Detalles de publicación
PP 010018
The redshift and broad band spectral energy distribution of NRAO 150
1-Instituto de Astrofisica de Canarias, E-38200 La Laguna
2-Departamento de Astrofisica Universidad de La Laguna, E-38205 La Laguna
3-Instituto de Astrofisica de Andalucia, E-18080 Granada
4-Institute for Astrophyisical Research, Boston University, Boston MA02215 - USA
5-Department of Physics & Astronomy, University of Shefield, UK
6-Isaac Newton Group of Telescopes, La Palma
\object{NRAO~150} is one of the brightest
radio and mm AGN sources on the northern sky. It has been revealed as an interesting
source where to study extreme relativistic jet phenomena.
However, its cosmological distance has not been reported so far,
because of its optical faintness produced by strong Galactic extinction.}
{Aiming at measuring the redshift of \object{NRAO~150}, and hence to start making possible quantitative studies from the source.}
{We have conducted spectroscopic and photometric observations of the source in the near-IR, as well as in the optical.}
{All such observations have been successful in detecting the source. The near--IR spectroscopic observations reveal strong H$\alpha$ and H$\beta$ emission lines from which the
cosmological redshift of \object{NRAO~150} ($z=1.517\pm0.002$) has been determined for the first time.
We classify the source as a flat--spectrum radio--loud quasar, for which we estimate a large super--massive black--hole mass $\sim5\times 10^{9} \mathrm{M_\odot}$.
After extinction correction, the new near-IR and optical data have revealed a high-luminosity continuum-emission
excess in the optical (peaking at $\sim2000$\,\AA, rest frame) that we attribute to thermal emission from the accretion disk for which we estimate a
high accretion rate, $\sim30$\,\% of the Eddington limit.}
{Comparison of these source properties, and its broad--band spectral--energy distribution, with those of \emph{Fermi} blazars allow us to predict
that \object{NRAO~150} is among the most powerful blazars, and hence a high luminosity --although not detected yet-- $\gamma$--ray emitter.}
radio and mm AGN sources on the northern sky. It has been revealed as an interesting
source where to study extreme relativistic jet phenomena.
However, its cosmological distance has not been reported so far,
because of its optical faintness produced by strong Galactic extinction.}
{Aiming at measuring the redshift of \object{NRAO~150}, and hence to start making possible quantitative studies from the source.}
{We have conducted spectroscopic and photometric observations of the source in the near-IR, as well as in the optical.}
{All such observations have been successful in detecting the source. The near--IR spectroscopic observations reveal strong H$\alpha$ and H$\beta$ emission lines from which the
cosmological redshift of \object{NRAO~150} ($z=1.517\pm0.002$) has been determined for the first time.
We classify the source as a flat--spectrum radio--loud quasar, for which we estimate a large super--massive black--hole mass $\sim5\times 10^{9} \mathrm{M_\odot}$.
After extinction correction, the new near-IR and optical data have revealed a high-luminosity continuum-emission
excess in the optical (peaking at $\sim2000$\,\AA, rest frame) that we attribute to thermal emission from the accretion disk for which we estimate a
high accretion rate, $\sim30$\,\% of the Eddington limit.}
{Comparison of these source properties, and its broad--band spectral--energy distribution, with those of \emph{Fermi} blazars allow us to predict
that \object{NRAO~150} is among the most powerful blazars, and hence a high luminosity --although not detected yet-- $\gamma$--ray emitter.}