Andrew Yee
December 20th 05, 06:31 PM
Office of Public Information
Eberly College of Science
Pennsylvania State University
University Park, Pennsylvania
SWIFT SCIENCE CONTACT AT PENN STATE:
Peter Mészáros
Head of the Swift science team and Holder of the Eberly Family Chair in
Astronomy and Astrophysics at Penn State
814-863-4167
P.I.O. CONTACTS:
Barbara K. Kennedy, Penn State PIO
814-863-4682
Dewayne Washington, NASA Goddard PIO
301-286-0040
Lynn Cominsky, Swift PIO
707-664-2655
14 December 2005
Cosmic Explosion Could Be Black Hole Swallowing Neutron Star
Scientists using the NASA Swift satellite have found evidence of a black
hole swallowing a neutron star. The discovery is reported in the December
15 issue of the journal Nature.
This rare event, seen on 24 July 2005, created a gamma-ray burst that
lasted only for a few milliseconds. Observations of the lingering
afterglow, however, provided evidence of what could have been the bizarre
demise of a neutron star orbiting a black hole. The black hole may have
first stretched the dense neutron star into a crescent, breaking off
crumbs in the process. The black hole then could have swallowed the star
largely in one gulp, feeding on the crumbs in the minutes and hours that
followed. Such a black hole would grow more massive, like a python that
downs a wild boar.
"For billions of years this black hole and neutron star orbited each other
in a gravitational tug-of-war," said Scott Barthelmy of NASA Goddard Space
Flight Center in Greenbelt, Maryland, lead author on one of three the
Nature articles on the subject. "The neutron star lost."
In recent months the Swift team has reported that "short" gamma-ray bursts
arise from a merger either between two neutron stars or a neutron star and
black hole. The specific scenario was not clear. This latest analysis of a
July burst, although not definitive, is the best evidence of a black
hole-neutron star merger, Barthelmy said.
A neutron star is the core remains of an exploded star once about 10 to 25
times more massive than our Sun. It contains about the Sun's mass crammed
into a sphere only about 12 miles across. A black hole is the core remains
of an even larger exploded star, over 25 times the mass of the Sun.
The July burst, called GRB 050724, was one of the most thoroughly observed
short gamma-ray bursts to date. Swift, NASA's Chandra telescope, and the
Keck Observatory in Hawaii, among other observatories, captured the burst
afterglow in detail. The combined data enabled scientists to speculate on
the nature of the merging objects.
If GRB 050724 were a merger of two neutron stars, there would not be many
crumbs falling into a black hole later. The two objects would smash,
instantly form a black hole, and after a modest afterglow no more light
would be seen. Similarly, two black holes would smash and release very
little residual light. But GRB 050724 had a long, flaring afterglow.
Peter Mészáros, the Holder of the Eberly Family Chair in Astronomy and
Astrophysics at Penn State, and Bing Zhang, of the University of Nevada in
Las Vegas, co-authors on the Barthelmy-led Nature article, theorize that
smaller flares of X-ray light and optical light, detected in the first
tens of seconds after GRB 050724, could have resulted from crumbs of the
neutron star falling into the black hole. Flares occurring later might be
from magnetized crumbs of gas, which would behave differently. Supporting
this merger scenario is the fact that GRB 050724 took place in the
outskirts of an old, elliptical galaxy filled with neutron stars and black
holes.
"Neutron stars are the densest objects known," said Mészáros. "There's
only one thing I know of that could rip apart a neutron star with bits
flying out, and that's a black hole. Now we have the first evidence that
this kind of merger might actually be occurring."
Numerical simulations by Melvyn Davies and Andrew King, and others at
Leicester University in England, have provided evidence for such a
disruption of a neutron star by a black hole, including the late infall of
crumbs of matter. Other simulations elsewhere indicate conversely that
neutron-star mergers would leave no flaring afterglow.
Nial Tanvir of the University of Hertfordshire in Hatfield, England, and
Edo Berger of the Carnegie Observatories in Pasadena are lead authors on
the two accompanying Nature articles, which describe follow-up
observations after Swift's detection of GRB 050724.
ABOUT SWIFT
Swift was launched in November 2004 and was fully operational by January
2005. Swift carries three main instruments: the Burst Alert Telescope, the
X-ray Telescope, and the Ultraviolet/Optical Telescope. Swift's gamma-ray
detector, the Burst Alert Telescope, provides the rapid initial location
and was built primarily by the NASA Goddard Space Flight Center in
Greenbelt and Los Alamos National Laboratory and constructed at GSFC.
Swift's X-Ray Telescope and UV/Optical Telescope were developed and built
by international teams led by Penn State and drew heavily on each
institution's experience with previous space missions. The X-ray Telescope
resulted from Penn State's collaboration with the University of Leicester
in England and the Brera Astronomical Observatory in Italy, and the
Ultraviolet/Optical Telescope from a collaboration with the Mullard Space
Science Laboratory of the University College-London. These three
telescopes give Swift the ability to do almost immediate follow-up
observations of most gamma-ray bursts because Swift can rotate so quickly
to point toward the source of the gamma-ray signal.
MOVIE CAPTIONS:
[Movie 1:
http://www.nasa.gov/mpeg/139515main_209.mpeg (4.1MB, no audio)]
Cosmic Explosion Could Be Black Hole Swallowing Neutron Star Animation
Scientists using the NASA Swift satellite have found evidence of a black
hole swallowing a neutron star. The black hole may have first stretched
the dense neutron star into a crescent and broken off crumbs in the
process. The black hole could have then swallowed the star largely in one
gulp, feeding on the crumbs in the minutes and hours that followed. Such a
black hole would grow more massive, like a python that downs a wild boar.
Credit: NASA/Dana Berry, Skyworks Digital
[Movie 2:
http://www.nasa.gov/mpeg/139514main_104%20Swift%20Spacecraft%20Turn%20t_NAS A%20WebV_1.mpeg
(800KB, no audio)]
Swift Spacecraft Animation
Swift, launched in November 2004, is a NASA mission in partnership with
the Italian Space Agency and the Particle Physics and Astronomy Research
Council, United Kingdom; and is managed by NASA Goddard. Penn State
controls science and flight operations from the Mission Operations Center
in University Park, Pennsylvania.
Credit: NASA
Eberly College of Science
Pennsylvania State University
University Park, Pennsylvania
SWIFT SCIENCE CONTACT AT PENN STATE:
Peter Mészáros
Head of the Swift science team and Holder of the Eberly Family Chair in
Astronomy and Astrophysics at Penn State
814-863-4167
P.I.O. CONTACTS:
Barbara K. Kennedy, Penn State PIO
814-863-4682
Dewayne Washington, NASA Goddard PIO
301-286-0040
Lynn Cominsky, Swift PIO
707-664-2655
14 December 2005
Cosmic Explosion Could Be Black Hole Swallowing Neutron Star
Scientists using the NASA Swift satellite have found evidence of a black
hole swallowing a neutron star. The discovery is reported in the December
15 issue of the journal Nature.
This rare event, seen on 24 July 2005, created a gamma-ray burst that
lasted only for a few milliseconds. Observations of the lingering
afterglow, however, provided evidence of what could have been the bizarre
demise of a neutron star orbiting a black hole. The black hole may have
first stretched the dense neutron star into a crescent, breaking off
crumbs in the process. The black hole then could have swallowed the star
largely in one gulp, feeding on the crumbs in the minutes and hours that
followed. Such a black hole would grow more massive, like a python that
downs a wild boar.
"For billions of years this black hole and neutron star orbited each other
in a gravitational tug-of-war," said Scott Barthelmy of NASA Goddard Space
Flight Center in Greenbelt, Maryland, lead author on one of three the
Nature articles on the subject. "The neutron star lost."
In recent months the Swift team has reported that "short" gamma-ray bursts
arise from a merger either between two neutron stars or a neutron star and
black hole. The specific scenario was not clear. This latest analysis of a
July burst, although not definitive, is the best evidence of a black
hole-neutron star merger, Barthelmy said.
A neutron star is the core remains of an exploded star once about 10 to 25
times more massive than our Sun. It contains about the Sun's mass crammed
into a sphere only about 12 miles across. A black hole is the core remains
of an even larger exploded star, over 25 times the mass of the Sun.
The July burst, called GRB 050724, was one of the most thoroughly observed
short gamma-ray bursts to date. Swift, NASA's Chandra telescope, and the
Keck Observatory in Hawaii, among other observatories, captured the burst
afterglow in detail. The combined data enabled scientists to speculate on
the nature of the merging objects.
If GRB 050724 were a merger of two neutron stars, there would not be many
crumbs falling into a black hole later. The two objects would smash,
instantly form a black hole, and after a modest afterglow no more light
would be seen. Similarly, two black holes would smash and release very
little residual light. But GRB 050724 had a long, flaring afterglow.
Peter Mészáros, the Holder of the Eberly Family Chair in Astronomy and
Astrophysics at Penn State, and Bing Zhang, of the University of Nevada in
Las Vegas, co-authors on the Barthelmy-led Nature article, theorize that
smaller flares of X-ray light and optical light, detected in the first
tens of seconds after GRB 050724, could have resulted from crumbs of the
neutron star falling into the black hole. Flares occurring later might be
from magnetized crumbs of gas, which would behave differently. Supporting
this merger scenario is the fact that GRB 050724 took place in the
outskirts of an old, elliptical galaxy filled with neutron stars and black
holes.
"Neutron stars are the densest objects known," said Mészáros. "There's
only one thing I know of that could rip apart a neutron star with bits
flying out, and that's a black hole. Now we have the first evidence that
this kind of merger might actually be occurring."
Numerical simulations by Melvyn Davies and Andrew King, and others at
Leicester University in England, have provided evidence for such a
disruption of a neutron star by a black hole, including the late infall of
crumbs of matter. Other simulations elsewhere indicate conversely that
neutron-star mergers would leave no flaring afterglow.
Nial Tanvir of the University of Hertfordshire in Hatfield, England, and
Edo Berger of the Carnegie Observatories in Pasadena are lead authors on
the two accompanying Nature articles, which describe follow-up
observations after Swift's detection of GRB 050724.
ABOUT SWIFT
Swift was launched in November 2004 and was fully operational by January
2005. Swift carries three main instruments: the Burst Alert Telescope, the
X-ray Telescope, and the Ultraviolet/Optical Telescope. Swift's gamma-ray
detector, the Burst Alert Telescope, provides the rapid initial location
and was built primarily by the NASA Goddard Space Flight Center in
Greenbelt and Los Alamos National Laboratory and constructed at GSFC.
Swift's X-Ray Telescope and UV/Optical Telescope were developed and built
by international teams led by Penn State and drew heavily on each
institution's experience with previous space missions. The X-ray Telescope
resulted from Penn State's collaboration with the University of Leicester
in England and the Brera Astronomical Observatory in Italy, and the
Ultraviolet/Optical Telescope from a collaboration with the Mullard Space
Science Laboratory of the University College-London. These three
telescopes give Swift the ability to do almost immediate follow-up
observations of most gamma-ray bursts because Swift can rotate so quickly
to point toward the source of the gamma-ray signal.
MOVIE CAPTIONS:
[Movie 1:
http://www.nasa.gov/mpeg/139515main_209.mpeg (4.1MB, no audio)]
Cosmic Explosion Could Be Black Hole Swallowing Neutron Star Animation
Scientists using the NASA Swift satellite have found evidence of a black
hole swallowing a neutron star. The black hole may have first stretched
the dense neutron star into a crescent and broken off crumbs in the
process. The black hole could have then swallowed the star largely in one
gulp, feeding on the crumbs in the minutes and hours that followed. Such a
black hole would grow more massive, like a python that downs a wild boar.
Credit: NASA/Dana Berry, Skyworks Digital
[Movie 2:
http://www.nasa.gov/mpeg/139514main_104%20Swift%20Spacecraft%20Turn%20t_NAS A%20WebV_1.mpeg
(800KB, no audio)]
Swift Spacecraft Animation
Swift, launched in November 2004, is a NASA mission in partnership with
the Italian Space Agency and the Particle Physics and Astronomy Research
Council, United Kingdom; and is managed by NASA Goddard. Penn State
controls science and flight operations from the Mission Operations Center
in University Park, Pennsylvania.
Credit: NASA