ALMA 1.3 mm Survey of Lensed Submillimeter Galaxies Selected by Herschel: Discovery of Spatially Extended SMGs and Implications

Abstract

We present an ALMA 1.3 mm (Band 6) continuum survey of lensed submillimeter galaxies (SMGs) at z = 1.0 to ∼3.2 with an angular resolution of ∼0 2. These galaxies were uncovered by the Herschel Lensing Survey and feature exceptionally bright far-infrared continuum emission (S peak  90 mJy) owing to their lensing magnification. We detect 29 sources in 20 fields of massive galaxy clusters with ALMA. Using both the Spitzer/IRAC (3.6/4.5 μm) and ALMA data, we have successfully modeled the surface brightness profiles of 26 sources in the rest-frame nearand far-infrared. Similar to previous studies, we find the median dust-to-stellar continuum size ratio to be small (R e,dust /R e,star = 0.38 ± 0.14) for the observed SMGs, indicating that star formation is centrally concentrated. This is, however, not the case for two spatially extended main-sequence SMGs with a low surface brightness at 1.3 mm (0.1 mJy arcsec −2 ), in which the star formation is distributed over the entire galaxy (R e,dust /R e,star > 1). As a whole, our SMG sample shows a tight anticorrelation between (R e,dust /R e,star ) and far-infrared surface brightness (Σ IR ) over a factor of ;1000 in Σ IR . This indicates that SMGs with less vigorous star formation (i.e., lower Σ IR ) lack central starburst and are likely to retain a broader spatial distribution of star formation over the whole galaxies (i.e., larger R e,dust /R e,star ). The same trend can be reproduced with cosmological simulations as a result of central starburst and potentially subsequent "inside-out" quenching, which likely accounts for the emergence of compact quiescent galaxies at z ∼ 2.

GOODS-ALMA 2.0: Source catalog, number counts, and prevailing compact sizes in 1.1 mm galaxies

“…2/3 of the sources had sizes a factor ×1.6 larger that the brighter sources and suggested that a substantial portion of the sub-mJy sources may be mildly more extended than brighter ones. Rujopakarn et al (2016) reported more extended galaxywide dust continuum emission at 1.1 mm in a sample of 11 normal MS SFGs, Cheng et al (2020) also found extended dust continuum emission at 870 µm in four DSFGs, mostly with mild IR luminosities log(L IR /L ) < 12.0, and Sun et al (2021) also found extended dust continuum emission at 1.3 µm in two DS-FGs with mild IR surface brightness associated to less vigorous star formation.…”

“…These findings are not only associated with the dust continuum, as other studies including CO lines (e.g., Puglisi et al 2019) or radio emission (e.g., Jiménez-Andrade et al 2019) have found more compact emission compared to the stellar sizes in these tracers as well. However, there are also examples of observations of more extended galaxy-wide dust continuum emission (e.g., Rujopakarn et al 2016;Cheng et al 2020;Sun et al 2021;Cochrane et al 2021) and simulations indicating that differential attenuation could play an important role in how observations compare the extent of the dust continuum emission to that of the stars (Popping et al 2021). Therefore, it remains to be understood how systematic compactness is in DSFGs.…”

The evolution of compact massive quiescent and star-forming galaxies derived from the Re–Rh and Mstar–Mh relations

“…Alternatively, an increasing SMHM at earlier epochs would necessarily require within our framework that only a relatively minor fraction of the CSFMGs quench during their compact phase, a scenario more consistent with an AGN-driven size evolution. We note that an unbiased view of the size growth of MGs requires both optical-NIR observations as well as FIR-submm observations (e.g., Barro et al 2016;Tadaki et al 2020;Sun et al 2021). Compact dust-enshrouded star formation activity can in fact occur over spatial scales a factor of ∼3 smaller that the measured in optical-NIR (e.g., Puglisi et al 2019;Jiménez-Andrade et al 2019).…”

Extensive Lensing Survey of Optical and Near-Infrared Dark Objects (El Sonido): HST H-Faint Galaxies behind 101 Lensing Clusters

“…We have selected 101 lensing cluster fields with sufficient imaging data to search for H-faint galaxies. This sample includes clusters from four subsets: (i) six HST Frontier Field clusters (HFF, Lotz et al 2017; same as BUFFALO, Steinhardt et al 2020), (ii) 21 CLASH clusters (Postman et al 2012), (iii) 41 RELICS clusters (Coe et al 2019), and (iv) 33 additional clusters observed by the two Herschel Key Programs, the Herschel Lensing Survey (HLS; Egami et al 2010, Sun et al 2021 and the Local Cluster Substructure Survey (LoCuSS; Smith et al 2010) with archival HST /WFC3-IR F160W imaging data on MAST 1 that were publicly available as of November 2020. All of these clusters have been observed by HST /WFC3-IR in the F160W band and Spitzer /IRAC in the CH1/CH2 at various depths, as further discussed in Appendix A.…”

“…16 of these clusters were observed by the HLS (Egami et al 2010) and A370 was observed by the PACS Evolutionary Probe (PEP; Lutz et al 2011). The observational settings and reduction of PACS data were detailed in Rawle et al (2016) and Sun et al (2021) and the output pixel scale is 1 pixel −1 at 100 µm and 2 pixel −1 at 160 µm. The typical resolution of PACS data is 7 at 100 µm and 12 at 160 µm.…”