ScienceProblem: NonCosmologicalRedshifts

PrimaryActor:

astronomer

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ScienceGoal:

Burbidge and co-workers, have argued (see e.g. Burbidge 2001) that some QSO's are considerably closer than normally thought and that their redshift is of largely intrinsic rather than cosmological origin. They argue that there is evidence for the physical association of QSO's with nearby galaxies, which is hard to explain if the big differences in redshift between local galaxy and hi-z QSO are cosmological in origin.

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DataSets:

QSO catalogues are cross referenced with galaxy catalogues to determine QSO association densities with galaxies at progressively larger distances. QSO's can be selected from a variety of data sources, including X-ray selected QSO's (e.g. Arp et al, 2001).

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ProblemDescription:

Because redshifts are normally used to measure distances, testing foir a noncosmological redshift component needs to be done by looking for physical associations between objects with differing redshifts. If the association is between a bright hi-z QSO and a faint nearby galaxy, then arguments that lensing is responsible for the brightening of the QSO are invoked. However, this is more problematic for associations between bright galaxies and QSO's (Burbidge 2001).

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CurrentSolution:

Compare bright QSO lists with galaxy lists to search for density enhancements of QSO's around galaxies.

Recently use of X-ray selected QSO's

Bell (2002) studied the distribution of compact QSO like objects around NGC 1068 and concluded that they were ejected from it.

Grazian et al (2000) have presented preliminary estimates of the local QSO luminosity function and discuss selection techniques based on photometry from the Guide Star and USNO catalogs with the Quasars being identified on the basis of their X-ray emission measured in the ROSAT All-Sky Survey. This work has not addressed the possible clustering of these nearby QSO's with local galaxies.

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VOSolution:

Search for correlations of QSO's with AGN's and build up a picture of whether or not there is evidence for ejection of these QSO like objects from the AGN.

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Discussion:

type here

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KeyReferences:

Bell, 2002, ApJ, 567, 801

Burbidge, 2001, PASP, 113, 899

Grazian et al, 2000, AJ, 119, 2540

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GoodStyle: Please add comments below. This area should be used for refinement of the above document. If you want to ask questions or start a dialogue with the author, please use (or create) a topic in the Science Problems Forum. For other ScienceProblems, refer to the ScienceProblemList.
Author: Once the refinements here and comments in the forum die down, perhaps you could rewrite the problem, incorporating the comments and refinements.

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associations - capability provided by other use cases

-- NicholasWalton - 17 Apr 2002

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-- NicholasWalton - 16 Apr 2002