1. 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

2. 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 starlightdust re-radiation Reddy et al. 2011 UV luminosity density dust-corrected SFR

3. At z > 3, the 4000Å 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:

4. 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?

5. 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?

6. Why CLASH data? 1.Deep WFC3 H-band images (27.5, 5σ) over 25 clusters, covering nearly 120 square arcmin 2.Deep IRAC ([3.6]+[4.5]um) imaging (5σ depth >24 mag) 3.Multi-wavelength HST+Spitzer observations allow for constrains on the SED 4.Cluster lensing helps to probe the intrinsically faint candidates 5.Wealth of existing and ongoing follow-up observations in other bands

7. [4.5um]<24.4, 4sigma H160w>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

8. z = 3.77 A V = 1.5 age = 1.58 Gyr  = 0.25 Gyr M * = 1.0x10 11 M sun Av-redshift contour plane

9. z = 4.82 A V = 1.1 age = 1.0 Gyr  = 0.25 Gyr M * = 8.9x10 11 M sun Or z = 1.11 A V = 7.8 age = 25 Myr  = 0.1 Gyr M * = 6.3x10 9 M sun, F160w IRAC

10. Can Herschel be helpful to constrain the SED? 1

11. 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 160um250um 350um 500um F606 F814 F125 F160 [3.6] um [4.5] um Candels /UDS

12. 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

13. z=4, confirmed from CO

14. Summary and future work Summary: 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: 1.Inspect whether the H-dropouts are lensed by clusters if they are at z~4. 2.Compare the physical properties of the H-dropouts (z, mass, morphology, size, color, environment, etc) to that in other fields, e.g, CANDLES/UDS. 3.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

15. Access to ALMA time?!