Monitoring the Variability of Intrinsic Absorption Lines in Quasar Spectra, ,

Misawa, Toru; Charlton, Jane C.; Eracleous, Michael

doi:10.1088/0004-637x/792/1/77

Cited by 35 publications

(69 citation statements)

References 89 publications

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“…The dependence of changes or fractional changes in Wrλ1548 on time intervals has been observed for BALs and mini-BALs (e.g., Filiz Ak et al2013;Misawa et al 2014), finding that the larger changes or fractional changes in Wrλ1548 are usually detected over the longer time intervals. For NALs, Hacker et al (2013) observed obvious correlation between fractional changes in Wrλ1548 and time intervals, but did not between changes in Wr and time intervals.…”

Section: [O Iii]; [O Ii])mentioning

confidence: 86%

“…We adopt the method provided by Misawa et al (2014) to calculate the value of σcont as follows. The value of σcont is related to the product of the line width near the pseudo-continuum fitting (λmax − λmin) and fluctuations of the pseudo-continuum fittings (σ pf ), namely, σcont ∝ (λmax − λmin)σ pf .…”

Section: Quasar Sample and Spectral Analysismentioning

confidence: 99%

“…of two observations, distances of absorbers with respect to central regions of quasars, gaseous densities and sizes of absorbers (e.g., Sargent et al 1988;Steidel & Sargent 1991;Wild et al 2008;Capellupo et al 2013;Hacker et al 2013;Misawa et al 2014). Figure 6 displays the distribution of differences in Wrλ1548 versus time intervals between two observations at absorber rest frame for all narrow C IV absorption systems.…”

Section: The C Iv Absorbersmentioning

confidence: 99%

“…Intrinsic absorption lines can show all kinds of line widths and appear at a very wide range of speed, with respect to quasars, from 10 2 km s −1 to 10 5 km s −1 (e.g., Tombesi et al 2010Tombesi et al , 2011Tombesi et al , 2013Gupta et al 2013a,b;Chen & Qin 2013). In term of line widths, intrinsic absorption lines can be divided into three classes: (1) narrow absorption lines (NALs) whose line widths are similar to those of intervening and associated absorption lines (e.g., Wise et al 2004); (2) broad absorption lines (BALs) with absorption troughs exceed 2000 km s −1 below 10% continuum (Weymann et al 1991); and (3) mini-broad absorption lines (min-BALs) of which line widths are between NALs and BALs (e.g., Misawa et al 2007Misawa et al , 2014.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is difficult to distinguish intrinsic NALs from intervening and associated absorption lines in the same spectrum, especially in low or moderate resolution spectra. Many previous studies have revealed that intrinsic absorption lines can vary in equivalent width over timescales of months to years (e.g., Wise et al 2004;Narayanan et al 2004;Gibson et al 2008Gibson et al , 2010Hamann et al 2011;Hacker et al 2013;Chen & Qin 2013;Misawa et al 2014). The line variability is a good indicator to determine whether NALs are truly intrinsic to quasars or not.…”

Section: Introductionmentioning

confidence: 99%

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Narrow absorption lines with two observations from the Sloan Digital Sky Survey

Chen¹,

Gu²,

Chen³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We assemble 3524 quasars from Sloan Digital Sky Survey (SDSS) with repeated observations to search for variations of narrow C IVλλ1548, 1551 and Mg IIλλ2796, 2803 absorption doublets in spectral regions shortward of 7000Å at the observed frame, which corresponds to time-scales of about 150 ∼ 2643 days at quasar rest frame. In these quasar spectra, we detect 3580 C IV absorption systems with z abs = 1.5188 ∼ 3.5212, and 1809 Mg II absorption systems with z abs = 0.3948 ∼ 1.7167. In term of the absorber velocity (β) distribution at quasar rest frame, we find a substantial number of C IV absorbers with β < 0.06, which might be connected to the absorptions of quasar outflows. The outflow absorptions peak at υ ≈ 2000 km s −1 and drop rapidly below the peak value. Among 3580 C IV absorption systems, 52 systems (∼ 1.5%) show obvious variations in equivalent widths at the absorber rest frame (W r ): 16 enhanced, 16 emerged, 12 weaken, and 8 disappeared systems, respectively. We find that changes in W r λ1548 are neither related to time-scales of the two SDSS observations, nor to absorber velocities at the quasar rest frame. Variable absorptions in low-ionization species are important to constraint the physical conditions of absorbing gas. There are two variable Mg II absorption systems measured from SDSS spectra detected by Hacker et al. However, in our Mg II absorption sample, we find that neither shows variable absorption with confident levels of > 4σ for λ2796 lines and > 3σ for λ2803 lines.

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Section: [O Iii]; [O Ii])mentioning

confidence: 86%

Section: Quasar Sample and Spectral Analysismentioning

confidence: 99%

Section: The C Iv Absorbersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Narrow absorption lines with two observations from the Sloan Digital Sky Survey

Chen¹,

Gu²,

Chen³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Time variations of narrow absorption lines in high resolution quasar spectra

Boissé

Bergeron

Prochaska

et al. 2015

A&A

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Aims. We have searched for temporal variations of narrow absorption lines in high resolution quasar spectra. A sample of five distant sources were assembled, for which two spectra are available, either VLT/UVES or Keck/HIRES, which were taken several years apart. Methods. We first investigate under which conditions variations in absorption line profiles can be detected reliably from high resolution spectra and discuss the implications of changes in terms of small-scale structure within the intervening gas or intrinsic origin. The targets selected allow us to investigate the time behaviour of a broad variety of absorption line systems by sampling diverse environments: the vicinity of active nuclei, galaxy halos, molecular-rich galaxy disks associated with damped Lyα systems, as well as neutral gas within our own Galaxy.Results. Intervening absorption lines from Mg ii, Fe ii, or proxy species with lines of lower opacity tracing the same kind of (moderately ionised) gas appear in general to be remarkably stable (1σ upper limits as low as 10% for some components on scales in the range 10-100 au), even for systems at z abs ≈ z e . Marginal variations are observed for Mg ii lines towards PKS 1229−021 at z abs = 0.83032; however, we detect no systems that display any change as large as those reported in low resolution SDSS spectra.The lack of clear variations for low β Mg ii systems does not support the existence of a specific population of absorbers made of sweptup gas towards blazars. In neutral or diffuse molecular media, clear changes are seen for Galactic Na i lines towards PKS 1229−02 (decrease in N by a factor of four for one of the five components over 9.7 yr), corresponding to structure on a scale of about 35 au, in good agreement with known properties of the Galactic interstellar medium. Tentative variations are detected for H 2 J = 3 lines towards FBQS J2340−0053 at z abs = 2.05454 ( 35% change in column density, N, over 0.7 yr in the rest frame), suggesting there is structure at the 10 au-scale for this warm molecular gas. A marginal change is also seen in C i from another velocity component of the same absorption system ( 70% variation in N(C i).

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SALT long-slit spectroscopy of quasar HE 0435-4312: fast displacement of the Mg II emission line

Šredzińska

Hryniewicz

Krupa

et al. 2017

A&A

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Context. The Mg II emission line is visible in the optical band for intermediate redshift quasars (0.4 < z < 1.6) and it is thus an extremely important tool to measure the black hole mass and to understand the structure of the Broad Line Region. Aims. We aim to determine the substructure and the variability of the Mg II line with the aim to identify which part of the line comes from a medium in Keplerian motion. Methods. Using the Southern African Large Telescope (SALT) with the Robert Stobie Spectrograph (RSS) we performed ten spectroscopic observations of quasar HE 0435-4312 (z = 1.2231) over a period of three years (Dec 23/24, 2012 to Dec 7/8, 2015. Results. Both the Mg II line and the Fe II pseudo-continuum increase with time. We clearly detect the systematic shift of the Mg II line with respect to the Fe II over the years, corresponding to the acceleration of 104 ± 14 km s −1 year −1 in the quasar rest frame. The Mg II line shape is clearly non-Gaussian but single-component, and the increase in line equivalent width and line shift is not accompanied with significant evolution of the line shape. We analyse the conditions in the Mg II and Fe II formation region and we note that the very large difference in the covering factor and the turbulent velocity also support the conclusion that the two regions are spatially separated. Conclusions. The measured acceleration of the line systematic shift is too large to connect it with the orbital motion at a distance of the Broad Line Region (BLR) in this source. It may imply a precessing inner disk illuminating the BLR. Further monitoring is still needed to better constrain the variability mechanism.

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Monitoring the Variability of Intrinsic Absorption Lines in Quasar Spectra, ,

Cited by 35 publications

References 89 publications

Narrow absorption lines with two observations from the Sloan Digital Sky Survey

Narrow absorption lines with two observations from the Sloan Digital Sky Survey

Time variations of narrow absorption lines in high resolution quasar spectra

SALT long-slit spectroscopy of quasar HE 0435-4312: fast displacement of the Mg II emission line

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