dc.contributor.author Gallerani, S en dc.contributor.author Pallottini, Andrea en dc.contributor.author Feruglio, C en dc.contributor.author Ferrara, A en dc.contributor.author Maiolino, Roberto en dc.contributor.author Vallini, L en dc.contributor.author Riechers, DA en dc.contributor.author Pavesi, R en dc.date.accessioned 2018-05-03T10:11:01Z dc.date.available 2018-05-03T10:11:01Z dc.date.issued 2018-01-01 en dc.identifier.issn 0035-8711 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/275485 dc.description.abstract We present the first attempt to detect outflows from galaxies approaching the Epoch of Reionization (EoR) using a sample of 9 star-forming ($\rm SFR=31\pm 20~M_{\odot}~yr^{-1}$) $z\sim 5.5$ galaxies for which the [CII]158$\mu$m line has been previously obtained with ALMA. We first fit each line with a Gaussian function and compute the residuals by subtracting the best fitting model from the data. We combine the residuals of all sample galaxies and find that the total signal is characterised by a flux excess of $\sim 0.5$ mJy extended over $\sim 1000$ km~s$^{-1}$. Although we cannot exclude that part of this signal is due to emission from faint satellite galaxies, we show that the most probable explanation for the detected flux excess is the presence of broad wings in the [CII] lines, signatures of starburst-driven outflows. We infer an average outflow rate of $\rm \dot{M}=54\pm23~ M_{\odot}~yr^{-1}$, providing a loading factor $\eta=\rm \dot{M}/SFR=1.7\pm1.3$ in agreement with observed local starbursts. Our interpretation is consistent with outcomes from zoomed hydro-simulations of {\it Dahlia}, a $z\sim 6$ galaxy ($\rm SFR\sim 100~\rm M_{\odot}~yr^{-1}$) whose feedback-regulated star formation results into an outflow rate $\rm \dot{M}\sim 30~ M_{\odot}~yr^{-1}$. The quality of the ALMA data is not sufficient for a detailed analysis of the [CII] line profile in individual galaxies. Nevertheless, our results suggest that starburst-driven outflows are in place in the EoR and provide useful indications for future ALMA campaigns. Deeper observations of the [CII] line in this sample are required to better characterise feedback at high-$z$ and to understand the role of outflows in shaping early galaxy formation. dc.publisher Oxford University Press dc.title ALMA suggests outflows in z ~ 5.5 galaxies en dc.type Article prism.endingPage 1917 prism.issueIdentifier 2 en prism.publicationDate 2018 en prism.publicationName Monthly Notices of the Royal Astronomical Society en prism.startingPage 1909 prism.volume 473 en dc.identifier.doi 10.17863/CAM.22718 dcterms.dateAccepted 2017-09-20 en rioxxterms.versionofrecord 10.1093/mnras/stx2458 en rioxxterms.version VoR * rioxxterms.licenseref.uri http://www.rioxx.net/licenses/all-rights-reserved en rioxxterms.licenseref.startdate 2018-01-01 en dc.contributor.orcid Pallottini, Andrea [0000-0002-7129-5761] dc.contributor.orcid Maiolino, Roberto [0000-0002-4985-3819] dc.identifier.eissn 1365-2966 rioxxterms.type Journal Article/Review en pubs.funder-project-id ECH2020 EUROPEAN RESEARCH COUNCIL (ERC) (695671) pubs.funder-project-id STFC (ST/M001172/1) pubs.funder-project-id STFC (ST/K003119/1) cam.orpheus.success Thu Jan 30 13:04:40 GMT 2020 - The item has an open VoR version. * rioxxterms.freetoread.startdate 2100-01-01
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