Neutral outflows in high-zQSOs

Astronomy and Astrophysics, vol. 674, pp. L5

Abstract

The OH+(11 − 10) absorption line is a powerful tracer of inflowing and outflowing gas in the predominantly atomic diffuse and turbulent halo surrounding galaxies. In this Letter, we present observations of OH+(11 − 10), CO(9-8) and the underlying dust continuum in five strongly lensedz ∼ 2 − 4 quasi-stellar objects (QSOs), using the Atacama Large Millimeter/submillimeter Array (ALMA) to detect outflowing neutral gas. Blue-shifted OH+(11 − 10) absorption is detected in three out of five QSOs and tentatively detected in a fourth. Absorption at systemic velocities is also detected in one source also displaying blue-shifted absorption. OH+(11 − 10) emission is observed in three out of five QSOs at systemic velocities and the OH+(21 − 10) transition is also detected in one source. CO(9-8) is detected in all five QSOs at high S/N, providing information on the dense molecular gas within the host galaxy. We compare our sample to high-zfar-infrared (FIR) luminous star-forming and active galaxies from the literature. We find no difference in OH+absorption line properties between active and star-forming galaxies with both samples roughly following the same optical depth-dust temperature relation. This suggests that these observables are driven by the same mechanism in both samples. Similarly, star-forming and active galaxies both follow the same OH+emission–FIR relation. Obscured QSOs display broader (> 800 km s−1) emission than the unobscured QSOs and all but one of the high-zstar-forming galaxies (likely caused by the warm molecular gas reservoir obscuring the accreting nucleus). Broader CO(9-8) emission (> 500 km s−1) is found in obscured versus unobscured QSOs, but overall they cover a similar range in line widths as the star-forming galaxies and follow the CO(9-8)–FIR luminosity relation found in low-zgalaxies. We find that outflows traced by OH+are only detected in extreme star-forming galaxies (indicated by broad CO(9-8) emission) and in both types of QSOs, which, in turn, display no red-shifted absorption. This suggests that diffuse neutral outflows in galaxy halos may be associated with the most energetic evolutionary phases leading up to and following the obscured QSO phase.

Authors 4

1. K. Butler corresponding Aachen Leiden Observatory

   Leiden University · Institut de Radioastronomie Millimétrique · Leiden Observatory

   Affiliation as printed

   Institut de Radioastronomie Millimétrique (IRAM) , 300 rue de la Piscine , 38400 Saint-Martin-d'Hères , France

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , the Netherlands

   Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38400 Saint-Martin-d'Hères, France

   Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands

2. Paul P. van der Werf Aachen Leiden Observatory

   Leiden University · Leiden Observatory

   Affiliation as printed

   Leiden Observatory , Leiden University , PO Box 9513 , 2300 RA Leiden , the Netherlands

   Leiden Observatory [Leiden] (P.O. Box 9513, NL-2300 RA Leiden - Netherlands)

3. A. Omont

   Centre National de la Recherche Scientifique · Institut d'Astrophysique de Paris · Sorbonne Université · Université Pierre-et-Marie-Curie

   Affiliation as printed

   Sorbonne Université , UPMC Université Paris

   and CNRS , UMR 7095 , Institut d'Astrophysique de Paris , 98b boulevard Arago , 75014 Paris , France

   IAP - Institut d'Astrophysique de Paris (98bis, bd Arago - 75014 Paris France - France)

4. P. Cox

   Institut d'Astrophysique de Paris · Sorbonne Université · Université Pierre-et-Marie-Curie

   Affiliation as printed

   Sorbonne Université , UPMC Université Paris

   IAP - Institut d'Astrophysique de Paris (98bis, bd Arago - 75014 Paris France - France)