The X-ray and radio connection in low-luminosity active nuclei

被引：0

作者：

Panessa, F. ^{[1
]}

Barcons, X. ^{[1
]}

Bassani, L. ^{[2
]}

Cappi, M. ^{[2
]}

Carrera, F.J. ^{[1
]}

Ho, L.C. ^{[3
]}

Pellegrini, S. ^{[4
]}

机构：

[1] Instituto de Física de Cantabria (CSIC-UC), Avda. de los Castros, 39005 Santander, Spain

[2] INAF - IASF, via P. Gobetti 101, 40129 Bologna, Italy

[3] Observatories of the Carnegie Institution of Washington, 813 Santa Barbara St., Pasadena, CA 91101, United States

[4] Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy

来源：

Astronomy and Astrophysics | 2007年 / 467卷 / 02期

关键词：

We present the results of the correlation between the nuclear 2-10 keV X-ray and radio (at 2 cm; 6; cm; and 20 cm) luminosities for a well-defined sample of local Seyfert galaxies. We use a sample of low luminosity radio galaxies (LLRGs) for comparison. In both Seyfert and LLRG samples; X-ray and radio luminosities are significantly correlated over 8 orders of magnitude; indicating that the X-ray and radio emission sources are strongly coupled. Moreover; both samples show a similar regression slope; LX L R0.97; but Seyfert galaxies are three orders of magnitude less luminous in the radio band than LLRGs. This suggests that either similar physical mechanisms are responsible for the observed emission or a combination of different mechanisms ends up producing a similar correlation slope. Indeed; the common belief for LLRG is that both the X-ray and radio emission are likely dominated by a relativistic jet component; while in Seyfert galaxies the X-ray emission probably arises from a disk-corona system and the radio emission is attributed to a jet/outflow component. We investigate the radio loudness issue in the two samples and find that the Seyfert galaxies and the LLRGs show a different distribution of the radio loudness parameters. No correlation is found between the luminosity and the radio loudness; however; the latter is related to the black hole mass and anti-correlated with the Eddington ratio. The dichotomy in the radio loudness between Seyfert and LLRG observed down to low Eddington ratios; L2-10; keV/LEdd; ∼; 10-8; does not support the idea that the origin of the radio loudness is due to a switch in the accretion mode. © ESO2007;

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页码：519 / 527