Wednesday, March 28, 2012

1203.5844 (B. P. Venemans et al.)

Detection of atomic carbon [CII] 158 micron and dust emission from a z=7.1 quasar host galaxy    [PDF]

B. P. Venemans, R. G. McMahon, F. Walter, R. Decarli, P. Cox, R. Neri, P. Hewett, D. J. Mortlock, C. Simpson, S. J. Warren
Using the IRAM Plateau de Bure Interferometer, we report the detection of the 158 micron [CII] emission line and underlying dust continuum in the host galaxy of the quasar ULAS J112001.48+064124.3 (hereafter J1120+0641) at z=7.0842+/-0.0004. This is the highest redshift detection of the [CII] line to date, and allows us to put first constraints on the physical properties of the host galaxy. The [CII] line luminosity is (1.2+/-0.2)x10^9 Lsun, which is a factor ~4 lower than observed in a luminous quasar at z=6.42 (SDSS J1148+5251). The underlying far-infrared continuum has a flux density of 0.61+/-0.16 mJy, similar to the average flux density of z~6 quasars that were not individually detected at similar frequencies. The far-infrared continuum detection implies a star-formation rate in the range 160-440 Msun/yr and a total dust mass in the host galaxy of (9+/-2)x10^7 Msun (both numbers have significant uncertainties given the unknown nature of dust at these redshifts). The [CII] line width of sigma_V=100+/-15 km/s is among the smallest observed when compared to the molecular line widths detected in z~6 quasars. Both the [CII] and dust continuum emission are spatially unresolved at the current angular resolution of 2.0x1.7 arcsec^2 (corresponding to 10x9 kpc^2 at the redshift of J1120+0641). The dynamical mass of the host implied by the observed line width is Mdyn < 1.4x10^11 Msun. If the bulge mass was close to the dynamical mass, then the black hole-bulge mass ratio is >10 times higher than observed locally.
View original: http://arxiv.org/abs/1203.5844

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