In the nearby
Whirlpool Galaxy and its companion galaxy, M51b, two supermassive black holes
warm up and consume surrounding material. These two monsters should be the most
luminous x-ray sources in sight, but a new study using observations from NASA's NuSTAR
(Nuclear Spectroscopic Telescope Array) mission shows that a much smaller object
compete with the two behemoter.
great features of the Whirlpool Galaxy – officially known as M51a – are
two long star-filled "arms" curl around the galactic center like
bands. The much smaller M51b adheres like a skin to the edge of
Whirlpool. Overall known as the M51, they merge two galaxies.
In the center
Of each galaxy, a supermassive black hole is millions of times more massive than
the sun. The galactic fusion should push large amounts of gas and dust into them
black holes and circuits around them. On the other hand, the intense gravity is off
black holes should cause the circuit material to heat and radiate, forming
Bright discs around each that can shine all the stars in their galaxies.
Black hole so clearly radiates in the X-ray area that scientists would expect
during a merger. Based on past observations from satellites that discover
Low-energy X-rays, such as NASA's Chandra X-ray
Observatory believed scientists to layer of gas and dust around
The black hole in the large galaxy blocked extra emission. But the new one
study, published in the Astrophysical Journal, used NuSTAR's high-energy X-ray
vision to lie under these layers and found out that the black hole is still lighter
still surprised by this discovery, "said study director author Murray Brightman,
a researcher at Caltech in Pasadena, California. "Galactic mergers are
is supposed to generate black growth in the hole, and the evidence for this will be strong
high energy x-ray emission. But we don't see it here. "
The most likely explanation is that black holes "flicker" below
galactic fusions rather than radiate with a more or less constant brightness
the whole process.
shimmering hypothesis is a new idea in the field, "says Daniel Stern, a
researcher at NASA's Jet Propulsion Laboratory in Pasadena and the project
scientist for NuSTAR. "We used to think of the black hole variation
originated in time frames of millions of years, but now we are thinking about these schedules
could be much shorter. Finding out how card is an area of active investigation. "
Small but Brilliant
the two black holes radiate less than researchers predicted in M51
The former also hosts an object that is millions of times smaller than
black hole is still shining with equal intensity. The two phenomena are not
connected, but they create a surprising X-ray landscape in the M51.
The little one
X-ray source is a neutron star, an incredibly tight nugget material left behind
Over after a massive star explodes at the end of its life. A typical neutron
the star is hundreds of thousands of times smaller in diameter than the sun
as wide as a large city – but has one to two times the mass. A teaspoon
neutron star material would weigh more than 1 billion tons.
Size, neutron stars often make known through intense light
emissions. The neutron star found in the M51 is even lighter than average and belongs to
for a newly discovered class known as ultra-luminous neutron stars. Brightman
said some researchers have suggested that strong magnetic fields are generated by
The neutron star could be responsible for the emission of a previous paper
by Brightman and colleagues about this neutron star support this hypothesis. Some
of the other bright, high-energy x-ray sources seen in these two galaxies could
also be neutron stars.
NuSTAR is one
Small Explorer mission led by Caltech and run by JPL for NASA's Science
Mission Directorate in Washington. NuSTAR was developed in collaboration with
Danish Technical University and the Italian Space Agency (ASI). The spacecraft
was built by Orbital Sciences Corporation in Dulles, Virginia (now part of
Northrop Grumman). NuSTAR's mission office is at UC Berkeley, and
The official data archive is on NASA's High Energy Astrophysics Science Archive
Research Center. ASI provides the mission's base station and a mirror
File. Caltech manages JPL to NASA
For more information on NuSTAR, visit:
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Jet Propulsion Laboratory, Pasadena, California.