Supermassive Black Hole Of A Nearby Dwarf Galaxy Is Actually Less Massive Than Expected


The plan, the important idea of knowing everything about any supermassive black hole must start from somewhere. And the best and most reasonable start is with the small black holes. So, starting little, scientists will get to the bottom of it. And for doing that, a team of scientists alongside Elena Gallo from the University of Michigan, who works as an astronomer, have discovered something important. More, specifically, the supermassive black hole at the center of a nearby galaxy is, in reality, less massive than expected.

Scientists calculated the mass of the black hole at the center of a nearby dwarf galaxy

The team of scientists with Elena Gallo has discovered a black hole in the center of a nearby dwarf galaxy. The galaxy is named NGC 4395, and its supermassive black hole is 40 times smaller than the astronomers thought it would be. The main idea of supermassive black holes, as their name says, is that they are, well, supermassive and they sit at the center of every galaxy.

But that’s not applicable to dwarf galaxies, as it seems, and is only available for massive galaxies such as the Milky Way. So, because of the recent findings, the scientists are investigating NGC 4395 by measuring it for gathering new information that could help them with the more prominent black holes.

For doing the measurements, the scientist has used a technique that measures the mass and monitories the radiation that is coming from the accretion disk situated around a supermassive black hole. The accretion disk is formed by a mass of matter that is collected through the gravitational pull of each black hole. The radiation that hits the gas is causing the atoms to go into a transition. This action is happening when the radiation travels from the accretion disk through a cloud of material and out of the black hole, and it’s called the broad line region.

Also, when the radiation passes, the atoms will settle back, and the transition is looking like a flash of brightness. So all these measurements of the accretion disk radiation to the broad-line region that causes flashes, they can estimate how far the black hole is from the broad-line itself. With this data, scientists can calculate the mass of a black hole.

The supermassive black hole of the nearby dwarf galaxy is less massive than expected

In the previous theories, scientists have thought that the distance depends on the black hole’s mass. The idea was that the larger the black hole is, the larger the range and the light will come with a delay from the accretion disk. To be more precise, the astronomers have calculated that it took 83 minutes plus, minus 14 minutes for the radiation to reach the broad-line region.

Yet, for calculating the mass of the supermassive black hole, they have used a high-quality spectrum of the GMOS spectrometer from GEMINI North telescope. So with a few details like the number, the speed of the broad-line region, the speed of light, and the gravitational constant, the scientists can find out that the black hole’s mass is around 10.000 times the mass of the Sun. That means 40 times lighter than they have thought initially, and the supermassive black hole from the NGC 4395 dwarf galaxy is the smallest one of its kind.

Furthermore, the astronomer Elena Gallo says that the dwarf galaxies aren’t explored enough, especially when it comes to their black holes. All the data are making the scientists question if every galaxy has a black hole. But the hope is not lost, because this information can help the astronomers to understand what shape has a giant black hole in other galaxies.

Finally, the findings have been possible through the collaboration between U-M Astronomy, the Department of Physics, and the Astronomy from Seoul National University. Also, the observations have been made with the Gemini North observatory from Hawaii and the MDM Observatory in Arizona.


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