitted by the de Vaucouleurs model, corresponds to a galaxy with I = 18.64 ± 0.11 and reff = 1.8 ± 0.4 arcsec. Interpreting this galaxy as the host galaxy of PKS 0735+178 we derive z = 0.45 ± 0.06 using the host galaxy as a “standard candle”. We also discuss the immediate optical environment of PKS 0735+178 and the identity of the MgII absorber at z = 0.424. Despite of the optimally chosen epoch and deep imaging we find the surface brightness profile of RGB 0136+391 to be consistent with a point source. By determining a lower limit for the host galaxy brightness by simulations, we derive z > 0.40 for this target.
Key words: galaxies: active / galaxies: nuclei / BL Lacertae objects: individual: RGB 0136+391 / BL Lacertae objects: individual: PKS 0735+178
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.