Hostname: page-component-cd9895bd7-8ctnn Total loading time: 0 Render date: 2024-12-18T23:05:44.697Z Has data issue: false hasContentIssue false
  • English
  • Français

Radio and Gamma-ray emission in nearby BL Lacs

Published online by Cambridge University Press:  25 July 2014

G. Giovannini ,
E. Liuzzo ,
B. Boccardi  and
M. Giroletti
G. Giovannini
Affiliation:
Department of Physics and Astronomy, via Ranzani 1, 40123 Bologna, Italy email: [email protected] Radioastronomy Institute/INAF, via Gobetti 101, 40129 Bologna, Italy
E. Liuzzo
Affiliation:
Radioastronomy Institute/INAF, via Gobetti 101, 40129 Bologna, Italy
B. Boccardi
Affiliation:
Max Planck Institute for Radioastronomy, Auf dem Hügel 69 53121 Bonn, Germany.
M. Giroletti
Affiliation:
Radioastronomy Institute/INAF, via Gobetti 101, 40129 Bologna, Italy
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The advent of Fermi is changing our understanding on the radio and γ-ray emission in active galactic nuclei. Unlike pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the γ-ray band. However, since they are relatively weak radio sources, most of their parsec-scale structure and their multifrequency properties are poorly understood and/or have not been investigated in a systematic fashion. Here we are analyzing the radio and γ-ray emission properties of a sample of 42 BL Lacs selected with no constraint on their radio and γ-ray emission. Thanks to new Very Long Baseline Array observations at 8 and 15 GHz for the whole sample, we discuss their parsec-scale structure. Parsec-scale radio emission is observed in the majority of the sources at both frequencies. The comparison between our results in radio and gamma-ray bands points out the presence of a large number of faint BL Lacs showing “non-classical” properties such as low source compactness, low core dominance, no gamma-ray emission.

Keywords

BL LacsVLBI
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 9 , Symposium S304: Multiwavelength AGN Surveys and Studies , October 2013 , pp. 200 - 203
Copyright
Copyright © International Astronomical Union 2014 

References

Abazajian, K. N., Adelman-McCarthy, J. K., Agüeros, M. A., et al. 2009 ApJS, 182, 543Google Scholar
Abdo, A. A., Ackermann, M., Ajello, M., et al. 2009 ApJ, 697, 1071Google Scholar
Ackermann, M., Ajello, M., Allafort, A., et al. 2011 ApJ, 743, 171Google Scholar
Atwood, W. B., Abdo, A. A., Ackermann, M., et al. 2009, ApJ, 697, 1071Google Scholar
Balmaverde, B., Capetti, A. 2006 A&A 447, 97Google Scholar
Cassaro, P., Stanghellini, C., Dallacasa, D., Bondi, M., & Zappalà, R. A. 2002 A&A 381, 378Google Scholar
Giovannini, G., Feretti, L., Venturi, T., et al. 1994 ApJ 435, 116Google Scholar
Giroletti, M., Giovannini, G., Taylor, G. B., & Falomo, R. 2004 ApJ 613, 752Google Scholar
Giroletti, M., Giovannini, G., Taylor, G. B., & Falomo, R. 2006 ApJ 646, 801Google Scholar
Liuzzo, E., Giovannini, G., Giroletti, M., & Taylor, G. B. 2009 A&A 505, 509Google Scholar
Liuzzo, E., Giroletti, M., Giovannini, G., Boccardi, B., et al. 2013 A&A 560, 23Google Scholar
Massaro, E., Giommi, P., Leto, C., et al. 2009 A&A 495, 691Google Scholar
Rector, T. A., Gabuzda, D. C., & Stocke, J. T. 2003 AJ 125, 1060Google Scholar
Wu, Z., Jiang, D. R., Gu, M., & Liu, Y. 2007 A&A 466, 63Google Scholar