Using NASA’s Neil Gehrels Swift Observatory, which launched in 2004, scientists have discovered a black hole in a distant galaxy repeatedly nibbling on a Sun-like star. The object heralds a new era of Swift science made possible by a novel method for analyzing data from the satellite’s X-ray Telescope (XRT).
“Swift’s hardware, software, and the
skills of its international team have enabled it to adapt to new areas of
astrophysics over its lifetime,” said Phil Evans, an astrophysicist at the
University of Leicester in the United Kingdom and longtime Swift team member.
“Neil Gehrels, the mission’s namesake, oversaw and encouraged many of those
transitions. Now, with this new ability, it’s doing even more cool science.”
Evans led a study about the unlucky star
and its hungry black hole, collectively called Swift J023017.0+283603 (or Swift
J0230 for short), which was published on Sept. 7 in Nature Astronomy.
Watch to learn how an update to NASA’s Neil Gehrels Swift Observatory allowed it to catch a supersized black hole in a distant galaxy munching repeatedly on a circling star. Credit: NASA's Goddard Space Flight Center
Download
high-resolution video and images from NASA’s Scientific Visualization Studio
When a star strays too close to a monster
black hole, gravitational forces create intense tides that break the star apart
into a stream of gas. The leading edge swings around the black hole, and the
trailing edge escapes the system. These destructive episodes are called tidal
disruption events. Astronomers see them as flares of multiwavelength light
created when the debris collides with a disk of material already orbiting the
black hole.
Recently, astronomers have been
investigating variations on this phenomena, which they call partial or
repeating tidal disruptions.
During these events, every time an
orbiting star passes close to a black hole, the star bulges outward and sheds
material, but survives. The process repeats until the star loses too much gas
and finally breaks apart. The characteristics of the individual star and black
hole system determine what kind of emission scientists observe, creating a wide
array of behaviors to categorize.
Previous examples include an outburst that occurred every 114 days, potentially caused by a giant star orbiting a black hole with 78 million times the Sun’s mass. Another recurred every nine hours around a black hole with 400,000 times the Sun’s mass, likely caused by an orbiting stellar cinder called a white dwarf.
Swift J0230 occurred over 500 million light-years away in a galaxy named 2MASX J02301709+2836050, captured here by the Pan-STARRS telescope in Hawaii. Credit: Neils Bohr Institute/Daniele Malesani
On June 22, 2022, the XRT captured Swift J0230 for the first time. It lit up in a galaxy around 500 million light-years away in the northern constellation Triangulum. Swift’s XRT observed nine additional outbursts from the same location roughly every few weeks.
Evans and his team propose that Swift
J0230 is a repeating tidal disruption of a Sun-like star orbiting a black hole
with over 200,000 times the Sun’s mass. They estimate the star loses around
three Earth masses of material on each pass. This system provides a bridge
between other types of suspected repeating disruptions and allowed scientists
to model how interactions between different star types and black hole sizes
affect what we observe.
“We searched and searched for the event
brightening in the data collected by Swift’s Ultraviolet/Optical Telescope,”
said Alice Breeveld, a research fellow at the University College London’s
Mullard Space Science Laboratory (MSSL) who has worked on the instrument since
before the satellite launched. “But there wasn’t any sign of it. The galaxy’s
variability was entirely in X-rays. That helped rule out some other potential
causes.”
Swift J0230’s discovery was possible
thanks to a new, automated search of XRT observations, developed by Evans,
called the Swift X-ray Transient Detector.
After the instrument observes a portion of
the sky, the data is transmitted to the ground, and the program compares it to
previous XRT snapshots of the same spot. If that portion of the X-ray sky has
changed, scientists get an alert. In the case of Swift J0230, Evans and his
colleagues were able to rapidly coordinate additional observations of the
region.
Swift was originally designed to study
gamma-ray bursts, the most powerful explosions in the cosmos. Since the
satellite launched, however, scientists have recognized its ability to study a
whole host of celestial objects, like tidal disruptions and comets.
“Swift J0230 was discovered only about two
months after Phil launched his program,” said S. Bradley Cenko, the mission’s
principal investigator at NASA’s
Goddard Space Flight Center in
Greenbelt, Maryland. “It bodes well for the detector’s ability to identify
other transient events and for Swift’s future exploring new spaces of science.”
Goddard manages the Swift mission in
collaboration with Penn State, the Los Alamos National Laboratory in New
Mexico, and Northrop Grumman Space Systems in Dulles, Virginia. Other partners
include Leicester, MSSL, Brera Observatory in Italy, and the Italian Space
Agency.
By Jeanette
Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Source: NASA’s Swift Learns a New Trick, Spots a Snacking Black Hole | NASA
No comments:
Post a Comment