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HEROs in an Overdense Region at z=2.4

HEROs in an Overdense Region at z=2.4. Myungshin Im (Seoul National University) & IRAC GTO team (PI: G. Fazio) Partial List of Collaborators: M. Pahre, H. Smith, S. Willner (SAO) + IRAC GTO. M. Lacy, F. Marleau, D. Fadda (SSC). What is HERO?.

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HEROs in an Overdense Region at z=2.4

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  1. HEROs in an Overdense Region at z=2.4 Myungshin Im (Seoul National University) & IRAC GTO team (PI: G. Fazio) Partial List of Collaborators: M. Pahre, H. Smith, S. Willner (SAO) + IRAC GTO. M. Lacy, F. Marleau, D. Fadda (SSC).

  2. What is HERO? According to the Cambridge International Dictionary of English, Hero, female also heroine (PERSON) noun[C] a person who is admired for having done something very brave or having achieved something great, or the main character in a book, film or play, esp., one who is admired for their good qualities. Hero, submarine sandwich (FOOD), noun[C] AMERICAN a long thin sandwich filed with cold meat, cheese, and salad. HERO, (OBJECT), noun[C] ASTRONOMY acronym for “Hyper Extremely Red Objet”. An astronomical object (very possibly a galaxy) which is invisible in the optical, and has a very red near-infrared (NIR) color (J-K > 3, Totani et al. 2001). ? August 2005, Lijiang, Extreme Starburst

  3. Actually, a Member of ERO (Extremely Red Object) Family… • (Normal) ERO: Optical – NIR Color Selected EROs (R-K > 5, I-K > 4 mag) – z > 1 • HERO (Hyper ERO): J-K > ~ 3.0 (Totani et al. 2001; Im et al. 2002) – z > 2.4 • IERO (IR-Selected ERO): IRAC-Color Selected EROs (Yan et al. 2004). • NERO (NIR-Selected ERO): J-K Red Galaxies – z > 1.5-2.0

  4. HERO (Hyper Extremely Red Object) J-K >~3mag z=2-3 old galaxy or z=2-3 dusty galaxy or z=10-13 LBG. Im et al. (2002) August 2005, Lijiang, Extreme Starburst

  5. Old Galaxy at High Redshift ERO Study was originally aimed to search for high-z massive, early-types. August2005, Lijiang, Extreme Starburst

  6. Young and Dusty Galaxy (Extreme Starburst?!) But, people realized that ERO population include many dusty starforming galaxies (~ 50%, e.g., Yan et al. 2004). August 2005, Lijiang, Extreme Starburst

  7. Infant Galaxy Shortly After Big Bang August 2005, Lijiang, Extreme Starburst

  8. Galaxy Formation in CDM Universe • Is is true that there are • very few massive, old • galaxies at high redshift? 2. When is the formation epoch of massive, old galaxies? 3. Is there any dependence on environment? (early formation in cluster?) Predictions: Fewer massive early-types at higher redshift. Earlier formation of massive objects in cluster environment.  Need for HEROs August 2005, Lijiang, Extreme Starburst

  9. 53W002 Field • 53W002 is a radio galaxy at z=2.4. • Lyman-alpha emitters at z ~ 2.4 in the vicinity of • 53W002 (Keel et al. 1999; Pascarelle et al. 1996; • Windhorst et al. 1997)  z=2.4 cluster of galaxies? • Recent observations reveal that this field contain • other interesting objects, such as submm galaxies • (Smail et al. 2002), and dozens of HEROs • (Hyper Extremely Red Objects; Im et al. 2002). Is this a high-z galaxy cluster? When did early-type galaxies form in cluster environment?

  10. Color-Magnitude Relation Im et al. (2005), from Palomar 5-m WIRC Obs. Z=3 Z=2 3 2.7 2 J-K Z=1 20 22 K August 2005, Lijiang, Extreme Starburst

  11. 53W002 vs. CDF-South 53W002 CDF-S J-K K (Vega) K (Vega) 18 vs 2 August 2005, Lijiang, Extreme Starburst

  12. Redshift Distribution(53W002) Overdensity at z ~ 2.4 ! (Keck LRIS-B: Colbert & Malkan 2005) August 2005, Lijiang, Extreme Starburst

  13. Spitzer Observation of the 53W002 Field (M. Pahre) 1 Hour Exposure in Each Passband (3.6, 4.5, 5.6, 8 micron). Field of View: 5x5 sq. arcmin. Sensitivity: 1 m Jy at 3.6 & 4.5 microns, 5 m Jy otherwise.

  14. Palomar WIRC Image (K, 2’ by 2’ Zoom-In) Green Circle: 53W002_HERO1 with K=21.5 mag 7 hrs on 5-m

  15. Spitzer IRAC Image (2’ by 2’ Zoom-In) 1 hr on 0.85m

  16. SED of HEROs 1 (Old or Dusty Galaxy at z ~ 2.4 • SED of the HERO is consistent with a moderately old galaxy at z ~ 2.4 • Stellar Mass of this object could be 1012 M_sun (Similar to Massive Galaxies at z=0 (Im et al. 2005, in preparation).

  17. SED of HEROs 2: AGN?

  18. SED of Lyman-alpha Emitters (z ~ 2.4) Submm 53W002 Fnu (uJy) Starforming Wavelength (micron)

  19. Conclusions • HEROs: -Not Lyman-break galaxies at z ~ 12. -Massive Red galaxies at z ~ 2.4 -Old or Dusty? Not Clear Yet. -Age > a few hundred Myrs (dusty). Age > 1Gyr (old) -E-like (3/11), AGN-like (3/11), Intermediate (5/11). • Lyman-alpha emitters: AGN or Young Gs (~ 50 – 100 Myr). • Spitzer Cycle 2 observation (MIPS 24) is underway to determine how dusty these HEROs and Lyman-alpha emitters are.

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