Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey

Serena Perrotta; Valentina D'Odorico; J. Xavier Prochaska; Stefano Cristiani; Guido Cupani; Sara Ellison; Sebastian Lòpez; George D. Becker; Trystyn A. M. Berg; Lise Christensen; Kelly D. Denney; Frederick Hamann; Isabelle Pâris; Marianne Vestergaard; Gábor Worseck

doi:10.1093/mnras/stw1703

Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey

Serena Perrotta, Valentina D'Odorico, J. Xavier Prochaska, Stefano Cristiani, Guido Cupani, Sara Ellison, Sebastian Lòpez, George D. Becker, Trystyn A. M. Berg, Lise Christensen, Kelly D. Denney, Frederick Hamann, Isabelle Pâris, Marianne Vestergaard, Gábor Worseck

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20 Citations (Scopus)

Abstract

We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and interveningNALs without taking into account any a priori definition or velocity cut-off. We analyse the spectra of 100 quasars with 3.5 < z_em < 4.5, observed with X-shooter/Very Large Telescope in the context of the XQ-100 Legacy Survey. We detect an ~8s excess in the CIV number density within 10 000 km s-1 of the quasar emission redshift with respect to the random occurrence of NALs. This excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of NALs. It extends far beyond the standard 5000 km s^-1 cutoff traditionally defined for associated absorption lines. We propose to modify this definition, extending the threshold to 10 000 km s^-1 when weak absorbers (equivalent width < 0.2Å) are also considered. We infer NV is the ion that better traces the effects of the quasar ionization field, offering the best statistical tool to identify intrinsic systems. Following this criterion, we estimate that the fraction of quasars in our sample hosting an intrinsic NAL system is 33 per cent. Lastly, we compare the properties of the material along the quasar line of sight, derived from our sample, with results based on close quasar pairs investigating the transverse direction. We find a deficiency of cool gas (traced by C II) along the line of sight connected to the quasar host galaxy, in contrast with what is observed in the transverse direction.

Original language	English
Journal	Monthly Notices of the Royal Astronomical Society
Volume	462
Pages (from-to)	3285-3301
ISSN	0035-8711
DOIs	https://doi.org/10.1093/mnras/stw1703
Publication status	Published - 1 Nov 2016

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jcap062016017Final published version, 423 KB

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Perrotta, S., D'Odorico, V., Prochaska, J. X., Cristiani, S., Cupani, G., Ellison, S., Lòpez, S., Becker, G. D., Berg, T. A. M., Christensen, L., Denney, K. D., Hamann, F., Pâris, I., Vestergaard, M., & Worseck, G. (2016). Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey. Monthly Notices of the Royal Astronomical Society, 462, 3285-3301. https://doi.org/10.1093/mnras/stw1703

Perrotta, S, D'Odorico, V, Prochaska, JX, Cristiani, S, Cupani, G, Ellison, S, Lòpez, S, Becker, GD, Berg, TAM, Christensen, L, Denney, KD, Hamann, F, Pâris, I, Vestergaard, M & Worseck, G 2016, 'Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey', Monthly Notices of the Royal Astronomical Society, vol. 462, pp. 3285-3301. https://doi.org/10.1093/mnras/stw1703

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title = "Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey",

abstract = "We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and interveningNALs without taking into account any a priori definition or velocity cut-off. We analyse the spectra of 100 quasars with 3.5 < zem < 4.5, observed with X-shooter/Very Large Telescope in the context of the XQ-100 Legacy Survey. We detect an ~8s excess in the CIV number density within 10 000 km s-1 of the quasar emission redshift with respect to the random occurrence of NALs. This excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of NALs. It extends far beyond the standard 5000 km s-1 cutoff traditionally defined for associated absorption lines. We propose to modify this definition, extending the threshold to 10 000 km s-1 when weak absorbers (equivalent width < 0.2{\AA}) are also considered. We infer NV is the ion that better traces the effects of the quasar ionization field, offering the best statistical tool to identify intrinsic systems. Following this criterion, we estimate that the fraction of quasars in our sample hosting an intrinsic NAL system is 33 per cent. Lastly, we compare the properties of the material along the quasar line of sight, derived from our sample, with results based on close quasar pairs investigating the transverse direction. We find a deficiency of cool gas (traced by C II) along the line of sight connected to the quasar host galaxy, in contrast with what is observed in the transverse direction.",

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author = "Serena Perrotta and Valentina D'Odorico and Prochaska, {J. Xavier} and Stefano Cristiani and Guido Cupani and Sara Ellison and Sebastian L{\`o}pez and Becker, {George D.} and Berg, {Trystyn A. M.} and Lise Christensen and Denney, {Kelly D.} and Frederick Hamann and Isabelle P{\^a}ris and Marianne Vestergaard and G{\'a}bor Worseck",

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T1 - Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey

AU - Perrotta, Serena

AU - D'Odorico, Valentina

AU - Prochaska, J. Xavier

AU - Cristiani, Stefano

AU - Cupani, Guido

AU - Ellison, Sara

AU - Lòpez, Sebastian

AU - Becker, George D.

AU - Berg, Trystyn A. M.

AU - Christensen, Lise

AU - Denney, Kelly D.

AU - Hamann, Frederick

AU - Pâris, Isabelle

AU - Vestergaard, Marianne

AU - Worseck, Gábor

N1 - 18 pages, 13 figures, 5 tables

PY - 2016/11/1

Y1 - 2016/11/1

N2 - We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and interveningNALs without taking into account any a priori definition or velocity cut-off. We analyse the spectra of 100 quasars with 3.5 < zem < 4.5, observed with X-shooter/Very Large Telescope in the context of the XQ-100 Legacy Survey. We detect an ~8s excess in the CIV number density within 10 000 km s-1 of the quasar emission redshift with respect to the random occurrence of NALs. This excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of NALs. It extends far beyond the standard 5000 km s-1 cutoff traditionally defined for associated absorption lines. We propose to modify this definition, extending the threshold to 10 000 km s-1 when weak absorbers (equivalent width < 0.2Å) are also considered. We infer NV is the ion that better traces the effects of the quasar ionization field, offering the best statistical tool to identify intrinsic systems. Following this criterion, we estimate that the fraction of quasars in our sample hosting an intrinsic NAL system is 33 per cent. Lastly, we compare the properties of the material along the quasar line of sight, derived from our sample, with results based on close quasar pairs investigating the transverse direction. We find a deficiency of cool gas (traced by C II) along the line of sight connected to the quasar host galaxy, in contrast with what is observed in the transverse direction.

AB - We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and interveningNALs without taking into account any a priori definition or velocity cut-off. We analyse the spectra of 100 quasars with 3.5 < zem < 4.5, observed with X-shooter/Very Large Telescope in the context of the XQ-100 Legacy Survey. We detect an ~8s excess in the CIV number density within 10 000 km s-1 of the quasar emission redshift with respect to the random occurrence of NALs. This excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of NALs. It extends far beyond the standard 5000 km s-1 cutoff traditionally defined for associated absorption lines. We propose to modify this definition, extending the threshold to 10 000 km s-1 when weak absorbers (equivalent width < 0.2Å) are also considered. We infer NV is the ion that better traces the effects of the quasar ionization field, offering the best statistical tool to identify intrinsic systems. Following this criterion, we estimate that the fraction of quasars in our sample hosting an intrinsic NAL system is 33 per cent. Lastly, we compare the properties of the material along the quasar line of sight, derived from our sample, with results based on close quasar pairs investigating the transverse direction. We find a deficiency of cool gas (traced by C II) along the line of sight connected to the quasar host galaxy, in contrast with what is observed in the transverse direction.

KW - astro-ph.GA

KW - astro-ph.CO

U2 - 10.1093/mnras/stw1703

DO - 10.1093/mnras/stw1703

M3 - Journal article

SN - 0035-8711

VL - 462

SP - 3285

EP - 3301

JO - Royal Astronomical Society. Monthly Notices

JF - Royal Astronomical Society. Monthly Notices

ER -

Nature and statistical properties of quasar associated absorption systems in the XQ-100 Legacy Survey

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