Unusual quasars from the Sloan Digital Sky Survey selected by means of Kohonen self-organising maps

Meusinger, H.; Schalldach, P.; Scholz, R.‐D.; Au, A. in der; Newholm, M.; Hoon, A. de; Kaminsky, B.

doi:10.1051/0004-6361/201118143

Cited by 51 publications

(54 citation statements)

References 154 publications

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“…However, another plausible explanation for the weak FUV continuum flux might be the hypothesis that there is simply no FUV flux emitted because of a nonexisting hot inner accretion disk. In the same spirit, some quasars have been identified that show unusual weak blue continua (e.g., Hall et al 2002;Meusinger et al 2012). We see no Lyman edge (λ < 912 Å) in our spectrum of PG 0043+039, in accordance to the ultraviolet composite spectrum of some AGN (Shull et al 2012).…”

Section: Opt/uv/x-ray Slopesupporting

confidence: 88%

The peculiar optical-UV X-ray spectra of the X-ray weak quasar PG 0043+039

Kollatschny

Schartel

Zetzl

et al. 2015

A&A

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Context. The object PG 0043+039 has been identified as a broad absorption line (BAL) quasar based on its UV spectra. However, this optical luminous quasar has not been detected before in deep X-ray observations, making it the most extreme X-ray weak quasar known today. Aims. This study aims to detect PG 0043+039 in a deep X-ray exposure. The question is what causes the extreme X-ray weakness of PG 0043+039? Does PG 0043+039 show other spectral or continuum peculiarities? Methods. We took simultaneous deep X-ray spectra with XMM-Newton, far-ultraviolet (FUV) spectra with the Hubble Space Telescope (HST), and optical spectra of PG 0043+039 with the Hobby-Eberly Telescope (HET) and Southern African Large Telescope (SALT) in July, 2013. Results. We have detected PG 0043+039 in our X-ray exposure taken in 2013. We presented our first results in a separate paper (Kollatschny et al. 2015). PG 0043+039 shows an extreme α ox gradient (α ox = −2.37). Furthermore, we were able to verify an X-ray flux of this source in a reanalysis of the X-ray data taken in 2005. At that time, it was fainter by a factor of 3.8 ±0.9 with α ox = −2.55. The X-ray spectrum is compatible with a normal quasar power-law spectrum (Γ = 1.70 +0.57 −0.45 ) with moderate intrinsic absorption (N H = 5.5 +6.9 −3.9 × 10 21 cm −2 ) and reflection. The UV/optical flux of PG 0043+039 has increased by a factor of 1.8 compared to spectra taken in the years 1990-1991. The FUV spectrum is highly peculiar and dominated by broad bumps besides Lyα. There is no detectable Lyman edge associated with the BAL absorbing gas seen in the CIV line. PG 0043+039 shows a maximum in the overall continuum flux at around λ ≈ 2500 Å in contrast to most other AGN where the maximum is found at shorter wavelengths. All the above is compatible with an intrinsically X-ray weak quasar, rather than an absorbed X-ray emission. Besides strong FeII multiplets and broad Balmer and HeI lines in the optical band we only detect a narrow [O ii]λ3727 emission line and a BAL system in the CaH λ3968, CaK λ3934 lines (blueshifted by 4900 km s −1 ) and in the He i λ3889 line (blueshifted by 5600 km s −1 ).

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Section: Opt/uv/x-ray Slopesupporting

confidence: 88%

The peculiar optical-UV X-ray spectra of the X-ray weak quasar PG 0043+039

Kollatschny

Schartel

Zetzl

et al. 2015

A&A

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“…SDSS J0802 + 5513 was later analyzed by Zhang et al (2010) but rejected as a LoBAL quasar since the Mg ii absorption line does not show a large enough blueshift, though the absorption trough is broader than their threshold value of Δv > 1,600 km s −1 . Using Kohonen self-organizing maps, Meusinger et al (2012) again classified SDSS J0802 + 5513 as an unusual LoBAL quasar with a red color and narrow absorption line troughs and confirmed the classification by visual inspection of its SDSS spectrum. The discrepant classification of the absorption lines in the quasar deserves further exploration.…”

Section: Introductionmentioning

confidence: 56%

UNSHIFTED METASTABLE He I* MINI-BROAD ABSORPTION LINE SYSTEM IN THE NARROW-LINE TYPE 1 QUASAR SDSS J080248.18+551328.9

Zhou

Jiang

et al. 2015

ApJ

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We report the identification of an unusual absorption-line system in the quasar SDSS J080248.18 + 551328.9 and present a detailed study of the system, incorporating follow-up optical and near-IR spectroscopy. A few tens of absorption lines are detected, including He i*, Fe ii*, and Ni ii*, which arise from metastable or excited levels, as well as resonant lines in Mg i, Mg ii, Fe ii, Mn ii, and Ca ii. All of the isolated absorption lines show the same profile of width Δv ∼ 1500 km s −1 centered at a common redshift as that of the quasar emission lines, such as [O ii], [S ii], and hydrogen Paschen and Balmer series. With narrow Balmer lines, strong optical Fe ii multiplets, and weak [O iii] doublets, its emission-line spectrum is typical for that of a narrow-line Seyfert 1 galaxy (NLS1). We have derived reliable measurements of the gas-phase column densities of the absorbing ions/levels. Photoionization modeling indicates that the absorber has a density of n H ∼ (1.0-2.5) × 10 5 cm −3 and a column density of N H ∼ (1.0-3.2) × 10 21 cm −2 and is located at R ∼ 100-250 pc from the central supermassive black hole. The location of the absorber, the symmetric profile of the absorption lines, and the coincidence of the absorptionand emission-line centroid jointly suggest that the absorption gas originates from the host galaxy and is plausibly accelerated by stellar processes, such as stellar winds and/or supernova explosions. The implications for the detection of such a peculiar absorption-line system in an NLS1 are discussed in the context of coevolution between supermassive black hole growth and host galaxy buildup.

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“…Heavily reddened QSOs have been widely detected (e.g. Hall et al 2002;Ellison et al 2004;Wang et al 2005;Jorgenson et al 2006;Meusinger et al 2012;Glikman et al 2012;Fynbo et al 2013). The SMC extinction curve commonly is used to deredden QSOs (e.g.…”

Section: Introductionmentioning

confidence: 99%

Extinction curve template for intrinsically reddened quasars

Zafar

Møller

Watson

et al. 2015

A&A

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We analyzed the near-infrared to UV data of 16 quasars with redshifts ranging from 0.71 < z < 2.13 to investigate dust extinction properties. The sample presented in this work was obtained from the High A V Quasar (HAQ) survey. The quasar candidates were selected from the Sloan Digital Sky Survey (SDSS) and the UKIRT Infrared Deep Sky Survey (UKIDSS), and follow-up spectroscopy was carried out at the Nordic Optical Telescope (NOT) and the New Technology Telescope (NTT). To study dust extinction curves intrinsic to the quasars, we selected 16 cases from the HAQ survey for which the Small Magellanic Cloud (SMC) law could not provide a good solution to the spectral energy distributions (SEDs). We derived the extinction curves using the Fitzpatrick & Massa (1986, ApJ, 307, 286, FM) law by comparing the observed SEDs to a combined previously published quasar template. The derived extinction, A V , ranges from 0.2-1.0 mag. All the individual extinction curves of our quasars are steeper (R V = 2.2-2.7) than that of the SMC, with a weighted mean value of R V = 2.4. We derived an average quasar extinction curve for our sample by simultaneously fitting SEDs by using the weighted mean values of the FM law parameters and a varying R V . The entire sample is well fit with a single best-fit value of R V = 2.2 ± 0.2. The average quasar extinction curve deviates from the steepest Milky Way and SMC extinction curves at a confidence level 95%. Such steep extinction curves suggest that a significant population of silicates is involved in producing small dust grains. Another possibility might be that the large dust grains may have been destroyed by the activity of the nearby active galactic nuclei (AGN), resulting in steep extinction curves.

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Unusual quasars from the Sloan Digital Sky Survey selected by means of Kohonen self-organising maps

Cited by 51 publications

References 154 publications

The peculiar optical-UV X-ray spectra of the X-ray weak quasar PG 0043+039

The peculiar optical-UV X-ray spectra of the X-ray weak quasar PG 0043+039

UNSHIFTED METASTABLE He I* MINI-BROAD ABSORPTION LINE SYSTEM IN THE NARROW-LINE TYPE 1 QUASAR SDSS J080248.18+551328.9

Extinction curve template for intrinsically reddened quasars

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