ALMA Lensing Cluster Survey: ALMA-Herschel Joint Study of Lensed Dusty Star-forming Galaxies across z ≃ 0.5 – 6
Fengwu Sun, Eiichi Egami, Seiji Fujimoto, Tim Rawle, F. E. Bauer, Kotaro Kohno, Ian Smail, Pablo G. Pérez‐González, Yiping Ao, S. C. Chapman, F. Combes, M. Dessauges‐Zavadsky, D. Espada, Jorge González-López, Anton M. Koekemoer, Vasily Kokorev, Minju Lee, Kana Morokuma-Matsui, A. Muñoz-Arancibia, Masamune Oguri, R. Pelló, Yoshihiro Ueda, R. Uematsu, Francesco Valentino, P. van der Werf, Gregory Walth, M. Zemcov, Adi Zitrin
Abstract
Abstract We present an ALMA-Herschel joint analysis of sources detected by the ALMA Lensing Cluster Survey (ALCS) at 1.15 mm. Herschel/PACS and SPIRE data at 100–500 μ m are deblended for 180 ALMA sources in 33 lensing cluster fields that are detected either securely (141 sources; in our main sample) or tentatively at S/N ≥ 4 with cross-matched HST/Spitzer counterparts, down to a delensed 1.15 mm flux density of ∼0.02 mJy. We performed far-infrared spectral energy distribution modeling and derived the physical properties of dusty star formation for 125 sources (109 independently) that are detected at >2 σ in at least one Herschel band. A total of 27 secure ALCS sources are not detected in any Herschel bands, including 17 optical/near-IR-dark sources that likely reside at z = 4.2 ± 1.2. The 16th, 50th, and 84th percentiles of the redshift distribution are 1.15, 2.08, and 3.59, respectively, for ALCS sources in the main sample, suggesting an increasing fraction of z ≃ 1 − 2 galaxies among fainter millimeter sources ( f 1150 ∼ 0.1 mJy). With a median lensing magnification factor of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>μ</mml:mi> <mml:mo>=</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2.6</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.8</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.6</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , ALCS sources in the main sample exhibit a median intrinsic star formation rate of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mn>94</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>54</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>84</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> M ⊙ yr −1 , lower than that of conventional submillimeter galaxies at similar redshifts by a factor of ∼3. Our study suggests weak or no redshift evolution of dust temperature with L IR < 10 12 L ⊙ galaxies within our sample at z ≃ 0 − 2. At L IR > 10 12 L ⊙ , the dust temperatures show no evolution across z ≃ 1–4 while being lower than those in the local universe. For the highest-redshift source in our sample ( z = 6.07), we can rule out an extreme dust temperature (>80 K) that was reported for MACS0416 Y1 at z = 8.31.