Comprehensive SPIRE Maps Combining HeRS and HeLMS Surveys for Detailed Submillimeter Analysis

Główne pojęcia

This work presents the largest extragalactic surveys at submillimeter wavelengths, combining the Herschel Redshift Survey (HeRS) and Herschel Large Mode Survey (HeLMS) to provide high-quality, consistent maps covering 360 square degrees near the celestial equator.

Streszczenie

The authors have regenerated Herschel-SPIRE maps covering a large 360 square degree region near the celestial equator, combining data from the Herschel Redshift Survey (HeRS) and Herschel Large Mode Survey (HeLMS). These maps are the largest extragalactic surveys designed to overlap with cosmic microwave background legacy fields at submillimeter wavelengths.
The maps were constructed using the latest Herschel data reduction pipeline and the SHIM map-making algorithm, which has been shown to outperform other methods in retaining fidelity across all angular scales. The final FITS files include the science image, error map, exposure map, and mask, all calibrated in Jy/beam.
This work improves upon previous heterogeneous analyses of these data, which were served on non-permanent archives and occasionally had errors discovered by the user community. The authors have provided vetted, error-free products with clear documentation on the data reduction and processing steps.
These comprehensive submillimeter maps will enable a wide range of extragalactic studies, from galaxy evolution to cosmic infrared background anisotropies, leveraging the overlap with other legacy survey fields like SDSS Stripe 82 and the Atacama Cosmology Telescope.

Statystyki

The maps cover an area of approximately 360 square degrees at 6, 8.3, and 12 arcsec per pixel resolution in the 250, 350, and 500 micron SPIRE bands, respectively.
The error maps represent the statistical noise in each pixel, not including the significant effect of confusion noise.
The map transfer function is 1% to angular scales of ~1 degree, with a 3dB point around 6 degrees.

Cytaty

"The data in this repository improve on previous analyses of these data, which were heterogeneously analyzed, served on non-permanent archives, and occasionally had errors discovered by the user community."
"Though we do not explicitly provide map transfer function estimates, the transfer function is 1% to angular scales of ∼1 degree, and thereafter falls exponentially with a 3dB point of ∼6 degrees."

Kluczowe wnioski z

SPIRE HeRS/HeLMS Combined SHIM Maps

by Michael Zemc... o arxiv.org 10-02-2024

https://arxiv.org/pdf/2410.00252.pdf

Głębsze pytania

How do the noise properties and transfer functions of these maps compare to other submillimeter surveys, such as those from the Planck satellite?

The noise properties of the SPIRE maps generated from the Herschel-SPIRE observations exhibit a robust methodology for estimating detector noise, particularly through the use of the SHIM map maker. This approach allows for a more accurate representation of noise variations across the map, especially in regions with low sample counts. The noise maps are derived from the variance of the residuals, which provides a better measure of statistical error compared to traditional methods. In contrast, the Planck satellite's submillimeter surveys, while also sophisticated, utilize different algorithms and calibration techniques that may not account for noise variations in the same detailed manner.
The transfer function of the SPIRE maps is characterized by a 1% fidelity up to angular scales of approximately 1 degree, with a 3dB point around 6 degrees, indicating that the maps retain high fidelity for large-scale structures. Planck's transfer functions, however, are optimized for cosmic microwave background (CMB) measurements and may not directly translate to the same angular scales relevant for submillimeter observations. Therefore, while both datasets are valuable, the SPIRE maps may provide finer details in the submillimeter regime, particularly for studies focused on dusty star-forming galaxies and cosmic infrared background anisotropies.

What are the potential biases or limitations in using these maps for studies of the cosmic infrared background anisotropies, and how can they be mitigated?

One significant limitation in using the SPIRE maps for cosmic infrared background anisotropies is the effect of confusion noise, which is not explicitly accounted for in the error maps provided. Confusion noise arises from the overlapping emissions of numerous faint sources, which can obscure the true background signal. This can lead to biases in the measured anisotropies, particularly in regions with high source density.
To mitigate these biases, researchers can employ several strategies. First, applying more sophisticated source extraction algorithms can help identify and subtract the contributions of individual sources from the maps, thereby reducing confusion noise. Additionally, combining the SPIRE maps with complementary data from other wavelengths, such as optical or radio surveys, can provide a more comprehensive view of the underlying structures and help disentangle the contributions to the cosmic infrared background. Furthermore, utilizing simulations to model the expected confusion noise and incorporating these models into the analysis can also enhance the robustness of the results.

Given the large sky coverage, what new insights into the large-scale structure of the universe can be gleaned by combining these submillimeter maps with other multiwavelength data?

The extensive sky coverage of the SPIRE maps, spanning approximately 360 square degrees, presents a unique opportunity to investigate the large-scale structure of the universe in conjunction with multiwavelength data. By integrating submillimeter observations with data from optical, infrared, and radio surveys, researchers can gain insights into the distribution and evolution of dusty star-forming galaxies, which are critical to understanding cosmic structure formation.
Combining these datasets allows for the cross-correlation of submillimeter emissions with galaxy redshift surveys, enabling the study of galaxy clustering and the relationship between star formation activity and large-scale structure. Additionally, the integration of CMB data from the Planck satellite can provide constraints on cosmological parameters and help elucidate the role of dark matter and dark energy in shaping the universe's structure.
Moreover, the multiwavelength approach can enhance the understanding of the cosmic infrared background by identifying the contributions from different galaxy populations and their evolutionary stages. This comprehensive analysis can lead to new discoveries regarding the formation and growth of cosmic structures, the role of feedback processes in galaxy evolution, and the overall history of star formation in the universe.