Gravity is an attractive force, and the larger something is, the stronger it becomes. We will never lift off the earth, and the earth will never leave the sun. Therefore, supermassive objects like galaxies might be expected to grow only by falling loose material. However, there is a limit to the growth of galaxies. Rather, galaxy growth is offset by the loss of gas into intergalactic space.galactic outflow.
Three processes contribute most to these galactic outflows. First, when a star forms, it releases a new burst of radiation that displaces the surrounding gas until it exits the galaxy. Astronomers call this process a shorthand notation.star formation. When matter falls in the following directions, the following processes occur: supermassive black holeIt is located at the center of almost every galaxy. As it falls towards the black hole, this material heats up and some of it escapes into bright streams,jet plane. This phenomenon is calledactive galactic nucleusOr AGN. Finally, the jet from the AGN heats the gas bubble, increasing its buoyancy until it disperses out of the galaxy. thisjet heatingThe hot bubbles prevent new material from falling into the galaxy, slowing its growth.
Astronomers know that these processes contribute to galactic outflow, but their relative importance is unknown. One astronomer investigated this question with the aim of determining which processes govern the outflow of galaxies and whether the dominant processes have changed over time. To achieve this goal, he found a way to express different units and measurements of each process in several galaxies so that previously observed datasets could be directly compared.
inprevious researchscientists created an equation to calculate star formation and the total outflow from the AGN into the galaxy. This equation applies to any galaxy, provided astronomers know how often stars form and how bright their AGNs are. Astronomers have information about how often stars form.literature reviewThe brightness of the AGN was more complex and depended on two variables: how likely the galaxy is to have an active center, and the size of the galaxy that can fuel the jet.
Astronomers found both information about AGN at:Another previous study. He then combined all the data he collected to calculate the total outflow of star formation and AGN. To find the individual contributions from each process, he recalculated the outflow for each galaxy twice. We first assumed no contribution from AGN and then no contribution from star formation.
To estimate the mass lost to jet heating, astronomers took several careful steps. First, he used a pattern foundIn a previous paperLarger jet-heated bubbles were shown to shine brighter. Knowing how brightly the bubbles glowed, they calculated how much energy the bubbles emit per second. With that information, he used relationships found on other sites.previous researchTo estimate how much material the energy from these hot, glowing bubbles can displace per year.
Because the galaxies the astronomer analyzed varied in size and age, they were able to group the results by mass and time. He discovered that the dominant process of galaxy outflow now depends on the galaxy's mass. The outflow in small galaxies is mainly due to star formation, while in large galaxies it is mainly due to AGN. However, this was not always the case. In giant galaxies about 10 to 11 billion years ago, all three processes contributed roughly equally.
The astronomer recognized that others could improve on his method in future research. For example, he acknowledged that current measurements of AGN and the bubbles it creates may significantly underestimate its true contribution. In addition, the mass lost by AGN jets heating other regions of the galaxy outside of the bubble was omitted because scientists discovered this only occurred in simulations, not telescope observations. But he concluded that even if the specific results were inaccurate, he had created a framework for comparing the factors that prevent galaxies from shrinking or growing.
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Source: sciworthy.com
