Broad Absorption Line Disappearance/Emergence in Multiple Ions in a Weak Emission-line Quasar

Yi, Wu; Vivek, M.; Brandt, W. N.; Wang, T.; Timlin, John; Ak, Nurten Filiz; Schneider, Donald P.; Fynbo, J. P. U.; Ni, Quan Xing; Vito, F.; Indahl, Briana L.; Sameer,

doi:10.3847/2041-8213/aafc1d

Cited by 18 publications

(44 citation statements)

References 57 publications

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“…Indeed, the recent spectrum obtained by Gemini/GMOS at MJD=58486 revealed a new Si iv BAL emerging within a very short timescale (<100 d in the quasar rest frame) after the C iv BAL emergence at the same velocity (see Fig. 2); furthermore, the lack of BAL emergence in Al iii or Mg ii confirms that the low-/high-velocity BAL absorbers most likely arise from two distinct locations along our LOS, as reported in Yi et al (2019b). The six-epoch sampling data enable the BAL-profile variability to be robustly traced (see Fig.…”

Section: J082747 and J235253supporting

confidence: 83%

“…For clarity, all the spectra were normalized at 3000 Å with a suitable smoothing. We note that the quasar (J082747) with both BAL disappearance and emergence was reported in Yi et al (2019b). In this work, we directly adopt the spectral measurements for the six quasars showing BAL transitions from the two previous studies and complement them with additional spectroscopic observations (the last sampling epoch spectrum for each quasar).…”

Section: Spectral Measurements and Bal-disappearance/emergence Criteriamentioning

confidence: 99%

“…Fortunately, they all have HiBALs and LoBALs at the same velocity, which provides valuable diagnostics to explore the nature of BAL outflows (e.g., Arav et al 2001;Moe et al 2009;Leighly et al 2019;Yi et al 2019a). Furthermore, the inner structure and physics of BAL outflows, as well as the main driver of BAL variability, can be well constrained with the aid of multiple spectroscopic epochs (e.g., Vivek et al 2018;Yi et al 2019b).…”

Section: Diversity Of Bal-profile Variabilitymentioning

confidence: 99%

“…J082747 was reported in Yi et al (2019b), in which its spectral properties and BAL-variability behaviors were analyzed using five spectroscopic epochs (from MJD=52266 to 58212). This quasar shows several prominent features, among which the most dramatic one is the observed BAL disappearance/emergence in multiple ions over the five epochs.…”

Section: J082747 and J235253mentioning

confidence: 99%

“…A complete BAL disappearance or emergence event, however, naturally addresses this challenge even with relatively low-quality spectra (See Section 6). Such events have been reported mostly in Hi-BALs (Hamann et al 2008;Filiz Ak et al 2012;Wang et al 2015;McGraw et al 2017;Stern et al 2017;De Cicco et al 2018;Rogerson et al 2018;Sameer et al 2019); by contrast, only three MgII-BAL disappearance and/or emergence cases have been reported to date (Junkkarinen et al 2001;Vivek et al 2012;Yi et al 2019b).…”

Section: Introductionmentioning

confidence: 99%

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Multi-epoch spectroscopy of Mg II broad absorption line transitions

Yi,

Timlin

2021

Preprint

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Built upon a sample of 134 quasars that was dedicated to a systematic study of Mg ii-BAL variability from Yi et al. (2019a), we investigate these quasars showing Mg ii-BAL disappearance or emergence with the aid of at least three epoch optical spectra sampled more than 15 yr in the observed frame. We identified 3/3 quasars undergoing pristine/tentative BAL transformations. The incidence of pristine BAL transformations in the sample is therefore derived to be 2.2 +2.2 −1.2 %, consistent with that of highionization BAL transformations from the literature. Adopting an average Mg ii-BAL disappearance timescale of rest-frame 6.89 yr among the six quasars, the average characteristic lifetime of Mg ii BALs in the sample is constrained to be >160 yr along our line of sight. There is a diversity of BAL-profile variability observed in the six quasars, probably reflecting a variety of mechanisms at work. Our investigations of Mg ii-BAL transitions, combined with observational studies of BAL transitions from the literature, imply an overall FeLoBAL/LoBAL→HiBAL/non-BAL transformation sequence along with a decrease in reddening. This sequence is consistent with the evacuation models for the origin of commonly seen blue quasars, in which LoBAL quasars are in a shorted-lived, blowout phase.

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Section: J082747 and J235253supporting

confidence: 83%

Section: Spectral Measurements and Bal-disappearance/emergence Criteriamentioning

confidence: 99%

Section: Diversity Of Bal-profile Variabilitymentioning

confidence: 99%

Section: J082747 and J235253mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multi-epoch spectroscopy of Mg II broad absorption line transitions

Yi,

Timlin

2021

Preprint

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Discovery of the first heavily obscured QSO candidate at z > 6 in a close galaxy pair

Vito

Brandt

Bauer

et al. 2019

A&A

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While theoretical arguments predict that most of the early growth of supermassive black holes (SMBHs) happened during heavily obscured phases of accretion, current methods used for selecting z > 6 quasars (QSOs) are strongly biased against obscured QSOs, thus considerably limiting our understanding of accreting SMBHs during the first gigayear of the Universe from an observational point of view. We report the Chandra discovery of the first heavily obscured QSO candidate in the early universe, hosted by a close (≈5 kpc) galaxy pair at z = 6.515. One of the members is an optically classified type-1 QSO, PSO167–13. The companion galaxy was first detected as a [C II] emitter by Atacama large millimeter array (ALMA). An X-ray source is significantly (P = 0.9996) detected by Chandra in the 2–5 keV band, with < 1.14 net counts in the 0.5–2 keV band, although the current positional uncertainty does not allow a conclusive association with either PSO167–13 or its companion galaxy. From X-ray photometry and hardness-ratio arguments, we estimated an obscuring column density of NH > 2 × 1024 cm−2 and NH > 6 × 1023 cm−2 at 68% and 90% confidence levels, respectively. Thus, regardless of which of the two galaxies is associated with the X-ray emission, this source is the first heavily obscured QSO candidate at z > 6.

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Chandra and Magellan/FIRE follow-up observations of PSO167–13: An X-ray weak QSO at z = 6.515

Vito

Brandt

Ricci

et al. 2021

A&A

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Context. The discovery of hundreds of quasi-stellar objects (QSOs) in the first gigayear of the Universe powered by already grown supermassive black holes (SMBHs) challenges our knowledge of SMBH formation. In particular, investigations of z > 6 QSOs that present notable properties can provide unique information on the physics of fast SMBH growth in the early Universe. Aims. We present the results of follow-up observations of the z = 6.515 radio-quiet QSO PSO167–13, which is interacting with a close companion galaxy. The PSO167–13 system has recently been proposed to host the first heavily obscured X-ray source at high redshift. The goals of these new observations are to confirm the existence of the X-ray source and to investigate the rest-frame UV properties of the QSO. Methods. We observed the PSO167–13 system with Chandra/ACIS-S (177 ks) and obtained new spectroscopic observations (7.2 h) with Magellan/FIRE. Results. No significant X-ray emission is detected from the PSO167–13 system, suggesting that the obscured X-ray source previously tentatively detected was either due to a strong background fluctuation or is highly variable. The upper limit (90% confidence level) on the X-ray emission of PSO167–13 (L2−10 keV < 8.3 × 1043 erg s−1) is the lowest available for a z > 6 QSO. The ratio between the X-ray and UV luminosity of αox < −1.95 makes PSO167–13 a strong outlier from the αox − LUV and LX − Lbol relations. In particular, its X-ray emission is more than six times weaker than the expectation based on its UV luminosity. The new Magellan/FIRE spectrum of PSO167–13 is strongly affected by unfavorable sky conditions, but the tentatively detected C IV and Mg II emission lines appear strongly blueshifted. Conclusions. The most plausible explanations for the X-ray weakness of PSO167–13 are intrinsic weakness or small-scale absorption by Compton-thick material. The possible strong blueshift of its emission lines hints at the presence of nuclear winds, which could be related to its X-ray weakness.

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Broad Absorption Line Disappearance/Emergence in Multiple Ions in a Weak Emission-line Quasar

Cited by 18 publications

References 57 publications

Multi-epoch spectroscopy of Mg II broad absorption line transitions

Multi-epoch spectroscopy of Mg II broad absorption line transitions

Discovery of the first heavily obscured QSO candidate at z > 6 in a close galaxy pair

Chandra and Magellan/FIRE follow-up observations of PSO167–13: An X-ray weak QSO at z = 6.515

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