A principal component analysis of quasar UV spectra at<i>z</i> ~  3

Pâris, Isabelle; Petitjean, P.; Rollinde, Emmanuel; Aubourg, É.; Busca, N. G.; Charlassier, R.; Delubac, Timothée; Hamilton, J. C.; Goff, J. M. Le; Palanque-Delabrouille, N.; Peirani, Sébastien; Pichon, C.; Rich, J.; Vargas-Magaña, Mariana; Yéche, C.

doi:10.1051/0004-6361/201016233

Cited by 121 publications

(199 citation statements)

References 45 publications

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“…The flux is calibrated by matching the spectra of simultaneously observed standard stars to the magnitude of their point spread function, and it is accurate to a level of a few per cent for λ obs > 4000Å (Adelman-McCarthy et al 2007, 2008. For λ obs < 4000Å, Pâris et al (2011) report systematic excess light in the SDSS DR7 spectra (see also Abazajian et al 2009). Since λ obs = 4000Å corresponds to λrest = 1450Å for the lowest z = 1.75 of our sample, the measurement of αUV is not affected by this systematic excess.…”

Section: The Data Analysismentioning

confidence: 99%

On the origins of C iv absorption profile diversity in broad absorption line quasars

Baskin

Laor

Hamann

2015

Monthly Notices of the Royal Astronomical Society

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There is a large diversity in the C iv broad absorption line (BAL) profile among BAL quasars (BALQs). We quantify this diversity by exploring the distribution of the C iv BAL properties, FWHM, maximum depth of absorption and its velocity shift (v md ), using the SDSS DR7 quasar catalogue. We find the following: (i) Although the median C iv BAL profile in the quasar rest-frame becomes broader and shallower as the UV continuum slope (α UV at 1700-3000Å) gets bluer, the median individual profile in the absorber rest-frame remains identical, and is narrow (FWHM = 3500 km s −1 ) and deep. Only 4 per cent of BALs have FWHM > 10, 000 km s −1 . (ii) As the He ii emission equivalent-width (EW) decreases, the distributions of FWHM and v md extend to larger values, and the median maximum depth increases. These trends are consistent with theoretical models in which softer ionizing continua reduce overionization, and allow radiative acceleration of faster BAL outflows. (iii) As α UV becomes bluer, the distribution of v md extends to larger values. This trend may imply faster outflows at higher latitudes above the accretion disc plane. (iv) For non-BALQs, the C iv emission line decreases with decreasing He ii EW, and becomes more asymmetric and blueshifted. This suggests an increasing relative contribution of emission from the BAL outflow to the C iv emission line as the ionizing spectral energy distribution (SED) gets softer, which is consistent with the increasing fraction of BALQs as the ionizing SED gets softer.

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Section: The Data Analysismentioning

confidence: 99%

On the origins of C iv absorption profile diversity in broad absorption line quasars

Baskin

Laor

Hamann

2015

Monthly Notices of the Royal Astronomical Society

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“…Estimating the exact value of the spectral flux density in the DLA trough is difficult, since the zero-level is not well-defined in SDSS spectra (Pâris et al 2011(Pâris et al , 2012.…”

Section: Dlas With Partial Coveragementioning

confidence: 99%

“…3, top). A template spectrum from the mean principal component analysis (PCA) quasar continuum (Pâris et al 2011) is adjusted with a power-law fit to each spectrum and scaled to provide the quasar continuum near the Lyα emission line (Fig. 3, center).…”

Section: Measuring Dla Column Densities and Emissionsmentioning

confidence: 99%

A glance at the host galaxy of high-redshift quasars using strong damped Lyman-αsystems as coronagraphs

Finley

Petitjean

Pâris

et al. 2013

A&A

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We searched quasar spectra from the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS) for the rare occurrences where a strong damped Lyman-α absorber (DLA) blocks the Broad Line Region emission from the quasar and acts as a natural coronagraph to reveal narrow Lyα emission from the host galaxy. We define a statistical sample of 31 DLAs in Data Release 9 (DR9) with log N(H i) ≥ 21.3 cm −2 located at less than 1500 km s −1 from the quasar redshift. In 25% (8) of these DLAs, a strong narrow Lyα emission line is observed with flux ∼25 × 10 −17 erg s −1 cm −2 on average. For DLAs without this feature in their troughs, the average 3-σ upper limit is <0.8 × 10 −17 erg s −1 cm −2 . Our statistical sample is nearly 2.5 times larger than the anticipated number of intervening DLAs in DR9 within 1 500 km s −1 of the quasar redshift. We also define a sample of 26 DLAs from DR9 and DR10 with narrow Lyα emission detected and no limit on the H i column density to better characterize properties of the host galaxy emission. Analyzing the statistical sample, we do not find substantial differences in the kinematics, metals, or reddening for the two populations with and without emission detected. The highly symmetric narrow Lyα emission line profile centered in the HI trough indicates that the emitting region is separate from the absorber. The luminosity of the narrow Lyα emission peaks is intermediate between that of Lyα emitters and radio galaxies, implying that the Lyα emission is predominantly due to ionizing radiation from the AGN. Galaxies neighboring the quasar host are likely responsible for the majority (>75%) of these DLAs, with only a minority (<25%) arising from H i clouds located in the AGN host galaxy.

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“…Regions of strong telluric features (atmosphere transparency <20%) were not used in the spectral analysis and are marked by small boxes at the top of each panel (NIR: Gemini observatory). The red line is the average z = 3 QSOs spectrum taken from Pâris et al (2011). Prominent absorption and emission lines from the quasar are indicated by vertical solid lines, and the absorption lines from the strong Mg ii absorber at z = 1.77425 by vertical dashed lines (see Table 8 18 April, 2010.…”

Section: Quasar Radiation Fieldmentioning

confidence: 99%

Galaxy counterparts of intervening high-zsub-DLAs/DLAs and Mg ii absorbers towards gamma-ray bursts

Schulze

Fynbo

Milvang-Jensen

et al. 2012

A&A

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We present the first search for galaxy counterparts of intervening high-z (2 < z < 3.6) sub-damped Lyα absorbers (sub-DLAs) and DLAs towards gamma-ray bursts (GRBs). Our final sample comprises five intervening sub-DLAs and DLAs in four GRB fields. To identify candidate galaxy counterparts of the absorbers we used deep optical-and near-infrared imaging, and low-, mid-and highresolution spectroscopy acquired with 6-m to 10-m class telescopes, the Hubble and the Spitzer Space Telescopes. Furthermore, we used the spectroscopic information and spectral-energy-distribution fitting techniques to study them in detail. Our main result is the detection and spectroscopic confirmation of the galaxy counterpart of the intervening DLA at z = 3.096 in the field of GRB 070721B (z GRB = 3.6298) as proposed by other authors. We also identify good candidates for the galaxy counterparts of the two strong Mg ii absorbers at z = 0.6915 and 1.4288 towards GRB 050820A (z GRB = 2.615). The properties of the detected DLA galaxy are typical for Lyman-break galaxies (LBGs) at similar redshifts; a young, highly star-forming galaxy that shows evidence for a galactic outflow. This supports the hypothesis that a DLA can be the gaseous halo of an LBG. In addition, we report a redshift coincidence of different objects associated with metal lines in the same field, separated by 130-161 kpc. The high detection rate of three correlated structures on a length scale as short as ∼150 kpc in two pairs of lines of sight is intriguing. The absorbers in each of these are most likely not part of the same gravitationally bound structure. They more likely represent groups of galaxies.

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A principal component analysis of quasar UV spectra atz ~ 3

Cited by 121 publications

References 45 publications

On the origins of C iv absorption profile diversity in broad absorption line quasars

On the origins of C iv absorption profile diversity in broad absorption line quasars

A glance at the host galaxy of high-redshift quasars using strong damped Lyman-αsystems as coronagraphs

Galaxy counterparts of intervening high-zsub-DLAs/DLAs and Mg ii absorbers towards gamma-ray bursts

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