Appearance versus disappearance of broad absorption line troughs in quasars

Mishra, Sapna; Vivek, M.; Chand, Hum; Joshi, Ravi

doi:10.1093/mnras/stab782

Cited by 11 publications

(5 citation statements)

References 63 publications

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“…The changes in the line of sight gas distribution is also suggested in the case of BAL-B and BAL-C through the presence of rapidly varying narrow absorption components as discussed above. Mishra et al (2021) have found the newly appeared BALs are associated with dimming of the quasars. Interestingly, the emergence of BAL-C happens close to the dimming episode in the lightcurve of J1322 + 0524 (see Fig.…”

Section: Photometric Variability Of J1322 + 0524mentioning

confidence: 93%

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Coordinated time variability of multi-phase ultra-fast outflows in J132216.25+052446.3

Aromal,

Srianand,

Petitjean

2022

Preprint

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We present a time variability analysis of broad absorption lines (BAL; spread over the velocity range of 5800-29000 km s −1 ) seen in the spectrum of J132216.25+052446.3 (𝑧 em = 2.04806) at ten different epochs spanning over 19 years. The strongest absorption component (BAL-A; spread over 5800-9900 km s −1 ) is made up of several narrow components having velocity separations close to C doublet splitting. The C , N and Si absorption from BAL-A show correlated optical depth variability without major changes in the velocity structure. A very broad and shallow absorption (BAL-C; spread over the velocity range 15000-29000 km s −1 ) emerged during our monitoring period coinciding with a dimming episode of J1322+0524. All the identified absorption lines show correlated variability with the equivalent widths increasing with decreasing flux. This together with the C emission line variability is consistent with ionization being the main driver of the correlated variability. The observed UV-continuum variations are weaker than what is required by the photo-ionization models. This together with a scatter in the C equivalent width at a given continuum flux can be understood if variations of the C ionizing photons are much larger than that of the UV continuum, the variations in the ionizing photon and UV fluxes are not correlated and/or the covering factor of the flow varies continuously. We suggest BAL-A is produced by a stable clumpy outflow located beyond the broad emission line region and BAL-C is a newly formed wind component located near the accretion disk and both respond to changes in the ionizing continuum.

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Section: Photometric Variability Of J1322 + 0524mentioning

confidence: 93%

“…13). Mishra et al (2021) interpreted the appearence of a new BAL component as the consequence of lower ionization. Alternatively, it is possible that both the dimming and BAL emergence can be related to changes in the accretion disk structure (see Vivek et al 2012, for discussions in the case of J1333+0012).…”

Section: Photometric Variability Of J1322 + 0524mentioning

confidence: 99%

Coordinated time variability of multi-phase ultra-fast outflows in J132216.25+052446.3

Aromal,

Srianand,

Petitjean

2022

Preprint

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“…The wind and jet connection from Mehdipour & Costantini (2019) cannot be due to synchronous effects, although the overall history of the AGN could be the connection. Studies of disappearing and appearing BALQSOs (De Cicco et al 2017;Mishra et al 2021) have placed the variational time scale for BALQSO winds, on the order of hundreds of years, to be much shorter than that of radio jets, on the order of Myrs. Therefore the BI to detection fraction correlation lacks the synchronicity one might expect in the evolutionary theory.…”

Section: Radio Interpretationmentioning

confidence: 99%

Connecting radio emission to AGN wind properties with Broad Absorption Line Quasars

Petley¹,

Morabito²,

Alexander³

et al. 2022

Preprint

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Broad Absorption Line Quasars (BALQSOs) show strong signatures of powerful outflows, with the potential to alter the cosmic history of their host galaxies. These signatures are only seen in ∼10% of optically selected quasars, although the fraction significantly increases in IR and radio selected samples. A proven physical explanation for this observed fraction has yet to be found, along with a determination of why this fraction increases at radio wavelengths. We present the largest sample of radio matched BALQSOs using the LOFAR Two-metre Sky Survey Data Release 2 and employ it to investigate radio properties of BALQSOs. Within the DR2 footprint, there are 3537 BALQSOs from Sloan Digital Sky Survey DR12 with continuum signal to noise ≥ 5. We find radio-detections for 1108 BALQSOs, with an important sub-population of 120 LoBALs, an unprecedented sample size for radio matched BALQSOs given the sky coverage to date. BALQSOs are a radio-quiet population that show an increase of ×1.50 radio-detection fraction compared to non-BALQSOs. LoBALs show an increase of ×2.22 that of non-BALQSO quasars. We show that this detection fraction correlates with wind-strength, reddening and C emission properties of BALQSOs and that these features may be connected, although no single property can fully explain the enhanced radio detection fraction. We create composite spectra for sub-classes of BALQSOs based on wind strength and colour, finding differences in the absorption profiles of radio-detected and radio-undetected sources, particularly for LoBALs. Overall, we favour a wind-ISM interaction explanation for the increased radio-detection fraction of BALQSOs.

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“…The presence of high-velocity outflows from AGN can be established from the evidence provided by the blue-shifted broad absorption lines (BALs) seen in the spectra of 10-20% of quasi-stellar objects (QSOs) 1 (Weymann et al 1991). BALQSOs are classified into three sub-classes based on the ionization state of the absorbing gas:(a) high-ionization BALQSOs (Hi-BALs) consists of absorption from high-ionization lines such as C , Si , and N (Gibson et al 2008;Filiz Ak et al 2013;Vivek et al 2016;Vivek 2019;Mishra et al 2021) (b) low-ionization BALQSOs (LoBALs) show absorption from low-ionization lines such as Mg and Al along with the high-ionization lines (Voit et al 1993;Vivek et al 2014Vivek et al , 2018Yi et al 2019), and (c) iron-LoBALs (FeLoBALs) are LoBALs with excited fine-structure Fe and/or Fe absorption lines (Vivek et al 2012;McGraw et al 2015). The observed BALQSO fraction is explained either by an orientation model, where the line of sight intersects with the BAL absorbing clouds in 10-20% QSOs (Weymann et al 1991;Elvis 2000), or an evolutionary model, where the QSO spends 10-20% of its lifetime in the BALQSO phase (Farrah et al 2007;Lipari et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Fraction of broad absorption line quasars in different radio morphologies

Nair,

Vivek

2022

Preprint

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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 catalog 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% 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 infra-red 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.

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Appearance versus disappearance of broad absorption line troughs in quasars

Cited by 11 publications

References 63 publications

Coordinated time variability of multi-phase ultra-fast outflows in J132216.25+052446.3

Coordinated time variability of multi-phase ultra-fast outflows in J132216.25+052446.3

Connecting radio emission to AGN wind properties with Broad Absorption Line Quasars

Fraction of broad absorption line quasars in different radio morphologies

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