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The Build-up of the Red Sequence in High Redshift Galaxy Clusters
Pierluigi Cerulo (CAS), Warrick J. Couch (AAO), Chris Lidman (AAO)
+HAWK-I Cluster collaboration
INAF Ossevatorio Astronomico di Capodimonte18 November 2015
Outline of the Talk
1) Introduction: galaxy evolution and environment, clusters of galaxies
2) The Sample: the HAWK-I Cluster Survey (HCS)
3) Results: i) the Build-up of the Red Sequence in the HCS ii) Morphological Evolution of Red Sequence Galaxies iii) Formation Age of the Red Sequence (work in progress)
4) Summary and Future Directions
Clusters of Galaxies as Cosmic Laboratories
Abell 370 (z=0.375)
GOODS South Field
The colour-magnitude diagram
Cerulo et al. (2015a, submitted.)
The Build-up of the Red Sequence at z ~ 1
The Evolution of the Cluster Red Sequence
Merson et al. (2015)
Romeo et al. (2008)
Romeo et al. (2015)
The Role of Stellar Mass
ClG 0218 (z=1.62)
Rudnick et al. (2012)
The Scientific Questions
1) What are the processes responsible for the build-up of the red sequence in clusters of galaxies?
2) What are the evolutionary paths followed by galaxies with different morphologies on the red sequence?
3) When was the red sequence built up?
The HAWK-I Cluster Survey (HCS)
Lidman et al. (2013)Delaye et al. (2014)Cerulo et al. (2014)
Credit ESO
Credit: Pablo McLoud
Credit: Gemini Observatory
The WIde-field Nearby Galaxy cluster Survey(WINGS)
Abell 119 (z=0.044)
- 78 clusters at 0.04 < z < 0.08 imaged in up to 5 bands from near-UV (U) to near-IR (K) (Fasano et al. 2006)- 48 clusters followed up spectroscopically with WHT and the AAT (WINGS-SPE, Cava et al. 2009)
Catalogues and data are publicly available
http://www.aao.gov.au/about-us
Credit: A. Tudorica/ESO
RCS0220 (z=1.03)
RCS2319 (z=0.91)
RX0152 (z=0.84)
RCS2345 (z=1.04)
XMMU0223 (z=1.22)XMM1229 (z=0.98)
RDCS1252 (z=1.24)
XMMU2235 (z=1.39)
XMMXCS2215 (z=1.46)
The Build-up of the Cluster Red Sequence(Cerulo et al. 2015a submitted)
The Evolution of the Colour-Magnitude RelationI : red sequence zero-point (average colour)
Cerulo et al. (2015a) submitted
The Evolution of the Colour-Magnitude RelationII : red sequence slope
Cerulo et al. (2015a) submitted
The Evolution of the Colour-Magnitude RelationII : red sequence slope
Cerulo et al. (2015a) submitted
The Accelerated Build-up of the Cluster Red Sequence
The build-up of the red sequence in clusters (black symbols) is accelerated with respect to the field (blue symbols) at low stellar masses=> halo mass sets the time-scales for star-formation quenching and red sequence assembly (Cerulo et al. 2015a submitted)
The Accelerated Build-up of the Cluster Red Sequence
Haines et al. (2008)Clusters vs Field at z = 0
Cerulo et al. (2015a) submitted
The Red Sequence in Low and High Mass Clusters
Cerulo et al. (2015a) submitted
The bright end of the red sequence (Mv < -22.0 mag) appears more developed in high halo mass clusters.
S0
Late-type spirals +
irregulars
Ellipticals
Early-type spirals
- Visual + automated classification
- 4 independent classifications (3 visual + 1 software-based)
- Used ACS F850LP images and only galaxies with F850LP < 24.0 mag
- Automated classification performed using galSVM(Huertas-Company et al. 2008, 2011)
The Morphological Transformations of Red Sequence Galaxies
(Cerulo et al. 2015b in prep.)
See Cerulo et al. (2014) for details on morphological classification.
Morphological Evolution
Cerulo et al (2015b) in preparation
Morphological Evolution
Cerulo et al (2015b) in preparation
Elliptical galaxies dominate the red sequence at z=1, while the red sequence of the low-z comparison sample is dominated by elliptical galaxies at the bright end and by S0 galaxies at the faint end => faint S0 galaxies joined the red sequence at later epochs and are probably the result of the morphological transformation of quiescent spiral galaxies (red spirals).
See Cerulo et al. (2014) for a discussion on the bright elliptical galaxies in WINGS
Spectral Properties of Red Sequence Galaxies with Different Morphologies
Elliptical Galaxies
S0 Galaxies
RCS0220 (z=1.03) (GMOS-N)
WARNING: VERY PRELIMINARY!!!! ANALYSIS STILL ONGOING
S0 spectra (see CaII H and K lines, Rose 1985 Index) indicate that these galaxiesmay host younger stellar populations with respect to elliptical galaxies on the red sequence => S0 have a different, more recent origin
Morphological Evolution of Galaxies
Mei et al. (2009)
Tran et al. (2007)
0.8 < z < 1.3
Z=0.8
The Age-Scatter Test(Bower, Lucey & Ellis 1992)
The Age-Scatter Test(Bower, Lucey & Ellis 1992)
Romeo A., Cerulo P. et al. in preparation
The Age-Scatter Test(Bower, Lucey & Ellis 1992)
Summary and Conclusions
The red sequence of galaxy clusters appears to be already assembled at z=1.5 with a negative slope as observed at lower redshifts
The red sequence in the HCS clusters underwent an accelerated build-up
The most massive HCS clusters host a population of massive red sequence galaxies 0.5-1.0 mag brighter than the rest of the red sequence
The cluster red sequence at z~1 is dominated by elliptical galaxies at all luminosities and stellar masses, while at z~0.05 S0 galaxies become the predominant population at Mv > -21.0 mag
S0 galaxies seem to host younger stellar populations compared to elliptical galaxies <= VERY PRELIMINARY RESULT
Future Directions
Analysis of stellar populations on the HCS red sequence;
analysis of the infall regions (preprocessing);
collaboration with theoretical astrophysicists to allow a coherent picture of galaxy evolution in clusters to be built.
Co-evolution of Structure and Stellar Populations in Galaxies
Nantais et al. (2013) Fritz et al. (2014)
Thank you