S319p.110 — Deep JVLA and ALMA observations of dusty star forming galaxies in protocluster 4C23.56 at z = 2.5

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Aug 10th at 6:00 PM until 6:00 PM




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Author(s): Minju Lee4, Kenta Suzuki1, Kotaro Kohno1, Yoichi Tamura1, Daisuke Iono3, Bunyo Hatsukade3, Kouichiro Nakanishi3, Ichi Tanaka3, Tadayuki Kodama3, Kenichi Tadaki2, Soh Ikarashi1, Junko Ueda3, Hideki Umehata1, Toshiki Saito4, Ryohei Kawabe4

Institution(s): 1. Institute of Astronomy, The University of Tokyo, 2. Max-Planck-Institut fuer extraterrestrische Physik (MPE), 3. National Astronomical Observatory of Japan (NAOJ), 4. The University of Tokyo

We present studies of protocluster members of z = 2.5 Hα emitters (HAEs) using radio (3 GHz) and sub-mm (270 GHz) with Karl Jansky Very Large Array (JVLA) and Atacama Large submm/Mm Array (ALMA), at z = 2.5. Our deep JVLA (1σ ~ 1.4 - 4.1 μJy/beam) and ALMA (1σ ~ 0.1 mJy/beam) observations have detected HAEs having star formation rates (SFRs) of ≥ 100 Msun/yr (assuming radio spectral index α = 0.7) and ≥ 60 Msun/yr (assuming Td = 35 K, β = 1.8). Among the 24 HAE samples, seven and four counterparts have been detected at radio and submm, respectively. Provided the stellar masses estimated from Subaru near infrared (NIR) observations, we find the detected HAEs have stellar masses of log(Mstar (Msun))≥ 10.1. Comparing the derived SFRs from radio and Hα emission, and excluding HAEs having AGN signatures, we measure the amount of dust attenuation in HAEs. We find a consistency with previous results which reports that massive galaxies tend to be more dusty than less massive ones. The dust continuum measurement is used to derive the total interstellar medium (ISM) masses of HAEs and we find the ISM mass fraction (MISM/(MISM + Mstar)) is tentatively low compared to the sample of the general field, i.e., COSMOS, at the same redshift. We discuss the implication of these results in the context of galaxy formation in the overdense regions at high redshift, which includes some galaxies in this field might have evolved already given their galaxy properties, i.e., stellar mass, SFR, ISM mass. Finally, we conclude that deeper and higher resolution observations toward this field are necessary to obtain larger galaxy samples of diverse physical properties and to compare with other environments.