Day 657

Thursday.

1405.2954
On the benefits of promoting diversity of ideas
Loeb

10 examples where astronomers believed that they knew the truth when data was scarce, leading to wrong strategic decisions in research plans, causing unnecessary delays in finding the truth.  Advocate affirmative action for diversity of ideas by telescope-time allocation committees and funding agencies.

1405.3303
Mass and magnification maps for the Hubble Space Telescope Frontier Fields clusters: implications for high redshift studies
Richard, … Limousin, Jullo, … Ebeling, Kneib, Natarajan, Egami, … Bower, et al

HFF is the largest HST program to probe the distant Universe by massive galaxy cluster lensing.  Present models of the mass distribution in 6 of the HFF cluster lenses, derived from a joint SL and WL analysis anchored by 618 multiple-image systems identified in existing HST data.  The resulting maps of the projected has distribution and of the gravitational magnification effectively calibrate the HFF clusters as gravitational telescopes.  Allowing the computation of search areas in the source plane, these maps are provided to the community to facilitate the exploitation of forthcoming HFF data for quantitative studies of the gravitationally lensed population of background galaxies.  Models of the gravitational magnification afforded by the HFF clusters allow quantification of the lensing-induced boost in sensitivity over blank-filed observations and predict that galaxies at z>10 and as faint as m(AB)=32 will be detectable, up to 2 mags fainter than the limit of HUDF.

1405.3440
Ultra-faint high-redshift galaxies in the Frontier Fields
Yue et al

In FF, galaxies as faint as m~33-34 AB mag at 1.6um can be detected.  Such faint galaxies are hosted by DM halos of mass ~1e9 Msun and dominate the ionizing photon budget over currently observed bright galaxies, thus allowing for the first time the investigation of the dominant reionization sources.  In addition, the observed number of these galaxies can be used to constrain the role of feedback in suppressing SF in small haloes: for example, if galaxy formation is suppressed in haloes with circular velocity v_c<50 km/s, galaxies fainter than m=31 should not be detected in the FFs.

1405.3582
Hubble Frontier Fields : High precision strong lensing analysis of the cluster MACSJ0416.1-2403 using ~200 multiple images
Jauzac et al

From 3-band HST/ACS observations, discover 51 new multiply-imaged systems for a total of 68 systems and 194 images.  They provide critical additional constraints that helps derive the mass distribution in the cluster core below the percent level.  In comparison, the earlier published mass model used the CLASH survey data with only 23 multiple systems.  Using LENSTOOL, build a high precision mass model that comprises of 2 cluster-scale DM haloes and 98 galaxy-scale haloes to describe the mass distribution of MACSJ0416.  Concentrating on the subset of 57 multiply imaged systems used in the optimization, the best-fit mass model has an average error on the predicted image positions of rms=0.68", almost a factor of 2 improvement compared to the rms=1.17" obtained with the pre-HFF mass model (which used only 17 multiply imaged systems).  THe total mass within an aperture of 200 kpc is found to be M=1.60pm0.01e14 Msun.  Finally, quantify the gain in precision on the magnification of high-z galaxies, and find an improvement by a factor of ~2.5x in the statistical error.  With the new HFF, entering the domain of high-precision mass measurement for massive galaxy clusters.