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Where does the Milky Way get its energy from? Scientists may have found the answer

Bob Benjamin was watching the Milky Way when he noticed something strange.

The professor at the University of Wisconsin-Madison’s Department of Astronomy and co-author of a new study saw a red, sloping structure that penetrated a hole in the dust in the dark center of the galaxy.

The tilted disc – This strange structure consists of ionized hydrogen gas or gas with enough energy to separate its electrons from atoms or molecules, which is visible through the red glow of the light. The phenomenon became known as the tilted disk because it appears to be tilted compared to the rest of the Milky Way, but scientists could not explain how it was formed. The scientific community received their answer when a team of astronomers had the rare opportunity to look at the tilted disk with optical light, which allowed them to observe their mysterious ionized gas.

Her research is in an article published in the journal last week Advances in science, and contains references to it What drives the Milky Way?.

An artistic impression of the tilted disk in the dusty center of the Milky Way.DHANESH KRISHNARAO / UNIVERSITY OF WISCONSIN-MADISON

The reason why astronomers are confused by the tilted disk is the amount of ionized hydrogen gas that a continuous energy source needs to keep the electrons separate, and they have not identified the energy source.

The study found that 48 percent of the hydrogen in the center of the Milky Way was ionized by an unknown source.

Matthew Haffner, assistant professor of physics and astronomy at Embry-Riddle and co-author of the study, explains that vision is knowledge when it comes to ionized gas.

“Without a constant source of energy, free electrons are usually found and recombine to return to a neutral state in a relatively short amount of time,” said Haffner in a statement published with the study. “Being able to see ionized gas in new ways should help us discover the types of sources that could be responsible for keeping all of the gas under tension.”

To identify the source of energy, the astronomers looked at the tilted disk through one of the empty dust and gas spots in the center of the Milky Way. They used the Wisconsin H-Alpha Mapper (WHAM) telescope at the Cerro Tololo Inter-American Observatory in Chile:

“The ability to perform these measurements in optical light made it much easier for us to compare the Milky Way core with other galaxies,” said Haffner.

Near the core of the Milky Way, the gas is ionized from the energy emitted by newly formed stars in the galaxy. However, further away from the center of the galaxy, the gas resembles that of a class of galaxies called LINERs or regions with low ionization (nucleus).

An aerial view of the tilted disc in the middle of the Milky Way.Dhanesh Krishnarao / University of Wisconsin-Madison

LINER galaxies make up about a third of the galaxies in the universe, and their centers have more radiation than galaxies that only form new stars, but less radiation than those with active supermassive black holes.

“Before this WHAM discovery, the Andromeda galaxy was the closest LINER spiral to us, but it is still millions of light years away,” said Haffner. “Since the core of the Milky Way is only tens of thousands of light years away, we can now examine a LINER region more closely.”

“Studying this expanded ionized gas should help us learn more about the current and past environment in the center of our galaxy.”

After the researchers have characterized the Milky Way using the radiation level at its center, the next step is to find out the mysterious energy source that ionizes the gas. To do this, they will wait for the successor to the WHAM telescope so that they can take a closer look at the gas.

Abstract: Optical emission lines are used to divide galaxies into three groups according to their dominant central radiation source: active galactic nuclei, star formation or regions with low ionization (nucleus) [LI(N)ERs] that can track ionizing radiation from older star populations. With the Wisconsin H-Alpha Mapper we measure the emission of optical lines in windows with low extinction within eight degrees from the Galactic Center. The emission is associated with the radius of 1.5 kiloparsec “tilted disk” of neutral gas. We modify a model of this disk and find that the observed hydrogen gas is at least 48% ionized. The relationship [NII] λ6584 Angström / Hα λ6563 Angström increases with the galactocentric radius from 0.3 to 2.5; [OIII] Sometimes λ5007 angstroms and Hβ-λ4861 angstroms are also detected. The line relationships for most tilted disk lines of sight are characteristic of LI (N) ER galaxies.

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