First optical measurements of Milky Way's Fermi Bubbles probe their
origin

Date:
June 3, 2020
Source:
University of Wisconsin-Madison
Summary:
Astronomers have for the first time measured the Fermi Bubbles in
the visible light spectrum. The Fermi Bubbles are two enormous
outflows of high-energy gas that emanate from the Milky Way and
the finding refines our understanding of the properties of these
mysterious blobs.



FULL STORY ========================================================================== [View of Milky Way (stock | Credit: (c) Matthew / stock.adobe.com]
View of Milky Way (stock image).

Credit: (c) Matthew / stock.adobe.com [View of Milky Way (stock | Credit:
(c) Matthew / stock.adobe.com] View of Milky Way (stock image).

Credit: (c) Matthew / stock.adobe.com Close Using the Wisconsin H-Alpha
Mapper telescope, astronomers have for the first time measured the
Fermi Bubbles in the visible light spectrum. The Fermi Bubbles are two
enormous outflows of high-energy gas that emanate from the Milky Way
and the finding refines our understanding of the properties of these
mysterious blobs.


==========================================================================
The research team from the University of Wisconsin-Madison, UW-Whitewater
and Embry-Riddle Aeronautical University measured the emission of light
from hydrogen and nitrogen in the Fermi Bubbles at the same position as
recent ultraviolet absorption measurements made by the Hubble Telescope.

"We combined those two measurements of emission and absorption to
estimate the density, pressure and temperature of the ionized gas,
and that lets us better understand where this gas is coming from,"
says Dhanesh Krishnarao, lead author of the new study and an astronomy
graduate student at UW-Madison.

The researchers announced their findings June 3 at the 236th meeting
of the American Astronomical Society, which was held virtually for the
first time since 1899, in response to the COVID-19 pandemic.

Extending 25,000 light years both above and below the center of the
Milky Way, the Fermi Bubbles were discovered in 2010 by the Fermi Gamma
Ray Telescope.

These faint but highly energetic outflows of gas are racing away from
the center of the Milky Way at millions of miles per hour. But while the
origin of the phenomenon has been inferred to date back several million
years ago, the events that produced the bubbles remain a mystery.

Now, with new measurements of the density and pressure of the ionized gas, researchers can test models of the Fermi Bubbles against observations.

"The other significant thing is that we now have the possibility
of measuring the density and pressure and the velocity structure in
many locations," with the all-sky WHAM telescope, says Bob Benjamin, a professor of astronomy at UW- Whitewater and co-author of the study. "We
can do an extensive mapping effort across the Fermi Bubbles above and
below the plane of the galaxy to see if the models that people have
developed are holding up. Because, unlike the ultraviolet data, we're
not limited to just specific lines of sight." Matt Haffner, professor
of physics and astronomy at Embry-Riddle Aeronautical University and
a co-author of the report, says the work demonstrates the usefulness
of the WHAM telescope, developed at UW-Madison, to tell us more about
the workings of the Milky Way. The central region of our home galaxy
has long been difficult to study because of gas blocking out view, but
WHAM has provided new opportunities to gather the kind of information
we have for distant galaxies.

"There are regions of the galaxy we can target with very sensitive
instruments like WHAM to get this kind of new information toward the
center that previously we are only able to do in the infrared and radio,"
says Haffner. "We can make comparisons to other galaxies by making the
same kind of measurements towards the center of the Milky Way."

========================================================================== Story Source: Materials provided
by University_of_Wisconsin-Madison. Original written by Eric
Hamilton. Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
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Illustration_showing_Fermi_Bubbles_--_huge_outflows_of_gas_extending_from
the_Milky_Way's_center ==========================================================================


Link to news story: https://www.sciencedaily.com/releases/2020/06/200603120542.htm https://www.sciencedaily.com/releases/2020/06/200603120542.htm

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