| Title: |
The Herschel -SPIRE Dark Field III: Probing the deepest Herschel field with SCUBA-2 |
| Authors: |
Parmar, Ayushi; Clements, David L; Pearson, Chris; Varnish, Thomas W O |
| Source: |
Monthly Notices of the Royal Astronomical Society ; ISSN 0035-8711 1365-2966 |
| Publisher Information: |
Oxford University Press (OUP) |
| Publication Year: |
2026 |
| Description: |
The Herschel-SPIRE Dark Field (SDF), originally observed for calibration of the SPIRE instrument, is the deepest far-infrared (FIR) field to date (equivalent exposure time of ∼700 hr deg−1) at wavelengths 250–500 μm, probing below the SPIRE confusion limit. We present SCUBA-2 850 μm observations covering the central Deep Region, detecting 36 sources with number counts consistent with previous surveys at this wavelength. Cross-identification with multiwavelength catalogues reveals 20 SPIRE-dropouts, whose stacked SPIRE fluxes suggest a photometric redshift of z ∼ 4. Photo-z estimates from the magphys, bagpipes and mmpz tools are consistent within the uncertainties for 3 sources (z ∼ 1–2), while 13 are inconsistent, and 20 lack sufficient data due to counterpart ambiguity or non-detections. We flag a total of 9 sources as potentially lensed and 15 as potential multiples. SED fitting yields average properties for SPIRE-detected sources of log10(LFIR / L⊙) = 13.6 ± 0.1, log10(Mdust / M⊙) = 8.1 ± 0.1, and SFRobsc = 7000 ± 1900 M⊙ yr−1. The stacked dropouts yield log10(LFIR / L$_{\odot }) = 12.8^{+0.5}_{-0.7} [12.5^{+0.4}_{-0.6}]$, log10(Mdust / M$_{\odot }) = 6.52^{+0.33}_{-0.41} [6.71^{+0.19}_{-0.23}]$, and SFR$_{\textrm{obsc}} = 700^{+1500}_{-560} [350^{+420}_{-250}]\,$ M⊙ yr−1 at a derived $z = 6.7^{+2.4}_{-3.0}$ [at a fixed $z = 4.0^{+0.1}_{-0.6}$] contributing ∼15 [∼2] per cent of the cosmic SFRD at that epoch. We find an excess at z ∼ 1 in the SFRD of SPIRE-detected sources, consistent with the sub-mJy bump in SPIRE number counts previously identified in this field, possibly tracing large-scale structure. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| DOI: |
10.1093/mnras/stag631 |
| DOI: |
10.1093/mnras/stag631/67725588/stag631.pdf |
| Availability: |
https://doi.org/10.1093/mnras/stag631; https://academic.oup.com/mnras/advance-article-pdf/doi/10.1093/mnras/stag631/67725588/stag631.pdf |
| Rights: |
https://creativecommons.org/licenses/by/4.0/ |
| Accession Number: |
edsbas.3955D5E4 |
| Database: |
BASE |