Redshift Determination and CO Line Excitation Modeling for the Multiply-Lensed Galaxy HLSW-01
Abstract
We report on the redshift measurement and CO line excitation of HERMES J105751.1+573027 (HLSW-01), a strongly lensed submillimeter galaxy discovered in Herschel/SPIRE observations as part of the Herschel Multi-tiered Extragalactic Survey (HerMES). HLSW-01 is an ultra-luminous galaxy with an intrinsic far-infrared luminosity of 1.4x10^(13) solar luminosities, and is lensed by a massive group of galaxies into at least four images with a total magnification of 10.9+/-0.7. With the 100 GHz instantaneous bandwidth of the Z-Spec instrument on the Caltech Submillimeter Observatory, we robustly identify a redshift of z=2.958+/-0.007 for this source, using the simultaneous detection of four CO emission lines (J = 7-6, J = 8-7, J = 9-8, and J = 10-9). Combining the measured line fluxes for these high-J transitions with the J = 1-0, J = 3-2 and J = 5-4 line fluxes measured with the Green Bank Telescope, the Combined Array for Research in Millimeter Astronomy, and the Plateau de Bure Interferometer, respectively, we model the physical properties of the molecular gas in this galaxy. We find that the full CO spectral line energy distribution is well described by warm, moderate-density gas with Tkin = 86-235 K and n(H2) = (1.1-3.5)x10^3 cm^(-3). However, it is possible that the highest-J transitions are tracing a small fraction of very dense gas in molecular cloud cores, and two-component models that include a warm/dense molecular gas phase with Tkin ~ 200 K, n(H2) ~ 10^5 cm^(-3) are also consistent with these data. Higher signal-to-noise measurements of the J(upper) > 7 transitions with high spectral resolution, combined with high spatial resolution CO maps, are needed to improve our understanding of the gas excitation, morphology, and dynamics of this interesting high-redshift galaxy.
Keywords
Cite
@article{arxiv.1104.4115,
title = {Redshift Determination and CO Line Excitation Modeling for the Multiply-Lensed Galaxy HLSW-01},
author = {K. S. Scott and R. E. Lupu and J. E. Aguirre and R. Auld and H. Aussel and A. J. Baker and A. Beelen and J. Bock and C. M. Bradford and D. Brisbin and D. Burgarella and J. M. Carpenter and P. Chanial and S. C. Chapman and D. L. Clements and A. Conley and A. Cooray and P. Cox and C. D. Dowell and S. Eales and D. Farrah and A. Franceschini and D. T. Frayer and R. Gavazzi and J. Glenn and M. Griffin and A. I. Harris and E. Ibar and R. J. Ivison and J. Kamenetzky and S. Kim and M. Krips and P. R. Maloney and H. Matsuhara and A. M. J. Mortier and E. J. Murphy and B. J. Naylor and R. Neri and H. T. Nguyen and S. J. Oliver and A. Omont and M. J. Page and A. Papageorgiou and C. P. Pearson and I. Perez-Fournon and M. Pohlen and J. I. Rawlings and G. Raymond and D. Riechers and G. Rodighiero and I. G. Roseboom and M. Rowan-Robinson and D. Scott and N. Seymour and A. J. Smith and M. Symeonidis and K. E. Tugwell and M. Vaccari and J. D. Vieira and L. Vigroux and L. Wang and G. Wright and J. Zmuidzinas},
journal= {arXiv preprint arXiv:1104.4115},
year = {2015}
}
Comments
18 pages, 5 figures, 2 table. Accepted for publication in ApJ