This artist's conception shows an edge-on view of the Milky Way galaxy and newly discovered gamma-ray jets extending from the central black hole.  Credit: David A. Aguilar (CfA)

Ghostly Jets Haunt the Milky Way’s Black Hole

Article Updated: 23 Dec , 2015

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A ghost is haunting the Milky Way’s central black hole, revealing the galactic nucleus was likely much more active in the past than it is now. Scientists using the Fermi space telescope have found faint apparitions of what must have been powerful gamma-ray jets emanating from our galaxy’s center.

“These faint jets are a ghost or after-image of what existed a million years ago,” said Meng Su, an astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), and lead author of a new paper in the Astrophysical Journal. “They strengthen the case for an active galactic nucleus in the Milky Way’s relatively recent past.”

This is the first time this type of jet has been detected from the Milky Way’s black hole. Scientists know that other active galaxies have cores that glow brightly, powered by supermassive black holes swallowing material, and often spit twin jets in opposite directions.

The two beams, or jets found by Fermi observations extend from the galactic center to a distance of 27,000 light-years above and below the galactic plane.
The newfound jets may be related to mysterious gamma-ray bubbles that Fermi detected in 2010. Those bubbles also stretch 27,000 light-years from the center of the Milky Way. However, where the bubbles are perpendicular to the galactic plane, the gamma-ray jets are tilted at an angle of 15 degrees. This may reflect a tilt of the accretion disk surrounding the supermassive black hole.

“The central accretion disk can warp as it spirals in toward the black hole, under the influence of the black hole’s spin,” explained co-author Douglas Finkbeiner of the CfA. “The magnetic field embedded in the disk therefore accelerates the jet material along the spin axis of the black hole, which may not be aligned with the Milky Way.”

The two structures also formed differently. The jets were produced when plasma squirted out from the galactic center, following a corkscrew-like magnetic field that kept it tightly focused. The gamma-ray bubbles likely were created by a “wind” of hot matter blowing outward from the black hole’s accretion disk. As a result, they are much broader than the narrow jets.

Both the jets and bubbles are powered by inverse Compton scattering. In that process, electrons moving near the speed of light collide with low-energy light, such as radio or infrared photons. The collision increases the energy of the photons into the gamma-ray part of the electromagnetic spectrum.

The discovery leaves open the question of when the Milky Way was last active. A minimum age can be calculated by dividing the jet’s 27,000-light-year length by its approximate speed. However, it may have persisted for much longer.

“These jets probably flickered on and off as the supermassive black hole alternately gulped and sipped material,” said Finkbeiner.

It would take a tremendous influx of matter for the galactic core to fire up again. Finkbeiner estimates that a molecular cloud weighing about 10,000 times as much as the Sun would be required.

“Shoving 10,000 suns into the black hole at once would do the trick. Black holes are messy eaters, so some of that material would spew out and power the jets,” he said.

Source: CfA

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Julien Redmond
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Julien Redmond
May 30, 2012 7:24 AM

so if the jets are only out 27000 light years docent that mean that they happened 27000 years ago?

Ionut Dumitrascu
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Ionut Dumitrascu
May 30, 2012 9:11 AM

No, because the jets did not “travel” at the speed of light. That’s why it’s said in the article: “A minimum age can be calculated by dividing the jet’s 27,000-light-year length by its approximate speed”.
As to what that approximate speed is…..smile I’ll leave it to someone more qualified to answer that.

SteveZodiac
Member
SteveZodiac
May 30, 2012 9:49 AM

Not very qualified but red/blue shift would tell you the speed of the jets, approximately because they are not moving directly towards or away.

the_only_fan
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the_only_fan
May 30, 2012 11:55 AM

you have take into account the forming time of the beam and the distance from the earth to the galactic center. you will arrive to quite some time

moozoo
Member
moozoo
May 30, 2012 9:15 AM

Would these jets have been visible when they where active?
Would they have affected life on earth in anyway?

Jon Souter
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Jon Souter
May 30, 2012 9:32 AM

> Would they have affected life on earth in anyway?

Only if the angle of the jets varied so much that they pointed directly in our direction.

As to what the effect of that would be at our distance from the galactic centre… that’s best answered by someone with a deeper understanding of the physics involved.

Stone Clark
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May 30, 2012 10:06 AM

Ummm… can you say Electric Universe?!?!

DrFlimmer
Member
DrFlimmer
May 30, 2012 12:17 PM

No, you can’t. wink

Jon Souter
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Jon Souter
May 30, 2012 4:39 PM

From the little I understand about Electric Universe / Plasma theory – the notion of black holes is not accepted.

What electric phenomena are likely to be causing the jets we see all over the visible universe?

Really20
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Really20
May 30, 2012 10:36 PM

TEU is merely another absurd “theory,” made by people who think that currently accepted astrophysics is based on “just” theories.

Olaf
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Olaf
May 30, 2012 4:41 PM

Can’t since black holes in EU is blasphemy!

Ignoramus1
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Ignoramus1
May 30, 2012 2:20 PM

“Both the jets and bubbles are powered by inverse Compton scattering”
Is that a fact?

DrFlimmer
Member
DrFlimmer
May 30, 2012 5:39 PM

It’s at least very likely, since high energetic electrons tend to upscatter “soft” radiation rather efficiently to gamma rays. And electrons that are shot out from the vicinity of a super massive black hole usually have VERY high energies.

Olaf
Member
Olaf
May 30, 2012 4:42 PM

Why are the jets not a spiral?

Lawrence B. Crowell
Member
Lawrence B. Crowell
May 30, 2012 8:44 PM
As a point of physics, the jet executes a cork screw motion because of angular momentum coupling between the black hole + accretion disk with the rest of the galaxy. If the angular momentum of the Bh+accretion disk is J and that of the rest of the galaxy is J’, then the inner product between these two angular momentum vectors J•J’ defines a part of the Hamiltonian of the system which pertains to angular momentum H = (1/2)(J^2 + J’^2) + c J•J’ The Hamiltonian is the “energy function.” Here c is a coupling constant, which is a bit complicated and not as relevant and the inner product of the two angular momentum vectors is equal to their… Read more »
IVAN3MAN_AT_LARGE
Member
IVAN3MAN_AT_LARGE
May 30, 2012 11:46 PM

Well, this is somewhat belated, but better late than never…

Here are links to two relevant papers:

Evidence for Gamma-ray Jets in the Milky Way;

Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?

TomN
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TomN
May 30, 2012 9:58 PM

Would these jets and the bubble have an effect on the formation and life cycle of globular clusters (like M13) that may inhabit that region around the core?

TomN
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TomN
May 30, 2012 9:58 PM

Would these jets and the bubble have an effect on the formation and life cycle of globular clusters (like M13) that may inhabit that region around the core?

Dov Henis
Member
Dov Henis
June 9, 2012 3:44 PM
Another look at the universe? Natural Selection Is Ubiquitous Higgs Particle? Dark Energy/Matter? Epigenetics? These Are YOK! Update Concepts-Comprehension… http://universe-life.com/2011/12/13/21st-century-science-whence-and-whither/ Evolution Is The Quantum Mechanics Of Natural Selection. The quantum mechanics of every process is its evolution. Quantum mechanics are mechanisms, possible or probable or actual mechanisms of natural selection. ================= Universe-Energy-Mass-Life Compilation http://universe-life.com/2012/02/03/universe-energy-mass-life-compilation/ A. The Universe From the Big-Bang it is a rationally commonsensical conjecture that the gravitons, the smallest base primal particles of the universe, must be both mass and energy, i.e. inert mass yet in motion even at the briefest fraction of a second of the pre Big Bang singularity. This is rationally commonsensical since otherwise the Big would not have Banged, the superposition of… Read more »
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