A Magellan M2FS Spectroscopic Survey of Galaxies at 5.5 &lt; z &lt; 6.8: Program Overview and a Sample of the Brightest Lyα Emitters

Jiang, Linhua; Shen, Yue; Bian, Fuyan; Zheng, Zhen-Ya; Wu, Jin; Oyarzún, Grecco A.; Blanc, Guillermo A.; Fan, Xiaohui; Ho, Luis C.; Infante, L.; Wang, Ran; Wu, Xue-Bing; Mateo, Mario; Bailey, John I.; Crane, Jeffrey D.; Olszewski, Edward W.; Shectman, Stephen; Thompson, I. B.; Walker, Matthew G.

doi:10.3847/1538-4357/aa8561

Cited by 30 publications

(35 citation statements)

References 128 publications

(199 reference statements)

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“…We aim to build a large and homogeneous sample of LAEs at z ≈ 5.7 and 6.5, and Lyman-break galaxies at 5.5 < z < 6.8. Our program overview paper 23 presents the details of the program, including the motivation, program design, target selection, M2FS observations, LAE identification, and scientific goals. The fields that we chose to observe are five well-studied fields, including the SXDS.…”

Section: The M2fs Survey Programmentioning

confidence: 99%

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A giant protocluster of galaxies at redshift 5.7

Jiang

Bian

et al. 2018

Nat Astron

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Galaxy clusters trace the largest structures of the Universe and provide ideal laboratories for studying galaxy evolution and cosmology 1,2 . Clusters with extended Xray emission have been discovered at redshifts up to z ≈ 2.5 3-7 . Meanwhile, there has been growing interest in hunting for protoclusters, the progenitors of clusters, at higher redshifts [8][9][10][11][12][13][14] . It is, however, very challenging to find the largest protoclusters at early times when they start to assemble. Here we report a giant protocluster of galaxies at 2 redshift z ≈ 5.7, when the Universe was only one billion years old. This protocluster occupies a volume of about 35 3 cubic co-moving megaparsecs (cMpc 3 ). It is embedded in an even larger overdense region with at least 41 spectroscopically confirmed, luminous Lyα-emitting galaxies (Lyα Emitters, or LAEs), including several previously reported LAEs 9 . Its LAE density is 6.6 times the average density at z ≈ 5.7. It is the only one of its kind in a LAE survey in four square degrees on the sky. Such a large structure is also rarely seen in current cosmological simulations. This protocluster will collapse into a galaxy cluster with a mass of (3.6 ± 0.9) × 10 15 solar masses (M⨀), comparable to those of the most massive clusters or protoclusters known to date.According to cosmological simulations, the largest protoclusters of galaxies extend over tens of co-moving megaparsecs at z > 5 (refs. 15,16). Deep, wide-area surveys are needed to find these giant structures at high redshift. We are carrying out a spectroscopic survey of galaxies in four square degrees on the sky, aiming to build a large and homogeneous sample of LAEs at z ≈ 5.7 and 6.5. We are observing five well-studied fields, including the Subaru XMM-Newton Deep Survey (SXDS) field 17 . These fields have deep optical imaging data in a series of broad and narrow bands, taken by the prime-focus imager Suprime-Cam on the 8.2m Subaru telescope. The combined SXDS images in five broad-band filters (BVRi'z') and two narrow-band filters (NB816 and NB921) have enabled us to efficiently select LAE candidates at z ≈ 5.7 and 6.5 via the Lyα technique 18-21 . From these LAE candidates, we identified a large overdense region at z ≈ 5.7 in the SXDS. Here we show that this overdense region contains a giant protocluster (SXDS_gPC for short) that will grow into a massive galaxy cluster.We carried out deep spectroscopic observations of SXDS_gPC using the fiber-fed, multi-object spectrograph M2FS 22 on the 6.5-m Magellan Clay telescope. M2FS has 256 optical fibers deployed over a circular field-of-view 29.2 arcminutes in diameter. SXDS_gPC and its surrounding environment were covered by one M2FS pointing that included z ≈ 5.7 LAE candidates brighter than NB816 = 25.8 mag (5σ detection for point sources; magnitudes are on the AB system), as well as a variety of galaxy candidates at other redshifts. We used a pair of red-sensitive gratings with a resolving power of about 2000. We obtained 7 hours of on-source integration (7 one-hour individ...

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Section: The M2fs Survey Programmentioning

confidence: 99%

“…The wavelength coverage is roughly from 7600 to 9600 Å. The design of the M2FS pointings or plug plates is described in the overview paper 23 . For the SXDS, we use five M2FS pointings to cover most of its area (~1.2 deg 2 ), including one pointing covering SXDS_gPC and its surrounding region.…”

Section: The M2fs Survey Programmentioning

confidence: 99%

A giant protocluster of galaxies at redshift 5.7

Jiang

Bian

et al. 2018

Nat Astron

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“…Bright targets from wide-field ground-based surveys (e.g. Bowler et al 2014;Matthee et al 2015;Hu et al 2016;Santos et al 2016;Zheng et al 2017;Jiang et al 2017;Shibuya et al 2018a) provide unique opportunities to obtain the first detailed and resolved studies of sources within the epoch of re-ionisation. These bright sources are particu-larly suitable for follow-up with ALMA (e.g.…”

Section: Introductionmentioning

confidence: 99%

On the nature and physical conditions of the luminous Ly α emitter CR7 and its rest-frame UV components

Sobral

Matthee

Brammer

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We present new HST/WFC3 observations and re-analyse VLT data to unveil the continuum, variability and rest-frame UV lines of the multiple UV clumps of the most luminous Lyα emitter at z = 6.6, CR7. Our re-reduced, flux calibrated X-SHOOTER spectra of CR7 reveal a Heii emission line in observations obtained along the major axis of Lyα emission with the best seeing conditions. Heii is spatially offset by ≈ +0.8 from the peak of Lyα emission, and it is found towards clump B. Our WFC3 grism spectra detects the UV continuum of CR7's clump A, yielding a power law with β = −2.5 +0.6 −0.7 and M U V = −21.87 +0.25 −0.20 . No significant variability is found for any of the UV clumps on their own, but there is tentative (≈ 2.2 σ) brightening of CR7 in F110W as a whole from 2012 to 2017. HST grism data fail to robustly detect rest-frame UV lines in any of the clumps, implying fluxes < ∼ 2 × 10 −17 erg s −1 cm −2 (3 σ). We perform cloudy modelling to constrain the metallicity and the ionising nature of CR7. CR7 seems to be actively forming stars without any clear AGN activity in clump A, consistent with a metallicity of ∼ 0.05 − 0.2 Z . Component C or an inter-clump component between B and C may host a high ionisation source. Our results highlight the need for spatially resolved information to study the formation and assembly of early galaxies.

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“…Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) survey: LAEs are promising probes for characterizing the cosmic reionization [11][12][13][32][33][34][35][36][37][38][39][40][41][42] . We are carrying out a large-area narrowband imaging survey, Lyman Alpha Galaxies in the Epoch of Reionization (LAGER), to search for the LAEs at z ∼ 7.0, using the Dark Energy Camera (DECam) installed on the Cerro Tololo Inter-American Observatory (CTIO).…”

Section: Methodsmentioning

confidence: 99%

A Lyman-α protocluster at redshift 6.9

Hu,

Wang,

Infante

et al. 2021

Preprint

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A Magellan M2FS Spectroscopic Survey of Galaxies at 5.5 < z < 6.8: Program Overview and a Sample of the Brightest Lyα Emitters

Cited by 30 publications

References 128 publications

A giant protocluster of galaxies at redshift 5.7

A giant protocluster of galaxies at redshift 5.7

On the nature and physical conditions of the luminous Ly α emitter CR7 and its rest-frame UV components

A Lyman-α protocluster at redshift 6.9

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