Extended Lyman-α emission towards the SPT2349-56 protocluster at z = 4.3

Yordanka Apostolovski, Manuel Aravena, Timo Anguita, Matthieu Bethermin, James Burgoyne, Scott Chapman, Carlos De Breuck, Anthony Gonzalez, Max Gronke, Lucia Guaita, Yashar Hezaveh, Ryley Hill, Sreevani Jarugula, Evelyn Johnston, Matt Malkan, Desika Narayanan, Cassie Reuter, Manuel Solimano, Justin Spilker, Nikolaus SulzenauerJoaquin Vieira, David Vizgan, Axel Weiß

Research output: Contribution to journalArticlepeer-review


Context. Deep spectroscopic surveys with the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed that some of the brightest infrared sources in the sky correspond to concentrations of submillimeter galaxies (SMGs) at high redshift. Among these, the SPT2349-56 protocluster system is amongst the most extreme examples given its high source density and integrated star formation rate. Aims. We conducted a deep Lyman-α line emission survey around SPT2349-56 using the Multi-Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) in order to characterize this uniquely dense environment. Methods. Taking advantage of the deep three-dimensional nature of this survey, we performed a sensitive search for Lyman-α emitters (LAEs) toward the core and northern extension of the protocluster, which correspond to the brightest infrared regions in this field. Using a smoothed narrowband image extracted from the MUSE datacube around the protocluster redshift, we searched for possible extended structures. Results. We identify only three LAEs at z = 4.3 in this field. This number is lower than expectations for blank fields, and is significantly lower than the number of previously identified SMGs in this system. We find an extended Lyman-α structure of about 60 × 60 kpc2 in size located 56 kpc east of the protocluster core. Three SMGs coincide spatially with the location of this structure. All the other SMGs are undetected in Lyman-α emission, which is consistent with the conspicuous dust obscuration in these systems. We conclude that either the three co-spatial SMGs or the protocluster core itself are feeding ionizing photons to the Lyman-α structure.

Original languageEnglish (US)
Article numberA64
JournalAstronomy and Astrophysics
StatePublished - Mar 1 2024


  • galaxies: formation
  • intergalactic medium

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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