Spectroscopic properties of radio-loud and radio-quiet quasars

Avinanda Chakraborty,Anirban Bhattacharjee

doi:10.1017/s1743921320002604

Avinanda Chakraborty, Anirban Bhattacharjee

Open Access

https://doi.org/10.1017/s1743921320002604

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Abstract

AbstractSurveys have shown radio-loud (RL) quasars constitute 10%-15% of the total quasar population and rest are radio-quiet (RQ). However, it is unknown if this radio-loud fraction (RLF) remains consistent among different parameter spaces. This study shows that RLF increases for increasing full width half maximum (FWHM) velocity of the Hβ broad emission line (z < 0.75). To analyse the reason, we compared bolometric luminosity of RL and RQ quasars sample which have FWHM of Hβ broad emission line greater than 15000km/s (High Broad Line or HBL) with which have FWHM of Hβ emission line less than 2500km/s (Low Broad Line or LBL). From the distributions we can conclude for the HBL, RQ and RL quasars are peaking separately and RL quasars are having higher values whereas for the LBL the peaks are almost indistinguishable. We predicted selection effects could be the possible reason but to conclude anything more analysis is needed. Then we compared our result with Wills & Brotherton (1995) and have shown that some objects from our sample do not follow the pattern of the logR vs FWHM plot where R is the ratio of 5 GHz radio core flux density with the extended radio lobe flux density.

Highlights

Quasars are the most luminous active galactic nuclei (AGN) and are powered by accretion of supermassive black holes (SMBHs) (Salpeter 1964; Lynden-Bell 1969)
Orientation of the quasars: to compare our result with other literature we looked for the ratio of 5 GHz core to extended component flux density R as a function of full width half maximum (FWHM) for the broad Hβ line for quasars plot of Wills & Browne (1986) From the plot we are getting high logR value for low FWHM
Our main goal is to investigate whether radio-loud fraction (RLF) is consistent across different parameter spaces and here we consider only broad Hβ lines

Summary

Introduction

Quasars are the most luminous active galactic nuclei (AGN) and are powered by accretion of supermassive black holes (SMBHs) (Salpeter 1964; Lynden-Bell 1969). (Jarvis & McLure 2006) These authors have presented a significant correlation between radio spectral index and broad-line width of the Hβ and Mg II emission lines ( 99.99%). These authors showed spectral index can be used as a proxy for source orientation. Van Gorkom et al 2015 compared between logR and logRv and two other indicators of orientation, the ratio of the optical continuum luminosity and emission-line luminosity (Yee & Oke (1978)) and the ratio of the jet power and the luminosity of the narrow-line region Rawlings & Saunders (1981)) It has been shown that normalizing the radio core luminosity by the optical continuum luminosity (logRv) (K-corrected) is a superior orientation indicator (Van Gorkom et al 2015). Van Gorkom et al 2015 compared between logR and logRv and two other indicators of orientation, the ratio of the optical continuum luminosity and emission-line luminosity (Yee & Oke (1978)) and the ratio of the jet power and the luminosity of the narrow-line region Rawlings & Saunders (1981))

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