Quasar Tsunamis Slam Immense Amounts Of Energy Through Galaxies

A quasar emits exceptionally large amounts of energy generated by a supermassive black hole fueled by infalling matter. NASA, ESA and J Olmsted (STScI)

Katy Pallister 20 Mar 2020, 16:33

For almost 30 years, NASA’s Hubble Space Telescope has helped scientists to explore the universe, from observations of Jupiter’s “Great Red Spot” to collecting data on galactic collisions. Now, the latest cosmic project the telescope has contributed towards has one of the most immense descriptions we've ever heard: “Quasar Tsunamis Rip Across Galaxies.”

Using Hubble’s ultraviolet observations, astronomers have managed to study the exceptionally large energy outputs from 13 quasars. Quasars are extremely remote celestial objects located at the center of massive galaxies, each containing a supermassive black hole. As the active black hole pulls in surrounding matter, it heats up gas around it to such extreme temperatures that it can shine 1,000 times brighter than its host galaxy.

The intense radiation emitted from the hot gas, which creates the quasar, also drives torrential winds that sweep material away from the galaxy’s center at velocities that are a few percent of the speed of light.

"No other phenomena carries more mechanical energy,” principal investigator Nahum Arav of Virginia Tech in Blacksburg, Virginia, explained in a statement. "The amount of mechanical energy that these outflows carry is up to several hundreds of times higher than the luminosity of the entire Milky Way galaxy."

This image shows Quasar 3C 273, observed by the Hubble Space Telescope. If you were to witness a quasar tsunami event, you would see a huge light show all over the galaxy, as the temperature at the shock front spikes to billions of degrees. NASA and J. Bahcall (IAS)

Described as the most energetic outflows ever witnessed in the universe, these up to 10-million-year-long quasar tsunamis snowplow hundreds of solar masses of material each year. Slamming through lanes of gas and dust in their host galaxies, these winds completely stop the formation of new stars. This could help to explain cosmological puzzles, such as why few large galaxies are observed in the universe and why there is a relationship between the mass of the galaxy and the mass of its central black hole.

"Both theoreticians and observers have known for decades that there is some physical process that shuts off star formation in massive galaxies, but the nature of that process has been a mystery,” said eminent cosmologist Jeremiah P. Ostriker, of Columbia University in New York and Princeton University in New Jersey. “Putting the observed outflows into our simulations solves these outstanding problems in galactic evolution."

Published in a series of six papers as a focus issue of The Astrophysical Journal Supplements, the findings used Hubble data of spectral “fingerprints” of light that the gas left in its wake. The shifted spectrum of these light absorption features enabled the astronomers to calculate the incredible speeds at which the gas was accelerated. On top of measuring the most energetic quasars ever observed, they also discovered that one outflow was accelerating faster than any other, increasing from nearly 69 million kilometers per hour (43 million mph) to roughly 74 million kilometers per hour (46 million mph) in a three-year period.

"Hubble's ultraviolet observations allow us to follow the whole range of energy output from quasars, from cooler gas to the extremely hot, highly ionized gas in the more massive winds," team member Gerard Kriss of the Space Telescope Science Institute in Baltimore, Maryland, added. "Such powerful outflows may yield new insights into the link between the growth of a central supermassive black hole and the development of its entire host galaxy."

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