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

Soh Ikarashi; Karina I. Caputi; Kouji Ohta; R. J. Ivison; Claudia D.P. Lagos; Laura Bisigello; Bunyo Hatsukade; Itziar Aretxaga; James S. Dunlop; David H. Hughes; Daisuke Iono; Takuma Izumi; Nobunari Kashikawa; Yusei Koyama; Ryohei Kawabe; Kotaro Kohno; Kentaro Motohara; Kouichiro Nakanishi; Yoichi Tamura; Hideki Umehata; Grant W. Wilson; Kiyoto Yabe; Min S. Yun

doi:10.3847/2041-8213/aa9572

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

Soh Ikarashi, Karina I. Caputi, Kouji Ohta, R. J. Ivison, Claudia D.P. Lagos, Laura Bisigello, Bunyo Hatsukade, Itziar Aretxaga, James S. Dunlop, David H. Hughes, Daisuke Iono, Takuma Izumi, Nobunari Kashikawa, Yusei Koyama, Ryohei Kawabe, Kotaro Kohno, Kentaro Motohara, Kouichiro Nakanishi, Yoichi Tamura, Hideki UmehataGrant W. Wilson, Kiyoto Yabe, Min S. Yun

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Abstract

We report the study of the far-infrared (IR) sizes of submillimeter galaxies (SMGs) in relation to their dustobscured star formation rate (SFR) and active galactic nuclei (AGN) presence, determined using mid-IR photometry. We determined the millimeter-wave (λ_obs = 1100 μm) sizes of 69 Atacama Large Millimeter/ submillimeter Array (ALMA)-identified SMGs, selected with ≥10 δ confidence on ALMA images (F₁₁₀₀ μm = 1.7-7.4 mJy). We found that all of the SMGs are located above an avoidance region in the sizeflux plane, as expected by the Eddington limit for star formation. In order to understand what drives the different millimeter-wave sizes in SMGs, we investigated the relation between millimeter-wave size and AGN fraction for 25 of our SMGs at z=1-3. We found that the SMGs for which the mid-IR emission is dominated by star formation or AGN have extended millimeter-sizes, with respective median R_c,e = 1.6_-0.21 ^+0.34 and 1.5 _-0.24 ^+0.93 kpc. Instead, the SMGs for which the mid-IR emission corresponds to star-forming/AGN composites have more compact millimeter-wave sizes, with median R_c,e1.0 _-0.20 ^+0.20kpc. The relation between millimeter-wave size and AGN fraction suggests that this size may be related to the evolutionary stage of the SMG. The very compact sizes for composite star-forming/AGN systems could be explained by supermassive black holes growing rapidly during the SMG coalescing, star-formation phase.

Original language	English
Article number	L36
Journal	Astrophysical Journal Letters
Volume	849
Issue number	2
DOIs	https://doi.org/10.3847/2041-8213/aa9572
Publication status	Published - 9 Nov 2017

Keywords / Materials (for Non-textual outputs)

galaxies: evolution
galaxies: formation
galaxies: high-redshift
submillimeter: galaxies

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10.3847/2041-8213/aa9572

https://arxiv.org/abs/1710.09021

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Ikarashi, S., Caputi, K. I., Ohta, K., Ivison, R. J., Lagos, C. D. P., Bisigello, L., Hatsukade, B., Aretxaga, I., Dunlop, J. S., Hughes, D. H., Iono, D., Izumi, T., Kashikawa, N., Koyama, Y., Kawabe, R., Kohno, K., Motohara, K., Nakanishi, K., Tamura, Y., ... Yun, M. S. (2017). Very Compact Millimeter Sizes for Composite Star-forming/AGN Submillimeter Galaxies. Astrophysical Journal Letters, 849(2), Article L36. https://doi.org/10.3847/2041-8213/aa9572

@article{8c904f85c8f44c9584a7b62415001dab,

title = "Very Compact Millimeter Sizes for Composite Star-forming/AGN Submillimeter Galaxies",

abstract = "We report the study of the far-infrared (IR) sizes of submillimeter galaxies (SMGs) in relation to their dustobscured star formation rate (SFR) and active galactic nuclei (AGN) presence, determined using mid-IR photometry. We determined the millimeter-wave (λobs = 1100 μm) sizes of 69 Atacama Large Millimeter/ submillimeter Array (ALMA)-identified SMGs, selected with ≥10 δ confidence on ALMA images (F1100 μm = 1.7-7.4 mJy). We found that all of the SMGs are located above an avoidance region in the sizeflux plane, as expected by the Eddington limit for star formation. In order to understand what drives the different millimeter-wave sizes in SMGs, we investigated the relation between millimeter-wave size and AGN fraction for 25 of our SMGs at z=1-3. We found that the SMGs for which the mid-IR emission is dominated by star formation or AGN have extended millimeter-sizes, with respective median Rc,e = 1.6-0.21 +0.34 and 1.5 -0.24 +0.93 kpc. Instead, the SMGs for which the mid-IR emission corresponds to star-forming/AGN composites have more compact millimeter-wave sizes, with median Rc,e1.0 -0.20 +0.20kpc. The relation between millimeter-wave size and AGN fraction suggests that this size may be related to the evolutionary stage of the SMG. The very compact sizes for composite star-forming/AGN systems could be explained by supermassive black holes growing rapidly during the SMG coalescing, star-formation phase.",

keywords = "galaxies: evolution, galaxies: formation, galaxies: high-redshift, submillimeter: galaxies",

author = "Soh Ikarashi and Caputi, {Karina I.} and Kouji Ohta and Ivison, {R. J.} and Lagos, {Claudia D.P.} and Laura Bisigello and Bunyo Hatsukade and Itziar Aretxaga and Dunlop, {James S.} and Hughes, {David H.} and Daisuke Iono and Takuma Izumi and Nobunari Kashikawa and Yusei Koyama and Ryohei Kawabe and Kotaro Kohno and Kentaro Motohara and Kouichiro Nakanishi and Yoichi Tamura and Hideki Umehata and Wilson, {Grant W.} and Kiyoto Yabe and Yun, {Min S.}",

year = "2017",

month = nov,

day = "9",

doi = "10.3847/2041-8213/aa9572",

language = "English",

volume = "849",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

publisher = "IOP Publishing",

number = "2",

}

Ikarashi, S, Caputi, KI, Ohta, K, Ivison, RJ, Lagos, CDP, Bisigello, L, Hatsukade, B, Aretxaga, I, Dunlop, JS, Hughes, DH, Iono, D, Izumi, T, Kashikawa, N, Koyama, Y, Kawabe, R, Kohno, K, Motohara, K, Nakanishi, K, Tamura, Y, Umehata, H, Wilson, GW, Yabe, K & Yun, MS 2017, 'Very Compact Millimeter Sizes for Composite Star-forming/AGN Submillimeter Galaxies', Astrophysical Journal Letters, vol. 849, no. 2, L36. https://doi.org/10.3847/2041-8213/aa9572

TY - JOUR

T1 - Very Compact Millimeter Sizes for Composite Star-forming/AGN Submillimeter Galaxies

AU - Ikarashi, Soh

AU - Caputi, Karina I.

AU - Ohta, Kouji

AU - Ivison, R. J.

AU - Lagos, Claudia D.P.

AU - Bisigello, Laura

AU - Hatsukade, Bunyo

AU - Aretxaga, Itziar

AU - Dunlop, James S.

AU - Hughes, David H.

AU - Iono, Daisuke

AU - Izumi, Takuma

AU - Kashikawa, Nobunari

AU - Koyama, Yusei

AU - Kawabe, Ryohei

AU - Kohno, Kotaro

AU - Motohara, Kentaro

AU - Nakanishi, Kouichiro

AU - Tamura, Yoichi

AU - Umehata, Hideki

AU - Wilson, Grant W.

AU - Yabe, Kiyoto

AU - Yun, Min S.

PY - 2017/11/9

Y1 - 2017/11/9

N2 - We report the study of the far-infrared (IR) sizes of submillimeter galaxies (SMGs) in relation to their dustobscured star formation rate (SFR) and active galactic nuclei (AGN) presence, determined using mid-IR photometry. We determined the millimeter-wave (λobs = 1100 μm) sizes of 69 Atacama Large Millimeter/ submillimeter Array (ALMA)-identified SMGs, selected with ≥10 δ confidence on ALMA images (F1100 μm = 1.7-7.4 mJy). We found that all of the SMGs are located above an avoidance region in the sizeflux plane, as expected by the Eddington limit for star formation. In order to understand what drives the different millimeter-wave sizes in SMGs, we investigated the relation between millimeter-wave size and AGN fraction for 25 of our SMGs at z=1-3. We found that the SMGs for which the mid-IR emission is dominated by star formation or AGN have extended millimeter-sizes, with respective median Rc,e = 1.6-0.21 +0.34 and 1.5 -0.24 +0.93 kpc. Instead, the SMGs for which the mid-IR emission corresponds to star-forming/AGN composites have more compact millimeter-wave sizes, with median Rc,e1.0 -0.20 +0.20kpc. The relation between millimeter-wave size and AGN fraction suggests that this size may be related to the evolutionary stage of the SMG. The very compact sizes for composite star-forming/AGN systems could be explained by supermassive black holes growing rapidly during the SMG coalescing, star-formation phase.

AB - We report the study of the far-infrared (IR) sizes of submillimeter galaxies (SMGs) in relation to their dustobscured star formation rate (SFR) and active galactic nuclei (AGN) presence, determined using mid-IR photometry. We determined the millimeter-wave (λobs = 1100 μm) sizes of 69 Atacama Large Millimeter/ submillimeter Array (ALMA)-identified SMGs, selected with ≥10 δ confidence on ALMA images (F1100 μm = 1.7-7.4 mJy). We found that all of the SMGs are located above an avoidance region in the sizeflux plane, as expected by the Eddington limit for star formation. In order to understand what drives the different millimeter-wave sizes in SMGs, we investigated the relation between millimeter-wave size and AGN fraction for 25 of our SMGs at z=1-3. We found that the SMGs for which the mid-IR emission is dominated by star formation or AGN have extended millimeter-sizes, with respective median Rc,e = 1.6-0.21 +0.34 and 1.5 -0.24 +0.93 kpc. Instead, the SMGs for which the mid-IR emission corresponds to star-forming/AGN composites have more compact millimeter-wave sizes, with median Rc,e1.0 -0.20 +0.20kpc. The relation between millimeter-wave size and AGN fraction suggests that this size may be related to the evolutionary stage of the SMG. The very compact sizes for composite star-forming/AGN systems could be explained by supermassive black holes growing rapidly during the SMG coalescing, star-formation phase.

KW - galaxies: evolution

KW - galaxies: formation

KW - galaxies: high-redshift

KW - submillimeter: galaxies

UR - http://www.scopus.com/inward/record.url?scp=85034451317&partnerID=8YFLogxK

U2 - 10.3847/2041-8213/aa9572

DO - 10.3847/2041-8213/aa9572

M3 - Article

AN - SCOPUS:85034451317

SN - 2041-8205

VL - 849

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L36

ER -

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

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