DECam\u2019s massive field of view<\/a>, the team conducted the largest on-sky area search ever around an early-universe quasar, trying to measure the density of its environment by counting the number of surrounding companion galaxies.<\/p>\nFor their investigation, the team needed a quasar with a well-defined distance. Luckily, quasar VIK 2348\u20133054 has a known distance, determined by previous observations with the Atacama Large Millimeter\/submillimeter Array (ALMA).<\/p>\n
DECam\u2019s three-square-degree field of view provided an expansive look at its cosmic neighbourhood.<\/p>\n
Serendipitously, DECam is also equipped with a narrowband filter perfectly matched for detecting its companion galaxies.<\/p>\n
\u201cThis quasar study really was the perfect storm,\u201d said Trystan Lambert, who led the study. \u201cWe had a quasar with a well-known distance, and DECam on the Blanco telescope offered the massive field of view and exact filter that we needed.\u201d<\/p>\n
Using distance measurements to map neighbourhoods<\/h3>\n DECam\u2019s specialised filter allowed the team to count the number of companion galaxies around the early-universe quasar by detecting a very specific type of light they emit, known as Lyman-alpha radiation.<\/p>\n
Lyman-alpha emitters are typically younger, smaller galaxies, and their Lyman-alpha emission can be used as a way to reliably measure their distances.<\/p>\n
Distance measurements for multiple Lyman-alpha emitters can then be used to construct a 3D map of a quasar\u2019s neighbourhood.<\/p>\n
After systematically mapping the region of space around quasar VIK J2348-3054, Lambert and his team found 38 companion galaxies in the wider environment around the quasar \u2014 out to a distance of 60 million light-years \u2014 which is consistent with what is expected for quasars residing in dense regions.<\/p>\n
However, they were surprised to find that within 15 million light-years of the quasar, there were no companions at all.<\/p>\n
DECam\u2019s role in offering new insights<\/h3>\n This finding illuminates the reality of past studies aimed at classifying early-universe quasars and proposes a possible explanation for their conflicting results.<\/p>\n
No other survey of this kind has used a search area as large as the one provided by DECam, so for smaller-area searches, a quasar\u2019s environment can appear deceptively empty.<\/p>\n
\u201cDECam\u2019s extremely wide view is necessary for studying quasar neighbourhoods thoroughly. You really have to open up to a larger area,\u201d Lambert explained.<\/p>\n
\u201cThis suggests a reasonable explanation as to why previous observations conflict with one another.\u201d<\/p>\n
Lambert\u2019s team is currently following up with additional observations to obtain spectra and confirm star formation suppression.<\/p>\n
They also plan to observe other quasars to build a more robust sample size.<\/p>\n","protected":false},"excerpt":{"rendered":"
A new study using the DECam points the way to an explanation for disparate observations of early-universe quasars.<\/p>\n","protected":false},"author":22,"featured_media":51369,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[771],"tags":[801,3477],"acf":[],"yoast_head":"\n
DOE\u2019s DECam offers fresh insights into early-universe quasars<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n \n \n \n \n \n\t \n\t \n\t \n