What is the origin of the stacked radio emission in radio-undetected quasars?: Insights from a radio-infrared image stacking analysis

Abstract

Radio emission in the brightest radio quasars can be attributed to processes inherent to SMBHs, while the origins of the radio fluxes in quasars without radio detections is still uncertain. We investigate the radio-infrared continuum of LOFAR radio-detected quasars (RDQs) and LOFAR radio-undetected quasars (RUQs) in the $9.3{\text{deg}}^2$ NDWFS-Boötes field; RUQs are quasars that are individually undetected at $\ge 5\sigma$ by LOFAR. We used a median image stacking procedure. This was done in the frequencies of 150 MHz, 325 MHz, 1.4 GHz and 3.0 GHz, and in nine infrared (ir) bands between $8$ and $500\mu \text{m}$. The radio and ir photometry allow us to derive the median spectral energy distributions of RDQs and RUQs in four z-bins between $0<z<6.15$. The ir star-formation rate (SFR) is compared with two independent radio-based star-formation (SF) tracers using the far-ir radio correlation (FIRC) of SF galaxies. We find a good agreement between our radio and ir SFR measurements and the FIRC predictions. Moreover, we use the FIRC predictions to establish the contribution due to SMBH accretion to the total radio-luminosity (RL). We show that SMBH accretion can account for $\sim 5-41\%$ of the total RL in median RUQs, while for median RDQs the contribution is $\sim 50-84\%$. This implies that vigorous SF activity is coeval with SMBH growth in our median stacked quasars. Furthermore, we investigated the radio-loudness parameter, $R$. For quasars with $R\ge -4.5$, the RL is consistent with being dominated by SMBH accretion, while for low RL quasars with $R<-4.5$ the relative contribution of SF to the radio fluxes increases as the SMBH component becomes weaker. We also find signatures of negative AGN feedback in the brightest median RDQs at 150 MHz. Finally, we found that spectral indices of quasars do not evolve significantly with z, but they become flatter towards lower freqs.

Accepted by A&A

References in corpus (52)

• Star Formation in AEGIS Field Galaxies since z=1.1 : The Dominance of Gradually Declining Star Formation, and the Main Sequence of Star-Forming Galaxies
• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• The Co-Evolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• Hot and cold gas accretion and feedback in radio-loud active galaxies
• Extreme gas kinematics in the z=2.2 powerful radio galaxy MRC1138-262: Evidence for efficient AGN feedback in the early Universe?
• The Radio-Loud Fraction of Quasars is a Strong Function of Redshift and Optical Luminosity
• On the origin of radio emission in radio quiet quasars
• Signals from the Noise: Image Stacking for Quasars in the FIRST Survey
• The Spitzer Deep, Wide-Field Survey
• Star Formation at $4<z<6$ From the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH)
• The Star Formation Main Sequence in the Hubble Space Telescope Frontier Fields
• The Blast Wave Model for AGN Feedback: Effects on AGN Obscuration
• The faint radio sky: radio astronomy becomes mainstream
• The far-infrared/radio correlation and radio spectral index of galaxies in the SFR-M* plane up to z 2
• The Half Million Quasars (HMQ) Catalogue
• Minkowski's Object: A Starburst Triggered by a Radio Jet, Revisited
• ALMA Observations Show Major Mergers Among the Host Galaxies of Fast-growing, High-redshift Supermassive Black Holes
• The radio structure of radio-quiet quasars
• The 1.28 GHz MeerKAT DEEP2 Image
• The Lockman Hole project: LOFAR observations and spectral index properties of low-frequency radio sources
• The mean star formation rates of unobscured QSOs: searching for evidence of suppressed or enhanced star formation
• The MOSDEF survey: AGN multi-wavelength identification, selection biases and host galaxy properties
• The WISSH quasars Project: II. Giant star nurseries in hyper-luminous quasars
• Fundamental differences in the radio properties of red and blue quasars: evolution strongly favoured over orientation
• Radio-Quiet Quasars in the VIDEO Survey: Evidence for AGN-powered radio emission at S_1.4GHz < 1 mJy
• Star formation in z>1 3CR host galaxies as seen by Herschel
• Evidence that the AGN dominates the radio emission in z ~ 1 radio-quiet quasars
• The Discovery of Three New z>5 Quasars in the AGN and Galaxy Evolution Survey
• Identifying the subtle signatures of feedback from distant AGN using ALMA observations and the EAGLE hydrodynamical simulations
• Correlations of Quasar Optical Spectra with Radio Morphology
• Fundamental differences in the radio properties of red and blue quasars: enhanced compact AGN emission in red quasars
• No signs of star formation being regulated in the most luminous quasars at z~2 with ALMA
• An ALMA CO(2-1) Survey of Nearby Palomar-Green Quasars
• Extreme star formation events in quasar hosts over $0.5<\text{z}<4$
• A Multi-wavelength Analysis of the Faint Radio Sky (COSMOS-XS): the Nature of the Ultra-faint Radio Population
• Herschel-ATLAS: Far-infrared properties of radio-loud and radio-quiet quasars
• An Investigation into the Effects of Luminosity on the Mid-Infrared Spectral Energy Distributions of Radio-Quiet Quasars
• Strong lensing reveals jets in a sub-microJy radio quiet quasar
• 325-MHz observations of the ELAIS-N1 field using the Giant Metrewave Radio Telescope
• Fundamental differences in the radio properties of red and blue quasars: Insight from the LOFAR Two-metre Sky Survey (LoTSS)
• Completing the Census of AGN in GOODS-S/HUDF: New Ultra-Deep Radio Imaging and Predictions for JWST
• LOFAR low-band antenna observations of the 3C295 and Bootes fields: source counts and ultra-steep spectrum sources
• Radio source stacking and the infrared / radio correlation at microJy flux densities
• Radio Detection of Radio-Quiet Galaxies
• PKS2250-41: a case study for triggering
• The PEP Survey: Infrared Properties of Radio-Selected AGN
• Observational evidence that positive and negative AGN feedback depends on galaxy mass and jet power
• VLA and ALMA observations of the lensed radio-quiet quasar SDSS J0924+0219: a molecular structure in a 3 microJy radio source
• The role of galaxy mass on AGN emission: a view from the VANDELS survey
• SMM J04135+10277: A distant QSO-starburst system caught by ALMA
• The optical luminosity function of LOFAR radio-selected quasars at $1.4\le z\le 5.0$ in the NDWFS-Boötes field

Cited by in corpus (2)

• Star formation history of $0.1\le \text{z}\le 1.5$ mass-selected galaxies in the ELAIS-N1 Field
• Wide-field GMRT imaging of X-shaped Radio-Galaxies: Spectral properties of 4C32.25 and 4C61.23