J/ApJ/814/95 Star formation rate of 4≲z≲8 galaxies (Finkelstein+, 2015)
An increasing stellar baryon fraction in bright galaxies at high redshift.
Finkelstein S.L., Song M., Behroozi P., Somerville R.S., Papovich C.,
Milosavljevic M., Dekel A., Narayanan D., Ashby M.L.N., Cooray A.,
Fazio G.G., Ferguson H.C., Koekemoer A.M., Salmon B., Willner S.P.
<Astrophys. J., 814, 95 (2015)>
=2015ApJ...814...95F 2015ApJ...814...95F (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Redshifts ; Ultraviolet
Keywords: early universe; galaxies: evolution; galaxies: formation;
galaxies: high-redshift; ultraviolet: galaxies
Abstract:
Recent observations have shown that the characteristic luminosity of
the rest-frame ultraviolet (UV) luminosity function does not
significantly evolve at 4<z<7 and is approximately MUV*∼21. We
investigate this apparent non-evolution by examining a sample of 173
bright, MUV←21 galaxies at z=4-7, analyzing their stellar
populations and host halo masses. Including deep Spitzer/IRAC imaging
to constrain the rest-frame optical light, we find that MUV*
galaxies at z=4-7 have similar stellar masses of
log(M/M☉)=9.6-9.9 and are thus relatively massive for these high
redshifts. However, bright galaxies at z=4-7 are less massive and have
younger inferred ages than similarly bright galaxies at z=2-3, even
though the two populations have similar star formation rates and
levels of dust attenuation for a fixed dust-attenuation curve.
Matching the abundances of these bright z=4-7 galaxies to halo mass
functions from the Bolshoi ΛCDM simulation implies that the
typical halo masses in ∼MUV* galaxies decrease from
log(Mh/M☉)=11.9 at z=4 to log(Mh/M☉)=11.4 at z=7.
Thus, although we are studying galaxies at a similar stellar mass
across multiple redshifts, these galaxies live in lower mass halos at
higher redshift. The stellar baryon fraction in ∼MUV* galaxies in
units of the cosmic mean Ωb/Ωm rises from 5.1% at z=4
to 11.7% at z=7; this evolution is significant at the ∼3σ level.
This rise does not agree with simple expectations of how galaxies
grow, and implies that some effect, perhaps a diminishing efficiency
of feedback, is allowing a higher fraction of available baryons to be
converted into stars at high redshifts.
Description:
We use the sample of ∼7500 galaxies at 4≲z≲8 from Finkelstein et al.
(F15; 2015, J/ApJ/810/71) and refer the reader to that paper for
details on the photometry, photometric redshift sample selection, and
derivation of UV absolute magnitude at 1500Å (MUV). From their full
catalog, here we analyze the 150, 75, 28, 18, and 3 galaxies with
MUV←21 at z=4,5,6,7, and 8, respectively, which come from the
CANDELS GOODS-South and North fields (with a total area of
∼280arcmin2). The redshift bins are bounded by Δz=±0.5 from
the central redshift.
We use the HST photometry from F15 that includes Advanced Camera for
Surveys (ACS) and WFC3 point-spread function (PSF)-matched total
fluxes in the wavelength range 0.4-1.8um. This catalog also includes
photometry from the Spitzer Space Telescope Infrared Array Camera
(IRAC) imaging of our fields.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 110 94 Stellar populations of bright galaxies at z=4
table4.dat 110 46 Stellar populations of bright galaxies at z=5
table5.dat 110 19 Stellar populations of bright galaxies at z=6
table6.dat 110 14 Stellar populations of bright galaxies at z=7
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See also:
II/261 : GOODS initial results (Giavalisco+, 2004)
J/ApJ/810/71 : UV mag of candidate galaxies at 3~<z~<8.5 (Finkelstein+, 2015)
J/ApJS/218/33 : Spitzer-CANDELS catalog within 5 deep fields (Ashby+, 2015)
J/ApJ/803/34 : z∼4-10 galaxies from HST legacy fields (Bouwens+, 2015)
J/MNRAS/440/2810 : Galaxy luminosity function at z ≃ 7 (Bowler+, 2014)
J/MNRAS/436/1919 : SCUBA observations of COSMOS galaxies (Casey+, 2013)
J/MNRAS/432/2696 : Galaxy luminosity function at z = 7-9 (McLure+, 2013)
J/ApJ/769/80 : Spitzer/IRAC observations of five deep fields (Ashby+, 2013)
J/ApJ/756/164 : UV galaxies in CANDELS from z=8 to z=4 (Finkelstein+, 2012)
J/ApJ/754/83 : UV continuum for z∼4-7 star-forming galaxies (Bouwens+, 2012)
J/ApJ/653/1004 : Galaxies at 1.4≲z≲3.0 in GOODS-North Field (Reddy+, 2006)
J/AJ/131/2766 : Quasar luminosity function from SDSS-DR3 (Richards+, 2006)
J/ApJ/622/772 : Redshift survey of submillimeter galaxies (Chapman+, 2005)
Byte-by-byte Description of file: table[3456].dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- ID Galaxy identifier (1)
14- 23 F10.6 deg RAdeg Right ascension in decimal degrees (J2000)
25- 34 F10.6 deg DEdeg Declination in decimal degrees (J2000)
36- 39 F4.2 --- z [3.5/7.7] Redshift
41- 44 F4.2 --- b_z [0.6/7.5] Minimum redshift
45 A1 --- --- [-]
46- 49 F4.2 --- B_z [3.6/7.9] Maximum redshift
51- 55 F5.2 [Msun] logM* [8.7/11.3] Log of stellar mass
57- 61 F5.2 [Msun] b_logM* [6.5/11.2] Minimum logM*
62 A1 --- --- [-]
63- 67 F5.2 [Msun] B_logM* [9.2/11.4] Maximum logM*
69- 72 I4 Myr Age [10/1015] Age
74- 76 I3 Myr b_Age [10/904] Minimum Age
77 A1 --- --- [-]
78- 81 I4 Myr B_Age [10/1015] Maximum Age
83- 86 F4.2 mag E(B-V) [0/0.4] B-V color excess
88- 91 F4.2 mag b_E(B-V) [0/0.4] Minimum E(B-V)
92 A1 --- --- [-]
93- 96 F4.2 mag B_E(B-V) [0.02/0.7] Maximum E(B-V)
98-101 I4 Msun/yr SFR [12/1066] Star formation rate
103-105 I3 Msun/yr b_SFR [0/863] Minimum SFR
106 A1 --- --- [-]
107-110 I4 Msun/yr B_SFR [15/1186] Maximum SFR
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Note (1): Identifier from Finkelstein+, 2015, J/ApJ/810/71
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 25-Feb-2016