Featured Research

from universities, journals, and other organizations

Dusty surprise around giant black hole

Date:
June 20, 2013
Source:
European Southern Observatory - ESO
Summary:
ESO’s Very Large Telescope Interferometer has gathered the most detailed observations ever of the dust around the huge black hole at the centre of an active galaxy. Rather than finding all of the glowing dust in a doughnut-shaped torus around the black hole, as expected, the astronomers find that much of it is located above and below the torus. These observations show that dust is being pushed away from the black hole as a cool wind — a surprising finding that challenges current theories and tells us how supermassive black holes evolve and interact with their surroundings.

This artist's impression shows the surroundings of the supermassive black hole at the heart of the active galaxy NGC 3783 in the southern constellation of Centaurus (The Centaur). New observations using the Very Large Telescope Interferometer at ESO's Paranal Observatory in Chile have revealed not only the torus of hot dust around the black hole but also a wind of cool material in the polar regions.
Credit: ESO/M. Kornmesser

ESO's Very Large Telescope Interferometer has gathered the most detailed observations ever of the dust around the huge black hole at the centre of an active galaxy. Rather than finding all of the glowing dust in a doughnut-shaped torus around the black hole, as expected, the astronomers find that much of it is located above and below the torus. These observations show that dust is being pushed away from the black hole as a cool wind -- a surprising finding that challenges current theories and tells us how supermassive black holes evolve and interact with their surroundings.

Related Articles


Over the last twenty years, astronomers have found that almost all galaxies have a huge black hole at their centre. Some of these black holes are growing by drawing in matter from their surroundings, creating in the process the most energetic objects in the Universe: active galactic nuclei (AGN). The central regions of these brilliant powerhouses are ringed by doughnuts of cosmic dust [1] dragged from the surrounding space, similar to how water forms a small whirlpool around the plughole of a sink. It was thought that most of the strong infrared radiation coming from AGN originated in these doughnuts.

But new observations of a nearby active galaxy called NGC 3783, harnessing the power of the Very Large Telescope Interferometer (VLTI) at ESO's Paranal Observatory in Chile [2], have given a team of astronomers a surprise. Although the hot dust -- at some 700 to 1000 degrees Celsius -- is indeed in a torus as expected, they found huge amounts of cooler dust above and below this main torus [3].

As Sebastian Hönig (University of California Santa Barbara, USA and Christian-Albrechts-Universität zu Kiel, Germany), lead author of the paper presenting the new results, explains, "This is the first time we've been able to combine detailed mid-infrared observations of the cool, room-temperature dust around an AGN with similarly detailed observations of the very hot dust. This also represents the largest set of infrared interferometry for an AGN published yet."

The newly-discovered dust forms a cool wind streaming outwards from the black hole. This wind must play an important role in the complex relationship between the black hole and its environment. The black hole feeds its insatiable appetite from the surrounding material, but the intense radiation this produces also seems to be blowing the material away. It is still unclear how these two processes work together and allow supermassive black holes to grow and evolve within galaxies, but the presence of a dusty wind adds a new piece to this picture.

In order to investigate the central regions of NGC 3783, the astronomers needed to use the combined power of the Unit Telescopes of ESO's Very Large Telescope. Using these units together forms an interferometer that can obtain a resolution equivalent to that of a 130-metre telescope.

Another team member, Gerd Weigelt (Max-Planck-Institut für Radioastronomie, Bonn, Germany), explains, "By combining the world-class sensitivity of the large mirrors of the VLT with interferometry we are able to collect enough light to observe faint objects. This lets us study a region as small as the distance from our Sun to its closest neighbouring star, in a galaxy tens of millions of light-years away. No other optical or infrared system in the world is currently capable of this."

These new observations may lead to a paradigm shift in the understanding of AGN. They are direct evidence that dust is being pushed out by the intense radiation. Models of how the dust is distributed and how supermassive black holes grow and evolve must now take into account this newly-discovered effect.

Hönig concludes, "I am now really looking forward to MATISSE, which will allow us to combine all four VLT Unit Telescopes at once and observe simultaneously in the near- and mid-infrared -- giving us much more detailed data." MATISSE a second generation instrument for the VLTI, is currently under construction.

Notes

[1] Cosmic dust consist of silicate and graphite grains -- minerals also abundant on Earth. The soot from a candle is very similar to cosmic graphite dust, although the size of the grains in the soot are ten or more times bigger than typical grain sizes of cosmic graphite grains.

[2] The VLTI is formed from a combination of the four 8.2-metre VLT Unit Telescopes, or the four moveable 1.8-metre VLT Auxiliary Telescopes. It makes use of a technique known as interferometry, in which sophisticated instrumentation combines the light from several telescopes into one observation. Although it usually does not produce actual images, this technique dramatically increases the level of detail that can be measured in the resulting observations, comparable to what a space telescope with a diameter of over 100 metres would measure.

[3] The hotter dust was mapped using the AMBER VLTI instrument at near-infrared wavelengths and the newer observations reported here used the MIDI instrument at wavelengths between 8 and 13 microns in the mid-infrared.


Story Source:

The above story is based on materials provided by European Southern Observatory - ESO. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. F. Ḧonig, M. Kishimoto, K. R. W. Tristram, M. A. Prieto, P. Gandhi, D. Asmus, R. Antonucci, L. Burtscher, W. J. Duschl, G. Weigelt. DUST IN THE POLAR REGION AS A MAJOR CONTRIBUTOR TO THE INFRARE D EMISSION OF ACTIVE GALACTIC NUCLEI. The Astrophysical Journal, July 10, 2013

Cite This Page:

European Southern Observatory - ESO. "Dusty surprise around giant black hole." ScienceDaily. ScienceDaily, 20 June 2013. <www.sciencedaily.com/releases/2013/06/130620071438.htm>.
European Southern Observatory - ESO. (2013, June 20). Dusty surprise around giant black hole. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2013/06/130620071438.htm
European Southern Observatory - ESO. "Dusty surprise around giant black hole." ScienceDaily. www.sciencedaily.com/releases/2013/06/130620071438.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Space & Time News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Soyuz Spacecraft Docks With International Space Station: NASA

Soyuz Spacecraft Docks With International Space Station: NASA

AFP (Nov. 24, 2014) — A Russian Soyuz spacecraft carrying Italy's first female astronaut safely docks with the International Space Station, according to NASA. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Multi-National Crew Safely Docks at Space Station

Multi-National Crew Safely Docks at Space Station

Reuters - US Online Video (Nov. 24, 2014) — A Russian Soyuz rocket delivers a multi-national trio to the International Space Station. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Raw: Soyuz Docks With Int'l Space Station

Raw: Soyuz Docks With Int'l Space Station

AP (Nov. 23, 2014) — A Russian capsule carrying three astronauts from Russia, the United States and Italy has arrived at the International Space Station. (Nov. 23) Video provided by AP
Powered by NewsLook.com
Raw: Crew Blasts Off for Int'l Space Station

Raw: Crew Blasts Off for Int'l Space Station

AP (Nov. 23, 2014) — A Russian capsule carrying three astronauts from Russia, the United States and Italy has blasted off for the International Space Station. (Nov. 23) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins