Quasars Have Fewer Close Companions than Normal Galaxies

Abstract

We investigate the distribution of companion galaxies around quasars using {\em Hubble Space Telescope} ({\em HST}) Advanced Camera for Surveys Wide Field Camera (ACS/WFC) archival images. Our master sample contains 532 quasars which have been observed by {\em HST} ACS/WFC, spanning a wide range of luminosity $(-31<M_i(z=2)<-23)$ and redshift ($0.3<z<3$). We search for companions around the quasars with projected distance of $10\text{ kpc}<d<100\text{ kpc}$. PSF subtraction is performed to enhance the completeness for close companions. The completeness is estimated to be high $(>90\%)$ even for the faintest companions of interest. The number of physical companions is estimated by subtracting a background density from the number density of projected companions. We divide all the companions into three groups (faint, intermediate and bright) according to their fluxes. A control sample of galaxies is constructed to have similar redshift distribution and stellar mass range as the quasar sample using the data from {\em HST} deep fields. We find that quasars and control sample galaxies have similar numbers of faint and bright companions, while quasars show a $3.7\sigma$ deficit of intermediate companions compared to galaxies. The numbers of companions in all three groups do not show strong evolution with redshift, and the number of intermediate companions around quasars decreases with quasar luminosity. Assuming that merger-triggered quasars have entered the final coalescence stage during which individual companions are no longer detectable at large separations, our result is consistent with a picture in which a significant fraction of quasars is triggered by mergers.

arXiv comment18 pages, 10 figures, accepted by ApJ

References in corpus (46)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies
• The many lives of active galactic nuclei: cooling flows, black holes and the luminosities and colours of galaxies
• Energy input from quasars regulates the growth and activity of black holes and their host galaxies
• Detailed Structural Decomposition of Galaxy Images
• Modeling feedback from stars and black holes in galaxy mergers
• A Unified, Merger-Driven Model for the Origin of Starbursts, Quasars, the Cosmic X-Ray Background, Supermassive Black Holes and Galaxy Spheroids
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• The Photometric Performance and Calibration of the HST Advanced Camera For Surveys
• The Hyper Suprime-Cam SSP Survey: Overview and Survey Design
• 3D-HST WFC3-selected Photometric Catalogs in the Five CANDELS/3D-HST Fields: Photometry, Photometric Redshifts and Stellar Masses
• The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
• Massive Molecular Outflows and Evidence for AGN Feedback from CO Observations
• The SDSS Quasar Survey: Quasar Luminosity Function from Data Release Three
• The 3D-HST Survey: Hubble Space Telescope WFC3/G141 grism spectra, redshifts, and emission line measurements for $\sim 100,000$ galaxies
• 3D-HST: A wide-field grism spectroscopic survey with the Hubble Space Telescope
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• Galaxy Pairs in the Sloan Digital Sky Survey I: Star Formation, AGN Fraction, and the Luminosity/Mass-Metallicity Relation
• Quasars, their host galaxies, and their central black holes
• How Do Massive Black Holes Get Their Gas?
• The Sloan Digital Sky Survey Quasar Catalog: Fourteenth Data Release
• The Sloan Digital Sky Survey Quasar Catalog: twelfth data release
• The bulk of the black hole growth since z~1 occurs in a secular universe: No major merger-AGN connection
• CANDELS: Constraining the AGN-Merger Connection with Host Morphologies at z~2
• Galaxy pairs in the Sloan Digital Sky Survey - IV: Interactions trigger AGN
• Major Galaxy Mergers Only Trigger the Most Luminous AGN
• Galaxy pairs in the Sloan Digital Sky Survey - VIII: The observational properties of post-merger galaxies
• Galaxy Pairs in the 2dF Survey I. Effects of Interactions in the Field
• Galaxy pairs in the Sloan Digital Sky Survey - IX: Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer
• The Effect of Mass Ratio on the Morphology and Time-scales of Disc Galaxy Mergers
• AGN Host Galaxies at z~0.4-1.3 : Bulge-dominated and Lacking Merger-AGN Connection
• A Near-Infrared Spectral Template for Quasars
• Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey
• HST WFC3/IR Observations of Active Galactic Nucleus Host Galaxies at z~2: Supermassive Black Holes Grow in Disk Galaxies
• The VIMOS VLT Deep Survey :Evolution of the major merger rate since z~1 from spectroscopicaly confirmed galaxy pairs
• The impact of galaxy interactions on AGN activity in zCOSMOS
• Host galaxies of luminous z$\sim$0.6 quasars: Major mergers are not prevalent at the highest AGN luminosities
• Incidence of WISE-Selected Obscured AGNs in Major Mergers and Interactions from the SDSS
• The most-luminous heavily-obscured quasars have a high merger fraction: morphological study of WISE-selected hot dust-obscured galaxies
• The Pair Fraction of Massive Galaxies at 0 < z < 3
• The near-to-mid infrared spectrum of quasars
• Massive Star-Forming Host Galaxies of Quasars on Sloan Digital Sky Survey Stripe 82
• A study of AGN and supernova feedback in simulations of isolated and merging disc galaxies
• Mergers as triggers for nuclear activity: A near-IR study of the close environment of AGN in the VISTA-VIDEO survey
• Constraining AGN Feedback in Massive Ellipticals with South Pole Telescope Measurements of the Thermal Sunyaev-Zel'dovich Effect
• The Sloan Digital Sky Survey Reverberation Mapping Project: Quasar Host Galaxies at $z<0.8$ from Image Decomposition

Cited by in corpus (4)

• A significant excess in major merger rate for AGNs with the highest Eddington ratios at z<0.2
• Low-redshift quasars in the SDSS Stripe 82 II: associated companion galaxies and signature of star formation
• Exploring the environment, magnetic fields, and feedback effects of massive high-redshift galaxies with [CII]
• Galaxy and Mass Assembly (GAMA): Low-redshift Quasars and Inactive Galaxies Have Similar Neighbors