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NGC 5813: An Intergalactic Weather Map
NGC 5813
NGC 5813
NGC 5813

  • This composite image is an intergalactic "weather map," showing the range of temperatures across a group of galaxies.

  • The galaxy at the center is an elliptical known as NGC 5813, which is about 105 million light years away.

  • Regular outbursts generated by the supermassive black hole in NGC 5813 keep gas from cooling down enough to form stars.

This composite image shows an intergalactic "weather map" around the elliptical galaxy NGC 5813, the dominant central galaxy in a galaxy group located about 105 million light years away from Earth. Just like a weather map for a local forecast on Earth, the colored circle depicts variations in temperature across a region. This particular map presents the range of temperature in a region of space as observed by NASA's Chandra X-ray Observatory, with the hotter temperatures shown in red and decreasingly cooler temperatures shown in orange, yellow, green, and blue. The numbers displayed when rolling your mouse over the image give the gas temperature in millions of degrees.

A notable feature of this image is the relatively small variation in temperature across the weather map, with a range of only about 30% across several hundred thousand light years. Without any sources of heat, the densest gas near the center of the map should cool to much lower temperatures as energy is lost because of radiation. However, outbursts generated by the supermassive black hole at the center of NGC 5813 provide heat, preventing the gas near the center of the galaxy from cooling to such low temperatures. This decreases the amount of cool gas available to form new stars. This process is analogous to the Sun providing heat for Earth's atmosphere and preventing water and water vapor from cooling and freezing.

How do outbursts generated by the black hole provide heat? Powerful jets produced as gas swirls toward the black hole push cavities into the hot gas and drive shock waves -- like sonic booms -- outwards, heating the gas. The shocks from the most recent outburst, which occurred about 3 million years ago in Earth's time frame, show up as a "figure eight" structure at the center of the image. This is the first system where the observed heating from shocks alone is sufficient to keep the gas from cooling indefinitely. These shocks allow the relatively tiny black hole to heat the huge area surrounding it, as shown here.

The gas around NGC 5813 shows evidence for three distinct outbursts from the black hole, which occurred 3 million, 20 million and 90 million years ago, in Earth's time frame. The average power of the two most recent outbursts differ by about a factor of six, showing that the power delivered by the jets can vary significantly over timescales of about 10 million years.

A paper describing these results has been accepted for publication in the Astrophysical Journal. The first author of the paper is Scott Randall from the Harvard-Smithsonian Center for Astrophysics (CfA) and the co-authors are Bill Forman from CfA; Simona Giacintucci from CfA and National Institute for Astrophysics (INAF) in Bologna, Italy; Paul Nulsen from CfA; Ming Sun from the University of Virginia; Christine Jones from CfA; Eugene Churazov from the Max Planck Institute for Astrophysics in Garching, Germany and the Space Research Institute in Moscow, Russia; Larry David and Ralph Kraft from CfA; Megan Donahue from Michigan State University; Elizabeth Blanton from Boston University; and Aurora Simionescu and Norbert Werner from Stanford University.

Fast Facts for NGC 5813:
Credit  X-ray: NASA/CXC/SAO/S.Randall et al., Optical: SDSS
Release Date  December 08, 2010
Scale  Image is 12 arcmin on a side (367,000 light years)
Category  Groups & Clusters of Galaxies
Coordinates (J2000)  RA 15h 01m 11.3s | Dec -01° 42´ 07.1"
Constellation  Virgo
Observation Date  Apr 2, 2005 & Jun 5, 2008
Observation Time  41 hours 20 min
Obs. ID  5907, 9517
Instrument  ACIS
References Randall, S, et al. 2010, ApJ (in press); arXiv:1006.4379
Color Code  X-ray (Blue); Optical (Yellow); Temperature Map (Pseudocolor: Red, Orange, Yellow, Green, Blue)
Distance Estimate  About 105 million light years
distance arrow
Visitor Comments (11)

I wonder how much influence "Space Weather" could have over a planets weather.

Posted by Mark Ballington on Friday, 12.10.10 @ 11:50am

I'm probably not the first to catch this but just in case in the second bullet point NGC 5813 is noted as being 105 light years away, the "million" was left out.

Posted by Jonathan Slavin on Friday, 12.10.10 @ 11:29am

In the bullet "The galaxy at the center is an elliptical known as NGC 5813 which is about 105 light years away"
isn't it 105 millions of light years?

Posted by Robert Hickman on Friday, 12.10.10 @ 03:26am

This is most interesting. It is interesting to note the slight, variations in the temperatures across the cluster of galaxies. Is this a good example of what the temperature range across the known universe would be? and if one single galaxy would be studied the same way would it show the same range of temperatures of the stars gases, etc. composing it?
Thanks, this was most educationally interesting.

Marvin L. S.

Posted by Marvin L. S. on Thursday, 12.9.10 @ 18:50pm

Should it be bigger 367,000 light years? Our milky way is 100,000 light years wide.

Posted by Roberto Gonzalez Davison on Thursday, 12.9.10 @ 14:00pm

One of the most mind opening pictures I have seen.

Posted by Hermogenes M. on Thursday, 12.9.10 @ 11:32am

Thank you for taking time to explain things to someone that does not understand much of anything about this. However I do love to learn and try to understand. I look forward to your releases, please keep them coming as I must be only one of thousands that feel the same. I am not very well educated so I need people like you that are dedicated to make sense of the laws of nature. Thank you, Mark

Posted by Mark Smith on Thursday, 12.9.10 @ 06:07am

The second bullet under the image needs to be corrected. Overall a fascinating presentation.

Posted by Frank Grotowski on Thursday, 12.9.10 @ 00:33am

Wow, thanks all for information. Take care and merry Christmas and a very learning new year.

Posted by rick moll on Wednesday, 12.8.10 @ 20:01pm

Hi there. Amazing that we can see galaxies 105 million LY away, and to think the photons we see are that old. Quick question, how do we know that the last "outburst" were 3 million years ago when it takes 105 million years to see the photons? Is it that the X-rays captured in this view travel 100 times faster than photons?

Posted by Anthony Hunt-Auckland NZ on Wednesday, 12.8.10 @ 16:25pm

Superb findings and excellent photos, keep sending such marvels.

Posted by srinivasa narayanan on Wednesday, 12.8.10 @ 15:33pm

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