Connecting the dots: Tracking galaxy evolution using constant cumulative number density at 3 ≤ z ≤ 7
- Department of Astronomy, The University of Texas at Austin, Austin, TX 78712 (United States)
- Department of Earth and Space Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043 (Japan)
Using the cosmological smoothed particle hydrodynamical code GADGET-3, we make a realistic assessment of the technique of using constant cumulative number density as a tracer of galaxy evolution at high redshift. We find that over a redshift range of 3 ≤ z ≤ 7 one can on average track the growth of the stellar mass of a population of galaxies selected from the same cumulative number density bin to within ∼0.20 dex. Over the stellar mass range that we probe (10{sup 10.4}⩽M{sub s}/M{sub ⊙}⩽10{sup 10.8} at z = 3 and 10{sup 8.5}⩽M{sub s}/M{sub ⊙}⩽10{sup 9.6} at z = 7), one can reduce this bias by selecting galaxies based on an evolving cumulative number density. We find that this cumulative number density evolution exhibits a trend toward higher values which can be quantified by simple linear formulations of −0.10Δz for descendants and 0.12Δz for progenitors. Utilizing such an evolving cumulative number density increases the accuracy of descendant/progenitor tracking by a factor of ∼2. This result is in excellent agreement, within 0.10 dex, with abundance matching results over the same redshift range. However, we find that our more physically realistic cosmological hydrodynamic simulations produce a much larger scatter in descendant/progenitor stellar masses than previous studies, particularly when tracking progenitors. This large scatter makes the application of either the constant cumulative number density or evolving cumulative number density technique limited to average stellar masses of populations only, as the diverse mass assembly histories caused by stochastic physical processes such as gas accretion or mergers lead to an even larger scatter in other physical properties such as metallicity and star formation rate.
- OSTI ID:
- 22887073
- Journal Information:
- Astrophysical Journal, Vol. 817, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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