Minor Mergers are not enough: The importance of Major Mergers during Brightest Cluster Galaxy assembly

Abstract

We investigate the roles of major and minor mergers during brightest cluster galaxy (BCG) assembly using surface brightness profiles, line indices, and fundamental plane relations. Based on our own sample and consistently reanalyzed Sloan Digital Sky Survey data, we find that BCGs and luminous normal ellipticals (LNEs) have similar central velocity dispersions, central absorption line strengths, and central surface brightnesses. However, BCGs are more luminous due to their much larger radial extent. These properties result in a flattening of the Faber$-$Jackson and Mg${}_{\mathrm{b}}-$luminosity relations above 10${}^{10.6}$ L${}_{\odot ,g^{\prime }}$. We use this effect to estimate an amount of $60-80$ of accreted and merged light in BCGs relative to LNEs, which agrees with results from cosmological simulations. We determine the contribution of this excess light (EL) at each radius from the difference between the surface flux profiles of BCGs and LNEs. It is small in the center but increases steeply to 50% at $\sim$3 kpc radius. The shape of these profiles suggests that BCGs could be formed from LNEs in three major merger processes. This is also consistent with the mild increase of the Sérsic indices from $n\approx 4$ to $n\approx 6$, as confirmed in merger simulations. We note that minor mergers cannot be the dominant origin of the BCG's EL because they deposit too few stars at intermediate radii $r\lesssim 20$ kpc. The shape of the EL profile also explains a detected offset of 0.14 dex of the fundamental planes for BCGs and LNEs relative to each other.

40 pages, 20 figures, 10 tables. Accepted for publication in ApJS

References in corpus (51)

• The NumPy array: a structure for efficient numerical computation
• The hierarchical formation of the brightest cluster galaxies
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• astroquery: An Astronomical Web-Querying Package in Python
• Rotation-Dependent Catastrophic Disruption of Gravitational Aggregates
• The 1% Concordance Hubble Constant
• How special are Brightest Group and Cluster Galaxies?
• The Importance of Mergers for the Origin of Intracluster Stars in Cosmological Simulations of Galaxy Clusters
• The luminosities, sizes and velocity dispersions of Brightest Cluster Galaxies: Implications for formation history
• A catalogue of 2D photometric decompositions in the SDSS-DR7 spectroscopic main galaxy sample: preferred models and systematics
• Curvature in the scaling relations of early-type galaxies
• Brightest Cluster Galaxies at the Present Epoch
• Intracluster Light at the Frontier II: The Frontier Fields Clusters
• SDSS-IV DR17: Final Release of MaNGA PyMorph Photometric and Deep Learning Morphological Catalogs
• The Metallicity Distribution of Intracluster Stars in Virgo
• SDSS-IV MaNGA: Modeling the Spectral Line Spread Function to Sub-Percent Accuracy
• Spectroscopic Determination of the Faint End of the Luminosity Function in the Nearby Galaxy Clusters A2199 and Virgo
• The Cluster Velocity Dispersion of the Abell 2199 cD Halo of NGC 6166
• Photometric Properties and Scaling Relations of Early Type Brightest Cluster Galaxies
• 2DPHOT: A Multi-purpose Environment for the Two-dimensional Analysis of Wide-field Images
• The MASSIVE Survey - VIII. Stellar Velocity Dispersion Profiles and Environmental Dependence of Early-Type Galaxies
• The X-Shooter Spectral Library (XSL): Data Release 2
• The Fundamental Plane of Early Type Galaxies in Nearby Clusters from the WINGS Database
• Evidence for recent star formation in BCGs: a correspondence between blue cores and UV excess
• Stellar atmospheric parameters for 754 spectra from the X-shooter Spectral Library
• Photometric dissection of Intracluster Light and its correlations with host cluster properties
• The stellar halos of ETGs in the IllustrisTNG simulations: II. Accretion, merger history, and dark halo connection
• The growth of brightest cluster galaxies in the TNG300 simulation:dissecting the contributions from mergers and in situ star formation
• LRS2: the new facility low resolution integral field spectrograph for the Hobby-Eberly Telescope
• Discovery of a Possible Splashback Feature in the Intracluster Light of MACS J1149.5+2223
• Stellar splashback: the edge of the intracluster light
• Sloshing in its cD halo: MUSE kinematics of the central galaxy NGC 3311
• The Kormendy Relation for early-type galaxies. Dependence on the magnitude range
• Accreted or Not Accreted? The Fraction of Accreted Mass in Galaxies from Simulations and Observations
• Toward Understanding the origin of the Fundamental Plane for Early-Type Galaxies
• The Rising Stellar Velocity Dispersion of M87 from Integrated Starlight
• The Fundamental Plane for early-type galaxies. Dependence on the magnitude range
• Comparing PyMorph and SDSS photometry. I. Background sky and model fitting effects
• The sigma - L correlation in Nearby Early-Type Galaxies
• The Stellar Mass Fundamental Plane: The virial relation and a very thin plane for slow-rotators
• The Transition Region between Brightest Cluster Galaxies and Intra-Cluster Light in Galaxy Groups and Clusters
• Kinematics of the diffuse intragroup and intracluster light in groups and clusters of galaxies in the Local Universe within 100 Mpc distance
• Deep spectroscopy of nearby galaxy clusters: II. The Hercules cluster
• MaNGA galaxy properties -- I. An extensive optical, mid-infrared photometric, and environmental catalogue
• Velocity dispersion of the brightest cluster galaxies in cosmological simulations
• YZiCS: On the Mass Segregation of Galaxies in Clusters
• The Most Predictive Physical Properties for the Stellar Population Radial Profiles of Nearby Galaxies
• Galaxy And Mass Assembly (GAMA): Defining Passive Galaxy Samples and Searching for the UV Upturn
• A Trail of the Invisible: Blue Globular Clusters Trace the Radial Density Distribution of the Dark Matter -- Case Study of NGC 4278
• The Fundamental Plane Relation of Early-Type Galaxies: Environmental Dependence
• The Dragonfly Wide Field Survey. II. Accurate Total Luminosities and Colors of Nearby Massive Galaxies and Implications for the Galaxy Stellar Mass Function

Cited by in corpus (11)

• Euclid: Early Release Observations -- The intracluster light and intracluster globular clusters of the Perseus cluster
• Characterising the intra-cluster light in The Three Hundred simulations
• The supermassive black hole merger driven evolution of high-redshift red nuggets into present-day cored early-type galaxies
• Triaxial Schwarzschild Models of NGC 708: a 10-billion solar mass black hole in a low dispersion galaxy with a Kroupa IMF
• Euclid preparation LXX. Forecasting detection limits for intracluster light in the Euclid Wide Survey
• Major Mergers Mean Major Offset: Drivers of Intrinsic Scatter in The $M_{GCS}-M_h$ Scaling Relation for Massive Elliptical Galaxies
• Star Formation, Nebulae, and Active Galactic Nuclei in CLASH Brightest Cluster Galaxies. I. Dependence on Core Entropy of Intracluster Medium
• Two-phase formation of galaxies: the coevolution between galaxies and dark matter halos
• Emergence of the Galaxy Morphology-Star Formation Activity-Clustercentric Radius Relations in Galaxy Clusters
• Is there a tilt in the fundamental (hyper)plane?
• Time Delay Cosmography: Analysis of Quadruply Lensed QSO SDSSJ1433 from Wendelstein Observatory