Galaxy growth by merging in the nearby universe

Tao Jiang, David W. Hogg, Michael R. Blanton

    Research output: Contribution to journalArticle

    Abstract

    We measure the mass growth rate by merging for a wide range of galaxy types. We present the small-scale (0.014 h -1 70 Mpc < r < 11 h 70 -1 Mpc) projected cross-correlation functions w(r p) of galaxy subsamples from the spectroscopic sample of the NYU Value-Added Galaxy Catalog (5 × 105 galaxies of redshifts 0.03 < z < 0.15) with galaxy subsamples from the Sloan Digital Sky Survey imaging (4 × 107 galaxies). We use smooth fits to de-project the two-dimensional functions w(r p) to obtain smooth three-dimensional real-space cross-correlation functions ξ(r) for each of several spectroscopic subsamples with each of several imaging subsamples. Because close pairs are expected to merge, the three-space functions and dynamical evolution time estimates provide galaxy accretion rates. We find that the accretion onto massive blue galaxies and onto red galaxies is dominated by red companions, and that onto small-mass blue galaxies, red and blue galaxies make comparable contributions. We integrate over all types of companions and find that at fixed stellar mass, the total fractional accretion rates onto red galaxies (∼3h 70 percent per Gyr) are greater than that onto blue galaxies (∼1h 70 percent per Gyr). These rates are almost certainly overestimates because we have assumed that all close pairs merge as quickly as the merger time that we used. One conclusion of this work is that if the total growth of red galaxies from z = 1 to z = 0 is mainly due to merging, the merger rates must have been higher in the past.

    Original languageEnglish (US)
    Article number140
    JournalAstrophysical Journal
    Volume759
    Issue number2
    DOIs
    StatePublished - Nov 10 2012

    Fingerprint

    universe
    galaxies
    accretion
    merger
    rate
    cross correlation
    function space
    stellar mass
    catalogs

    Keywords

    • cosmology: observations
    • galaxies: evolution
    • galaxies: fundamental parameters
    • galaxies: General
    • galaxies: interactions
    • methods: statistical

    ASJC Scopus subject areas

    • Space and Planetary Science
    • Astronomy and Astrophysics

    Cite this

    Galaxy growth by merging in the nearby universe. / Jiang, Tao; Hogg, David W.; Blanton, Michael R.

    In: Astrophysical Journal, Vol. 759, No. 2, 140, 10.11.2012.

    Research output: Contribution to journalArticle

    Jiang, Tao ; Hogg, David W. ; Blanton, Michael R. / Galaxy growth by merging in the nearby universe. In: Astrophysical Journal. 2012 ; Vol. 759, No. 2.
    @article{95ef7790b4864dcf99cf8e92b727b632,
    title = "Galaxy growth by merging in the nearby universe",
    abstract = "We measure the mass growth rate by merging for a wide range of galaxy types. We present the small-scale (0.014 h -1 70 Mpc < r < 11 h 70 -1 Mpc) projected cross-correlation functions w(r p) of galaxy subsamples from the spectroscopic sample of the NYU Value-Added Galaxy Catalog (5 × 105 galaxies of redshifts 0.03 < z < 0.15) with galaxy subsamples from the Sloan Digital Sky Survey imaging (4 × 107 galaxies). We use smooth fits to de-project the two-dimensional functions w(r p) to obtain smooth three-dimensional real-space cross-correlation functions ξ(r) for each of several spectroscopic subsamples with each of several imaging subsamples. Because close pairs are expected to merge, the three-space functions and dynamical evolution time estimates provide galaxy accretion rates. We find that the accretion onto massive blue galaxies and onto red galaxies is dominated by red companions, and that onto small-mass blue galaxies, red and blue galaxies make comparable contributions. We integrate over all types of companions and find that at fixed stellar mass, the total fractional accretion rates onto red galaxies (∼3h 70 percent per Gyr) are greater than that onto blue galaxies (∼1h 70 percent per Gyr). These rates are almost certainly overestimates because we have assumed that all close pairs merge as quickly as the merger time that we used. One conclusion of this work is that if the total growth of red galaxies from z = 1 to z = 0 is mainly due to merging, the merger rates must have been higher in the past.",
    keywords = "cosmology: observations, galaxies: evolution, galaxies: fundamental parameters, galaxies: General, galaxies: interactions, methods: statistical",
    author = "Tao Jiang and Hogg, {David W.} and Blanton, {Michael R.}",
    year = "2012",
    month = "11",
    day = "10",
    doi = "10.1088/0004-637X/759/2/140",
    language = "English (US)",
    volume = "759",
    journal = "Astrophysical Journal",
    issn = "0004-637X",
    publisher = "IOP Publishing Ltd.",
    number = "2",

    }

    TY - JOUR

    T1 - Galaxy growth by merging in the nearby universe

    AU - Jiang, Tao

    AU - Hogg, David W.

    AU - Blanton, Michael R.

    PY - 2012/11/10

    Y1 - 2012/11/10

    N2 - We measure the mass growth rate by merging for a wide range of galaxy types. We present the small-scale (0.014 h -1 70 Mpc < r < 11 h 70 -1 Mpc) projected cross-correlation functions w(r p) of galaxy subsamples from the spectroscopic sample of the NYU Value-Added Galaxy Catalog (5 × 105 galaxies of redshifts 0.03 < z < 0.15) with galaxy subsamples from the Sloan Digital Sky Survey imaging (4 × 107 galaxies). We use smooth fits to de-project the two-dimensional functions w(r p) to obtain smooth three-dimensional real-space cross-correlation functions ξ(r) for each of several spectroscopic subsamples with each of several imaging subsamples. Because close pairs are expected to merge, the three-space functions and dynamical evolution time estimates provide galaxy accretion rates. We find that the accretion onto massive blue galaxies and onto red galaxies is dominated by red companions, and that onto small-mass blue galaxies, red and blue galaxies make comparable contributions. We integrate over all types of companions and find that at fixed stellar mass, the total fractional accretion rates onto red galaxies (∼3h 70 percent per Gyr) are greater than that onto blue galaxies (∼1h 70 percent per Gyr). These rates are almost certainly overestimates because we have assumed that all close pairs merge as quickly as the merger time that we used. One conclusion of this work is that if the total growth of red galaxies from z = 1 to z = 0 is mainly due to merging, the merger rates must have been higher in the past.

    AB - We measure the mass growth rate by merging for a wide range of galaxy types. We present the small-scale (0.014 h -1 70 Mpc < r < 11 h 70 -1 Mpc) projected cross-correlation functions w(r p) of galaxy subsamples from the spectroscopic sample of the NYU Value-Added Galaxy Catalog (5 × 105 galaxies of redshifts 0.03 < z < 0.15) with galaxy subsamples from the Sloan Digital Sky Survey imaging (4 × 107 galaxies). We use smooth fits to de-project the two-dimensional functions w(r p) to obtain smooth three-dimensional real-space cross-correlation functions ξ(r) for each of several spectroscopic subsamples with each of several imaging subsamples. Because close pairs are expected to merge, the three-space functions and dynamical evolution time estimates provide galaxy accretion rates. We find that the accretion onto massive blue galaxies and onto red galaxies is dominated by red companions, and that onto small-mass blue galaxies, red and blue galaxies make comparable contributions. We integrate over all types of companions and find that at fixed stellar mass, the total fractional accretion rates onto red galaxies (∼3h 70 percent per Gyr) are greater than that onto blue galaxies (∼1h 70 percent per Gyr). These rates are almost certainly overestimates because we have assumed that all close pairs merge as quickly as the merger time that we used. One conclusion of this work is that if the total growth of red galaxies from z = 1 to z = 0 is mainly due to merging, the merger rates must have been higher in the past.

    KW - cosmology: observations

    KW - galaxies: evolution

    KW - galaxies: fundamental parameters

    KW - galaxies: General

    KW - galaxies: interactions

    KW - methods: statistical

    UR - http://www.scopus.com/inward/record.url?scp=84868135676&partnerID=8YFLogxK

    UR - http://www.scopus.com/inward/citedby.url?scp=84868135676&partnerID=8YFLogxK

    U2 - 10.1088/0004-637X/759/2/140

    DO - 10.1088/0004-637X/759/2/140

    M3 - Article

    VL - 759

    JO - Astrophysical Journal

    JF - Astrophysical Journal

    SN - 0004-637X

    IS - 2

    M1 - 140

    ER -