Radio Dichotomy in Active Galactic Nuclei and Black Hole X-ray Binaries

  • a project financed from the government budget through the STAR-C1 program of the ROmanian Space Agency (ROSA)
  • period: 19 November 2012 - 30 September 2015
  • amount awarded: 850,000 lei (~187,500 euro)

Research team:

Summary:

We carry out a research program consisting of data analysis and theoretical investigation of the radio dichotomy in active galactic nuclei (AGN) and black hole X-ray binaries (BHXBs). AGN seem to show a dichotomy in their radio emission, with some having powerful radio-emitting jets (radio-loud), and other having weak jets (radio-quiet). However, the existence of the radio-loudness dichotomy in AGN is still a matter of debate. The resolution of this issue is essential for the AGN unification scheme. The first goal of this research is to understand the mechanisms that may lead to the differences in radio-emission in AGN. The second goal of the project is to extend the study of the radio loudness bi-modality to the BHXBs with the aim of illuminating similarities and differences between super-massive black holes located at the center of AGN and stellar-mass black holes observed in X-ray binaries. Indications for the radio loudness dichotomy are expected from different radio and X-ray spectral characteristics, jet structure, and our understanding of relativistic flows. Using advances in these fields, we explore how the black hole parameters determine structural differences in the jets on the tens of kiloparsec scale, which shall lead to new ideas regarding the radio loud/radio quiet dichotomy.
                    
Updated Sikora sample (Sikora et al. 2007).                   X-ray selected sample. Total radio
Core radio luminosity at 5 GHz vs. B-band                      luminosity at 5 GHz (from Veron catalog)
nuclear luminosity.                                                               vs. X-ray nuclear luminosity.

References:

Blandford, R. D. & Znajek, R. L. 1977, MNRAS, 179, 433
Broderick, J. W. & Fender, R. P. 2011, MNRAS, 417, 184
Caramete, L. I. & Biermann, P. L. 2010, A&A, 521, 55
Gallo, E., Fender, R. P., & Pooley, G. G. 2003, MNRAS, 344, 60
Garofalo, D., Evans, D. A., & Sambruna, R. M. 2010, MNRAS, 406, 975
Ho, L. C. 2002, ApJ, 564, 120
Kellermann, K. I., Sramek, R., Schmidt, M., Shapper, D. B., & Green, R. 1989, AJ, 98, 1195
Sikora , M., Stawarz , L ., & Lasota , J. P. 2007, ApJ, 658, 815

Articles:

Dutan, I. & Caramete, L. I., Ultra-High-Energy Cosmic Rays from Low-Luminosity Active Galactic Nuclei, 2015
Astroparticle Physics, Volume 62, p. 206-216

                     
Energy spectrum: blue = observed spectrum                     3D reprezentation of the UHECR trajectories
by the Pierre Auger Observatory; red = from 1D               using CRPropa simulations.
CRPropa simulations; black = from Mathematica
simulations.

Conferences, meetings, and talks:

Special guests at the ISS:

Public outreach: