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1. The One-hundred-deg 2 DECam Imaging in Narrowbands (ODIN): Survey Design and Science Goals

   https://doi.org/10.3847/1538-4357/ad165e  

   Lee, Kyoung-Soo ; Gawiser, Eric ; Park, Changbom ; Yang, Yujin ; Valdes, Francisco ; Lang, Dustin ; Ramakrishnan, Vandana ; Moon, Byeongha ; Firestone, Nicole ; Appleby, Stephen ; et al ( February 2024 , The Astrophysical Journal)

   We describe the survey design and science goals for One-hundred-deg²DECam Imaging in Narrowbands (ODIN), a NOIRLab survey using the Dark Energy Camera (DECam) to obtain deep (AB ∼ 25.7) narrowband images over an unprecedented area of sky. The three custom-built narrowband filters,N419,N501, andN673, have central wavelengths of 419, 501, and 673 nm and respective FWHM of 7.5, 7.6, and 10.0 nm, corresponding to Lyαatz= 2.4, 3.1, and 4.5 and cosmic times of 2.8, 2.1, and 1.4 Gyr, respectively. When combined with even deeper, public broadband data from the Hyper Suprime-Cam, DECam, and in the future, the Legacy Survey of Space and Time, the ODIN narrowband images will enable the selection of over 100,000 Lyα-emitting (LAE) galaxies at these epochs. ODIN-selected LAEs will identify protoclusters as galaxy overdensities, and the deep narrowband images enable detection of highly extended Lyαblobs (LABs). Primary science goals include measuring the clustering strength and dark matter halo connection of LAEs, LABs, and protoclusters, and their respective relationship to filaments in the cosmic web. The three epochs allow for the redshift evolution of these properties to be determined during the period known as Cosmic Noon, where star formation was at its peak. The narrowband filter wavelengths are designed to enable interloper rejection and further scientific studies by revealing [Oii] and [Oiii] atz= 0.34, Lyαand Heii1640 atz= 3.1, and Lyman continuum plus Lyαatz= 4.5. Ancillary science includes similar studies of the lower-redshift emission-line galaxy samples and investigations of nearby star-forming galaxies resolved into numerous [Oiii] and [Sii] emitting regions.

    

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2. A Massive Protocluster Anchored by a Luminous Quasar at z = 6.63

   https://doi.org/10.3847/2041-8213/ad20ef  

   Wang, Feige ; Yang, Jinyi ; Hennawi, Joseph F. ; Fan, Xiaohui ; Yue, Minghao ; Bañados, Eduardo ; Bechtel, Shane ; Bian, Fuyan ; Bosman, Sarah ; Champagne, Jaclyn B. ; et al ( February 2024 , The Astrophysical Journal Letters)

   Protoclusters, the progenitors of galaxy clusters, trace large scale structures in the early Universe and are important to our understanding of structure formation and galaxy evolution. To date, only a handful of protoclusters have been identified in the Epoch of Reionization. As one of the rarest populations in the early Universe, distant quasars that host active supermassive black holes are thought to reside in the most massive dark matter halos at that cosmic epoch and could thus potentially pinpoint some of the earliest protoclusters. In this Letter, we report the discovery of a massive protocluster around a luminous quasar atz= 6.63. This protocluster is anchored by the quasar and includes three [Cii] emitters atz∼ 6.63, 12 spectroscopically confirmed Lyαemitters (LAEs) at 6.54 <z≤ 6.64, and a large number of narrow-band-imaging selected LAE candidates at the same redshift. This structure has an overall overdensity of$\delta ={3.3}_{-0.9}^{+1.1}$within ∼35 × 74 cMpc²on the sky and an extreme overdensity ofδ> 30 in its central region (i.e.,R≲ 2 cMpc). We estimate that this protocluster will collapse into a galaxy cluster with a mass of${6.9}_{-1.4}^{+1.2}\times {10}^{15}{M}_{\odot }$at the current epoch, more massive than the most massive clusters known in the local Universe such as Coma. In the quasar vicinity, we discover a double-peaked LAE, which implies that the quasar has a UV lifetime greater than 0.8 Myrs and has already ionized its surrounding intergalactic medium.

    

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3. Introducing the Texas Euclid Survey for Lyα (TESLA) Survey: Initial Study Correlating Galaxy Properties to Lyα Emission

   https://doi.org/10.3847/1538-4357/acc403  

   Chávez Ortiz, Óscar A. ; Finkelstein, Steven L. ; Davis, Dustin ; Leung, Gene ; Mentuch Cooper, Erin ; Bagley, Micaela ; Larson, Rebecca ; Casey, Caitlin M. ; McCarron, Adam P. ; Gebhardt, Karl ; et al ( July 2023 , The Astrophysical Journal)

   We present the Texas Euclid Survey for Lyα(TESLA), a spectroscopic survey in the 10 deg²of the Euclid North Ecliptic Pole (NEP) field. Using TESLA, we study how the physical properties of Lyαemitters (LAEs) correlate with Lyαemission to understand the escape of Lyαemission from galaxies at redshifts of 2–3.5. We present an analysis of 43 LAEs performed in the NEP field using early data from the TESLA survey. We use Subaru Hyper Suprime-Cam imaging in thegrizybands, Spitzer/IRAC channels 1 and 2 from the Hawaii 20 deg²(H20) survey, and spectra acquired by the Visible Integral-Field Replicable Unit Spectrograph (VIRUS) on the Hobby–Eberly Telescope. We perform spectral energy distribution (SED) fitting to compute the galaxy properties of 43 LAEs, and study correlations between stellar mass, star formation rate (SFR), and dust to the Lyαrest-frame equivalent width (W_Lyα). We uncover marginal (1σsignificance) correlations between stellar mass andW_Lyα, and SFR andW_Lyα, with a Spearman correlation coefficient of −0.${34}_{-.14}^{+.17}$and −0.${37}_{-.14}^{+.16}$, respectively. We show that theW_Lyαdistribution of the 43 LAEs is consistent with being drawn from an exponential distribution with an e-folding scale ofW₀= 150 Å. Once complete the TESLA survey will enable the study of ≳50,000 LAEs to explore more correlations between galaxy properties andW_Lyα. The large sample size will allow the construction of a predictive model forW_Lyαas a function of SED-derived galaxy properties, which could be used to improve Lyα-based constraints on reionization.

    

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4. Probing Patchy Reionization with the Void Probability Function of Lyα Emitters

   https://doi.org/10.3847/1538-4357/ac9b57  

   Perez, Lucia A. ; Malhotra, Sangeeta ; Rhoads, James E. ; Laursen, Peter ; Wold, Isak G. B. ( November 2022 , The Astrophysical Journal)

   We probe what constraints for the global ionized hydrogen fraction the void probability function (VPF) clustering can give for the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) narrowband survey as a function of area. Neutral hydrogen acts like a fog for Lyαemission, and measuring the drop in the luminosity function of Lyαemitters (LAEs) has been used to constrain the ionization fraction in narrowband surveys. However, the clustering of LAEs is independent of the luminosity function’s inherent evolution, and can offer additional constraints for reionization under different models. The VPF measures how likely a given circle is to be empty. It is a volume-averaged clustering statistic that traces the behavior of higher-order correlations, and its simplicity offers helpful frameworks for planning surveys. Using the Jensen et al. simulations of LAEs within various amounts of ionized intergalactic medium, we predict the behavior of the VPF in one (301 × 150.5 × 30 Mpc³), four (5.44 × 10⁶Mpc³), or eight (1.1 × 10⁷Mpc³) fields of LAGER imaging. We examine the VPF at 5′ and 13′, corresponding to the minimum scale implied by the LAE density and the separation of the 2D VPF from random, and the maximum scale from the eight-field 15.5 deg²LAGER area. We find that even a single DECam field of LAGER (2–3 deg²) could discriminate between mostly neutral versus ionized. Additionally, we find four fields allow for the distinction between 30%, 50%, and 95% ionized, and eight fields could even distinguish between 30%, 50%, 73%, and 95% ionized.

    

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5. Evaluating Lyα Emission as a Tracer of the Largest Cosmic Structure at z ∼ 2.47

   https://doi.org/10.3847/1538-4357/ac9ea4  

   Huang, Yun ; Lee, Kyoung-Soo ; Cucciati, Olga ; Lemaux, Brian C. ; Sawicki, Marcin ; Malavasi, Nicola ; Ramakrishnan, Vandana ; Xue, Rui ; Cassara, Letizia P. ; Chiang, Yi-Kuan ; et al ( December 2022 , The Astrophysical Journal)

   Abstract The discovery and spectroscopic confirmation of Hyperion, a protosupercluster at z ∼ 2.47, provides an unprecedented opportunity to study distant galaxies in the context of their large-scale environment. We carry out deep narrowband imaging of a ≈1° × 1° region around Hyperion and select 157 Ly α emitters (LAEs). The inferred LAE overdensity is δ g ≈ 40 within an effective volume of 30 × 20 × 15 cMpc 3 , consistent with the fact that Hyperion is composed of multiple protoclusters and will evolve into a supercluster with a total mass of M tot ≈ 1.4 × 10 15 M ⊙ at z = 0. The distribution of LAEs closely mirrors that of known spectroscopic members, tracing the protocluster cores and extended filamentary arms connected to them, suggesting that they trace the same large-scale structure. By cross-correlating the LAE positions with H i tomography data, we find weak evidence that LAEs may be less abundant in the highest H i regions, perhaps because Ly α is suppressed in such regions. The Hyperion region hosts a large population of active galactic nuclei (AGNs) ≈ 12 times more abundant than that in the field. The prevalence of AGNs in protocluster regions hints at the possibility that they may be triggered by physical processes that occur more frequently in dense environments, such as galaxy mergers. Our study demonstrates LAEs as reliable markers of the largest cosmic structures. When combined with ongoing and upcoming imaging and spectroscopic surveys, wide-field narrowband imaging has the potential to advance our knowledge in the formation and evolution of cosmic structures and of their galaxy inhabitants. 

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