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Obscured star formation in Lyα blobs at z = 3.1

Tamura, Y. and Matsuda, Y. and Ikarashi, S. and Scott, K. S. and Hatsukade, B. and Umehata, H. and Saito, T. and Nakanishi, K. and Yun, M. S. and Ezawa, H. and Hughes, D. H. and Iono, D. and Kawabe, R. and Kohno, K. and Wilson, G. W. (2013) Obscured star formation in Lyα blobs at z = 3.1. Monthly Notices of the Royal Astronomical Society, 430 (4). pp. 2768-2773. ISSN 0035-8711.

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We present results from the AzTEC/ASTE 1.1-mm imaging survey of 35 Lyα blobs (LABs) found in the SSA22 protocluster at z = 3.1. These 1.1-mm data reach an rms noise level of 0.7–1 mJy beam^(−1), making this the largest millimetre-wave survey of LABs to date. While one (or possibly two) out of 35 LABs might be detected at 3σ level, no significant (≥3.5σ) emission is found in any of individual 35 LABs. From this, we estimate 3σ upper limits on the far-infrared luminosity of L_FIR < 2 × 10^(12) L_⊙ (the dust temperature of 35 K and the emissivity index of 1.5 are assumed). Stacking analysis reveals that the 1.1-mm flux density averaged over the LABs is S_(1.1 mm) < 0.40 mJy (3σ), which places a constraint of LFIR < 4.5 × 10^(11) L_⊙. These data constrain the dust spectral energy distributions of the LABs more tightly than ever if their spectral indices at rest-frame wavelength of ≈ 240 μm are similar to those found in (ultra-)luminous infrared galaxies at 0.2 < z < 0.3. Our results suggest that LABs on average have little ultraluminous obscured star formation, in contrast to a long-believed picture that LABs undergo an intense episode of dusty star formation activities with star formation rates of ∼10^3  M_⊙ yr^(−1). Observations with the Atacama Large Millimeter/submillimeter Array are needed to directly study the obscured part of star formation activity in the LABs.

Item Type:Article
Related URLs:
URLURL TypeDescription
Nakanishi, K.0000-0002-6939-0372
Yun, M. S.0000-0001-7095-7543
Iono, D.0000-0002-2364-0823
Kawabe, R.0000-0002-8049-7525
Kohno, K.0000-0002-4052-2394
Additional Information:© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 January 11. Received 2013 January 9; in original form 2012 May 30. First published online: February 8, 2013. We would like to acknowledge the AzTEC/ASTE team who made the observations possible. We thank T. Yamada and T. Hayashino for providing the Subaru images. We would also like to thank R. Ivison for providing the new VLA image. YT is supported by JSPS Grant-in-Aid for Research Activity Start-up (no. 23840007). KSS is supported by the National Radio Astronomy Observatory, which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. BH is supported by Research Fellowship for Young Scientists from JSPS. AzTEC/ASTE observations were partly supported by KAKENHI (no. 19403005, 20001003). The ASTE project is driven by Nobeyama Radio Observatory (NRO), a branch of NAOJ, in collaboration with University of Chile, and Japanese institutes including University of Tokyo, Nagoya University, Osaka Prefecture University, Ibaraki University and Hokkaido University. The Herschel- ATLAS is a project with Herschel, which is an ESA space observatory with science instruments provided by European-led principal investigator consortia and with important participation from NASA. The H-ATLAS website is
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Japan Society for the Promotion of Science (JSPS)23840007
National Radio Astronomy ObservatoryUNSPECIFIED
Japan Society for the Promotion of Science (JSPS)19403005
Japan Society for the Promotion of Science (JSPS)20001003
Subject Keywords:galaxies: evolution; galaxies: formation; galaxies: high-redshift
Issue or Number:4
Record Number:CaltechAUTHORS:20130603-134537956
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:38762
Deposited By: Jason Perez
Deposited On:03 Jun 2013 21:41
Last Modified:09 Mar 2020 13:19

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