Scientists using the Hubble Space Telescope have detected quasars sending outbursts of energy roaring through their galaxies, according to new research.
Researchers at Virginia Tech and the Space Telescope Science Institute are reporting three of the most energetic quasar outbursts ever measured. These outflows not only present a puzzle to astronomers trying to understand how they form and accelerate, but they also provide important data to theorists trying to figure out what forces are driving galaxy formation. These outbursts, like waves ripping through the galaxy, release a truly incomprehensible amount of energy.
“[The Milky Way] is a medium-to-large scale galaxy, and the total amount of radiation coming out of it is basically a number times 1044 ergs per second,” explained lead author Nahum Arav from Virginia Tech. “The outflows we see are producing 100 times more kinetic energy than the whole output of our galaxy in visible light.”
Quasars are extremely luminous galactic centres, which scientists think surround the supermassive black holes at the centres of galaxies. The black holes don’t produce the radiation directly; instead, the radiation results from the interaction between the black hole’s incredible gravity and the matter surrounding it. While we often write about beams of radiation spewing from galactic centres at nearly the speed of light, these outflows from quasars are slightly different: They’re more like spheres of energy expanding outward at thousands of kilometres per second.
Given how powerful the outflows of energy from quasars are, they’ve drawn lots of interest from scientists like Arav. Some of the biggest questions astronomers want to answer about these outflows are: What causes them? Why do they accelerate? How do they relate to other aspects of the galactic centres? And how do they impact the evolution of the galaxy overall?
Here, the researchers measured 13 quasar outflows using the Hubble Cosmic Origins Spectrograph (COS), which measures the spectra, or specific wavelengths of radiation, released by these outbursts. Spectra tell astronomers what elements are contained in the outflows, as well as their temperature and speed. Hubble, located in space, is uniquely equipped to study these outflows; Earth’s atmosphere absorbs some ultraviolet and other wavelengths of light, hiding important details from ground-based telescopes.
This study and accompanying analyses included measurements of three of the most energetic outflows yet, as well as an outflow accelerating from 19,000 km/s to 20,500 km/s – around 42.5 million to 46 million miles per hour. They hope to use these measurements to test theories of how these outflows form and progress.
These measurements are also of importance to theorists. Arav explained that models of galaxy formation overestimate the number of large galaxies. Quasar outbursts provide a means to shut off galaxy formation. “Putting the observed outflows into our simulations solves these outstanding problems in galactic evolution,” Jeremiah P. Ostriker, a cosmologist with Columbia University and Princeton University who not involved in this new research, said in a Hubble press release.
The researchers have published data on the survey in a slew of papers in The Astrophysical Journal Supplements.
As with all astronomy surveys, a clearer picture will come with more data, and the researchers have submitted proposals to extend their observations of these outflows.
Featured image: Illustration: NASA, ESA, and J. Olmsted (STScI)