Issue |
A&A
Volume 477, Number 2, January II 2008
|
|
---|---|---|
Page(s) | 513 - 516 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20078492 | |
Published online | 06 November 2007 |
Redshift limits of BL Lacertae objects from optical spectroscopy
Astrophysical Institute, Department of Physics and Astronomy, Ohio University, Athens, Ohio, 45701, USA e-mail: jfinke@ssd5.nrl.navy.mil
Received:
16
August
2007
Accepted:
29
October
2007
Context.BL Lacertae objects have been the targets for numerous recent multiwavelength campaigns, continuum spectral variability studies, and theoretical spectral and variability modeling. A meaningful interpretation of the results of such studies requires a reliable knowledge of the objects' redshifts; however, the redshifts for many are still unknown or uncertain.
Aims.Therefore, we hope to determine or constrain the redshifts of six BL Lac objects with unknown or poorly known redshifts.
Methods.Observations were made of these objects with the MDM 2.4 m Hiltner telescope. Although no spectral features were detected, and thus no redshifts could be measured, lower redshift limits were assigned to the objects based on the expected equivalent widths of absorption features in their host galaxies. Redshifts were also estimated for some objects by assuming the host galaxies are standard candles and using host galaxy apparent magnitudes taken from the literature.
Results.The commonly used redshift of
for 1219+285 is almost certainly wrong, while
the redshifts of the other objects studied remain undetermined.
Key words: galaxies: BL Lacertae objects: general / galaxies: distances and redshifts
© ESO, 2007
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