Deep view of the intracluster light in the Coma cluster of galaxies

¹ Instituto de Astrofísica de Andalucía–CSIC, Glorieta de la Astronomía s/n, E-18008 Granada, Spain
² Observatório Nacional, Rua General José Cristino, 77 – Bairro Imperial de São Cristóvão, Rio de Janeiro 20921-400, Brazil
³ Departamento de Física de la Tierra y Astrofísica, Universidad Complutense de Madrid, E-28040 Madrid, Spain
⁴ Instituto de Astrofísica de Canarias, c/ Vía Láctea s/n, E-38205 La Laguna, Tenerife, Spain
⁵ Departamento de Astrofísica, Universidad de La Laguna, E-38206 La Laguna, Tenerife, Spain
⁶ Department of Astronomy, Yonsei University, 50 Yonsei-ro, Seoul 03722, Korea
⁷ Department of Astronomy, University of Michigan, 311 West Hall, 1085 South University Ave., Ann Arbor, MI 48109-1107, USA
⁸ Eureka Scientific, 2452 Delmer St. Suite 100, Oakland, CA 94602, USA
⁹ Observatório do Valongo, Universidade Federal do Rio de Janeiro, Ladeira do Pedro Antônio 43, Rio de Janeiro, RJ 20080-090, Brazil
¹⁰ Department of Physics & Astronomy, University of California Los Angeles, 430 Portola Plaza, Los Angeles, CA 90095-1547, USA
¹¹ Department of Astronomy, University of Washington, 3910 15th Avenue, NE, Seattle, WA 98195, USA

^⋆ Corresponding author; yojite@iaa.es

Received: 26 September 2024
Accepted: 17 December 2024

Abstract

The detection and study of the intracluster light (ICL) in rich clusters of galaxies has been a longstanding challenge and key focus. Using the lowest-surface-brightness images of the Coma cluster of galaxies in the g and r bands, from the Halos and Environment of Nearby Galaxies (HERON) Coma Cluster Project, we obtained the most extensive image of ICL in a single cluster to date, spreading over 1.5 Mpc from the cluster core. The unprecedented wealth of spectroscopic data from the Dark Energy Spectroscopic Instrument (DESI) Early Data Release, along with a compilation from the NASA/IPAC Extragalactic Database and available data from the literature, enabled the identification of 2157 galaxy members within Coma; on this basis, 42 distinct groups were identified. The synergy between these high-quality data allowed us to: (1) calculate ICL fractions of 19.9 ± 0.5% and 19.6 ± 0.6% in the g and r bands, respectively, consistent with a dynamically active cluster; (2) unveil Coma’s faintest tidal features; and (3) provide a comprehensive picture of the dynamics and interactions within this complex system. Our findings indicate that the ICL connects several of these groups in a filamentous network, from which we can infer ongoing dynamical processes. In particular, we identified a faint stellar bridge linking the core of Coma with the galaxy NGC 4839, providing compelling evidence that this galaxy has already traversed the central region of the cluster.