Although immense for our standards, supermassive black holes are very small compared to their host galaxies – the equivalent of a penny in relation to the size of the entire moon. Still, astronomers believe that they have an immense influence on the galaxies they inhabit.
Researchers want to use NASA’s James Webb Space Telescope to study the effect that three quasars have on their host galaxies in a program called Q3D, which analyzes several different wavelengths of light and assembles a three-dimensional map of the generated cosmic winds.
At the center of virtually every galaxy is a supermassive black hole (ours is called Sagittarius A *). As such, they weigh millions or billions of times the mass of the Sun and devour the superheated gas rotating disk that surrounds them. When the gas on that disk falls towards the black hole, it releases an enormous amount of energy, which creates a bright and powerful galactic nucleus: the quasar, one of the most brilliant and energetic objects in the universe.
By sucking the matter from its neighboring galaxies, quasars heat the materials around them, creating overheated disks that emit “winds” by magnetic pressure and radiation. These winds are so powerful that they reduce the formation of stars around the galactic core. Astronomers believe that quasar energy is responsible for limiting the growth of massive galaxies.
“Physically very small objects, supermassive black holes seem to have a huge impact on the evolution of galaxies and, eventually, on the way our universe looks today,” explains Dominika Wylezalek, a researcher at the University of Heidelberg in Germany and leader of the team at Q3D.
The hypothesis of the critical role of quasars in limiting the growth of galaxies has been around for two decades, but observational evidence is lacking. Scientists believe that the winds of a quasar expel the equivalent of hundreds of solar masses of material each year – sweeping the material’s galactic disk that would otherwise have formed new stars.
But looking at the power and range of quasars in their galaxies is a challenge that the Webb telescope could change. In addition to its greater sensitivity, resolution and infrared vision, the telescope that will be launched in 2021 has three-dimensional image spectroscopy. This observation technique allows the team of researchers to obtain detailed measurements of the light for each pixel in the field of view.
How the James Webb Space Telescope uses its integral field unit to generate three-dimensional image spectroscopy. Video: STScI
By bringing together several images at slightly different wavelengths, scientists are able to spatially map the movements of the gas within the galaxy in three dimensions. “Image spectroscopy is important to us because the winds in these distant quasars are not necessarily symmetrical,” explains astronomer Sylvain Veilleux, from the University of Maryland, College Park.
If quasar flows are proven to prevent the gas in a galaxy from forming new stars and making it grow, scientists will take a huge step in understanding how galaxies evolve from the beginning of the universe to today.