Publications of The Korean Astronomical Society (천문학논총)

The Korean Astronomical Society (한국천문학회)
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DISCOVERY OF A STRONG LENSING GALAXY EMBEDDED IN A CLUSTER AT z = 1.62

  • WONG, KENNETH C. (Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA)) ;
  • TRAN, KIM-VY H. (George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University) ;
  • SUYU, SHERRY H. (Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA)) ;
  • MOMCHEVA, IVELINA G. (Astronomy Department, Yale University) ;
  • BRAMMER, GABRIEL B. (Space Telescope Science Institute) ;
  • BRODWIN, MARK (Department of Physics and Astronomy, University of Missouri) ;
  • GONZALEZ, ANTHONY H. (Department of Astronomy, University of Florida) ;
  • HALKOLA, ALEKSI (Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA)) ;
  • KACPRZAK, GLENN G. (Swinburne University of Technology) ;
  • KOEKEMOER, ANTON M. (Space Telescope Science Institute) ;
  • PAPOVICH, CASEY J. (George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics & Astronomy, Texas A&M University) ;
  • RUDNICK, GREGORY H. (Department of Physics and Astronomy, The University of Kansas)
  • Received : 2014.11.30
  • Accepted : 2015.06.30
  • Published : 2015.09.30
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Abstract

We identify a strong lensing galaxy in the cluster IRC 0218 that is spectroscopically confirmed to be at z = 1.62, making it the highest-redshift strong lens galaxy known. The lens is one of the two brightest cluster galaxies and lenses a background source galaxy into an arc and a counterimage. With Hubble Space Telescope (HST) grism and Keck/LRIS spectroscopy, we measure the source redshift to be $z_S=2.26$. Using HST imaging, we model the lens mass distribution with an elliptical power-law profile and account for the effects of the cluster halo and nearby galaxies. The Einstein radius is $^{\theta}E=0.38^{+0.02{\prime}{\prime}}_{-0.01}$ ($3.2^{+0.2}_{-0.1}kpc$) and the total enclosed mass is $M_{tot}(<^{\theta}_E)=1.8^{+0.2}_{-0.1}{\times}10^{11}M_{\odot}$. We estimate that the cluster environment contributes ~ 10% of this total mass. Assuming a Chabrier IMF, the dark matter fraction within $^{\theta}E$ is $f^{Chab}_{DM}=0.3^{+0.1}_{-0.3}$, while a Salpeter IMF is marginally inconsistent with the enclosed mass ($f^{Salp}_{DM}=-0.3^{+0.2}_{-0.5}$).

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References

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