Netherlands Institute for Radio Astronomy (ASTRON) | 2019 Mar 18
An international team of astrophysicists observed for the first time that the jet of a quasar is less powerful on long radio wavelengths than earlier predicted. This discovery gives new insights in the evolution of quasar jets. They made this observation using the international Low Frequency Array (LOFAR) telescope, that produced high resolution radio images of quasar 4C+19.44 located over 5 billion light-years from Earth.The radio jet of the quasar 4C+19.44, powered by a supermassive black hole lying in
the center of its host galaxy and shining at long radio wavelengths as seen by the
LOFAR radio telescope (magenta). The background image shows neighboring galaxies
in the visible light highlighted thanks to the Hubble Space Telescope (cyan and
orange) having the radio jet passing into the dark voids of intergalactic space
(Harris et al 2019 ApJ). Credit: NASA/HST/LOFAR/J. DePasquale
Supermassive black holes, many millions of times more massive than our Sun reside in the central regions of galaxies. They grow even larger by attracting and consuming nearby gas and dust. If they consume material rapidly, the infalling matter shines brightly and the source is known as a quasar. Some of this infalling matter is not digested, but instead is ejected in the form of so-called jets that punch through the surrounding galaxy and into intergalactic space for millions of light years. These jets, shining brightly at radio wavelengths, are composed of particles accelerated up to nearly the speed of light, but exactly how these particles achieve energies not attainable on the Earth is yet to be completely solved.
The discovery on quasar 4C+19.44 gives new insights to the balance between the energy in the field surrounding the quasar and that residing in the quasar jet. This finding indicates to an intrinsic property of the source rather than due to absorption effects. It implies that the energy budget available to accelerate particles and the balance between energy stored in particles and in the magnetic field, is less than expected. ...
LOFAR Observations of 4C+19.44: On the Discovery of Low-
Frequency Spectral Curvature in Relativistic Jet Knots ~ D. E. Harris et al
- Astrophysical Journal 873(1):21 (2019 Mar 01) DOI: 10.3847/1538-4357/ab01ff