A search for CI J=2--1 emission in IRAS F10214+4724

Abstract

Sensitive new observations of the fine structure line $^3$P$_2$$\to $ $^3$P$_1$ (J=2--1) of the neutral atomic carbon CI ($\nu_{rest}\sim 809$ GHz) in the strongly lensed Ultra Luminous Infrared Galaxy (ULIRG) IRAS F10214+4724 at z=2.3 with the mm/sub-mm telescope James Clerk Maxwel (JCMT) are presented. These do not confirm the presence of emission from this line at the flux levels or angular extent previously reported in the literature. The new 2$\sigma $ upper limits are: $\rm S_{CI}\la 7 Jy km s^{-1}$ (central position), and $\rm < S_{CI} > \la 8.5 Jy km s^{-1}$ (average over the two $\rm [\delta (RA), \delta (Dec)]=[0'',\pm 10'']$ positions). A CI emission assumed fully concomitant with the bulk of H$_2$ and confined entirely within the strongly lensed object yields an upper limit of $\rm M_{CI}(H_2)\la 1.5 \times 10^{10} M_{\odot}$, compatible with the reported CO-derived H$_2$ gas mass, within the uncertainties of the two methods. A comparison with the recent detection of the $^3$P$_1$$\to $ $^3$P$_0$ (J=1--0) line in this galaxy by Weiss et al. (2004) is made and the large discrepancy with the previous CI measurements is briefly discussed.