The search for variable quasars and galaxies suitable for cosmological radio measurements: quasar 0235+16
Abstract
The first results of the search for extragalactic radio sources suitable for cosmological measurements are presented. The sequence of outbursts, observed in quasar 0235+16 over 1.5 years (from July 1981 to December 1982) at eight frequencies ranging from 0.3 to 15 GHz, is analyzed with the aid of the "hedgehog" model. The simulated spectra agree with the observed spectra using a X^2^-test at a 0.05 significance level (or a 0.95 confidence level). The observed phenomena are interpreted as synchrotron emission from a continuous narrow jet of relativistic particles moving in a strong radial magnetic field; the variability of the spectrum is caused by the time variation of the flow. The jet starts at a distance of 10^19^ cm from the active nucleus. The observed brightness temperature and magnetic field near the jet base were estimated to be less than 4 x 10^11^ K and 0.5 G, respectively. The BL Lacertae object 0235+16 can be used for radio measurements of the Hubble constant and the deceleration parameter of the Universe by the previously proposed technique based on the hedgehog model.
- Publication:
-
Astronomy Letters
- Pub Date:
- January 1994
- Bibcode:
- 1994AstL...20....3K