VLA reveals 'bashful' black hole in neighboring galaxy

VLA reveals 'bashful' black hole in neighboring galaxy
The galaxy M32 is a small satellite of the larger, spiral Andromeda Galaxy (M31), as shown in this visible-light image. The inset is a combined radio/optical/X-ray image of M32. The diffuse purple is the visible starlight of M32. The central white object in the inset is the center of M32, where there is both radio and X-ray emission. Red shows radio-emitting objects, including a pair of presumed planetary nebulae (left center), and the green is an object strongly emitting X-rays. Credit: Bill Saxton, NRAO/AUI/NSF; Yang et al.; NASA, ESA, Digitized Sky Survey 2 (Acknowledgement: Davide DeMartin).

Thanks to the extraordinary sensitivity of the Karl G. Jansky Very Large Array (VLA), astronomers have detected what they believe is the long-sought radio emission coming from a supermassive black hole at the center of one of our closest neighboring galaxies. Evidence for the black hole's existence previously came only from studies of stellar motions in the galaxy and from X-ray observations.

The galaxy, called Messier 32 (M32), is a satellite of the Andromeda Galaxy, our own Milky Way's giant neighbor. Unlike the Milky Way and Andromeda, which are star-forming spiral galaxies, M32 is an elliptical galaxy, with little star formation. About 2.5 million light-years from Earth, M32 is much smaller than either the Milky Way or Andromeda.

Supermassive are found at the cores of most galaxies, and as those black holes draw in matter from their surroundings, jets of material propelled to speeds close to that of light by the black holes often generate detectable with radio telescopes. The intensity of this depends on how voraciously the black hole is consuming surrounding matter. The central black holes of the Milky Way and Andromeda are quite weak radio emitters compared to many other galaxies.

"The very faint radio emission we think is coming from M32's central black hole indicates that this object's activity is among the weakest yet found, along with the Milky Way and Andromeda," said Yang Yang, of Nanjing University in China. "Studying such quiescent black holes gives us an excellent opportunity to advance our presently-poor understanding of their physics," she added.

The discovery was made possible by the dramatic improvement in sensitivity, or the ability to detect extremely faint radio waves, produced by a decade-long, $98 million upgrade of the VLA's electronic systems that was completed in 2012. The new VLA observations were able to detect radio emission roughly 90 times fainter than previous studies of M32.

The VLA image showed a faint radio-emitting object at the location where X-rays are being emitted and around which stars near the galaxy's center appear to be orbiting. "This tells us that the radio emission most likely is coming from the black hole, but we want to do further observations to confirm this," Yang said.

M32's black hole contains about 2.5 million times the mass of the Sun, compared to the Milky Way black hole's 4 million.

The VLA also revealed three radio-emitting objects that, the scientists said, are planetary nebulae previously seen with visible-light telescopes. Planetary nebulae are spheres of gas blown off during late stages in the lives of stars like our Sun. The M32 VLA image represents the first detection by a radio telescope of such objects at the far edges of our Local Group of galaxies.

Yang led a research team of astronomers from China and the U.S. Lorant Sjouwerman of the National Radio Astronomy Observatory was instrumental in obtaining and reducing the VLA data for the study. The scientists are reporting their findings in the Astrophysical Journal Letters.

Explore further

Astronomers find unexpected 'storm' at galaxy's core

Journal information: Astrophysical Journal Letters

Citation: VLA reveals 'bashful' black hole in neighboring galaxy (2015, June 17) retrieved 27 June 2019 from https://phys.org/news/2015-06-vla-reveals-bashful-black-hole.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Feedback to editors

User comments

Jun 17, 2015
M32 is likely a globular cluster ejected from M31 and now all grown up into a satellite galaxy. The new matter therein forming the stars of the daughter galaxy is ejected therefrom that green core star they now discovered. They even discovered new stars forming near the core where new matter is highly concentrated! Since the core is likely not yet quite super-duper massive, the surrounding region is likely less violent with stellar winds than larger galaxies (with bigger bulges), permitting star formation in the local vicinity.

2+2.... It ain't rocket science.

Jun 17, 2015
Ah the godsend of science. Yes, it such a savior to be praised. I prefer to truly understand, rather than blindly follow favored protocols. Stick to your science. You are safer there. There are plenty of higher authorities to fall back on.

Jun 17, 2015
The perspective on the top image is messing with me. Are we looking at Andromeda from below or above? I realize in space that's not a very meaningful preposition. The question I'm asking is "Is M32 on the back edge of Andromeda or the front?" "Visually and Actually" If we are looking at Andromeda from "below" it could look closer to the back side but then actually be in the foreground but further away from the closest edge of Andromeda. My brain is not handling the picture very well. :(

Jun 18, 2015
andromeda seems to have a few more toys hanging around it. 2.5Msolmasses at its core? geez and it has another dense dwarf elliptical. our milky way seems like fodder with our modern calculations and collision predictions. what a bummer.

Jun 18, 2015
I have not seen whirlpool to throw up jets of water. Black holes do not seem to obey the known laws of physics. Neither the facts or logic. These objects are invisible. When something is invisible and elusive, probably does not exist. For some people it is convenient to build theories about something which is invisible and elusive and can not be observed directly to verify whether the theories are correct. They earn time like this. With such theories you can achieve an enviable career in today's world at the expense of conscience.

Jun 18, 2015
Hi Viko,

Just because you cannot see something doesn't mean its effects cannot be observed and measured.
See Also: Electrons

A whirlpool is not an accurate analogue to a black hole. This analogy is so bad I feel you cannot be making this argument in good faith.

Jun 18, 2015
I mean fictional meta physical phenomena which can not be observed and can not be experimented on it. The question is which efect? From the fictional black hole or other physical objects working on quite another principle that recognizes the physical laws?

Jun 18, 2015
You are doing very strange analogy. Planets and stars obey the laws of physics and are visible without any serious difficulties unlike the hypothetical black holes, hidden behind the event horizon. Do you think that the vacuum of space have infinit gravitational or electeromagnetic permeability?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more