Featured Research

from universities, journals, and other organizations

Black holes turn up the heat for the Universe

Date:
May 15, 2012
Source:
Heidelberg Institute for Theoretical Studies
Summary:
Astrophysicists have just discovered a new heating source in cosmological structure formation. Until now, astrophysicists thought that super-massive black holes could only influence their immediate surroundings. Scientists have now discovered that diffuse gas in the universe can absorb luminous gamma-ray emission from black holes, heating it up strongly. This surprising result has important implications for the formation of structures in the universe.

A supermassive black hole is surrounded by a dust ring (torus). The collapse of gas onto the black hole launches an energetic jet of matter and radiation, which is transported over cosmological distances. A jet that is pointing into our direction is called a "blazar."
Credit: ESA/NASA, the AVO project and Paolo Padovani

Astrophysicists have just discovered a new heating source in cosmological structure formation. Until now, astrophysicists thought that super-massive black holes could only influence their immediate surroundings. A collaboration of scientists at the Heidelberg Institute for Theoretical Studies (HITS) and in Canada and the US have now discovered that diffuse gas in the universe can absorb luminous gamma-ray emission from black holes, heating it up strongly. This surprising result has important implications for the formation of structures in the universe.

The results have just been published in The Astrophysical Journal and Monthly Notices of the Royal Astronomical Society.

Every galaxy hosts a supermassive black hole at its center. Such black holes can emit high-energy gamma rays and are then called blazars. Whereas other radiation such as visible light and radio waves traverses the universe without problems, this is not the case for high-energy gamma rays. This particular radiation interacts with the optical light that is emitted by galaxies, transforming it into the elementary particles electrons and positrons. Initially, these elementary particles move almost at the speed of light. But as they are slowed down by the ambient diffuse gas, their energy is converted into heat, just like in other braking processes. As a result, the surrounding gas is heated efficiently. In fact, the temperature of the gas at mean density becomes ten times higher, and in "under-dense" regions more than one hundred times higher than previously thought.

A Journey into the Cosmic Youth

"Blazars rewrite the thermal history of the universe," emphasizes Dr. Christoph Pfrommer (HITS), one of the authors. But how can this idea be tested? In the optical spectra of quasars there is a plethora of lines, called the "line forest." The forest originates from the absorption of ultra-violet light by neutral hydrogen in the young Universe. If the gas becomes hotter, weak lines in the forest are broadened. This effect represents an excellent opportunity to measure temperatures in the early Universe, while it was still growing up. The astrophysicists at HITS checked this newly postulated heating process for the first time with detailed supercomputer simulations of the cosmological growth of structures. Surprisingly, the lines were broadened just enough so that their properties perfectly matched those of the observed lines. "This allows us to elegantly solve a long-standing problem with the quasar data," says Dr. Ewald Puchwein, who conducted the large simulations on the supercomputer at HITS.

How Black Holes Influence the Formation of Galaxies

What are the further consequences of this new heating process? The forest of lines in the quasar spectra originates from density fluctuations in the Universe. In the course of cosmic evolution, the densest fluctuations collapse to form galaxies and galaxy clusters, as observed in the local Universe. Diffuse gas that is too hot cannot collapse. Hence, the formation of dwarf galaxies is slowed or even entirely suppressed. This could be the key to the solution of another long-standing problem in the theory of galaxy formation: why do we observe fewer dwarf galaxies in the vicinity of the Milky Way and in the underdense regions than predicted by cosmological simulations?

Prof. Volker Springel, scientific group leader at HITS, explains: "The process of blazar heating is especially exciting since this single effect is able to simultaneously solve several different puzzles in cosmological structure formation." The group plans to further improve their simulation models for a still deeper understanding of the nature of blazar heating and its implications for today's Universe.


Story Source:

The above story is based on materials provided by Heidelberg Institute for Theoretical Studies. Note: Materials may be edited for content and length.


Journal References:

  1. Ewald Puchwein, Christoph Pfrommer, Volker Springel, Avery E. Broderick, Philip Chang. The Lyman-alpha forest in a blazar-heated Universe. Monthly Notices of the Royal Astronomical Society, 2012 [link]
  2. C. Pfrommer, P. Chang, and A. E. Broderick. The Cosmological Impact of Luminous TeV Blazars III: Implications for Galaxy Clusters and the Formation of Dwarf Galaxies. The Astrophysical Journal, 2012 [link]
  3. P. Chang, A. E. Broderick, and C. Pfrommer. The Cosmological Impact of Luminous TeV Blazars II: Rewriting the Thermal History of the Intergalactic Medium. The Astrophysical Journal, 2012 [link]
  4. A. E. Broderick, P. Chang, and C. Pfrommer. The Cosmological Impact of Luminous TeV Blazars I: Implications of Plasma Instabilities for the Intergalactic Magnetic Field and Extragalactic Gamma-Ray Background. The Astrophysical Journal, 2012 [link]

Cite This Page:

Heidelberg Institute for Theoretical Studies. "Black holes turn up the heat for the Universe." ScienceDaily. ScienceDaily, 15 May 2012. <www.sciencedaily.com/releases/2012/05/120515093947.htm>.
Heidelberg Institute for Theoretical Studies. (2012, May 15). Black holes turn up the heat for the Universe. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2012/05/120515093947.htm
Heidelberg Institute for Theoretical Studies. "Black holes turn up the heat for the Universe." ScienceDaily. www.sciencedaily.com/releases/2012/05/120515093947.htm (accessed September 30, 2014).

Share This



More Space & Time News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Water You Drink Might Be Older Than The Sun

The Water You Drink Might Be Older Than The Sun

Newsy (Sep. 27, 2014) — Researchers at the University of Michigan simulated the birth of planets and our sun to determine whether water in the solar system predates the sun. Video provided by Newsy
Powered by NewsLook.com
First Woman Cosmonaut in 17 Years Blasts Off for ISS

First Woman Cosmonaut in 17 Years Blasts Off for ISS

AFP (Sep. 26, 2014) — A Russian Soyuz spacecraft carrying an American astronaut and two Russian cosmonauts, including the first woman cosmonaut in 17 years, blasted off on schedule Friday. Duration: 00:35 Video provided by AFP
Powered by NewsLook.com
Water Discovery On Small Planet Could Be Key To Earth 2.0

Water Discovery On Small Planet Could Be Key To Earth 2.0

Newsy (Sep. 25, 2014) — Scientists have discovered traces of water in the atmosphere of a distant, Neptune-sized planet. Video provided by Newsy
Powered by NewsLook.com
Raw: US-Russian Crew Lifts Off for Space Station

Raw: US-Russian Crew Lifts Off for Space Station

AP (Sep. 25, 2014) — A U.S.-Russian space crew has blasted off successfully for the International Space Station. The Russian Soyuz-TMA14M spacecraft lifted off from the Russian-leased Baikonur launch facility in Kazakhstan. (Sept. 25) 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