Very Compact Millimeter Sizes for Composite Star-forming/AGN Submillimeter Galaxies

Ikarashi, Soh; Caputi, K.; Ohta, Kouji; Ivison, R. J.; Lagos, Claudia del P.; Bisigello, Laura; Hatsukade, Bunyo; Aretxaga, I.; Dunlop, James; Hughes, D. H.; Iono, Daisuke; Izumi, Teruo; Kashikawa, Nobunari; Koyama, Yusei; Kawabe, Ryohei; Kohno, Kotaro; Motohara, Kentaro; Nakanishi, Koichiro; Tamura, Motohide; Umehata, Hideki; Wilson, Grant; Yabe, Kiyoto; Yun, Min S.

doi:10.3847/2041-8213/aa9572

Cited by 38 publications

(53 citation statements)

References 51 publications

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“…1 (e.g. Simpson et al 2015b;Ikarashi et al 2017) therefore we expect the majority of our detections to be marginally resolved. To ensure we are not biased against selecting extended sources, by remaining sensitive to extended flux from our SMGs, we employed a 0.…”

Section: Data Reductionmentioning

confidence: 87%

“…To simplify these comparisons we have limited them in general to flux-limited samples from: 1. larger unbiased blank-field surveys at 850 µm (as there is evidence of differences compared to populations selected in the far-infrared and millimetre, e.g. Smolčić et al 2012;Koprowski et al 2014;Scudder et al 2016;Ikarashi et al 2017); 2. with deep (< 1 mJy rms) interferometric identifications in the same waveband as any initial single-dish selection, if appropriate (c.f. Barger et al 2014;Umehata et al 2014;Hill et al 2018); 3. and which are not explicitly lensed, owing to the potential selection effects and variable flux limits as well as uncertainties from cluster lenses and especially galaxy-scale lensed samples (e.g.…”

Section: Introductionmentioning

confidence: 99%

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An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: source catalogue and properties

Stach

Dudzevičiūtė

Smail

et al. 2019

Monthly Notices of the Royal Astronomical Society

117

213

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We present the catalogue and properties of sources in AS2UDS, an 870-µm continuum survey with the Atacama Large Millimetre/sub-millimetre Array (ALMA) of 716 single-dish sub-millimetre sources detected in the UKIDSS/UDS field by the SCUBA-2 Cosmology Legacy Survey. In our sensitive ALMA follow-up observations we detect 708 sub-millimetre galaxies (SMGs) at > 4.3σ significance across the ∼ 1-degree diameter field. We combine our precise ALMA positions with the extensive multi-wavelength coverage in the UDS field to fit the spectral energy distributions of our SMGs to derive a median redshift of z phot = 2.61±0.09. This large sample reveals a statistically significant trend of increasing sub-millimetre flux with redshift suggestive of galaxy downsizing. 101 ALMA maps do not show a > 4.3σ SMG, but we demonstrate from stacking Herschel SPIRE observations at these positions, that the vast majority of these blank maps correspond to real single-dish sub-millimetre sources. We further show that these blank maps contain an excess of galaxies at z phot = 1.5-4 compared to random fields, similar to the redshift range of the ALMA-detected SMGs. In addition, we combine X-ray and mid-infrared active galaxy nuclei activity (AGN) indicators to yield a likely range for the AGN fraction of 8-28 % in our sample. Finally, we compare the redshifts of this population of high-redshift, strongly star-forming galaxies with the inferred formation redshifts of massive, passive galaxies being found out to z ∼ 2, finding reasonable agreement -in support of an evolutionary connection between these two classes of massive galaxy.

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Section: Data Reductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: source catalogue and properties

Stach

Dudzevičiūtė

Smail

et al. 2019

Monthly Notices of the Royal Astronomical Society

117

213

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“…The low number of galaxies with measured ALMA sizes in the literature makes it difficult to constrain the size distribution of dust emission in galaxies. Recent studies (e.g., Barro et al 2016;Rujopakarn et al 2016;Elbaz et al 2018;Ikarashi et al 2017;Fujimoto et al 2017) with sufficient resolution to measure ALMA sizes of galaxies suggest that dust emission takes place within compact regions of the galaxy.…”

Section: Galaxy Sizesmentioning

confidence: 99%

GOODS-ALMA: 1.1 mm galaxy survey

Franco

Elbaz

Béthermin

et al. 2018

A&A

203

295

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Aims. We present a 69 arcmin2 ALMA survey at 1.1 mm, GOODS-ALMA, matching the deepest HST-WFC3 H-band part of the GOODS-South field. Methods. We tapered the 0″24 original image with a homogeneous and circular synthesized beam of 0″60 to reduce the number of independent beams – thus reducing the number of purely statistical spurious detections – and optimize the sensitivity to point sources. We extracted a catalog of galaxies purely selected by ALMA and identified sources with and without HST counterparts down to a 5σ limiting depth of H = 28.2 AB (HST/WFC3 F160W). Results. ALMA detects 20 sources brighter than 0.7 mJy at 1.1 mm in the 0″60 tapered mosaic (rms sensitivity σ ≃ 0.18 mJy beam−1) with a purity greater than 80%. Among these detections, we identify three sources with no HST nor Spitzer-IRAC counterpart, consistent with the expected number of spurious galaxies from the analysis of the inverted image; their definitive status will require additional investigation. We detect additional three sources with HST counterparts either at high significance in the higher resolution map, or with different detection-algorithm parameters ensuring a purity greater than 80%. Hence we identify in total 20 robust detections. Conclusions. Our wide contiguous survey allows us to push further in redshift the blind detection of massive galaxies with ALMA with a median redshift of z = 2.92 and a median stellar mass of M⋆ = 1.1 × 1011 M⊙. Our sample includes 20% HST-dark galaxies (4 out of 20), all detected in the mid-infrared with Spitzer-IRAC. The near-infrared based photometric redshifts of two of them (z ∼ 4.3 and 4.8) suggest that these sources have redshifts z > 4. At least 40% of the ALMA sources host an X-ray AGN, compared to ∼14% for other galaxies of similar mass and redshift. The wide area of our ALMA survey provides lower values at the bright end of number counts than single-dish telescopes affected by confusion.

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“…A subset of our sample were observed at 1.1 mm with ∼ 0. 7 resolution using ALMA by Ikarashi et al (2017) who studied a sample of millimetre sources selected from the 1.1-mm AzTEC map of the UDS field. Unsurprisingly the sources in this bright 1.1-mm sample overlap with brighter 870 µm sources in the S2CLS map and as a result 65 of the 69 sources in Ikarashi et al (2017) are also included in AS2UDS, of which 30 are in our high-resolution 0.…”

Section: Sizes Measurements From the Visibility Planementioning

confidence: 99%

“…Previous morphological studies (with sufficiently high signalto-noise detections) of SMGs at sub-/millimetre wavelengths have been limited either by moderate resolutions (Simpson et al 2015b;Ikarashi et al 2017) or modest sized samples (Hodge et al 2016;Gullberg et al 2018;Hodge et al 2019). Our sample of 153 SMGs detected at S/N > 8 in 0.…”

Section: Size and Shape Evolutionmentioning

confidence: 99%

An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: high-resolution dust continuum morphologies and the link between sub-millimetre galaxies and spheroid formation

Gullberg

Smail

Swinbank

et al. 2019

Monthly Notices of the Royal Astronomical Society

Self Cite

100

171

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We present an analysis of the morphology and profiles of the dust continuum emission in 153 bright sub-millimetre galaxies (SMGs) detected with ALMA at signal to noise ratios of > 8 in high-resolution 0. 18 (∼ 1 kpc) 870 µm maps. We measure sizes, shapes and light profiles for the rest-frame far-infrared emission from these luminous starforming systems and derive a median effective radius (R e ) of 0. 10 ± 0. 04 for our sample with a median flux of S 870 = 5.6 ± 0.2 mJy. We find that the apparent axial ratio (b/a) distribution of the SMGs peaks at b/a ∼ 0.63 ± 0.02 and is best described by triaxial morphologies, while their emission profiles are best fit by a Sérsic model with n 1.0 ± 0.1, similar to exponential discs. This combination of triaxiality and n ∼ 1 Sérsic index are characteristic of bars and we suggest that the bulk of the 870 µm dust continuum emission in the central ∼ 2 kpc of these galaxies arises from bar-like structures. As such we caution against using the orientation of shape of the bright dust continuum emission at resolution to assess either the orientation of any disc on the sky or tits inclination. By stacking our 870 µm maps we recover faint extended dust continuum emission on ∼ 4 kpc scales which contributes 13 ± 1% of the total 870 µm emission. The scale of this extended emission is similar to that seen for the molecular gas and rest-frame optical light in these systems, suggesting that it represents an extended dust and gas disc at radii larger than the more active bar component. Including this component in our estimated size of the sources we derive a typical effective radius of 0. 15 ± 0. 05 or 1.2 ± 0.4 kpc. Our results suggest that kpc-scale bars are ubiquitous features of high star-formation rate systems at z 1, while these systems also contain fainter and more extended gas and stellar envelopes. We suggest that these features, seen some 10-12 Gyrs ago, represent the formation phase of the earliest galactic-scale components: stellar bulges.

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Very Compact Millimeter Sizes for Composite Star-forming/AGN Submillimeter Galaxies

Cited by 38 publications

References 51 publications

An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: source catalogue and properties

An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: source catalogue and properties

GOODS-ALMA: 1.1 mm galaxy survey

An ALMA survey of the SCUBA-2 Cosmology Legacy Survey UKIDSS/UDS field: high-resolution dust continuum morphologies and the link between sub-millimetre galaxies and spheroid formation

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