The HST survey of the B2 sample of radio galaxies: Detection of two optical jets^*

¹ Istituto di Radioastronomia, Via Gobetti 101, 40129, Bologna, Italy
² Osservatorio Astronomico di Bologna, Via Ranzani, 1, 40127, Bologna, Italy
³ Osservatorio Astronomico di Torino, Strada Osservatorio 25, 10025, Pino Torinese, Italy
⁴ Istituto di Fisica, Università degli Studi di Bologna, 40126, Bologna, Italy
⁵ Netherlands Foundation for Research in Astronomy, Postbus 2, 7990AA, Dwingeloo, The Netherlands
⁶ Space Science and Technology Department, CLRC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, UK
⁷ University of Oxford, Department of Astrophysics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK

P. Parma.

Received: 5 August 2002
Accepted: 8 October 2002

Abstract

We present HST observations of previously undetected optical jets in the low-luminosity radio galaxies B2 0755+37 and B2 1553+24. We show that there is accurate spatial coincidence between optical and radio emission, implying that the former is likely to be synchrotron radiation. The physical properties of the jets are similar to those known previously: their radio-optical spectral indices are ≈0.7 and in B2 0755+37, the spectrum steepens between optical and X-ray wavelengths. Our results support the hypothesis that optical emission is detectable from jets orientated within ≈20° of the line of sight for the B2 sample.