lefor jc 16 nov 2012akhlaghi/journalclub/pdfs/... · 2012-11-15 · astronomy)and)compu/ng)a&c)...
TRANSCRIPT
Astronomy and Compu/ng A&C
• A new Journal • Elsevier • h:p://www.journals.elsevier.com/astronomy-‐and-‐compu/ng/
CLASH: The enhanced lensing efficiency of the highly elongated merging cluster MACS J0416.1-‐2403
Zitrin et al. 1211.2797
• CLASH is a 524 orbit program to use the lensing proper/es of 25 galaxy clusters to constrain their mass distribu/ons, esp DM in the clsuter cores. 20 of them are X-‐ray selected. Other goals to deetct Type Ia SN, charact galaxies at z>7 and study evolu/on of the galaxies in these clusters. J0416 is a “high magnifica/on” cluster in the CLASH survey. 20 are “dynamically relaxed”.
• 70 new mul/ple images and 23 background sources. • Enhanced lensing efficiency compared to other lenses (efficiency= #mult images generated per
cri/cal area). Elonga/on boosts the number of images per cri/cal area by a factor of 2.5, due to increased ra/o of caus/c area rela/ve to cri/cal area.
• Efficiency is related to ellip/city, substructure and distance from center. • Massive, more concentrated clusters show more mul/ple images • Mass profile in the center is important. J0416 has 2 main mass components and the separa/on
between them enlarges the cri/cal area by a factor of 2. • This was iden/fied in the Massive Cluster Survey (MACS), and classified it as merging. Part of MACS
because of X-‐ray brightness, and double peaked x-‐ray structure. • Performed 2 modeling techniques. First used PIEMD, with an ellip/cal Gaussian and 6 parameters.
Second method was PIEMD with an ellip/cal NFW to represent the DM. • Models showed increased density of mult images with ellip/city and lower separa/on between
merging clumps