Evidence for photoionization-driven variability in narrow absorption lines

Lu, Wenjuan; Lin, Ying-Ru; Qin, Yi-Ping; Huang, Wei-Rong; Pan, Cai-Juan; Huang, Hong-Yan; Yao, Meiyi; Nong, Wei-Jing; Yao, Zhi-Kao; Lu, Mei-Mei; Pan, Da-Sheng; Huang, Hong-Qiang; Han, Qing-Lin

doi:10.1093/mnrasl/slx013

Cited by 14 publications

(6 citation statements)

References 41 publications

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“…Major evidence for ionization driven absorption line variability for a large sample of quasars are presented in Filiz Ak et al (2013); Wang et al (2015); He et al (2017); Lu et al (2017Lu et al ( , 2018. Using a sample of 291 quasars, Filiz Ak et al (2013) used the coordinated variations between different absorption components as a diagnostic for ionization driven BAL variability.…”

Section: Discussionmentioning

confidence: 99%

“…They concluded that BAL variabilities in 80 percent cases are driven by changes in the continuum. Lu et al (2017) adopted the method of Wang et al (2015) to study photo-ionization driven absorption line variability in a sample of 40 narrow absorption line quasars and reported a strong correlation between absorption line and continuum variability. Using the spectral flux at 1450 Å and 1700 Å, Lu et al (2018) reported moderate correlations between the fractional changes in the equivalent width and the continuum for a large sample of C iv and Si iv BALs.…”

Section: Discussionmentioning

confidence: 99%

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Ionization-driven intrinsic absorption line variability of BAL quasars in the Stripe 82 region

Vivek

2019

Monthly Notices of the Royal Astronomical Society

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We investigate the connection between the intrinsic C iv absorption line variability and the continuum flux changes of broad absorption line (BAL) quasars using a sample of 78 sources in the Stripe 82 region. The absorption trough variability parameters are measured using the archival multi-epoch spectroscopic data from the Sloan Digital Sky Survey (SDSS), and the continuum flux variability parameters are estimated from the photometric light curves obtained by the SDSS and the Catalina Real-Time Survey (CRTS) surveys. We find evidence for weak correlations (ρ s ∼ 0.3) between the intrinsic C iv absorption line variability and the quasar continuum variability for the final sample of 78 BAL quasars. The correlation strengths improve (ρ s ∼ 0.5) for the "high-SNR" sample sources that have higher spectral signal-to-noise ratio. Using two subsets of the high-SNR sample differing on the absorption trough depth, we find that the shallow trough sub-set shows an even stronger correlation (ρ s ∼ 0.6), whereas the deep trough sub-set does not show any correlation between the absorption line variability and the continuum variability. These results point to the important role of saturation effects in the correlation between the absorption line variability and the continuum variability of BAL quasars. Considering other effects that can also smear the correlation, we conclude that the actual correlation between the absorption line and continuum variability is even stronger.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Ionization-driven intrinsic absorption line variability of BAL quasars in the Stripe 82 region

Vivek

2019

Monthly Notices of the Royal Astronomical Society

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“…Recently, Lu et al (2017) have found a strong anticorrelation between the variations of NALs and that of the continuum, using a sample of two-epoch optical spectra of 40 quasars with 52 variable C iv λλ1548,1551 doublets (the sample is from Chen et al 2015). Now in this Letter, we find out the anticorrelation between the variations of BALs and the continuum too.…”

Section: Other Properties Of the Absorbersmentioning

confidence: 99%

Correlation between the variation of the ionizing continuum and broad absorption lines

Lin

Qin

2017

Monthly Notices of the Royal Astronomical Society: Letters

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In this Letter, we present an analysis of the relation between the variability of broad absorption lines (BALs) and that of the continuum. Our sample is multi-epoch observations of 483 quasars by the Sloan Digital Sky Survey-I/II/III (SDSS-I/II/III). We derive the fractional flux variations of the continuum and fractional equivalent width (EW) variations for C iv and Si iv BALs, and explore the correlations between the three. Our results reveal moderate anticorrelations with high significance level between the fractional flux variations of the continuum and fractional EW variations for both C iv and Si iv BALs. We also prove a significant positive correlation between the fractional EW variations for C iv and Si iv BALs, which is in agreement with several previous studies. Our discoveries can serve as evidence for the idea: Change of an ionizing continuum is the primary driver of BAL variability.

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“…Hamann et al 2008;Shi et al 2016;Hemler et al 2019) or the ionization variation of the outflowing gas (e.g. Grier et al 2015;Lu et al 2017;Lu et al 2018;Hemler et al 2019). Whichever of the above two reasons, BAL variation on short time-scales can Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…Gibson et al 2008;Wildy et al 2014;Vivek et al 2014), but several recent studies have provided evidence of anticorrelations between the variations of absorption lines and the continuum (e.g. Lu et al 2018;Lu & Lin 2018b for BAL;Lu et al 2017;Chen et al 2018b,a for NAL).…”

Section: Introductionmentioning

confidence: 99%

Correlation between the ionizing continuum and the variable C iv broad absorption line in multi-epoch observations of SDSS J141007.74+541203.3

Huang

Pan

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Correlation between the variations of quasar absorption lines and the ionizing continuum have been recently confirmed in systematic studies. However, no convincing individual case is reported. We present a statistical analysis of the variable C iv broad absorption line (BAL) in the quasar SDSS J141007.74+541203.3, which have been observed with 44 epochs by the Sloan Digital Sky Survey Data Release 14. Grier et al. (2015) has recently concluded that the most likely cause of the variability of the BAL in SDSS J141007.74+541203.3 is a rapid response to changes in the incident ionizing continuum. In this paper, we confirm the anticorrelation between the equivalent width of BALs and the flux of the continuum based on the spectra of this quasar that show significant variations, which serve as another independent evidence for the view of Grier et al. (2015).

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Evidence for photoionization-driven variability in narrow absorption lines

Cited by 14 publications

References 41 publications

Ionization-driven intrinsic absorption line variability of BAL quasars in the Stripe 82 region

Ionization-driven intrinsic absorption line variability of BAL quasars in the Stripe 82 region

Correlation between the variation of the ionizing continuum and broad absorption lines

Correlation between the ionizing continuum and the variable C iv broad absorption line in multi-epoch observations of SDSS J141007.74+541203.3

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