the extremely red objects in the clash fields the extremely red galaxies in clash fields xinwen shu...
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The Extremely Red Objects in the CLASH Fields
The Extremely Red Galaxies in CLASH Fields
Xinwen Shu (CEA, Saclay and USTC)
CLASH 2013 Team meeting – September 16-18 2013, London, UK
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Mapping the visible Universe
Bouwens et al 2012
1. Determine the CSFRD with different
SFR estimators up to z=11
2. Measure contributions by different
galaxy populations to the global CSFRD
at different redshifts
3. Link galaxy populations and dark
matter halos at different cosmic epochs
4. Build up an empirical picture for
galaxy formation and evolution
5. Understand physical mechanisms
driving galaxy evolution
starlight dustre-radiation
Reddy et al. 2011
UV luminosity density
dust-corrected SFR
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At z > 3, the 4000A break is shifted to wavelengths λ > 1.6 μm, implying that the potentially oldest and/or most dusty galaxies at those redshifts could be missed even by deep near-IR surveys.
Mobasher et al. 2005
Steidel+03, Franx+02, Daddi+04
Color selection of high-z galaxies:
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H-[3.6]>4
Dusty galaxies with an evolved stellar population at z>4
SMG 850 5 by Wang et al. (2009)‐
Completing the census of star formation and the assembling history of stellar mass densities
NIR dropout?
More sources of this kind displaying extremely red color H-[3.6]>4?
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Four H-[3.6]>4 galaxies in GOODS/ERS (50 arcmin^2, Huang et al. 2011): Possibilities: 1.Very dusty SED at z~1-2 2.Old stellar population at z>4.5, the iceberg of a larger population of z > 3 galaxies?
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Why CLASH data?1. Deep WFC3 H-band images (27.5, 5σ) over 25
clusters, covering nearly 120 square arcmin2. Deep IRAC ([3.6]+[4.5]um) imaging (5σ depth
>24 mag)3. Multi-wavelength HST+Spitzer observations
allow for constrains on the SED4. Cluster lensing helps to probe the intrinsically
faint candidates5. Wealth of existing and ongoing follow-up
observations in other bands
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[4.5um]<24.4, 4sigmaH160w>27.5, 5sigma Totally 13 candidates with H-[4.5]>4 over 23 CLASH clusters, including 8 detected in H-band, and 5 not (~110 arcmin^2)
7/8 H-band detected sources with photometric redshift between z~3.7-5.1
CLASH data
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z = 3.77AV = 1.5age = 1.58 Gyrt = 0.25 GyrM* = 1.0x1011 Msun
Av-redshift contour plane
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z = 4.82AV = 1.1age = 1.0 Gyrt = 0.25 GyrM* = 8.9x1011 Msun Orz = 1.11AV = 7.8age = 25 Myrt = 0.1 GyrM* = 6.3x109 Msun,
F160w IRAC
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Can Herschel be helpful to constrain the SED?
1
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Comparison with Candels/UDS : Herschel puts constraint on the nature of extremely H-[4.5]>4 sources in the Candels/UDS field (in progress)
Evidence for the presence of dusty and old stellar population
8um 24um 100um 160um 250um 350um 500um
F606 F814 F125 F160 [3.6] um [4.5] umCandels/UDS
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H-dropouts in the cluster MACS 0429: Overdensity or lensed multiple images?
Candels/UDS: 25/180 arcmin^2
GOODS/ERS: 4/50 arcmin^2
M0429: 4 /4.8 arcmin^2
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z=4, confirmed from CO
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Summary and future workSummary:1.We identified 13 extremely red H-[4.5]>4 galaxies in the CLASH fields (over 23 clusters)2.For 8 sources, SED fitting to the HST+IRAC photometry indicates that 5 of them are likely massive galaxies at z~4 (logM*~11.01-11.98), though very dusty low-z solutions cannot be ruled out.3.None of sources is detected with Herschel (but the data are shallow)4.One cluster (M0429) shows an overdensity of H-dropouts or lensed multiple images, but improved estimation on redshift is required, e.g., CO lines?
Future work: 5.Inspect whether the H-dropouts are lensed by clusters if they are at z~4.6.Compare the physical properties of the H-dropouts (z, mass, morphology, size, color, environment, etc) to that in other fields, e.g, CANDLES/UDS.7.Need to look at the 24um emission to check the possibility of obscured AGNs (from Leonidas’ mosaic?).4. Sub-millimeter follow-up with ALMA?, redshift and dust continuum
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Access to ALMA time?!