J/MNRAS/473/1977    H-alpha emitters in/towards USS 1558      (Shimakawa+, 2018)

MAHALO Deep Cluster Survey. I. Accelerated and enhanced galaxy formation in the densest regions of a protocluster at z = 2.5. Shimakawa R., Kodama T., Hayashi M., Prochaska J.X., Tanaka I., Cai Z., Suzuki T.L., Tadaki K.-I., Koyama Y. <Mon. Not. R. Astron. Soc. 473, 1977 (2018)> =2018MNRAS.473.1977S 2018MNRAS.473.1977S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Redshifts Keywords: galaxies: evolution - galaxies: formation - galaxies: high-redshift Abstract: We carried out deep Hα narrowband imaging with 10h net integrations towards the young protocluster, USS1558-003 at z=2.53 with the Subaru Telescope. This system is composed of four dense groups with massive local overdensities, traced by 107 Hα emitters (HAEs) with stellar masses and dust-corrected star formation rates down to 1x108M and 3M/yr, respectively. We have investigated the environmental dependence of various physical properties within the protocluster by comparing distributions of HAEs in higher and lower densities with a standard Kolmogorov-Smirnov test. At 97 per cent confidence level, we find enhanced star formation across the star-forming main sequence of HAEs living in the most extreme 'supergroup', corresponding to the top quartile of overdensities. Furthermore, we derive distribution functions of Hα luminosity and stellar mass in group and intergroup regions, approximately corresponding to 30 and 8 times higher densities than the general field. As a consequence, we identify 0.7 and 0.9dex higher cut-offs in Hα luminosity and stellar mass functions in the dense groups, respectively. On the other hand, HAEs in the intergroup environment of the protocluster show similar distribution functions to those of field galaxies despite residing in significant overdensities. In the early phase of cluster formation, as inferred from our results, the densest parts in the protocluster have had an accelerated formation of massive galaxies. We expect that these eventually grow and transform into early-type galaxies at the bright end of the red sequence as seen in present-day rich clusters of galaxies. Description: This work combines the multi-broad-band and deep narrowband images (Fig. 1) taken from the early data of the MAHALO-Subaru campaign (S10B-028I, Kodama et al.; Hayashi et al. 2012ApJ...757...15H 2012ApJ...757...15H; Kodama et al. 2013, Proc. IAU Symp., 295, 74), the new data by MDCS (S15A-047, Kodama et al.; Hayashi et al., 2016ApJ...826L..28H 2016ApJ...826L..28H), and deep F160W/WFC3 photometry taken by the Hubble Space Telescope (HST). Objects: ----------------------------------------------- RA (J2000) DE Designation(s) ----------------------------------------------- 16 01 17.5 -00 28 47 USS 1558-003 4C -00.62 ----------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file tablea1.dat 92 107 Catalogue of the HAE sample in USS 1558 -------------------------------------------------------------------------------- Byte-by-byte Description of file: tablea1.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 3- 5 I3 --- ID Identification number 7- 13 F7.4 --- z ?=- Spectroscopic redshift 15 A1 --- LAE [0/1] Note (1) 19- 21 I3 --- b5th Mean projected distance 23- 27 F5.2 [Msun] logM* Stellar mass 29- 32 F4.2 [Msun] e_logM* Error on Stellar mass (lower value) 34- 37 F4.2 [Msun] E_logM* Error on Stellar mass (upper value) 39- 42 F4.2 mag E(B-V) Redenning 44- 47 F4.2 mag e_E(B-V) Error on Redenning (lower value) 49- 52 F4.2 mag E_E(B-V) Error on Redenning (upper value) 54- 57 F4.2 [Msun/yr] logSFR Hα star formation rate 59- 62 F4.2 [Msun/yr] e_logSFR Error on Hα star formation rate (lower value) 65- 68 F4.2 [Msun/yr] E_logSFR Error on Hα star formation rate (upper value) 71- 75 F5.2 [kpc] logRe ?=- Effective radius 77- 80 F4.2 [kpc] e_logRe ?=- rms uncertainty on Effective radius 83- 87 F5.2 mag J-Ks ?=- J-Ks colour index 89- 92 F4.2 mag e_J-Ks ?=- rms uncertainty J-Ks colour index -------------------------------------------------------------------------------- Note (1): 1: Dual Hα and Lyα emitters identified by Shimakawa et al. (2017MNRAS.468L..21S 2017MNRAS.468L..21S) -------------------------------------------------------------------------------- History: From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Nov-2020
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