J/ApJ/845/172 LAE candidates around bright Lyα blobs (Badescu+, 2017)
Discovery of a protocluster associated with a Lyα blob pair at z = 2.3.
Badescu T., Yang Y., Bertoldi F., Zabludoff A., Karim A., Magnelli B.
<Astrophys. J., 845, 172 (2017)>
=2017ApJ...845..172B 2017ApJ...845..172B
ADC_Keywords: Intergalactic medium ; Equivalent widths
Keywords: galaxies: clusters: general; galaxies: formation;
galaxies: high-redshift; intergalactic medium;
large-scale structure of universe
Abstract:
Bright Lyα blobs (LABs)-extended nebulae with sizes of ∼100kpc
and Lyα luminosities of ∼1044erg/s -- often reside in
overdensities of compact Lyα emitters (LAEs) that may be galaxy
protoclusters. The number density, variance, and internal kinematics
of LABs suggest that they themselves trace group-like halos. Here, we
test this hierarchical picture, presenting deep, wide-field Lyα
narrowband imaging of a 1°x0.5° region around a LAB pair at
z=2.3 discovered previously by a blind survey. We find 183 Lyα
emitters, including the original LAB pair and three new LABs with
Lyα luminosities of (0.9-1.3)x1043erg/s and isophotal areas of
16-24arcsec2. Using the LAEs as tracers and a new kernel density
estimation method, we discover a large-scale overdensity (Bootes
J1430+3522) with a surface density contrast of δΣ=2.7, a
volume density contrast of δ∼10.4, and a projected diameter of
∼20 comoving Mpc. Comparing with cosmological simulations, we conclude
that this LAE overdensity will evolve into a present-day Coma-like
cluster with log(M/M☉)∼15.1±0.2. In this and three other
wide-field LAE surveys re-analyzed here, the extents and peak
amplitudes of the largest LAE overdensities are similar, not
increasing with survey size, and implying that they were indeed the
largest structures then and today evolve into rich clusters.
Intriguingly, LABs favor the outskirts of the densest LAE
concentrations, i.e., intermediate LAE overdensities of
δΣ=1-2. We speculate that these LABs mark infalling
protogroups being accreted by the more massive protocluster.
Description:
We obtain narrowband images covering a total area of ∼1°x0.5°
around the two known Lyα blobs (Yang+ 2009ApJ...693.1579Y 2009ApJ...693.1579Y) using
the Mosaic1.1 camera on the Kitt Peak National Observatory (KPNO)
Mayall 4m telescope.
In Figure 1 we show the areas covered by the National Optical
Astronomical Observatory (NOAO) Deep Wide-field Survey (NDWFS) and the
locations of our two pointings (hereafter Bootes1 and Bootes2)
centered on 14:31:42.22,+35:31:19.9 and 14:28:54.08,+35:31:19.9.
Observations were carried out on 2011 April 29 and 30, with exposure
times of 7.3 and 6.0hr, respectively.
The filter has a central wavelength of λc=4030Å and a
bandwidth of ΔλFWHM=47Å, corresponding to the
Lyα emission at z=2.3. Apart from the narrowband (NB) images, we
also use NDWFS broadband BW-, R-, and I-band images for continuum
estimation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 43 183 Catalog of Lyα emitter candidates
table2.dat 61 5 Properties of Lyα blobs
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See also:
J/ApJS/157/1 : Red-Sequence Cluster Survey (Gladders+, 2005)
J/PASJ/57/165 : Lyα emitters in the SUBARU Deep Field (Taniguchi+, 2005)
J/ApJ/641/140 : Optical counterparts in the NDWFS Bootes field (Brand+, 2006)
J/ApJ/667/79 : Lyα emission-line galaxies at z=3.1 (Gronwall+, 2007)
J/A+A/461/823 : Candidate Lyα emitting galaxies (Venemans+, 2007)
J/ApJ/673/143 : HST photometry of TN J1338-1942 (Overzier+, 2008)
J/MNRAS/400/L66 : Lyα emitters near B3 J2330+3927 (Matsuda+, 2009)
J/A+A/498/13 : Lyman-α emitters from redshifts z∼2-3 (Nilsson+, 2009)
J/A+A/512/A12 : VLT/VIMOS spectroscopy in GOODS-South field (Balestra+, 2010)
J/ApJ/736/31 : HETDEX pilot survey. II. 1.9<z<3.8 LAEs (Blanc+, 2011)
J/ApJ/744/110 : LAE galaxies between 2.1=<z≤3.1 (Ciardullo+, 2012)
J/ApJ/759/133 : z=2.4 Lyα emitters in the 53W002 field (Mawatari+, 2012)
J/ApJ/769/79 : Spitzer obs. of radio-loud AGNs (CARLA) (Wylezalek+, 2013)
J/ApJ/796/64 : Hβ & Lyα emitting galaxies at z∼2 (Ciardullo+, 2014)
J/A+A/570/A55 : Spiderweb galaxy 870um and 1.4GHz images (Dannerbauer+, 2014)
J/ApJS/216/27 : Galaxy clusters discovered in the SPT-SZ survey (Bleem+, 2015)
J/ApJ/823/11 : Candidate Lyα emitting galaxies at z∼3.8 (Dey+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg [216.8/218.3] Right Ascension (J2000)
11- 19 F9.6 deg DEdeg [35.2/35.9] Declination (J2000)
21- 28 E8.2 10-7W LLya [2.4e+41/2.3e+43] Lyman α luminosity of
the object; in erg/s units
30- 36 E7.1 10-7W e_LLya [2.2e+41/7.9e+41] Error for LLya
38- 43 I6 0.1nm EWLya [68/145015] Equivalent width, Lyman α
emission; in Angstrom units
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Object Name (1)
13- 14 I2 h RAh [14] Hour of Right Ascension (J2000)
16- 17 I2 min RAm [30/32] Minute of Right Ascension (J2000)
19- 22 F4.1 s RAs Second of Right Ascension (J2000)
24- 24 A1 --- DE- [+] Sign of the Declination (J2000)
26- 27 I2 deg DEd [35] Degree of Declination (J2000)
29- 30 I2 arcmin DEm [33/47] Arcminute of Declination (J2000)
32- 33 I2 arcsec DEs Arcsecond of Declination (J2000)
35- 39 F5.3 10+36W LLya [0.9/2.7] Lyman α luminosity of the
object; in 1043erg/s units
41- 45 F5.3 10+36W e_LLya [0.08/0.2] Error for LLya
47- 50 F4.1 arcsec2 Size [15.5/43] Size
52- 54 F3.1 arcsec2 e_Size [1.6/7] Uncertainty in Size
56- 59 F4.1 % Frac [93.9/97.5]? Recovery fraction (2)
61- 61 I1 --- Ref [1/2] Source (1)
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Note (1): We adopt a naming convention such that the four Lyα blobs in
the original wide and shallow survey (Yang et al. 2009ApJ...693.1579Y 2009ApJ...693.1579Y)
(Ref = 1) are Bootes-LAB1 to Bootes-LAB4 and that the three new
Lyα blobs found in this study are Bootes-LAB5 to Bootes-LAB7
(Ref = 2). Note that Bootes-LAB3 and Bootes-LAB4 are not included in
the table because they were not covered by this new survey.
Note (2): The recovery fraction is defined as the fraction of times the
Lyα blob candidate is recovered with a size above 16arcsec2.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 10-Apr-2018