Quasars ignite two types of fireworks

Quasars ignite not one, but two types of fireworks. Not only does the nucleus of a galaxy emit bright light, but stellar birth explosions outside of the nucleus also regularly cause cosmic fireworks. These are the findings of international research at the ALMA Observatory in Chile, led by Professor Peter Barthel from the Kapteyn Institute at the University of Groningen (UG). The astronomers published their findings in today’s edition of the journal Astrophysical Journal Letters.

Quasars are the ultra-luminous nuclei of galaxies located billions of light years away. They shine so brightly because of super-massive black holes, which suck matter in and heat it up until it glows. But the luminosity of the quasar itself makes it very difficult to study its host galaxy. Several years ago, Barthel’s team suspected that the host galaxies of quasars were producing numerous new stars. The new ALMA observations have confirmed this.

The ALMA images of three distant quasars clearly show that stellar birth explosions are responsible for heating up some of the dust. Barthel: ‘The millimetre emission that we have detected proves the existence of stellar birth explosions. In addition, they take place just outside the brightly shining nuclei. This causes double fireworks.’

UG student José Versteeg played an important role in analysing the data. Versteeg: ‘All three quasars show these double fireworks. We are publishing our detailed analysis of quasar 3C298 now, before we complete the study.’

ALMA
The ALMA Observatory is a network of millimetre and sub-millimetre telescopes standing on a five-kilometre-high plateau in the Chilean Andes. The telescopes use an extremely high resolution to make images of the millimetre radio emission from astronomical objects. ALMA can capture the emissions of cold gas from atoms and minute molecules. It can also detect warm clouds of cosmic dust containing large molecules.

Source: press release Nederlandse Onderzoekschool voor Astronomie (NOVA)