We present a multiwavelength study of the double radio-relic cluster A1240 at z = 0.195. Our Subaru-based weak-lensing analysis detects three mass clumps forming an ∼4 Mpc filamentary structure elongated in a north-south orientation. The northern ( M200=2.61-0.60+0.51×1014M⊙) and middle ( M200=1.09-0.43+0.34×1014M⊙) mass clumps separated by ∼1.3 Mpc are associated with A1240 and colocated with the X-ray peaks and cluster galaxy overdensities revealed by Chandra and MMT/Hectospec observations, respectively. The southern mass clump ( M200=1.78-0.55+0.44×1014M⊙), ∼1.5 Mpc to the south of the middle clump, coincides with the galaxy overdensity in A1237, the A1240 companion cluster at z = 0.194. Considering the positions, orientations, and polarization fractions of the double radio relics measured by the LOFAR study, we suggest that A1240 is a postmerger binary system in the returning phase with a time since collision of ∼1.7 Gyr. With the SDSS DR16 data analysis, we also find that A1240 is embedded in the much larger scale (∼80 Mpc) filamentary structure whose orientation is in remarkable agreement with the hypothesized merger axis of A1240.
Bibliographical noteFunding Information:
This work was supported by the K-GMT Science Program (PID: MMT-2019A-004) of the Korea Astronomy and Space Science Institute (KASI). The observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. This work is based in part on data collected at the Subaru Telescope and obtained from the SMOKA, which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan. H.C. and K.F. thank Ho Seong Hwang for providing guidance on the MMT/Hectospec data reduction. H.C. acknowledges support from the Brain Korea 21 FOUR Program. M.J.J. acknowledges support for the current research from the National Research Foundation (NRF) of Korea under programs 2017R1A2B2004644 and 2020R1A4A2002885.
© 2022. The Author(s). Published by the American Astronomical Society.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science