J/ApJ/736/43ivo://CDS.VizieR/J/ApJ/736/43doi:10.26093/cds/vizier.17360043CDSCain B.Schechter P.L.Bautz M.W.2013-06-23T21:48:29Z2013-01-23T08:40:05ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgalaxy-clustersastronomical-modelsgravitational-lensingMeasuring dark matter substructure within galaxy cluster halos is a fundamental probe of the {Lambda}CDM model of structure formation. Gravitational lensing is a technique for measuring the total mass distribution which is independent of the nature of the gravitating matter, making it a vital tool for studying these dark-matter-dominated objects. We present a new method for measuring weak gravitational lensing flexion fields, the gradients of the lensing shear field, to measure mass distributions on small angular scales. While previously published methods for measuring flexion focus on measuring derived properties of the lensed images, such as shapelet coefficients or surface brightness moments, our method instead fits a mass-sheet transformation invariant Analytic Image Model (AIM) to each galaxy image. This simple parametric model traces the distortion of lensed image isophotes and constrains the flexion fields. We test the AIM method using simulated data images with realistic noise and a variety of unlensed image properties, and show that it successfully reproduces the input flexion fields. We also apply the AIM method for flexion measurement to Hubble Space Telescope observations of A1689 and detect mass structure in the cluster using flexion measured with this method. We also estimate the scatter in the measured flexion fields due to the unlensed shape of the background galaxies and find values consistent with previous estimates.2011ApJ...736...43Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/736/43CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)J/ApJ/723/1678 : LensPerfect A1689 analysis (Coe+, 2010)J/ApJ/668/643 : Multiply imaged gravitational lens systems (Limousin+, 2007)J/MNRAS/372/1425 : Gravitational lensing analysis of A1689 (Halkola+, 2006)J/ApJ/621/53 : Multiple arc systems in A1689 (Broadhurst+, 2005)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/736/43https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/736/43http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/736/43https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/736/43https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/736/43http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/736/43GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/736/43/table2 (Position, fit, and error values for the model parameters of the 50 objects in the A1689 field with the best 1-flexion estimates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/736/43/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/736/43/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/736/43/table2?GETtext/xml+votable180.050000true197.89375-1.3255830.0055555555555555566/26189https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/736/43?format=asciidefaultJ/ApJ/736/43/table2Position, fit, and error values for the model parameters of the 50 objects in the A1689 field with the best 1-flexion estimatese_tc1c1 uncertaintyarcsecstat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/50] Object number (\dicS{[CSB2011] NN} in Simbad)meta.id;meta.mainintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainlogS0Log of S_0_ in units of e^-^/s (1)log(s**-1)stat.fit.paramfloate_logS0S0 uncertaintylog(s**-1)stat.errorfloattc1{theta}_c1_ position angle in the image plane c1 (1)arcsecpos.posAng;obs.imagefloattc2{theta}_c2_ position angle in the image plane c2 (1)arcsecpos.posAng;obs.imagefloate_tc2c2 uncertaintyarcsecstat.errorfloatalphaImage scale (=AB^0.5^ with A and B: semi-axes; see equation 11) (1)arcsecstat.fit.paramfloate_alphaalpha uncertaintyarcsecstat.error;pos.eq.rafloate1Ellipticity parameter 1 (1)stat.fit.paramfloate_e1e1 uncertaintystat.errorfloate2Ellipticity parameter 2 (1)stat.fit.paramfloate_e2e2 uncertaintystat.errorfloatp111-flexion parameter 1 {psi}_11_ (2)arcsec**-1stat.fit.paramfloate_p11p11 uncertaintyarcsec**-1stat.errorfloatp121-flexion parameter 2 {psi}_12_ (2)arcsec**-1stat.fit.paramfloate_p12p12 uncertaintyarcsec**-1stat.errorfloatp313-flexion parameter 1 {psi}_31_ (2)arcsec**-1stat.fit.paramfloate_p31p31 uncertaintyarcsec**-1stat.errorfloatp323-flexion parameter 2 {psi}_32_ (2)arcsec**-1stat.fit.paramfloate_p32p32 uncertaintyarcsec**-1stat.errorfloat