THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES the BRIGHT-END of the SUB-MILLIMETER NUMBER COUNTS

J. M. Simpson; Ian Smail; A. M. Swinbank; S. C. Chapman; J. E. Geach; R. J. Ivison; A. P. Thomson; I. Aretxaga; A. W. Blain; W. I. Cowley; Chian Chou Chen; K. E K Coppin; J. S. Dunlop; A. C. Edge; D. Farrah; E. Ibar; A. Karim; K. K. Knudsen; R. Meijerink; M. J. Michałowski; D. Scott; M. Spaans; P. P. Van Der Werf

doi:10.1088/0004-637X/807/2/128

THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES the BRIGHT-END of the SUB-MILLIMETER NUMBER COUNTS

J. M. Simpson, Ian Smail, A. M. Swinbank, S. C. Chapman, J. E. Geach, R. J. Ivison, A. P. Thomson, I. Aretxaga, A. W. Blain, W. I. Cowley, Chian Chou Chen, K. E K Coppin, J. S. Dunlop, A. C. Edge, D. Farrah, E. Ibar, A. Karim, K. K. Knudsen, R. Meijerink, M. J. MichałowskiD. Scott, M. Spaans, P. P. Van Der Werf

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

We present high-resolution 870 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) continuum maps of 30 bright sub-millimeter sources in the UKIDSS UDS field. These sources are selected from deep, 1 degree2 850 μm maps from the SCUBA-2 Cosmology Legacy Survey, and are representative of the brightest sources in the field (median S<inf>SCUBA-2</inf>= 8.7 ± 0.4 mJy). We detect 52 sub-millimeter galaxies (SMGs) at >4σ significance in our 30 ALMA maps. In 61<inf>-15</inf>+19% of the ALMA maps the single-dish source comprises a blend of ≥2 SMGs, where the secondary SMGs are Ultra-luminous Infrared Galaxies (ULIRGs) with L<inf>IR</inf> ≳ 1012 L<inf>⊙</inf>. The brightest SMG contributes on average 80<inf>-2</inf>+6% of the single-dish flux density, and in the ALMA maps containing ≥2 SMGs the secondary SMG contributes 25<inf>-5</inf>+1% of the integrated ALMA flux. We construct source counts and show that multiplicity boosts the apparent single-dish cumulative counts by 20% at S<inf>870</inf> > 7.5 mJy, and by 60% at S<inf>870</inf> > 12 mJy. We combine our sample with previous ALMA studies of fainter SMGs and show that the counts are well-described by a double power law with a break at 8.5 ± 0.6 mJy. The break corresponds to a luminosity of ∼6 × 1012 L<inf>⊙</inf> or a star formation rate (SFR) of ∼103 M<inf>⊙</inf> yr-1. For the typical sizes of these SMGs, which are resolved in our ALMA data with R<inf>e</inf> = 1.2 ± 0.1 kpc, this yields a limiting SFR density of ∼100 M<inf>⊙</inf> yr-1 kpc-2 Finally, the number density of S<inf>870</inf> ≳ 2 mJy SMGs is 80 ± 30 times higher than that derived from blank-field counts. An over-abundance of faint SMGs is inconsistent with line-of-sight projections dominating multiplicity in the brightest SMGs, and indicates that a significant proportion of these high-redshift ULIRGs are likely to be physically associated.

Original language	English
Article number	128
Number of pages	13
Journal	Astrophysical Journal
Volume	807
Issue number	2
DOIs	https://doi.org/10.1088/0004-637X/807/2/128
Publication status	Published - 10 Jul 2015

Keywords

galaxies: abundances
galaxies: high-redshift
galaxies: star formation
galaxies: starburst
submillimeter: galaxies

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10.1088/0004-637X/807/2/128

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Simpson, J. M., Smail, I., Swinbank, A. M., Chapman, S. C., Geach, J. E., Ivison, R. J., Thomson, A. P., Aretxaga, I., Blain, A. W., Cowley, W. I., Chen, C. C., Coppin, K. E. K., Dunlop, J. S., Edge, A. C., Farrah, D., Ibar, E., Karim, A., Knudsen, K. K., Meijerink, R., ... Van Der Werf, P. P. (2015). THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES the BRIGHT-END of the SUB-MILLIMETER NUMBER COUNTS. Astrophysical Journal, 807(2), [128]. https://doi.org/10.1088/0004-637X/807/2/128

@article{d790faebc93349d5a6b6f1c8ef17868e,

title = "THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES the BRIGHT-END of the SUB-MILLIMETER NUMBER COUNTS",

abstract = "We present high-resolution 870 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) continuum maps of 30 bright sub-millimeter sources in the UKIDSS UDS field. These sources are selected from deep, 1 degree2 850 μm maps from the SCUBA-2 Cosmology Legacy Survey, and are representative of the brightest sources in the field (median SSCUBA-2= 8.7 ± 0.4 mJy). We detect 52 sub-millimeter galaxies (SMGs) at >4σ significance in our 30 ALMA maps. In 61-15+19% of the ALMA maps the single-dish source comprises a blend of ≥2 SMGs, where the secondary SMGs are Ultra-luminous Infrared Galaxies (ULIRGs) with LIR ≳ 1012 L⊙. The brightest SMG contributes on average 80-2+6% of the single-dish flux density, and in the ALMA maps containing ≥2 SMGs the secondary SMG contributes 25-5+1% of the integrated ALMA flux. We construct source counts and show that multiplicity boosts the apparent single-dish cumulative counts by 20% at S870 > 7.5 mJy, and by 60% at S870 > 12 mJy. We combine our sample with previous ALMA studies of fainter SMGs and show that the counts are well-described by a double power law with a break at 8.5 ± 0.6 mJy. The break corresponds to a luminosity of ∼6 × 1012 L⊙ or a star formation rate (SFR) of ∼103 M⊙ yr-1. For the typical sizes of these SMGs, which are resolved in our ALMA data with Re = 1.2 ± 0.1 kpc, this yields a limiting SFR density of ∼100 M⊙ yr-1 kpc-2 Finally, the number density of S870 ≳ 2 mJy SMGs is 80 ± 30 times higher than that derived from blank-field counts. An over-abundance of faint SMGs is inconsistent with line-of-sight projections dominating multiplicity in the brightest SMGs, and indicates that a significant proportion of these high-redshift ULIRGs are likely to be physically associated.",

keywords = "galaxies: abundances, galaxies: high-redshift, galaxies: star formation, galaxies: starburst, submillimeter: galaxies",

author = "Simpson, {J. M.} and Ian Smail and Swinbank, {A. M.} and Chapman, {S. C.} and Geach, {J. E.} and Ivison, {R. J.} and Thomson, {A. P.} and I. Aretxaga and Blain, {A. W.} and Cowley, {W. I.} and Chen, {Chian Chou} and Coppin, {K. E K} and Dunlop, {J. S.} and Edge, {A. C.} and D. Farrah and E. Ibar and A. Karim and Knudsen, {K. K.} and R. Meijerink and Micha{\l}owski, {M. J.} and D. Scott and M. Spaans and {Van Der Werf}, {P. P.}",

year = "2015",

month = jul,

day = "10",

doi = "10.1088/0004-637X/807/2/128",

language = "English",

volume = "807",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "2",

}

Simpson, JM, Smail, I, Swinbank, AM, Chapman, SC, Geach, JE, Ivison, RJ, Thomson, AP, Aretxaga, I, Blain, AW, Cowley, WI, Chen, CC, Coppin, KEK, Dunlop, JS, Edge, AC, Farrah, D, Ibar, E, Karim, A, Knudsen, KK, Meijerink, R, Michałowski, MJ, Scott, D, Spaans, M & Van Der Werf, PP 2015, 'THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES the BRIGHT-END of the SUB-MILLIMETER NUMBER COUNTS', Astrophysical Journal, vol. 807, no. 2, 128. https://doi.org/10.1088/0004-637X/807/2/128

TY - JOUR

T1 - THE SCUBA-2 COSMOLOGY LEGACY SURVEY

T2 - ALMA RESOLVES the BRIGHT-END of the SUB-MILLIMETER NUMBER COUNTS

AU - Simpson, J. M.

AU - Smail, Ian

AU - Swinbank, A. M.

AU - Chapman, S. C.

AU - Geach, J. E.

AU - Ivison, R. J.

AU - Thomson, A. P.

AU - Aretxaga, I.

AU - Blain, A. W.

AU - Cowley, W. I.

AU - Chen, Chian Chou

AU - Coppin, K. E K

AU - Dunlop, J. S.

AU - Edge, A. C.

AU - Farrah, D.

AU - Ibar, E.

AU - Karim, A.

AU - Knudsen, K. K.

AU - Meijerink, R.

AU - Michałowski, M. J.

AU - Scott, D.

AU - Spaans, M.

AU - Van Der Werf, P. P.

PY - 2015/7/10

Y1 - 2015/7/10

N2 - We present high-resolution 870 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) continuum maps of 30 bright sub-millimeter sources in the UKIDSS UDS field. These sources are selected from deep, 1 degree2 850 μm maps from the SCUBA-2 Cosmology Legacy Survey, and are representative of the brightest sources in the field (median SSCUBA-2= 8.7 ± 0.4 mJy). We detect 52 sub-millimeter galaxies (SMGs) at >4σ significance in our 30 ALMA maps. In 61-15+19% of the ALMA maps the single-dish source comprises a blend of ≥2 SMGs, where the secondary SMGs are Ultra-luminous Infrared Galaxies (ULIRGs) with LIR ≳ 1012 L⊙. The brightest SMG contributes on average 80-2+6% of the single-dish flux density, and in the ALMA maps containing ≥2 SMGs the secondary SMG contributes 25-5+1% of the integrated ALMA flux. We construct source counts and show that multiplicity boosts the apparent single-dish cumulative counts by 20% at S870 > 7.5 mJy, and by 60% at S870 > 12 mJy. We combine our sample with previous ALMA studies of fainter SMGs and show that the counts are well-described by a double power law with a break at 8.5 ± 0.6 mJy. The break corresponds to a luminosity of ∼6 × 1012 L⊙ or a star formation rate (SFR) of ∼103 M⊙ yr-1. For the typical sizes of these SMGs, which are resolved in our ALMA data with Re = 1.2 ± 0.1 kpc, this yields a limiting SFR density of ∼100 M⊙ yr-1 kpc-2 Finally, the number density of S870 ≳ 2 mJy SMGs is 80 ± 30 times higher than that derived from blank-field counts. An over-abundance of faint SMGs is inconsistent with line-of-sight projections dominating multiplicity in the brightest SMGs, and indicates that a significant proportion of these high-redshift ULIRGs are likely to be physically associated.

AB - We present high-resolution 870 μm Atacama Large Millimeter/sub-millimeter Array (ALMA) continuum maps of 30 bright sub-millimeter sources in the UKIDSS UDS field. These sources are selected from deep, 1 degree2 850 μm maps from the SCUBA-2 Cosmology Legacy Survey, and are representative of the brightest sources in the field (median SSCUBA-2= 8.7 ± 0.4 mJy). We detect 52 sub-millimeter galaxies (SMGs) at >4σ significance in our 30 ALMA maps. In 61-15+19% of the ALMA maps the single-dish source comprises a blend of ≥2 SMGs, where the secondary SMGs are Ultra-luminous Infrared Galaxies (ULIRGs) with LIR ≳ 1012 L⊙. The brightest SMG contributes on average 80-2+6% of the single-dish flux density, and in the ALMA maps containing ≥2 SMGs the secondary SMG contributes 25-5+1% of the integrated ALMA flux. We construct source counts and show that multiplicity boosts the apparent single-dish cumulative counts by 20% at S870 > 7.5 mJy, and by 60% at S870 > 12 mJy. We combine our sample with previous ALMA studies of fainter SMGs and show that the counts are well-described by a double power law with a break at 8.5 ± 0.6 mJy. The break corresponds to a luminosity of ∼6 × 1012 L⊙ or a star formation rate (SFR) of ∼103 M⊙ yr-1. For the typical sizes of these SMGs, which are resolved in our ALMA data with Re = 1.2 ± 0.1 kpc, this yields a limiting SFR density of ∼100 M⊙ yr-1 kpc-2 Finally, the number density of S870 ≳ 2 mJy SMGs is 80 ± 30 times higher than that derived from blank-field counts. An over-abundance of faint SMGs is inconsistent with line-of-sight projections dominating multiplicity in the brightest SMGs, and indicates that a significant proportion of these high-redshift ULIRGs are likely to be physically associated.

KW - galaxies: abundances

KW - galaxies: high-redshift

KW - galaxies: star formation

KW - galaxies: starburst

KW - submillimeter: galaxies

UR - http://www.scopus.com/inward/record.url?scp=84936989106&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/807/2/128

DO - 10.1088/0004-637X/807/2/128

M3 - Article

AN - SCOPUS:84936989106

VL - 807

JO - Astrophysical Journal

JF - Astrophysical Journal

SN - 0004-637X

IS - 2

M1 - 128

ER -

THE SCUBA-2 COSMOLOGY LEGACY SURVEY: ALMA RESOLVES the BRIGHT-END of the SUB-MILLIMETER NUMBER COUNTS

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