870 Micron Observations of Nearby 3CRR Radio Galaxies

We present submillimeter continuum observations at 870 μm of the cores of low-redshift 3CRR radio galaxies, observed at the Heinrich Hertz Submillimeter Telescope. The cores are nearly flat-spectrum between the radio and submillimeter, which implies that the submillimeter continuum is likely to be synchrotron emission and not thermal emission from dust. The emitted power from nuclei detected at optical wavelengths and in the X-rays is similar in the submillimeter, optical, and X-rays. The submillimeter-to-optical and X-ray power ratios suggest that most of these sources resemble misdirected BL Lac–type objects with synchrotron emission peaking at low energies. However, we find three exceptions, the FR I galaxy 3C 264 and the FR II galaxies 3C 390.3 and 3C 338 with high X-ray–to–submillimeter luminosity ratios. These three objects are candidate misdirected high- or intermediate-energy peaked BL Lac–type objects. With additional infrared observations and from archival data, we compile spectral energy distributions for a subset of these objects. The steep dips observed near the optical wavelengths in many of these objects suggest that extinction inhibits the detection and reduces the flux of optical continuum core counterparts. High-resolution near- or mid-infrared imaging may provide better measurements of the underlying synchrotron emission peak.