%0 Generic %1 Smail2011 %A Smail, Ian %A Swinbank, A. M. %A Ivison, R. J. %A Ibar, E. %D 2011 %K [CII] high-z molecules %T The potential influence of far-infrared emission lines on the selection of high-redshift galaxies %U http://arxiv.org/abs/1104.1758 %X We investigate whether strong molecular and atomic emission lines at far-infrared wavelengths can influence the identification and derived properties of galaxies selected from broad-band, far-infrared or submillimetre observations. Several of these lines, e.g. CII158um, have been found to be very bright in some high-redshift galaxies, with fluxes of >0.1-1% of the total far-infrared luminosity, and may be even brighter in certain populations at high redshifts. At redshifts where these lines fall in instrument pass-bands they can significantly increase the broad-band flux measurements. We estimate that the contributions from line emission could boost the apparent broad-band flux by >20-40% in the Herschel and SCUBA-2 bands. Combined with the steep source counts in the submillimetre and far-infrared bands, line contamination has potentially significant consequences for the properties of sources detected in flux-limited continuum surveys, biasing the derived redshift distributions and bolometric luminosities. Indeed, it is possible that some z>4 sources found in 850-um surveys are being identified in part due to line contamination from strong CII emission. These biases may be even stronger for less-luminous and lower-metallicity populations at high redshifts which are observable with ALMA and which may have even stronger line-to-continuum ratios.

@misc{Smail2011, abstract = { We investigate whether strong molecular and atomic emission lines at far-infrared wavelengths can influence the identification and derived properties of galaxies selected from broad-band, far-infrared or submillimetre observations. Several of these lines, e.g. [CII]158um, have been found to be very bright in some high-redshift galaxies, with fluxes of >0.1-1% of the total far-infrared luminosity, and may be even brighter in certain populations at high redshifts. At redshifts where these lines fall in instrument pass-bands they can significantly increase the broad-band flux measurements. We estimate that the contributions from line emission could boost the apparent broad-band flux by >20-40% in the Herschel and SCUBA-2 bands. Combined with the steep source counts in the submillimetre and far-infrared bands, line contamination has potentially significant consequences for the properties of sources detected in flux-limited continuum surveys, biasing the derived redshift distributions and bolometric luminosities. Indeed, it is possible that some z>4 sources found in 850-um surveys are being identified in part due to line contamination from strong [CII] emission. These biases may be even stronger for less-luminous and lower-metallicity populations at high redshifts which are observable with ALMA and which may have even stronger line-to-continuum ratios. }, added-at = {2011-04-12T15:35:38.000+0200}, author = {Smail, Ian and Swinbank, A. M. and Ivison, R. J. and Ibar, E.}, biburl = {https://www.bibsonomy.org/bibtex/213710c18da3c1361ccb4e29a5eb2bd0a/miki}, description = {[1104.1758] The potential influence of far-infrared emission lines on the selection of high-redshift galaxies}, interhash = {7b1f7fa60e5d9238f4eaaaa648fe1b86}, intrahash = {13710c18da3c1361ccb4e29a5eb2bd0a}, keywords = {[CII] high-z molecules}, note = {cite arxiv:1104.1758 Comment: MNRAS letter, in press}, timestamp = {2011-04-12T15:35:38.000+0200}, title = {The potential influence of far-infrared emission lines on the selection of high-redshift galaxies}, url = {http://arxiv.org/abs/1104.1758}, year = 2011 }