J/ApJ/923/143       HectoMAP Cluster Survey: clusters & BCGs       (Sohn+, 2021)
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The HectoMAP Cluster Survey: spectroscopically identified clusters and their
brightest cluster galaxies (BCGs).
    Sohn J., Geller M.J., Hwang Ho S., Diaferio A., Rines K.J., Utsumi Y.
   <Astrophys. J., 923, 143 (2021)>
   =2021ApJ...923..143S
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ADC_Keywords: Clusters, galaxy; Redshifts; Velocity dispersion; Surveys;
              Spectra, optical; Magnitudes, absolute; Galaxies, spectra; Colors
Keywords: Redshift surveys ; Galaxy clusters ; Brightest cluster galaxies ;
          Large-scale structure of the universe

Abstract:
    We apply a friends-of-friends (FoF) algorithm to identify galaxy
    clusters and we use the catalog to explore the evolutionary synergy
    between brightest cluster galaxies (BCGs) and their host clusters. We
    base the cluster catalog on the dense HectoMAP redshift survey
    (2000 redshifts deg^-2^). The HectoMAP FoF catalog includes
    346 clusters with 10 or more spectroscopic members within the range
    0.05<z<0.55 and with a median z=0.29. We list these clusters and their
    members. We also include central velocity dispersions ({sigma}_*,BCG_)
    for the FoF cluster BCGs, a distinctive feature of the HectoMAP FoF
    catalog. HectoMAP clusters with higher galaxy number density (80
    systems) are all genuine clusters with a strong concentration and a
    prominent BCG in Subaru/Hyper Suprime-Cam images. The phase-space
    diagrams show the expected elongation along the line of sight.
    Lower-density systems include some low reliability systems. We
    establish a connection between BCGs and their host clusters by
    demonstrating that {sigma}_*,BCG_/{sigma}_cl_ decreases as a function
    of cluster velocity dispersion ({sigma}_cl_), in contrast, numerical
    simulations predict a constant {sigma}_*,BCG_/{sigma}_cl_. Sets of
    clusters at two different redshifts show that BCG evolution in massive
    systems is slow over the redshift range z<0.4. The data strongly
    suggest that minor mergers may play an important role in BCG evolution
    in clusters with {sigma}_cl_<300km/s. For lower mass systems
    ({sigma}_cl_<300km/s), major mergers may play a significant role. The
    coordinated evolution of BCGs and their host clusters provides an
    interesting test of simulations in high-density regions of the
    universe.

Description:
    The Sloan Digital Sky Survey (SDSS) DR16 (Ahumada+ 2020, V/154) is the
    photometric basis of HectoMAP. See Section 2.1.

    The HectoMAP spectroscopy comes from two major spectroscopic surveys:
    SDSS/BOSS (Baryon Oscillation Spectroscopic Survey) and our own
    Multi-Mirror Telescope (MMT)/Hectospec survey. We first compiled the
    SDSS DR16 spectroscopy which includes 25524 SDSS and BOSS redshifts
    within the HectoMAP field. The typical redshift uncertainty of these
    SDSS/BOSS measurements is ~36km/s. The Hectospec survey was carried
    out from 2009-2019. See Section 2.2.

File Summary:
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 FileName   Lrecl  Records   Explanations
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ReadMe         80        .   This file
table1.dat     63      346   FoF clusters in HectoMAP
table2.dat     64     5992   HectoMAP FoF cluster members
table3.dat     62      346   BCGs of in the HectoMAP FoF clusters
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See also:
 VII/4   : Abell and Zwicky Clusters of Galaxies (Abell+ 1974)
 VII/86  : Groups of Galaxies. I. Nearby Groups (Huchra+ 1982)
 VII/110 : Rich Clusters of Galaxies (Abell+ 1989)
 V/154   : Sloan Digital Sky Surveys (SDSS), Release 16 (DR16) (Ahumada+, 2020)
 J/AJ/113/483    : Groups of Galaxies (Ramella+ 1997)
 J/MNRAS/301/881 : The ROSAT brightest cluster sample - I. (Ebeling+, 1998)
 J/ApJS/129/435  : NORAS galaxy cluster survey. I. (Bohringer+, 2000)
 J/MNRAS/337/256 : Galaxy in low X-ray luminosity clusters (Balogh+, 2002)
 J/MNRAS/348/866 : 2dFGRS Percolation-Inferred Galaxy Group (2PIGG) (Eke+, 2004)
 J/AJ/127/1811   : Catalog of SDSS compact groups of galaxies (Lee+, 2004)
 J/ApJS/167/1    : Galaxy groups and clusters from SDSS (Berlind+, 2006)
 J/ApJS/183/197  : Galaxy clusters identified from the SDSS-DR6 (Wen+, 2009)
 J/ApJS/191/254  : GMBCG galaxy cluster catalog from SDSS DR7 (Hao+, 2010)
 J/A+A/514/A102  : SDSS DR7 groups of galaxies (Tago+, 2010)
 J/ApJ/746/178   : The augmented maxBCG cluster catalog (Rykoff+, 2012)
 J/A+A/540/A106  : SDSS-DR8 groups and clusters of galaxies (Tempel+, 2012)
 J/ApJ/767/15    : Hectospec Cluster Survey (HeCS) (Rines+, 2013)
 J/MNRAS/444/147 : Richness of galaxy clusters (Oguri, 2014)
 J/ApJ/785/104   : redMaPPer. I. Algorithm applied to SDSS DR8 (Rykoff+, 2014)
 J/A+A/566/A1    : Flux- & volume-limited groups for SDSS gal. (Tempel+, 2014)
 J/ApJS/216/27   : Galaxy clusters discovered in SPT-SZ survey (Bleem+, 2015)
 J/A+A/581/A41   : OmegaWINGS BV phot. of galaxy clusters (Gullieuszik+, 2015)
 J/ApJS/224/1    : redMaPPer cluster catalog from DES data (Rykoff+, 2016)
 J/ApJS/225/23   : Compact groups of gal. from SDSS-DR12 (MLCG) (Sohn+, 2016)
 J/A+A/588/A14   : Friends-of-friends galaxy group finder (Tempel+, 2016)
 J/AJ/153/220    : NORAS II. I. First results (Bohringer+, 2017)
 J/ApJS/229/20   : MMT/Hectospec redshift survey for Abell 2029 (Sohn+, 2017)
 J/PASJ/70/S20   : HSC Wide S16A cluster catalog (Oguri+, 2018)
 J/ApJ/862/172   : HeCS-red: Hectospec surveys of redMaPPer cl. (Rines+, 2018)
 J/ApJ/855/100   : The HectoMAP cluster survey. II. X-ray clusters (Sohn+, 2018)
 J/ApJ/856/172   : The HectoMAP cluster survey. I. (Sohn+, 2018)
 J/ApJS/240/33   : MaDCoWS. I. Catalog of z~1 galaxy clusters (Gonzalez+, 2019)
 J/ApJ/871/129   : A redshift catalog of the galaxy cluster A2029 (Sohn+, 2019)
 J/ApJ/891/129   : The HeCS-omnibus catalog: SDSS & MMT sp. obs. (Sohn+, 2020)
 J/ApJ/909/129   : HectoMAP redshift survey DR1 (Sohn+, 2021)

Byte-by-byte Description of file: table1.dat
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   Bytes Format Units   Label      Explanations
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   1-  4 A4     ---     ---        [HMRM]
   5-  7 I03    ---     HMRM       [1/346] HectoMAP FoF Cluster ID
   9- 18 F10.6  deg     RAdeg      [200.3/249.7] Right Ascension (J2000)
  20- 28 F9.6   deg     DEdeg      [42.5/44] Declination (J2000)
  30- 37 F8.6   ---     z          [0.059/0.55] Central cluster redshift
  39- 41 I3     ---     Nmem       [10/146] Number of FoF cluster members
  43- 45 I3     ---     Nsp        [10/302] Number of spectroscopically
                                    identified members (1)
  47- 50 I4     km/s    vdisp      [97/1019] Velocity dispersion
  52- 54 I3     km/s  e_vdisp      [19/245] Velocity dispersion error
  56- 59 F4.2   ---     Density    [0.04/0.34] Galaxy number density
  61- 61 A1     ---     Den        [HL] Density regime flag (2)
  63- 63 A1     ---     BCG        [YN] Brightest cluster member flag (Y=central
                                    galaxy is the brightest cluster member)
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Note (1): Number of spectroscopically identified members fainter than
          rMAG=-19.72
Note (2): Density regime flag as follows:
    H = high-density regime (80 occurrences);
    L = low-density regime (266 occurrences).
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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-  4 A4     ---      ---        [HMRM]
   5-  7 I03    ---      HMRM       [1/346] HectoMAP FoF Cluster ID
   9- 27 I19    ---      OBJID      SDSS DR16 Object ID
  29- 38 F10.6  deg      RAdeg      [200.27/249.7] Right Ascension (J2000)
  40- 48 F9.6   deg      DEdeg      [42.5/44] Declination (J2000)
  50- 56 F7.5   ---      zspec      [0.059/0.55] Spectroscopic redshift
  58- 64 F7.5   ---    e_zspec      [1e-5/0.0006]? Redshift error
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Byte-by-byte Description of file: table3.dat
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   Bytes Format Units    Label     Explanations
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   1-  4 A4     ---      ---       [HMRM]
   5-  7 I03    ---      HMRM      [1/346] HectoMAP FoF Cluster ID
   9- 27 I19    ---      OBJID     SDSS DR16 Object ID
  29- 34 F6.2   mag      rMag      [-25.6/-20.7] r-band absolute magnitude
  36- 39 F4.2   mag    e_rMag      [0.01/2] r-band absolute magnitude error
  41- 44 F4.2   ---      g-r       [0.4/9.85] g-r color index
  46- 49 F4.2   ---      Dn4000    [1.1/4.64] Dn4000 age index (1)
  51- 54 F4.2   ---    e_Dn4000    [0.01/0.6]? Dn4000 error (NULL value="Inf")
  56- 58 I3     km/s     vdisp     [97/597]?=-99 Stellar velocity dispersion
  60- 62 I3     km/s   e_vdisp     [5/89]?=-99 Stellar velocity dispersion error
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Note (1): The Dn4000 index, a stellar population age indicator (e.g.,
    Kauffmann+ (2003MNRAS.341...33K)). Following the definition from
    Balogh+ (1999ApJ...527...54B), we compute the flux ratio between
    4000-4100{AA} and 3850-3950{AA}:
    D_n_4000=F_{lambda}_(4000-4100)/F_{lambda}_(3850-3950).
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History:
    From electronic version of the journal

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(End)                    Prepared by [AAS], Emmanuelle Perret [CDS]  19-May-2023