Cheshire Cat Project

Irwin+15:

CCD images to construct color-magnitude diagram ,then for candidates, with r' above 22mag and r' - i < 0.8 : Spectra obtained with GMOS, R400 grating centred at 7000 angstrom, 2.5hr exposure. There are 34 galaxies with consistent redshifts with Cheshire cat.

Combine with Bayliss+11 ,there are 48 galaxies with spec-z consistent with Cheshire cat.

For Two BCG:

Eastern eye z=0.426 , 19 members

Western eye z=0.433, 29 members

Redshift difference correspond to 1800 km s-1 rest-frame velocity. So they are at same distance but high relative velocity.

Irwin+15 argued that it is a Line of Sight Merger, the seperation is 12 Mpc. This is supported by X-ray from chandra that centre of X-ray emission is between two BCGs , and the centre of gravitational lens arc is also located midway between two BCGs.

There are 4 gravitational lensed arc in this system with GMOS, with 1.5 hr exposure. Redshifts are 2.198, 0.9657,2.783 and 0.802.

There is no RA DEC coordinates of lensed arc published, I am identifying them myself currently.

Identified lensed arc published in Bayliss+11

There are several images available in Hubble Legacy Archive, 3 exposures each from 2013 and 2014 March, with total 2000-ish sec in 110 filter and 160 filter, and 4800 sec from 390 filter. Also there are vis images from 2009 Apr, in 450, 606 and 814 filter.

2009 image in 606 filter in Hubble Legacy Archive

I propose we use 0.03 degree FOV for the cheshire cat, which is around 9 times of the outermost Einstein radii, this should be the most efficient set-up as we will compromise the number of cluster members if smaller FOV is used and reducing the resolution if we use larger FOV.

In such configuration, 18 cluster members are included. galaxy mass map generated with WSLAP+ using NFW profile (with no ellipticity).

Galaxy Mass map generated from WSLAP+

Some publications related to this project

Irwin et al. 2015 ApJ 806:268 https://arxiv.org/pdf/1505.05501.pdf

Bayliss et al 2011 ApJS 193:8 https://arxiv.org/pdf/1010.2714.pdf

Oguri et al 2012 MNRAS 420:3213 https://arxiv.org/pdf/1109.2594.pdf

Wiesner et al. 2012 ApJ 761:1 https://arxiv.org/pdf/1211.1421.pdf