High-resolution observations of SDSS J080800.99+483807.7 in the optical and radio domains. A possible example of jet-triggered star formation

摘要

Double-lobe radio galaxies are ideally suited to investigate the interactionof the individual components of the radio structure with the intergalacticmedium and the interstellar medium of the host galaxy. SDSS J080800.99+483807.7has been serendipitously discovered in MERLIN 18 cm observations to be adouble-lobed radio galaxy. Because it is an optically faint source, basicinformation like redshift, linear size, and structure has been incomplete untilnow. Furthermore, there are no spectra of this source available in anydatabases. The goal of this work is to derive the main physical properties ofSDSS J080800.99+483807.7 and study the possible interaction between the radiojets and the interstellar medium of the host galaxy. To achieve this goal, weused optical spectroscopy and radio interferometry. The radio data wereobtained with MERLIN at 18 cm and the optical data with the Multi-Object DoubleSpectrograph (MODS) at the Large Binocular Telescope (LBT). The redshift of thegalaxy is z = 0.2805 +/- 0.0003, resulting in a linear size of the observedradio structure of ~ 26.3 kpc. The optical line emission as well as theinfrared and radio continuum emission suggest a high star-formation activity.In addition, we estimated the mass of the central black hole to be log(MBH/Msun) ~ 6.9. The MODS spectrum and the optical images from Sloan DigitalSky Survey suggest that SDSS J080800.99+483807.7 is an elliptical host galaxy.In combination with the overall radio structure, we argue that the starformation could be the result of the back-flow along the jet and theinterstellar medium of the host.