Hubble discovers that Milky Way core drives wind at 2 million miles per hour

January 6, 2015 by Felicia Chou
This graphic shows how NASA's Hubble Space Telescope probed the light from a distant quasar to analyze the so-called Fermi Bubbles, two lobes of material being blown out of the core of our Milky Way galaxy. The quasar's light passed through one of the bubbles. Imprinted on that light is information about the outflow's speed, composition, and eventually mass. The outflow was produced by a violent event that happened about 2 million years ago in our galaxy's core. Credit: NASA, ESA, and A. Feild (STScI)

(Phys.org)—At a time when our earliest human ancestors had recently mastered walking upright, the heart of our Milky Way galaxy underwent a titanic eruption, driving gases and other material outward at 2 million miles per hour.

Now, at least 2 million years later, astronomers are witnessing the aftermath of the explosion: billowing clouds of gas towering about 30,000 light-years above and below the plane of our galaxy.

The enormous structure was discovered five years ago as a gamma-ray glow on the sky in the direction of the . The balloon-like features have since been observed in X-rays and radio waves. But astronomers needed NASA's Hubble Space Telescope to measure for the first time the velocity and composition of the mystery lobes. They now seek to calculate the mass of the material being blown out of our galaxy, which could lead them to determine the outburst's cause from several competing scenarios.

Astronomers have proposed two possible origins for the bipolar lobes: a firestorm of star birth at the Milky Way's center or the eruption of its supermassive black hole. Although astronomers have seen gaseous winds, composed of streams of charged particles, emanating from the cores of other galaxies, they are getting a unique, close-up view of our galaxy's own fireworks.

"When you look at the centers of other galaxies, the outflows appear much smaller because the galaxies are farther away," said Andrew Fox of the Space Telescope Science Institute in Baltimore, Maryland, lead researcher of the study. "But the outflowing clouds we're seeing are only 25,000 light-years away in our galaxy. We have a front-row seat. We can study the details of these structures. We can look at how big the bubbles are and can measure how much of the sky they are covering."

Fox's results will be published in The Astrophysical Journal Letters and will be presented at the American Astronomical Society meeting in Seattle, Washington.

The giant lobes, dubbed Fermi Bubbles, initially were spotted using NASA's Fermi Gamma-ray Space Telescope. The detection of high-energy gamma rays suggested that a violent event in the galaxy's core aggressively launched energized gas into space. To provide more information about the outflows, Fox used Hubble's Cosmic Origins Spectrograph (COS) to probe the ultraviolet light from a distant quasar that lies behind the base of the northern bubble. Imprinted on that light as it travels through the lobe is information about the velocity, composition, and temperature of the expanding gas inside the bubble, which only COS can provide.

Fox's team was able to measure that the gas on the near side of the bubble is moving toward Earth and the gas on the far side is travelling away. COS spectra show that the gas is rushing from the galactic center at roughly 2 million miles an hour (3 million kilometers an hour).

"This is exactly the signature we knew we would get if this was a bipolar outflow," explained Rongmon Bordoloi of the Space Telescope Science Institute, a co-author on the science paper. "This is the closest sightline we have to the galaxy's center where we can see the bubble being blown outward and energized."

The COS observations also measure, for the first time, the composition of the material being swept up in the gaseous cloud. COS detected silicon, carbon, and aluminum, indicating that the gas is enriched in the heavy elements produced inside stars and represents the fossil remnants of .

COS measured the temperature of the gas at approximately 17,500 degrees Fahrenheit, which is much cooler than most of the super-hot gas in the outflow, thought to be at about 18 million degrees Fahrenheit. "We are seeing cooler gas, perhaps interstellar gas in our galaxy's disk, being swept up into that hot outflow," Fox explained.

This is the first result in a survey of 20 faraway quasars whose light passes through gas inside or just outside the Fermi Bubbles—like a needle piercing a balloon. An analysis of the full sample will yield the amount of mass being ejected. The astronomers can then compare the outflow mass with the velocities at various locations in the bubbles to determine the amount of energy needed to drive the outburst and possibly the origin of the explosive event.

One possible cause for the outflows is a star-making frenzy near the galactic center that produces supernovas, which blow out gas. Another scenario is a star or a group of stars falling onto the Milky Way's . When that happens, superheated by the black hole blasts deep into space. Because the bubbles are short-lived compared to the age of our galaxy, it suggests this may be a repeating phenomenon in the Milky Way's history. Whatever the trigger is, it likely occurs episodically, perhaps only when the black hole gobbles up a concentration of material.

"It looks like the outflows are a hiccup," Fox said. "There may have been repeated ejections of material that have blown up, and we're catching the latest one. By studying the light from the other quasars in our program, we may be able to detect the fossils of previous outflows."

Galactic winds are common in star-forming , such as M82, which is furiously making stars in its core. "It looks like there's a link between the amount of star formation and whether or not these outflows happen," Fox said. "Although the Milky Way overall currently produces a moderate one to two stars a year, there is a high concentration of star formation close to the core of the galaxy."

Explore further: Observing galactic 'blow out': Stellar growth spurts stunt future growth

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13 comments

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billpress11
1.1 / 5 (9) Jan 06, 2015
This is a very interesting article. But there may be another explanation for the expelled charged particles from the center of our galaxy. Our spiral galaxy may have a galaxy sized magnetic field surrounding it in the shape of a washer like magnetic field. Gases in the center of our galaxy could be ionized by the magnetic field an expelled out both poles and accelerated to high velocities over the millions of years.
shavera
4 / 5 (12) Jan 06, 2015
ITT: People who don't know basic electromagnetics will be telling us that physicists who've trained their whole lives don't understand E&M because some dude a half-century ago or more said so.
Mike_Massen
3.5 / 5 (11) Jan 06, 2015
billpress11 speculated
But there may be another explanation for the expelled charged particles from the center of our galaxy. Our spiral galaxy may have a galaxy sized magnetic field surrounding it in the shape of a washer like magnetic field. Gases in the center of our galaxy could be ionized by the magnetic field an expelled out both poles and accelerated to high velocities over the millions of years
Um sort of doubt it, Y because of this thing called Physics.

ie. A magnetic field & electric field has a particular & precise relationship and all subject to Special & General Relativity... To have a 'washer' shaped field means a toroid which means a certain dynamic of moving charges to maintain such motion long enough & be intrinsically stable. In the essentially gravitationally chaotic state of star orbitals of immense permutation it doesnt follow such stability would occur AND be self-supporting, there are always immense negative feedback effects in magnetics...
shiner421
1 / 5 (5) Jan 06, 2015
I think the title should be change dto read:

Hubble calculates that Milky Way core drives wind at 2 million miles per hour.

Because the hubble telescope didnt take an actual measurement and fly throught the entire galaxy and measure this. As I have grown older I am finding that as cool as articles like these sound, when I think about it even just a little bit there is no way to verify this. It is not proof of the speed of particles at the center of the galaxy, it is nothing more than supposition.

Just like the article I read that made this claim:

"If you take all the air molecules out of every person in the world and squished all their atoms together, they would all fit in the space of a tennis ball" - or something like that. Absolute absurdity. I dont believe that can even be calculated, let alone proven.

Perfect example of the media getting ahold of something and blowing it way out of proportion.
billpress11
1 / 5 (4) Jan 06, 2015
Mike, here is a link that has the opposite opinion. There are plenty of other links that maintain that galaxies can have a magnetic field.

JPL | News | Planck Takes Magnetic Fingerprint of Our Galaxy
www.jpl.nasa.gov/...lease...
Jet Propulsion Laboratory
May 6, 2014 - Magnetic field of our Milky Way galaxy The magnetic field of our Milky Way galaxy as seen by the Planck satellite, a European Space Agency ...
Mike_Massen
3 / 5 (4) Jan 06, 2015
billpress11 replied
Mike, here is a link that has the opposite opinion
Crap, not opposite just different - Doh !

billpress11
There are plenty of other links that maintain that galaxies can have a magnetic field
Doh ! Where did I ever say galaxies cannot have a magnetic field or moments or vectors. your specific washer however doesn't hold H2O - like the idea ice will eventually sublime despite coldness of space, Physics yah know ;-)

btw: Your link of (suffix "release..." means what ?)
http://www.jpl.na...lease...

Resolves to Off target:-
http://www.jpl.na...ndex.php

Your link is munted; your paste, ref is invalid, U mistyped, whatever, a chance U can actually CHECK it before posting ? saves time, adds credibility to U & enlighten those other than myself who might be of the opinion U misread the context of my reply to your first posting here, thanks.

This
http://www.jpl.na...ure=4137

bye
billpress11
1 / 5 (3) Jan 06, 2015
Here is a link with the view of the magnetic fields of many galaxies. Yes, some even resemble to magnetic field of a magnetized washer.

Images for shape of galaxy magnetic fields
billpress11
1 / 5 (3) Jan 06, 2015
Sorry the link did not come up, maybe this one will.

https://www.googl...MQsAQ4Cg

Well Mike, you certainly implied that a spiral galaxy could not have a magnetic field like a magnetic washer.

Quote Mike: "Um sort of doubt it, Y because of this thing called Physics.

ie. A magnetic field & electric field has a particular & precise relationship and all subject to Special & General Relativity... To have a 'washer' shaped field means a toroid which means a certain dynamic of moving charges to maintain such motion long enough & be intrinsically stable. In the essentially gravitationally chaotic state of star orbitals of immense permutation it doesnt follow such stability would occur AND be self-supporting, there are always immense negative feedback effects in magnetics...

movementiseternal
Jan 06, 2015
This comment has been removed by a moderator.
Osiris1
1 / 5 (2) Jan 07, 2015
The man said something about an eruption from the galactic supermassive black hole??!! That would mean forces inside the hole expelling something large out of it. How can that be? Now stars pull matter from other stars in binary systems, etc. all the time. All it needs are forces that overcome the gravity at the surface of the star. All black holes were once stars, so maybe a very large entity going very fast...... from somewhere else ..... or a primordial string of immense size.....
Just like gunfights in the old west, there is always something bigger, stronger, faster......somewhere!
Mike_Massen
3.4 / 5 (5) Jan 07, 2015
billpress11 claimed
Well Mike, you certainly implied that a spiral galaxy could not have a magnetic field like a magnetic washer
No, I made no such implication, here is what I specifically said "..To have a 'washer' SHAPED FIELD means a toroid which means a certain dynamic of moving charges to maintain such motion long enough & be intrinsically stable."

ie.
A field like a magnetic washer (ie poles on faces etc) was NOT your question, it was "... shape of a washer like magnetic field", ie. a SPECIFIC distinction.

My comment was about toroids, hence my comment stands "Um sort of doubt it, Y because of this thing called Physics." for the reasons given.

billpress11, being precise in your question would have saved time, fields can have wide topological variants, poles like faces on a "magnetic washer" might be but, even then evidence is useful. However, magnetic washers generate fields by static magnetic domains, stellar motion predominantly chaotic ie different.
Mike_Massen
3 / 5 (4) Jan 07, 2015
movementiseternal claimed
.. no pulling force!There is no curving space!All system have own inside movement / pressure / pushing force!All visible universe system expanding, but space dont, because space is eternal and infinity place which is no.hing!Nucleus of atoms expanfing and recycling expanding movement / energy with eachother!Also photons expanding and recycling expanding movement with eachother!Also galaxys centre supermassive concentrations expanding and emit expanding particle which have a nature of expanding matter!Too difficult understund for you?Onesimpleprinciple comEternalRecycling
Rather than telling us what is NOT, please craft a paragraph of say 6 sentences which actually describe the fundamentals so we don't have to lurch to a site which 'might' just be there for spam, hit rates, distraction.

Identify salient points, focus on essentials AND maths, then, maybe then, U can collaborate & craft an experiment to address it, can U pls ?

English ?
Tuxford
1 / 5 (3) Jan 07, 2015
The observation just lends more support for LaViolette's model. See my comments therein for more explanation.

http://phys.org/n...axy.html

http://phys.org/n...ers.html

http://phys.org/n...ter.html

And this latest one too lends support for supermassive 'grey' holes. Singularity nonsense is a math fantasy. No qualified mechanical engineer would ponder such a condition as reality.

http://phys.org/n...ack.html

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