WILDTHING: Impact of the intergalactic medium on observed LAE Clustering and Protocluster Detection
Akriti Singh
The Lyman-alpha (Lyα) emission line (λ_rest-frame ≈ 1216 Å) is the strongest recombination line of neutral hydrogen. Given the wavelength of Lyα emission, LAEs can be detected up to z ≈ 6 using ground-based photometric surveys, making them an ideal tool for tracing the large-scale structure of the universe and finding protoclusters, filaments, and the underlying density field.
Clustering studies of LAEs are also used to study the expansion history of the universe. One way to detect LAEs is by measuring the excess of their flux in a narrow band centered at the observed wavelength of Lyα with respect to a broad band covering the rest-frame UV continuum wavelengths. However, Lyman-alpha radiative transfer is very sensitive to local astrophysical conditions and makes the selection of LAEs quite complex. Lyman-alpha is a resonant line, easily scattered by neutral hydrogen, which increases the path traveled by the photons through the neutral medium and also modifies the frequency of the scattered Lyman-alpha photons. The intergalactic medium (IGM) and interstellar medium (ISM) can impact the observed spatial
distribution and properties of the LAEs and can introduce dramatic biases in the interpretation of data from surveys that use LAEs to trace large-scale structure and constrain cosmological models. The Wide-area Investigation of Lyman-alpha Emission Dissipating Through Intergalactic Neutral Gas (WILDTHING) survey is the first large-area survey designed to detect the effect of IGM on the observed clustering of LAEs. The WILDTHING survey uses 72 square degrees of narrow-band observations combined with archival broadband data to detect LAEs at z = 4.5. To compare the observations with models, we have five simulations of LAEs with different LAE-IGM couplings ranging from weak coupling to strong coupling. In this talk, I will discuss the effect of IGM coupling on the clustering of LAEs as observed using WILDTHING observations and simulations. Furthermore, I have used Voronoi Tessellations to trace the density field and find protoclusters in the 72 square degrees of WILDTHING observations and simulations. I will also present our results on the effect of IGM absorption on the detectability of protoclusters and density maps using LAEs. Including the effect of IGM on the selection of LAEs will result in a better interpretation of the results of surveys that use LAEs to look for protoclusters. These surveys include the ongoing ODIN, HETDEX, and DESY surveys.
Event Timeslots (1)
Mon
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