Q1146111B,C quasar pair: illusion or delusion?
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Auteurs : E. S. Phinney ; R. D. BlandfordSource :
- Nature [ 0028-0836 ] ; 1986-06-05.
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DOI: 10.1038/321569b0
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Phinney</name><affiliation><mods:affiliation>Theoretical Astrophysics, 13033 Caltech, Pasadena, California 91125, USA</mods:affiliation></affiliation></author><author><name sortKey="Blandford, R D" sort="Blandford, R D" uniqKey="Blandford R" first="R. D." last="Blandford">R. D. Blandford</name><affiliation><mods:affiliation>Theoretical Astrophysics, 13033 Caltech, Pasadena, California 91125, USA</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">Nature</title><idno type="ISSN">0028-0836</idno><imprint><publisher>Nature Publishing Group</publisher><date type="published" when="1986-06-05">1986-06-05</date><biblScope unit="volume">321</biblScope><biblScope unit="issue">6070</biblScope><biblScope unit="page" from="569">569</biblScope><biblScope unit="page" to="570">570</biblScope></imprint><idno type="ISSN">0028-0836</idno></series><idno type="istex">351B743D4DB41D988359861177FC85A5CEC1BA1E</idno><idno type="DOI">10.1038/321569b0</idno><idno type="ArticleID">321569b0</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0028-0836</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader></TEI><istex><corpusName>nature</corpusName><author><json:item><name>E.S. 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BLANDFORD</name><affiliations><json:string>Theoretical Astrophysics, 13033 Caltech, Pasadena, California 91125, USA</json:string></affiliations></json:item></author><articleId><json:string>321569b0</json:string></articleId><language><json:string>unknown</json:string></language><originalGenre><json:string>Scientific Correspondence</json:string></originalGenre><qualityIndicators><score>0.521</score><pdfVersion>1.4</pdfVersion><pdfPageSize>581.102 x 793.701 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>0</keywordCount><abstractCharCount>0</abstractCharCount><pdfWordCount>9</pdfWordCount><pdfCharCount>52</pdfCharCount><pdfPageCount>2</pdfPageCount><abstractWordCount>1</abstractWordCount></qualityIndicators><title>Q1146111B,C quasar pair: illusion or delusion?</title><genre><json:string>article</json:string></genre><host><volume>321</volume><pages><last>570</last><first>569</first></pages><issn><json:string>0028-0836</json:string></issn><issue>6070</issue><genre><json:string>journal</json:string></genre><language><json:string>unknown</json:string></language><title>Nature</title></host><categories><wos><json:string>MULTIDISCIPLINARY SCIENCES</json:string></wos></categories><publicationDate>1986</publicationDate><copyrightDate>1986</copyrightDate><doi><json:string>10.1038/321569b0</json:string></doi><id>351B743D4DB41D988359861177FC85A5CEC1BA1E</id><score>3.5932603</score><fulltext><json:item><original>true</original><mimetype>application/pdf</mimetype><extension>pdf</extension><uri>https://api.istex.fr/document/351B743D4DB41D988359861177FC85A5CEC1BA1E/fulltext/pdf</uri></json:item><json:item><original>false</original><mimetype>application/zip</mimetype><extension>zip</extension><uri>https://api.istex.fr/document/351B743D4DB41D988359861177FC85A5CEC1BA1E/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/351B743D4DB41D988359861177FC85A5CEC1BA1E/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a">Q1146111B,C quasar pair: illusion or delusion?</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>Nature Publishing Group</publisher><availability><p>©1986 Nature Publishing Group</p></availability><date>1986</date></publicationStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a">Q1146111B,C quasar pair: illusion or delusion?</title><author xml:id="author-1"><persName><forename type="first">E.S.</forename><surname>PHINNEY</surname></persName><affiliation>Theoretical Astrophysics, 13033 Caltech, Pasadena, California 91125, USA</affiliation></author><author xml:id="author-2"><persName><forename type="first">R.D.</forename><surname>BLANDFORD</surname></persName><affiliation>Theoretical Astrophysics, 13033 Caltech, Pasadena, California 91125, USA</affiliation></author></analytic><monogr><title level="j">Nature</title><idno type="pISSN">0028-0836</idno><imprint><publisher>Nature Publishing Group</publisher><date type="published" when="1986-06-05"></date><biblScope unit="volume">321</biblScope><biblScope unit="issue">6070</biblScope><biblScope unit="page" from="569">569</biblScope><biblScope unit="page" to="570">570</biblScope></imprint></monogr><idno type="istex">351B743D4DB41D988359861177FC85A5CEC1BA1E</idno><idno type="DOI">10.1038/321569b0</idno><idno type="ArticleID">321569b0</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>1986</date></creation><langUsage><language ident="en">en</language></langUsage></profileDesc><revisionDesc><change when="1986-06-05">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><original>false</original><mimetype>text/plain</mimetype><extension>txt</extension><uri>https://api.istex.fr/document/351B743D4DB41D988359861177FC85A5CEC1BA1E/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="corpus nature, element headerx not found" wicri:toSee="no header"><istex:xmlDeclaration>version="1.0"</istex:xmlDeclaration><istex:docType PUBLIC="-//NPG//DTD headerx//EN" URI="headerx.dtd" name="istex:docType"></istex:docType><istex:document><headerx><ArticleIdList><ArticleId>321569b0</ArticleId></ArticleIdList><pubfm><jtl>Nature</jtl><vol>321</vol><iss>6070</iss><idt>19860605</idt><categ id="sc"></categ><pp><spn>569</spn><epn>570</epn></pp><issn>0028-0836</issn><cpg><cpy>1986</cpy><cpn>Nature Publishing Group</cpn></cpg><doi>10.1038/321569b0</doi></pubfm><fm><atl>Q1146+111B,C quasar pair: illusion or delusion?</atl><aug><au><fnm>E.S.</fnm><snm>PHINNEY</snm><inits>E. S.</inits></au><au><fnm>R.D.</fnm><snm>BLANDFORD</snm><inits>R. D.</inits></au><aff>Theoretical Astrophysics, 130–33 Caltech, Pasadena, California 91125, USA</aff></aug></fm><bdy>
SIR-The quasar pair Q1146+111B,C' has been re-observed by Turner et al.2 who argue that it comprises two gravitat-ionally lensed images of a single source. In this letter, we show that we are probably observing two distinct though neighbouring quasars.
Were quasars placed randomly on the sky, the probability of finding another quasar of apparent magnitude m within an angle 9 of a given quasar would be3 Pr(0, m) - njtO2, where n(m) is the sky density of quasars brighter than magnitude m. For Q1146+111B,C, 0 = 157 arc s, n (18.5) 1 per deg2 (ref. 4), giving Pr 6 x 103. However, quasars are probably not distributed uniformly throughout the Universe, and there is evidence that they are clustered in much the same way as are galaxies56 (but see ref. 7), so their two-point correlation function is (r) - (r/rQ)l'8, where r0 = 5(1 + z)-'/T' Mpc, h = the Hubble constant //0/100 km s"1 Mpc"1 and the cosmological density parameter Q0 = I. The probability associated with this excess for a given quasar to have a companion within angle 0 brighter than magnitude m is then
where D(z) is the angular diameter distance of the quasar, and I (L,z) the integral luminosity function for quasars with luminosity L(m,z). Now, 4 (L,z) = (dn/dz)/D2(l + z)1/2 (ref. 8) and observations4 indicate that for 0.5 z 2, quasars of a given magnitude are uniformly distributed in redshift with dn/dz - Q.5n. Substitution in equation (1) then gives Pc(9,m,z) = 38(1 + z)(vl + z -l)03(0D)d/i/dz for DO ^ 2r(), where n is per steradian and 9 in radians. Numerically, pc 2 x icr4.
Published quasar catalogues910 contain N(19) 2,000 quasars brighter than B = 19. Unpublished surveys probably treble this number. The expected number of random associations with the separation and magnitude of Q1146+111B,C is NPr(l51 arc s, 18.5)72 20, which is roughly what is observed5 9. The expected number of closely clustered companions is NPC(151 arc s, 18.5, 1.0)72 1. Hence we would expect by now to have discovered of the order of one physically associated pair of magnitude 18.5 quasars separated in angle by less than 157 arc s and in velocity by the velocity dispersion of small groups which dominate the correlation function, 300 km s'1. We should not be unduly surprised if Ql 146+11 IB ,C fails tests of the lensing hypothesis11 - it may be that expected pair.
In conclusion, we suggest that the necessity for lensing in some of the other gravitational lens candidates should be re-examined. This is especially important for faint quasars when there is no independent evidence for lensing (for example, an intervening giant galaxy or distortion of background galaxies) and no sign of common spectroscopic or. morphological peculiarities. (Overall spectral dissimilarity need not rule out lensing because quasars can very significantly in the time delay between two images.) The quasar pairs Q2345+007A,B (ref. 12) and Q1635+267A,B (ref. 13) in which the fainter quasars are both roughly magnitude 21 both give Pc = Pr 2 x 10"4, if we assume that the correlation function is valid for proper distances 20 kpc (as it is for the galaxy-galaxy correlation14; it has been suggested that the quasar-galaxy correlation function is even higher15'16). It is therefore not unreasonable that these two pairs comprise distinct objects; since Pr Pc we should expect to find a few similarly separated quasars with discrepant redshifts, for example, Q1548+ 114A,B(ref. 17).
We thank Ramesh Narayan for helpful suggestions. We acknowledge support by NSF Presidential Young Investigator grant AST84-51725 and grants from the Exxon Education Foundation and Boeing Company (E.S.P.) and NSF grant AST84-15355 (R.D.B.).
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Soc.</jtl> <vid>212</vid>, <ppf>15p</ppf>–<ppl>20p</ppl> (<cd year="1985">1985</cd>).</reftxt></bib></bibl></bm></headerx></istex:document></istex:metadataXml><mods version="3.6"><titleInfo><title>Q1146111B,C quasar pair: illusion or delusion?</title></titleInfo><titleInfo type="alternative" contentType="CDATA"><title>Q1146111B,C quasar pair: illusion or delusion?</title></titleInfo><name type="personal"><namePart type="given">E.S.</namePart><namePart type="family">PHINNEY</namePart><affiliation>Theoretical Astrophysics, 13033 Caltech, Pasadena, California 91125, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">R.D.</namePart><namePart type="family">BLANDFORD</namePart><affiliation>Theoretical Astrophysics, 13033 Caltech, Pasadena, California 91125, USA</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="article" displayLabel="Scientific Correspondence"></genre><originInfo><publisher>Nature Publishing Group</publisher><dateIssued encoding="w3cdtf">1986-06-05</dateIssued><copyrightDate encoding="w3cdtf">1986</copyrightDate></originInfo><language><languageTerm type="code" authority="iso639-2b">eng</languageTerm><languageTerm type="code" authority="rfc3066">en</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><relatedItem type="host"><titleInfo><title>Nature</title></titleInfo><genre type="journal" displayLabel="journal"></genre><identifier type="ISSN">0028-0836</identifier><part><date>1986</date><detail type="volume"><caption>vol.</caption><number>321</number></detail><detail type="issue"><caption>no.</caption><number>6070</number></detail><extent unit="pages"><start>569</start><end>570</end></extent></part></relatedItem><identifier type="istex">351B743D4DB41D988359861177FC85A5CEC1BA1E</identifier><identifier type="DOI">10.1038/321569b0</identifier><identifier type="ArticleID">321569b0</identifier><accessCondition type="use and reproduction" contentType="copyright">©1986 Nature Publishing Group</accessCondition><recordInfo><recordContentSource>NATURE</recordContentSource></recordInfo></mods></metadata><enrichments><istex:catWosTEI uri="https://api.istex.fr/document/351B743D4DB41D988359861177FC85A5CEC1BA1E/enrichments/catWos"><teiHeader><profileDesc><textClass><classCode scheme="WOS">MULTIDISCIPLINARY SCIENCES</classCode></textClass></profileDesc></teiHeader></istex:catWosTEI></enrichments><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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