Search for: All records

Context.Submillimeter galaxies (SMGs) constitute a key population of bright star-forming galaxies at high-redshift. These galaxies challenge galaxy formation models, particularly regarding the reproduction of their observed number counts and redshift distributions. Furthermore, although SMGs contribute significantly to the cosmic star formation rate density (SFRD), their precise role remains uncertain. Upcoming surveys, such as the Ultra Deep Survey with the TolTEC camera, are expected to offer valuable insights into SMG properties and their broader impact in the Universe. Aims.Robust modeling of SMGs in a cosmological representative volume is necessary to investigate their nature in preparation for next-generation submillimeter surveys. Here, we test different parametric models for SMGs in large-volume hydrodynamical simulations, assess their contribution to the SFRD, and build expectations for future submillimeter surveys. Methods.We implement and test parametric relations derived from radiative transfer calculations across three cosmological simulation suites: EAGLE, IllustrisTNG, and FLAMINGO. We place particular emphasis on the FLAMINGO simulations due to their large volume and robust statistical sampling of SMGs. Based on the model that best reproduces observational number counts, we forecast submillimeter fluxes within the simulations, analyze the properties of SMGs, and evaluate their evolution over cosmic time. Results.Our results show that the FLAMINGO simulation reproduces the observed redshift distribution and source number counts of SMGs without requiring a top-heavy initial mass function. On the other hand, the EAGLE and IllustrisTNG simulations show a deficit of bright SMGs. We find that SMGs with S₈₅₀ > 1 mJy contribute up to ∼27% of the cosmic SFRD atz ∼ 2.6 in the FLAMINGO simulation, which is consistent with recent observations. Flux density functions reveal a rise in SMG abundance fromz = 6 toz = 2.5 that is followed by a sharp decline in the number of brighter SMGs fromz = 2.5 toz = 0. Leveraging the SMG population in FLAMINGO, we forecast that the TolTEC UDS will detect ∼80 000 sources over 0.8 deg²at 1.1 mm (at the 4σdetection limit), capturing about 50% of the cosmic SFRD atz ∼ 2.5. 

Aims.We investigate the physical properties and redshift evolution of simulated galaxies residing in unvirialized cosmic structures (i.e., protoclusters) at cosmic noon, to understand the influence of the environment on galaxy formation. This work is intended to build clear expectations for the ongoing ODIN (One-hundred-deg²DECam Imaging in Narrowbands) survey, which is mapping large-scale structures atz= 2.4,3.1, and 4.5 using Lyα-emitting galaxies (LAEs) as tracers. Methods.From the IllustrisTNG simulations, we define subregions centered on the most massive clusters ranked by total stellar mass atz= 0 and study the properties of galaxies within, including those of LAEs. To model the LAE population, we take a semi-analytical approach that assigns Lyαluminosity and equivalent width based on the UV luminosities to galaxies in a probabilistic manner. We investigate stellar mass, star formation rate (SFR), major merger events, and specific star formation rate of the population of star-forming galaxies and LAEs in the field- and protocluster environment and trace their evolution across cosmic time betweenz= 0−4. Results.We find that the overall shape of the UV luminosity function in simulated protocluster environments is characterized by a substantially shallower faint-end slope and a large excess on the bright end, signaling different formation histories for galaxies therein. The difference is milder for the Lyαluminosity function. While protocluster galaxies follow the same SFR-M_★scaling relation as average field galaxies, a larger fraction appears to have experienced major mergers in the last 200 Myr and as a result shows enhanced star formation at a ≈60% level, leading to a flatter distribution in both SFR and M_★relative to galaxies in the average field. We find that protocluster galaxies, including LAEs, begin to quench much earlier (z∼0.8−1.6) than field galaxies (z∼0.5−0.9); our result is in qualitative agreement with recent observational results and highlights the importance of large-scale environment on the overall formation history of galaxies. 

Abstract The One-hundred-deg²DECam Imaging in Narrowbands (ODIN) survey is carrying out a systematic search for protoclusters during Cosmic Noon, using Lyα-emitting galaxies (LAEs) as tracers. Once completed, ODIN aims to identify hundreds of protoclusters at redshifts of 2.4, 3.1, and 4.5 across seven extragalactic fields, covering a total area of up to 91 deg². In this work, we report the high clustering strength of the ODIN protoclusters, determined via measurements of their cross-correlation with LAEs. Our sample consists of 150 protocluster candidates atz = 2.4 and 3.1, identified in two ODIN fields with a total area of 13.9 deg². Atz = 2.4 and 3.1, the inferred protocluster biases are $6.6_{-1.1}^{+1.3}$and $6.1_{-1.1}^{+1.3}$, corresponding to mean halo masses of $\log 〈M/M_{\odot }〉=13.53_{-0.24}^{+0.21}$and $12.96_{-0.33}^{+0.28}$, respectively. By the present day, these protoclusters are expected to evolve into virialized galaxy clusters with a mean mass of ∼10^14.5M_⊙. By comparing the observed number density of protoclusters to that of halos with the same measured clustering strength, we find that the completeness of our sample is of order unity. Finally, the similar descendant masses derived for our samples atz= 2.4 and 3.1, assuming that the halo number density remains constant, suggest that they represent similar structures observed at different cosmic epochs. As a consequence, any observed differences between the two samples can be understood as redshift evolution. The ODIN protocluster samples will thus provide valuable insights into the cosmic evolution of cluster galaxies. 

Abstract We present a proof-of-concept simulation-based inference on Ω_mandσ₈from the Sloan Digital Sky Survey (SDSS) Baryon Oscillation Spectroscopic Survey (BOSS) LOWZ Northern Galactic Cap (NGC) catalog using neural networks and domain generalization techniques without the need of summary statistics. Using rapid light-cone simulations L-picola, mock galaxy catalogs are produced that fully incorporate the observational effects. The collection of galaxies is fed as input to a point cloud-based network,Minkowski-PointNet. We also add relatively more accurate Gadgetmocks to obtain robust and generalizable neural networks. By explicitly learning the representations that reduce the discrepancies between the two different data sets via the semantic alignment loss term, we show that the latent space configuration aligns into a single plane in which the two cosmological parameters form clear axes. Consequently, during inference, the SDSS BOSS LOWZ NGC catalog maps onto the plane, demonstrating effective generalization and improving prediction accuracy compared to non-generalized models. Results from the ensemble of 25 independently trained machines find Ω_m= 0.339 ± 0.056 andσ₈= 0.801 ± 0.061, inferred only from the distribution of galaxies in the light-cone slices without relying on any indirect summary statistics. A single machine that best adapts to the Gadgetmocks yields a tighter prediction of Ω_m= 0.282 ± 0.014 andσ₈= 0.786 ± 0.036. We emphasize that adaptation across multiple domains can enhance the robustness of the neural networks in observational data. 

Abstract In this work, we test the frequent assumption that Lyα-emitting galaxies (LAEs) are experiencing their first major burst of star formation at the time of observation. To this end, we identify 74 LAEs from the ODIN Survey with rest-UV-through-NIR photometry from UVCANDELS. For each LAE, we perform nonparametric star formation history (SFH) reconstruction using the Dense Basis Gaussian-process-based method of spectral energy distribution fitting. We find that a strong majority (67%) of our LAE SFHs align with the frequently assumed archetype of a first major star formation burst, with at most modest star formation rates (SFRs) in the past. However, the rest of our LAE SFHs have significant amounts of star formation in the past, with 28% exhibiting earlier bursts of star formation, with the ongoing burst having the highest SFR (dominant bursts) and the final 5% having experienced their highest SFR in the past (nondominant bursts). Combining the SFHs indicating first and dominant bursts, ∼95% of LAEs are experiencing their largest burst yet: a formative burst. We also find that the fraction of total stellar mass created in the last 200 Myr is ∼1.3 times higher in LAEs than in mass-matched Lyman break galaxy (LBG) samples, and that a majority of LBGs are experiencing dominant bursts, reaffirming that LAEs differ from other star-forming galaxies. Overall, our results suggest that multiple evolutionary paths can produce galaxies with strong observed Lyαemission. 

Abstract To understand the formation and evolution of massive cosmic structures, studying them at high redshift, in the epoch when they formed the majority of their mass, is essential. The One-hundred-deg²DECam Imaging in Narrowbands (ODIN) survey is undertaking the widest-area narrowband program to date, to use Lyα-emitting galaxies (LAEs) to trace the large-scale structure (LSS) of the Universe on the scale of 10–100 cMpc at three cosmic epochs. In this work, we present results atz= 3.1 based on early ODIN data in the COSMOS field. We identify protoclusters and cosmic filaments using multiple methods and discuss their strengths and weaknesses. We then compare our observations against the IllustrisTNG suite of cosmological hydrodynamical simulations. The two are in excellent agreement, identifying a similar number and angular size of structures above a specified density threshold. We successfully recover the simulated protoclusters with log(M_z=0/M_⊙) ≳ 14.4 in ∼60% of the cases. With these objects, we show that the descendant masses of our observed protoclusters can be estimated purely based on our 2D measurements, finding a medianz= 0 mass of ∼10^14.5M_⊙. The lack of information on the radial extent of each protocluster introduces a ∼0.4 dex uncertainty in its descendant mass. Finally, we show that the recovery of the cosmic web in the vicinity of protoclusters is both efficient and accurate. The similarity of our observations and the simulations implies that our structure selection is likewise robust and efficient, demonstrating that LAEs are reliable tracers of the LSS. 

Abstract We test whether Lyα emitters (LAEs) and Lyman-break galaxies (LBGs) can be good tracers of high-zlarge-scale structures, using the Horizon Run 5 cosmological hydrodynamical simulation. We identify LAEs using the Lyαemission line luminosity and its equivalent width, and LBGs using the broadband magnitudes atz∼ 2.4, 3.1, and 4.5. We first compare the spatial distributions of LAEs, LBGs, all galaxies, and dark matter around the filamentary structures defined by dark matter. The comparison shows that both LAEs and LBGs are more concentrated toward the dark matter filaments than dark matter. We also find an empirical fitting formula for the vertical density profile of filaments as a binomial power-law relation of the distance to the filaments. We then compare the spatial distributions of the samples around the filaments defined by themselves. LAEs and LBGs are again more concentrated toward their filaments than dark matter. We also find the overall consistency between filamentary structures defined by LAEs, LBGs, and dark matter, with the median spatial offsets that are smaller than the mean separation of the sample. These results support the idea that the LAEs and LBGs could be good tracers of large-scale structures of dark matter at high redshifts.