From end to end, the newly discovered gamma-ray bubbles extend 50,000 light-years, or roughly half of the Milky Way's diameter, as shown in this illustration.  Credit: NASA

Fermi Telescope Finds Giant Structure in the Milky Way

Article Updated: 24 Dec , 2015

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From a NASA press release:

NASA’s Fermi Gamma-ray Space Telescope has unveiled a previously unseen structure centered in the Milky Way. The feature spans 50,000 light-years and may be the remnant of an eruption from a supersized black hole at the center of our galaxy.

“What we see are two gamma-ray-emitting bubbles that extend 25,000 light-years north and south of the galactic center,” said Doug Finkbeiner, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who first recognized the feature. “We don’t fully understand their nature or origin.”

The structure spans more than half of the visible sky, from the constellation Virgo to the constellation Grus, and it may be millions of years old. A paper about the findings has been accepted for publication in The Astrophysical Journal.

Finkbeiner and Harvard graduate students Meng Su and Tracy Slatyer discovered the bubbles by processing publicly available data from Fermi’s Large Area Telescope (LAT). The LAT is the most sensitive and highest-resolution gamma-ray detector ever launched. Gamma rays are the highest-energy form of light.

Other astronomers studying gamma rays hadn’t detected the bubbles partly because of a fog of gamma rays that appears throughout the sky. The fog happens when particles moving near the speed of light interact with light and interstellar gas in the Milky Way. The LAT team constantly refines models to uncover new gamma-ray sources obscured by this so-called diffuse emission. By using various estimates of the fog, Finkbeiner and his colleagues were able to isolate it from the LAT data and unveil the giant bubbles.

Scientists now are conducting more analyses to better understand how the never-before-seen structure was formed. The bubble emissions are much more energetic than the gamma-ray fog seen elsewhere in the Milky Way. The bubbles also appear to have well-defined edges. The structure’s shape and emissions suggest it was formed as a result of a large and relatively rapid energy release — the source of which remains a mystery.

One possibility includes a particle jet from the supermassive black hole at the galactic center. In many other galaxies, astronomers see fast particle jets powered by matter falling toward a central black hole. While there is no evidence the Milky Way’s black hole has such a jet today, it may have in the past. The bubbles also may have formed as a result of gas outflows from a burst of star formation, perhaps the one that produced many massive star clusters in the Milky Way’s center several million years ago.

“In other galaxies, we see that starbursts can drive enormous gas outflows,” said David Spergel, a scientist at Princeton University in New Jersey. “Whatever the energy source behind these huge bubbles may be, it is connected to many deep questions in astrophysics.”

Hints of the bubbles appear in earlier spacecraft data. X-ray observations from the German-led Roentgen Satellite suggested subtle evidence for bubble edges close to the galactic center, or in the same orientation as the Milky Way. NASA’s Wilkinson Microwave Anisotropy Probe detected an excess of radio signals at the position of the gamma-ray bubbles.

The Fermi LAT team also revealed Tuesday the instrument’s best picture of the gamma-ray sky, the result of two years of data collection.

“Fermi scans the entire sky every three hours, and as the mission continues and our exposure deepens, we see the extreme universe in progressively greater detail,” said Julie McEnery, Fermi project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.
NASA’s Fermi is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

“Since its launch in June 2008, Fermi repeatedly has proven itself to be a frontier facility, giving us new insights ranging from the nature of space-time to the first observations of a gamma-ray nova,” said Jon Morse, Astrophysics Division director at NASA Headquarters in Washington. “These latest discoveries continue to demonstrate Fermi’s outstanding performance.”

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Navneeth
Member
Navneeth
November 9, 2010 12:21 PM

Whoa! I hope the press image is not exaggerated.

Aqua4U
Member
November 9, 2010 3:18 PM

WHOA Nelly!! Any polarization evident? I wonder what this galaxy’s lobes would look like?

lars
Member
lars
November 9, 2010 10:24 PM

Proving once again:
There is no substitute for the accurate collection of data !!!
Bravo Fermi !!!

But now we have as our foible, the correct interpretation of that data !

Greg
Member
Greg
November 9, 2010 11:27 PM

The orientation of these bubbles along the galacic poles and centered as they are I think unmistakably points the finger at the SMBH as the source. Finding evidence for large gamma ray outbursts should not be too surprising, considering evidence from quasars both near and far. Eventually we should learn the kinds of things the SMBH snacks upon and what types of outbursts they produce from observations of active galactic nuclei that are relatively nearby. I have speculated that perhaps a pulsar or large star being ripped apart as it wanders too close to the SMBH could produce such an outburst.

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 10, 2010 5:21 AM
This is interesting news, which is welcome from an astrophysics perspective, but troublesome from a particle physics perspective. However, maybe this replaces problematic particle physics data with astrophysics data. My sense of course is that these lobes are the remnants of galactic jets or activity in the galaxy center produced by a black hole. The Milky Way galaxy has a modest SMBH that weighs in at 10 million solar masses. Over the past month, science news sites and blogs have been abuzz over a possible sighting of dark matter, based on a paper by Fermilab’s Dan Hooper and NYU’s Lisa Goodenough. This time, the reports say, a number of cosmologists (Michael Turner) have found these data to be… Read more »
tsdisee
Member
tsdisee
November 10, 2010 8:39 AM

Great!
I love to know:
1 how faint is that gamma-ray bubble? only be seen until today
2 Do you mean more and more dark matter turning to the “bright side”?
how fast is the turning rate.
3 Do they have radio or UV counterparts ?

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 10, 2010 10:05 AM
How long will dark matter last? That is an interesting question. I will attempt to calculate an estimate for that. The volume of a galactic halo is about 10^{18} cubic light years or 10^{66}m^3. The mass of DM in a galaxy is about 10^{11} solar masses or 10^{41}kg. Therefore the density is 10^{-24}kg/m^3 over all. However, for the central region of a galaxy this density may be about 100 times that, so each cubic meter has maybe 10^{-22}kg of DM. Now a proton has a mass of about 10^{-27}kg and a DM particle we might estimate has about 100 protons of mass. So a cubic meter of space might have 1000 DM particles in it. Now this matter… Read more »
Aqua4U
Member
November 10, 2010 10:10 AM

The magnetic field of a simple bar magnet looks surprisingly similar…

Aqua4U
Member
November 10, 2010 10:13 AM

Rotate both of the above images 90 degrees to match the illustration above…

Olaf
Member
Olaf
November 10, 2010 4:55 PM

I am just wondering why 2 spheres?
I would expect an hourglass shape.

Bravehart
Member
Bravehart
November 10, 2010 8:05 PM

We better watch these G-ray bubbles closely, the rate of growed will be
important as well as the time frame, it is a sign of what comes next.
It may develop into jets or it will burst, in each case it will cause trouble for us!
I was expecting a light dome but we are already past that, this is not about what
happen in the past but what is to come! It took only two centuries to grow to its
present size and that is fast in universal time.

damian
Member
November 11, 2010 1:26 AM

The image is an illustration.

Find the real data here:
http://www.nasa.gov/mission_pages/GLAST/news/new-structure.html

I have to wonder if the jets are part of a galaxy’s interstellar gas accretion mechanism.

As noted in this Post:

Galaxy Growth Not Always Result of Violent Collisions

I expect that the energy jets would follow field lines across the galactic sheath. Much as field lines in a magnet might. ? Or or solar Helio-sheath.

Where they interact with the intergalactic medium gamma rays are generated?

Catamarion
Guest
Catamarion
November 11, 2010 3:16 AM

Our scientists still do not recognize one important thing: All the matter that exists in this galaxy (except for later captured one) came OUT of the black hole at the galactic center.

When galaxies start forming, the jets are visible and they have active nucleus – the black hole is spewing out matter which then becomes stars and planets (Centaurus A).

Later, the jets subside and the energy coming out of the black hole is reduced. What they’ve just discovered are the traces of energy coming OUT of the black hole. Energy that sustains this galaxy and keeps this galaxy in one piece.

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 11, 2010 5:36 AM

Catamarion: I just can’t let this go by. Black holes are gravitational wells which are so intense that spacetime is curved at some length smaller than a critical radius so as to be removed from the universe. As it is said, black holes are black because light is unable to escape. There is nothing which can escape a black hole in a causal manner. Black holes do quantum mechanically radiation matter out, but for a black hole larger than the mass of the sun this is negligible.

Jets do not emerge from a black hole, but are due to plasma physics of material outside a black hole.

LC

Olaf
Member
Olaf
November 11, 2010 6:02 AM

@Catamarion
The jets are not coming from inside the black hole. The jets is the mass outside the black-hole getting accelerated by magnetic fields of the black hole and ejected upwards and downwards. This mass never got in a black hole.

tsdisee
Member
tsdisee
November 11, 2010 6:30 AM

LAWRENCE B. CROWELL:
thank you very much. though I can hardly follow your calculations. I just don’t know how do explain the shape of that 2 blobs via DM.
They looks more like a remnant of jets for a glance. I know remnants of supernova prefer high-energy band too. Accelerated by shocks
PS:
I thought you may calculate the annihilation rate through the total gamma flux of the FERMI discovery.

Lawrence B. Crowell
Member
Lawrence B. Crowell
November 11, 2010 7:05 AM
I brought up the DM because the FERMI Gamma rays telescope spacecraft has found signatures of DM decay by leptonic channels. The leptonic decay channel in the 10 GeV energy range is to me surprising. The question I have is to what degree these data interpreted as galactic activity, presumably due to a SMBH and past jet activity, and DM decays have been separated from each other. The two data sets need to be filtered appropriately. This data was recently reported by Hooper and Goodenough last month. The two lobes pictured here have features I might expect from galactic activity. This might reflect some MeV particles or photons leaving the region near the galaxy core which then irradiate… Read more »
Catamarion
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Catamarion
November 11, 2010 8:46 AM
OK, they are not coming directly FROM the black hole. I agree. But what if a black hole is a downstepper of incoming energy from higher dimensions? We would not see it if it existed in (say) 5th-7th dimension only, serving as a portal downstepping the energy to our 4D time-space universe. It really does not matter whether the energy comes from the black hole or appears as a ring near to the black hole, wherefrom it is then ejected to the space. Stop looking at a black hole as a devourer. What if it is an energy giver? If the matter in this whole universe once came out of a singularity (so-called Big Bang), why wouldn’t be… Read more »
Catamarion
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Catamarion
November 11, 2010 9:16 AM
Let me explain my reasoning. Let’s say we existed as 2D creatures, in which case our galaxy would be a 2D object drawn on a large sheet of paper. Let’s say that those 2D creatures living in that flat galaxy would start pondering wherefrom all that ink is coming that is used to draw this huge galaxy. Now imagine a 3D ink pen placed perpendicularly to 2D galaxy with the tip touching the paper at the center of that galaxy and actually bleeding the ink. How would those 2D creatures see it? To them, the ink would be coming out of nowhere to their 2D reality. For them, it would be a miracle. And what if that is… Read more »
Olaf
Member
Olaf
November 11, 2010 9:33 AM

@Catamarion, logical reasoning does not mean it is true in reality.
You create an idea and then try to find a story around it to fit your idea.

wpDiscuz