In this study, we investigated the orientation model of Broad Absorption Line (BAL) quasars using a sample of sources that are common in Sloan Digital Sky Survey (SDSS) Data Release (DR)-16 quasar catalogue and Very Large Array (VLA)-Faint Images of the Radio Sky at Twenty Centimeters (FIRST) survey. Using the radio cut-out images from the FIRST survey, we first designed a deep-learning model using convolutional neural networks (CNN) to classify the quasar radio morphologies into the core-only, young jet, single lobe, or triples. These radio morphologies are further sub-classified into core-dominated and lobe-dominated sources. The CNN models can classify the sources with a high precision of >98 $${{\ \rm per\ cent}}$$ for all the morphological sub-classes. The average BAL fraction in the resolved core, core-dominated, and lobe-dominated quasars are consistent with the BAL fraction inferred from radio and infrared surveys. We also present the distribution of BAL quasars as a function of quasar orientation by using the radio core-dominance as an orientation indicator. A similar analysis is performed for HiBALs, LoBALs, and FeLoBALs. All the radio morphological sub-classes and BAL sub-classes show an increase in BAL fraction at high orientation angles of the jets with respect to the line of sight. Our analysis suggests that BAL quasars are more likely to be found in viewing angles close to the equatorial plane of the quasar. However, a pure orientation model is inadequate, and a combination of orientation and evolution is probably the best way to explain the complete BAL phenomena.
Nair, A. and Vivek, M.. "Fraction of broad absorption line quasars in different radio morphologies." Monthly Notices of the Royal Astronomical Society, vol. 511, no. 4, Jan. 2022. https://doi.org/10.1093/mnras/stac204
Nair, A., & Vivek, M. (2022). Fraction of broad absorption line quasars in different radio morphologies. Monthly Notices of the Royal Astronomical Society, 511(4). https://doi.org/10.1093/mnras/stac204
Nair, A., and Vivek, M., "Fraction of broad absorption line quasars in different radio morphologies," Monthly Notices of the Royal Astronomical Society 511, no. 4 (2022), https://doi.org/10.1093/mnras/stac204
@article{osti_1847194,
author = {Nair, A. and Vivek, M.},
title = {Fraction of broad absorption line quasars in different radio morphologies},
annote = {ABSTRACT In this study, we investigated the orientation model of Broad Absorption Line (BAL) quasars using a sample of sources that are common in Sloan Digital Sky Survey (SDSS) Data Release (DR)-16 quasar catalogue and Very Large Array (VLA)-Faint Images of the Radio Sky at Twenty Centimeters (FIRST) survey. Using the radio cut-out images from the FIRST survey, we first designed a deep-learning model using convolutional neural networks (CNN) to classify the quasar radio morphologies into the core-only, young jet, single lobe, or triples. These radio morphologies are further sub-classified into core-dominated and lobe-dominated sources. The CNN models can classify the sources with a high precision of >98 ${{\ \rm per\ cent}}$ for all the morphological sub-classes. The average BAL fraction in the resolved core, core-dominated, and lobe-dominated quasars are consistent with the BAL fraction inferred from radio and infrared surveys. We also present the distribution of BAL quasars as a function of quasar orientation by using the radio core-dominance as an orientation indicator. A similar analysis is performed for HiBALs, LoBALs, and FeLoBALs. All the radio morphological sub-classes and BAL sub-classes show an increase in BAL fraction at high orientation angles of the jets with respect to the line of sight. Our analysis suggests that BAL quasars are more likely to be found in viewing angles close to the equatorial plane of the quasar. However, a pure orientation model is inadequate, and a combination of orientation and evolution is probably the best way to explain the complete BAL phenomena.},
doi = {10.1093/mnras/stac204},
url = {https://www.osti.gov/biblio/1847194},
journal = {Monthly Notices of the Royal Astronomical Society},
issn = {ISSN 0035-8711},
number = {4},
volume = {511},
place = {United Kingdom},
publisher = {Oxford University Press},
year = {2022},
month = {01}}
US Department of Energy (USDOE), Washington, DC (United States). Office of Science, Sloan Digital Sky Survey (SDSS); University of Mumbai (India)
Sponsoring Organization:
Alfred P. Sloan Foundation; USDOE; USDOE Office of Science (SC); University of Utah
OSTI ID:
1847194
Alternate ID(s):
OSTI ID: 1982641
Journal Information:
Monthly Notices of the Royal Astronomical Society, Journal Name: Monthly Notices of the Royal Astronomical Society Journal Issue: 4 Vol. 511; ISSN 0035-8711