Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Astronomers put quasars in their place

04.10.2002


A team of UK astronomers, led by postgraduate student Ed Hawkins, has made a decisive step toward resolving an argument that has rumbled on in the astronomical community for decades. The scientists from the University of Nottingham have been investigating the properties of quasars and nearby galaxies. As part of this study, they have overturned previous analyses which suggested that these two classes of object are physically associated, thus confirming the alternative, more widely-held view that quasars are some of the most distant objects in the Universe.



Quasars are star-like in appearance, but seem to be flying away from Earth at velocities comparable to the speed of light. The majority of astronomers believe that this high speed is a result of the expansion of the Universe, and that the quasars are traveling so fast because they are at enormous distances. However, a vociferous minority, including such notable figures as the great astronomer Fred Hoyle, has argued forcefully that quasars are much closer by. In particular, they have pointed to apparent associations between quasars and nearby galaxies, suggesting that the quasars have somehow been ejected from these galaxies in the recent past.

One of the pieces of evidence to support this idea was the tentative discovery that quasars only seem to move away from galaxies at particular speeds: for example, a surprisingly large number of quasars seem to be moving relative to neighbouring galaxies at speeds of 59% of the speed of light. If the quasars were actually on the far side of the Universe, how would they know to move at exactly 59% of the speed of light relative to a completely unrelated foreground galaxy?


Very little progress has been made toward resolving this controversy, essentially because there just hasn`t been enough data to tell whether the apparent associations between galaxies and quasars are real or just coincidences. However, this has all changed with two newly-completed huge surveys undertaken with the Anglo-Australian Telescope, one measuring the positions and velocities of 200,000 galaxies, and the other measuring the same quantities for 25,000 quasars. "These enormous new data sets offered a great opportunity to take another look at this question," said Hawkins. "To do as fair a test as possible, we discussed with the supporters of both theories what they would expect to see before we analyzed the data."

By carefully sifting through these datasets, Hawkins and collaborators found 1647 examples of quasars that appear close to galaxies, and hence might be associated. Sadly for the nearby-quasar supporters, there was no excess of quasars moving at 59% of the speed of light, or any of the other "magic speeds" that had previously been tentatively identified. Without this evidence to support an association between quasars and galaxies, the case for quasars being flung out of nearby galaxies is much weakened.

Hawkins concluded "it`s a shame, as it would have been great to find that the conventional view of quasars is all wrong. However, it`s also something of a relief to know that most astronomers have not been barking up completely the wrong tree for the last thirty years."

Prof. Michael Merrifield | alfa

More articles from Physics and Astronomy:

nachricht Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology

nachricht NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>