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 pcerulo@astro.swin.edu.au INAF Ossevatorio Astronomico di Capodimonte 18 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 GOODS South Field Abell 370 (z=0.375)
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 Romeo et al. (2008) Merson et al. (2015)
The Role of Stellar Mass ClG 0218 (z=1.62) Romeo et al. (2015) 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) Credit ESO Credit: Pablo McLoud Credit: Gemini Observatory Lidman et al. (2013) Delaye et al. (2014) Cerulo et al. (2014)
The WIde-field Nearby Galaxy cluster Survey (WINGS) Credit: A. Tudorica/ESO http://www.aao.gov.au/about-us 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
RX0152 (z=0.84) RCS0220 (z=1.03) RDCS1252 (z=1.24) RCS2319 (z=0.91) RCS2345 (z=1.04) XMMU2235 (z=1.39) XMM1229 (z=0.98) XMMU0223 (z=1.22) XMMXCS2215 (z=1.46)
The Build-up of the Cluster Red Sequence (Cerulo et al. 2015a submitted)
The Evolution of the Colour-Magnitude Relation I : red sequence zero-point (average colour) Cerulo et al. (2015a) submitted
The Evolution of the Colour-Magnitude Relation II : red sequence slope Cerulo et al. (2015a) submitted
The Evolution of the Colour-Magnitude Relation II : 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 Cerulo et al. (2015a) submitted Haines et al. (2008) Clusters vs Field at z = 0
The Red Sequence in Low and High Mass Clusters The bright end of the red sequence (Mv < -22.0 mag) appears more developed in high halo mass clusters. Cerulo et al. (2015a) submitted
The Morphological Transformations of Red Sequence Galaxies (Cerulo et al. 2015b in prep.) Ellipticals S0 Early-type spirals Late-type spirals + irregulars - 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) 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 RCS0220 (z=1.03) (GMOS-N) Elliptical Galaxies S0 Galaxies WARNING: VERY PRELIMINARY!!!! ANALYSIS STILL ONGOING S0 spectra (see CaII H and K lines, Rose 1985 Index) indicate that these galaxies may host younger stellar populations with respect to elliptical galaxies on the red sequence => S0 have a different, more recent origin
Morphological Evolution of Galaxies 0.8 < z < 1.3 Z=0.8 Mei et al. (2009) Tran et al. (2007)
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