Credit X-ray: NASA/CXC/Queen's Univ. Belfast/M. Nicholl et al.; Optical/IR: PanSTARRS, NSF/Legacy Survey/SDSS;
Illustration: Soheb Mandhai / The Astro Phoenix; Image Processing: NASA/CXC/SAO/N. Wolk
This artist’s illustration shows a disk of material (red, orange, and yellow) that was created after a supermassive black hole (depicted on the right) tore apart a star through intense tidal forces. Over the course of a few years, this disk expanded outward until it intersected with another object — either a star or a small black hole — that is also in orbit around the giant black hole. Each time this object crashes into the disk, it sends out a burst of X-rays detected by Chandra. The inset shows Chandra data (purple) and an optical image of the source from Pan-STARRS (red, green, and blue).
In 2019, an optical telescope in California noticed a burst of light that astronomers later categorized as a “tidal disruption event”, or TDE. These are cases where black holes tear stars apart if they get too close through their powerful tidal forces. Astronomers gave this TDE the name of AT2019qiz.
Meanwhile, scientists were also tracking instances of another type of cosmic phenomena occasionally observed across the Universe. These were brief and regular bursts of X-rays that were near supermassive black holes. Astronomers named these events “quasi-periodic eruptions,” or QPEs.
This latest study gives scientists evidence that TDEs and QPEs are likely connected. The researchers think that QPEs arise when an object smashes into the disk left behind after the TDE. While there may be other explanations, the authors of the study propose this is the source of at least some QPEs.
In 2023, astronomers used both Chandra and Hubble to simultaneously study the debris left behind after the tidal disruption had ended. The Chandra data were obtained during three different observations, each separated by about 4 to 5 hours. The total exposure of about 14 hours of Chandra time revealed only a weak signal in the first and last chunk, but a very strong signal in the middle observation.
From there, the researchers used NASA’s Neutron Star Interior
Composition Explorer (NICER) to look frequently at AT2019qiz for
repeated X-ray bursts. The NICER data showed that AT2019qiz erupts
roughly every 48 hours. Observations from NASA’s Neil Gehrels Swift
Observatory and India’s AstroSat telescope cemented the finding.
The ultraviolet
data from Hubble, obtained at the same time as the Chandra
observations, allowed the scientists to determine the size of the disk
around the supermassive black hole. They found that the disk had become
large enough that if any object was orbiting the black hole and took
about a week or less to complete an orbit, it would collide with the
disk and cause eruptions.
This result has implications for searching for more quasi-periodic
eruptions associated with tidal disruptions. Finding more of these would
allow astronomers to measure the prevalence and distances of objects in
close orbits around supermassive black holes. Some of these may be
excellent targets for the planned future gravitational wave observatories.
The paper describing these results appears in the October 9, 2024
issue of the journal Nature. The first author of the paper is Matt
Nicholl (Queen’s University Belfast in Ireland) and the full list of
authors can be found in the paper, which is available online at: https://arxiv.org/abs/2409.02181
NASA's Marshall Space Flight Center manages the Chandra program. The
Smithsonian Astrophysical Observatory's Chandra X-ray Center controls
science operations from Cambridge, Massachusetts, and flight operations
from Burlington, Massachusetts.
Visual Description:
The black hole sits halfway down our right edge of the vertical image. It resembles a jet black semicircle with a domed cap of pale blue light. The bottom half of the circular black hole is hidden behind the disk of stellar material. In this illustration, the disk is viewed edge on. It resembles a band of swirling yellow, orange, and red gas, cutting diagonally from our middle right toward our lower left.
Near our lower left, the outer edge of the stellar debris disk overlaps with a bright blue sphere surrounded by luminous white swirls. This sphere represents a neighboring star crashing through the disk. The stellar disk is the wreckage of a destroyed star. An electric blue and white wave shows the hottest gas in the disk.
As the neighboring star crashes through the disk it leaves behind a trail of gas depicted as streaks of fine mist. Bursts of X-rays are released and are detected by Chandra.
Superimposed in the upper left corner of the illustration is an inset box showing a close up image of the source in X-ray and optical light. X-ray light is shown as purple and optical light is white and beige.
Fast Facts for AT2019qiz:
Scale: Image is about 5 arcmin (305,000 light-years) across. X-ray movie is about 1 arcminute (61,000 light-years) across.
Category: Black Holes, Quasars & Active Galaxies
Coordinates (J2000): RA 4h 46m 37.9s | Dec -10° 13´ 34.9"
Constellation: Eridanus
Observation Dates: 3 observations between Dec 09, 2023 and Dec 10, 2023
Observation Time: 13 hours 58 minutes
Obs. ID: 26788, 29099, 29100
Instrument: ACIS
References: Nicholl, M, et al., 2024, Nature; arXiv:2409.02181
Color Code: X-ray: purple; Optical/IR: red, green, and blue.
Distance Estimate: About 210 million light-years (z=0.0151)
