On the formation time scale of massive cluster ellipticals based on deep near-IR spectroscopy at z~2

Masayuki Tanaka (NAOJ)Sune Toft (DARK), Alexis Finoguenov (Helsinki),Mohammad Mirkazemi (MPE), Dave Wilman (MPE), John Mulchaey (Carnegie),Ueda Yoshihiro (Kyoto), Yongquan Xue (Penn State), Niel Brandt (Penn State),Danilo Marchesini (Tufts), Andrew Zirm (DARK), Carlos De Breuck (ESO), Tadayuki Kodama (NAOJ), Yusei Koyama (NAOJ), Jaron Kurk (MPE), Ichi Tanaka (NAOJ)

1 – stellar populations of galaxies in high-z groups/clusters

2 – formation timescale of massive cluster ellipticals

1 – A very low-mass group at z=1.61

A group of galaxies at z=1.61 in the Chandra Deep Field SouthTanaka et al. 2013 PASJ, 65, 17

Psuedo-color image based on ACS/WFC3 images from CANDELS

Note that this system is NOT the Kurk+09 system.

A group of galaxies at z=1.61 in the Chandra Deep Field SouthTanaka et al. 2013 PASJ, 65, 17

Psuedo-color image based on ACS/WFC3 images from CANDELS

M200 ~ 3x10^13 MsunA progenitor of today's cluster of typical mass

Note that this system is NOT the Kurk+09 system.

Color-magnitude diagram

Photo-z member candidates

Mags/Colors are from ACS/WFC3 from CANDELS.

Spectroscopically confirmed fg/bg galaxies.

Tanaka et al. 2013, PASJ, 65 17

Color-magnitude diagram

Photo-z member candidates

Mags/Colors are from ACS/WFC3 from CANDELS.

Spectroscopically confirmed fg/bg galaxies.

Tanaka et al. 2013, PASJ, 65 17

Surprisingly prominent red sequence!Bright members are almost exclusively red.- No MIPS detection of these red galaxies.- Most of these galaxies are early-type galaxies.- AGN fraction ~ 40%

Deep nearIR spectroscopy with MOIRCS

7 hours integration on one of the brightest members...

Object spectrum

Noise spectrum

Deep nearIR spectroscopy with MOIRCS

7 hours integration on one of the brightest members...Binnig helps reduce non-Gaussian noise due to sky residuals.

Object spectrum

Noise spectrum

Spectrophotometric fit

cD galaxy of the group. Note the large stellar mass.

Tanaka et al. in prep.

Spectrophotometric fit

Tanaka et al. in prep.

Compared to the field, galaxies in groups and clusters have

-- lower SFRs (this work)-- higher SFRs (Tran+ 2010, Joana’s talk)-- similar SFRs (Ziparo+ 2013)

Stellar populations in z~1.5 systems

There seems to be a large diversity in galaxy populations in high-z systemsWe should probably move on to do statistical work.

How do we get deep data over a large area?

2 – A forming cluster at z=2.16

PKS1138 at z=2.16

Tanaka, De Breuck, Venemans, Kurk et al. 2010 A&A

Koyama et al. 2013 MNRAS, 428, 1551

Spectrophotometric fits again...

We identified 11 proto-cluster members this way.

Tanaka et al. 2013 ApJ, 772, 113

Nascent red sequence

A bit busy plot, but the colored objects are likely members.Note that the quiescent galaxies lie on the reddest part of the red sequence.

Tanaka et al. 2013 ApJ, 772, 113

Stacked spectrum of the 4 quiescent galaxies

No strong emissoin lines and the galaxies are indeed quiescent.Possible CaIIH+K feature...?

Best-fit model spectrum shifted downwards for clarity

Atmospheric absorption

Tanaka et al. 2013 ApJ, 772, 113

Constraints on the formation time scale

Free parameters are :(1) formation redshift (or age), (2) extinction, (3) star formation time scale

(A) Location of the red sequence on a color-magnitude diagram:z_f ~ 4 (assums tau_v=0 and tau=0)

(B) Full spectral fitting:

(C) Dn4000 (insensitive to dust):tau <~ 0.5 Gyr

Affected by systematics in the zero points.

tv is forced to be 0

Affected by flux calibration uncertainty

Not strongly affected by flux calibration uncertainty

Formation timescale

Recent numerical simulations of early-type galaxy formation by Johansson et al. (2012) suggest the formation timescale of ~1.5Gyr.

Missing ingredients in sims? Or, high density environment is important?Of course the number suffers from uncertainty in SPS models.

e-folding timescale of ~1.5Gyr.

Hyper Suprime-Cam (HSC)1.5 deg diameter FoV

A 300-night survey with HSC has just started!

HSC-Wide: ~26-ish mags in grizy over 1400sqdegHSC-Deep: ~27-ish mags in grizy plus a few NBs over 28sqdegHSC-UltraDeep: ~27.5-ish mags in BB and several NBs over 3sqdeg

Weak-lensing cosmology, transients, MW and local galaxies, AGNs/QSOs at z>~6, galaxies, clusters, etc, etc.

Public data release planned every 1-2 years. So stay tuned!

Survey strategy

HSC-Wide1400 sq. deg.10-min in BB

HSC-Deep28 sq. deg.

2-4 hours in BB+NB

HSC-Ultra Deep3.5 sq. deg.

10-30 hours in BB+NB

g 10 hours 28.1r 10 hours 27.7i 20 hours 27.4z 27 hours 26.8y 27 hours 26.3

g 2 hours 27.5r 2 hours 27.1i 3 hours 26.8z 3 hours 26.0y 3 hours 25.3

g 10 min 26.7r 10 min 26.2i 20 min 26.0z 20 min 25.2y 20 min 24.4

Filter exp.time 2”mag. lim.

A weather factor is included in the mag limits for D and UD.

Target fields

Wide : Spring/Autumn equatorial region + HectoMAP region

Deep : XMM-LSS, E-COSMOS, ELAIS-N1, DEEP2-F3

UDeep : SXDS (XMM-LSS), COSMOS