The Infrared Jet in 3C31

Abstract

We report the detection of infrared emission from the jet of the nearby FR I radio galaxy 3C 31. The jet was detected with the IRAC instrument on Spitzer at 4.5 micron, 5.8 micron, and 8.0 micron out to 30" (13 kpc) from the nucleus. We measure radio, infrared, optical, and X-ray fluxes in three regions along the jet determined by the infrared and X-ray morphology. Radio through X-ray spectra in these regions demonstrate that the emission can be interpreted as synchrotron emission from a broken power-law distribution of electron energies. We find significant differences in the high energy spectra with increasing distance from the nucleus. Specifically, the high energy slope increases from 0.86 to 1.72 from 1 kpc to 12 kpc along the jet, and the spectral break likewise increases in frequency along the jet from 10-100's of GHz to ~20 THz. Thus the ratio of IR to X-ray flux in the jet increases by at least an order of magnitude with increasing distance from the nucleus. We argue that these changes cannot simply be the result of spectral aging and that there is ongoing particle acceleration through this region of the jet. The effects of mass loading, turbulence, and jet deceleration, however these processes modify the jet flow in detail, must be causing a change in the electron energy distribution and the efficiency of particle acceleration.

11 pages in emulateApJ format, 10 figures, 2 tables

References in corpus (25)

• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• Detailed Structural Decomposition of Galaxy Images
• The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission
• A Systematic Study of Radio-Induced X-ray Cavities in Clusters, Groups, and Galaxies
• Chandra X-Ray Observatory (CXO):Overview
• Filaments, Bubbles, and Weak Shocks in the Gaseous Atmosphere of M87
• Radio and X-ray observations of the jet in Centaurus A
• Dynamical models for jet deceleration in the radio galaxy 3C 31
• Relativistic models and the jet velocity field in the radio galaxy 3C 31
• The Spitzer Deep, Wide-Field Survey
• The origins of X-ray emission from the hotspots of FRII radio sources
• A Chandra observation of the X-ray environment and jet of 3C31
• Chandra observations of the X-ray jet in 3C66B
• Chandra Observations of the X-ray Jet in Centaurus A
• Shedding New Light on the 3C 273 Jet with the Spitzer Space Telescope
• Spatial Distribution of Warm Dust in Early-Type Galaxies
• The inner jet of radio galaxy NGC 315 as observed with Chandra and the VLA
• The infrared jet in Centaurus A: multiwavelength constraints on emission mechanisms and particle acceleration
• Multifrequency VLA observations of the FR I radio galaxy 3C 31: morphology, spectrum and magnetic field
• Adiabatic relativistic models for the jets in the radio galaxy 3C 31
• Thermal and Non-Thermal Infrared Emission from M87
• Evidence for Non-Hydrostatic Gas Motions in the Hot ISM of Centaurus A
• Infrared-red Cores in Nearby Elliptical Galaxies
• The Infrared Jet In 3C66B
• Spitzer Observations of Centaurus A: Infrared Synchrotron Emission from the Northern Lobe

Cited by in corpus (7)

• Systematic properties of decelerating relativistic jets in low-luminosity radio galaxies
• Star Formation Suppression Due to Jet Feedback in Radio Galaxies with Shocked Warm Molecular Gas
• LOFAR reveals the giant: a low-frequency radio continuum study of the outflow in the nearby FR I radio galaxy 3C 31
• The spectra of jet bases in FR I radio galaxies: implications for particle acceleration
• Examining High Energy Radiation Mechanisms of Knots and Hotspots in Active Galactic Nucleus Jets
• Searching for Nuclear Obscuration in the Infrared Spectra of Nearby FR I Radio Galaxies
• Dust heating in the cores of 3CRR radio galaxies