Core Radio and Optical Emission in Nearby FR I Radio Galaxies

Abstract

In this paper we analyze the relation between radio, optical continuum and Halpha+[NII] emission from the cores of a sample of 21 nearby Fanaroff & Riley type I galaxies as observed with the VLBA and HST. The emission arises inside the inner tens of parsec of the galaxies. Core radio emission is observed in 19/20 galaxies, optical core continuum emission is detected in 12/21 galaxies and Halpha+[NII] core emission is detected in 20/21 galaxies. We confirm the recently detected linear correlation between radio and optical core emission in FR I galaxies and show that both core emissions also correlate with central Halpha+[NII] emission. The tight correlations between radio, optical and Halpha+[NII] core emission constrain the bulk Lorentz factor to gamma ~ 2-5 and gamma =< 2 for a continuous jet and a jet consisting of discrete blobs, respectively, assuming jet viewing angles in the range [30deg,90deg]. Radio and optical core emissions are likely to be synchrotron radiation from the inner jet, possibly with a significant contribution from emission by an accretion disk and/or flow. Elliptical galaxies with LINER nuclei without large-scale radio jets seem to follow the core emission correlations found in FR I galaxies. This suggests that the central engines could be very similar for the two classes of AGNs.

46 pages, 10 figures and 8 tables. Accepted for publication in AJ. Corrected few typos in text

References in corpus (4)

• VLBI Observations of a Complete Sample of Radio Galaxies. 10 Years Later
• The central kiloparsec of starbursts and AGN: The La Palma connection
• Dusty Nuclear Disks and Filaments in Early Type Galaxies
• A Large-Scale Jet and FR I Radio Source in a Spiral Galaxy: The Host Properties and External Environment

Cited by in corpus (48)

• Nuclear Activity in Nearby Galaxies
• Radio-Loudness of Active Galactic Nuclei: Observational Facts and Theoretical Implications
• Hot Gas In and Around Elliptical Galaxies
• Radio Sources in Low-Luminosity Active Galactic Nuclei.IV. Radio Luminosity Function, Importance of Jet Power, and Radio Properties of the Complete Palomar Sample
• Quantifying the Coexistence of Massive Black Holes and Dense Nuclear Star Clusters
• Mechanical AGN Feedback: Controlling the Thermodynamical Evolution of Elliptical Galaxies
• Hubble Space Telescope Imaging of Brightest Cluster Galaxies
• Low-Luminosity Active Galactic Nuclei: Are They UV-Faint and Radio Loud?
• The X-ray Jets of Active Galaxies
• On the origin of X-ray emission in some FR Is: ADAF or jet?
• The HST view of LINERs nuclei: evidence for a dual population?
• Emission lines and optical continuum in low-luminosity radio galaxies
• An Attempt to Probe the Radio Jet Collimation Regions in NGC 4278, NGC 4374 (M84), and NGC 6166
• No evidence for a different accretion mode for all 3CR FR I radio galaxies
• The X-ray-faint Emission of the Supermassive Nuclear Black Hole of IC1459
• Rotation-Measures across Parsec-scale Jets of FRI radio galaxies
• The 1.6 micron near infrared nuclei of 3C radio galaxies: Jets, thermal emission or scattered light?
• Hubble Space Telescope Observations of NGC 6240: a Case Study of an Ultra-Luminous Infrared Galaxy with Obscured Activity
• VLBA Observations of Mrk 6: Probing the Jet-Lobe Connection
• Optical Nuclei of Radio-loud AGN and the Fanaroff-Riley Divide
• The HST view of the nuclear emission line region in low luminosity radio-galaxies
• STIS spectroscopy of the emission line gas in the nuclei of nearby FR-I galaxies
• Dust tori in radio galaxies
• A dichotomy in the orientation of dust and radio jets in nearby low-power radio galaxies
• Multiwavelength evidence of the physical processes in radio jets
• What do HST and Chandra tell us about the jet and the nuclear region of the radio galaxy 3C270?
• Determining the core radio luminosity function of radio AGNs via copula
• The Ages of Elliptical Galaxies from Mid-Infrared Emission
• The nuclear SED of NGC6251: a BL Lac in the center of an FR I radio galaxy
• VLBA and Chandra Observations of Jets in FRI radio galaxies: Constraints on Jet Evolution
• Gamma-ray observations of low-luminosity active galactic nuclei
• On the Evolution of the Cores of Radio Sources and Their Extended Radio Emission
• BeppoSAX Observations of Centaurus A: the Hard Continuum and the Iron Line Feature
• Discovery of a luminous water megamaser in the FRII radiogalaxy 3C403
• The Toomre Sequence Revisited with HST/NICMOS: Nuclear Brightness Profiles and Colors of Interacting and Merging Galaxies
• Direct Evidence from Spitzer for a low-luminosity AGN at the center of the Elliptical Galaxy NGC 315
• The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey III. Optical Identifications and New Redshifts
• 3C66B as a TeV radiogalaxy
• A panchromatic review of thermal and nonthermal active galactic nuclei
• B2 0648+27: a radio galaxy in a major merger
• Unification of BL Lac objects, FR I and FR II(G) radio galaxies and Doppler factor Estimation for BL Lac Objects
• The innermost region of the water megamaser radio galaxy 3C403
• Unification in the low radio luminosity regime; evidence from optical line emission
• Broadband Modeling of Low Luminosity Active Galactic Nuclei Detected in Gamma Rays
• The peculiar WAT NGC 2329 with Seyfert/FR I-like radio lobes
• A relation between circumnuclear HI, dust, and optical cores in low-power radio galaxies
• Searching for Nuclear Obscuration in the Infrared Spectra of Nearby FR I Radio Galaxies
• Origin of the X-ray Emission in the Nuclei of FR Is