CO(1-0) observations of SMGs†
Harris et al., 2010, ApJ, 723, 1139†
http://adsabs.harvard.edu/abs/2010ApJ...723.1139H
- GBT/Zpectrometer observations.
- We report detections of three z ~ 2.5 submillimeter-selected galaxies (SMGs; SMM J14011+0252, SMM J14009+0252, SMM J04431+0210) in the lowest rotational transition of the carbon monoxide molecule (CO J = 1-0) and one nondetection (SMM J04433+0210).
- For the three galaxies we detected, we find a line-integrated brightness temperature ratio of the J = 3-2 and 1-0 lines of 0.68 ± 0.08; the 1-0 line is stronger than predicted by the frequent assumption of equal brightnesses in the two lines and by most single-component models.
Scott et al. 2011, ApJ, 733, 29†
http://adsabs.harvard.edu/abs/2011ApJ...733...29S
- 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).
- 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.
Swinbank et al. 2010, Nature, 464, 733 ††
http://adsabs.harvard.edu/abs/2010Natur.464..733S
- The mid- and far-infrared colours (S24/ S70=0.4 +/- 0.2) and red optical/near-infrared colours also suggest that the galaxy lies beyond the cluster at z>1.5 (ref. 10 and Supplementary Information), and indeed detection of carbon monoxide (CO) J=1–0 emission at 34.64GHz unambiguously identified the redshift as z=2.3259 +/- 0.0001.
Danielson et al. 2011, MNRAS,†
http://adsabs.harvard.edu/abs/2011MNRAS.410.1687D
- We present an analysis of the molecular and atomic gas emission in the rest-frame far-infrared and submillimetre from the lensed z= 2.3 submillimetre galaxy SMM J2135-0102. We obtain very high signal-to-noise ratio detections of 11 transitions from three species and limits on a further 20 transitions from nine species. We use the 12CO, [C I] and HCN line strengths to investigate the gas mass, kinematic structure and interstellar medium (ISM) chemistry and find strong evidence for a two-phase medium within this high-redshift starburst galaxy, comprising a hot, dense, luminous component and an underlying extended cool, low-excitation massive component. Employing a suite of photodissociation region models, we show that on average the molecular gas is exposed to an ultraviolet (UV) radiation field that is ˜1000 times more intense than the Milky Way, with star-forming regions having a characteristic density of n˜ 104 cm-3. Thus, the average ISM density and far-UV radiation field intensity are similar to those found in local ultraluminous infrared galaxies (ULIRGs) and to those found in the central regions of typical starburst galaxies, even though the star formation rate is far higher in this system. The 12CO spectral line energy distribution and line profiles give strong evidence that the system comprises multiple kinematic components with different conditions, including temperature, and line ratios suggestive of high cosmic-ray flux within clouds, likely as a result of high star formation density. We find tentative evidence of a factor of ˜4 temperature range within the system. We expect that such internal structures are common in high-redshift ULIRGs but are missed due to the poor signal-to-noise ratio of typical observations.
Frayer et al. 2011, ApJ, 726, 22†
http://adsabs.harvard.edu/abs/2011ApJ...726L..22F
- The Zpectrometer instrument on the Green Bank Telescope (GBT) was used to measure the redshifts and constrain the masses of the cold molecular gas reservoirs for two candidate high-redshift lensed sources.
- We derive CO(1-0) redshifts of z = 3.042 ± 0.001 and z = 2.625 ± 0.001, and measure molecular gas masses of (1-3) ×1010 M sun, corrected for lens amplification and assuming a conversion factor of α = 0.8 M sun( K km s-1 pc2)-1.
high resolution CO(1-0) imaging of SMGs†
Riechers, et al., 2011, ApJ, in press (EVLA special issue）†
http://adsabs.harvard.edu/abs/2011arXiv1105.4177R
- We report the detection of spatially resolved CO(1-0) emission in the z~3.4 submillimeter galaxies (SMGs) SMM J09431+4700 and SMM J13120+4242, using the Expanded Very Large Array (EVLA).
Riechers et al. 2011, ApJ, in press (EVLA special issue)†
http://adsabs.harvard.edu/abs/2011arXiv1106.2553R
- We report the detection of CO(1-0) emission in the strongly lensed high-redshift quasars IRAS F10214+4724 (z=2.286), the Cloverleaf (z=2.558), RX J0911+0551 (z=2.796), SMM J04135+10277 (z=2.846), and MG 0751+2716 (z=3.200), using the Expanded Very Large Array and the Green Bank Telescope.
- Based on CO line ratios relative to previously reported observations in J>=3 rotational transitions and line excitation modeling, we find that the CO(1-0) line strengths in our targets are consistent with single, highly-excited gas components with constant brightness temperature up to mid-J levels. We thus do not find any evidence for luminous extended, low excitation, low surface brightness molecular gas components.
- These properties are comparable to those found in z>4 quasars with existing CO(1-0) observations. These findings stand in contrast to recent CO(1-0) observations of z~2-4 submillimeter galaxies (SMGs), which have lower CO excitation and show evidence for multiple excitation components, including some low-excitation gas. These findings are consistent with the picture that gas-rich quasars and SMGs represent different stages in the early evolution of massive galaxies.
Riechers et al. 2011, ApJ, 733, L11†
http://adsabs.harvard.edu/abs/2011ApJ...733L..11R
- We report the detection of spatially extended CO(J = 1→0) and CO(J = 5→4) emission in the z = 2.49 submillimeter galaxy (SMG) J123707+6214, using the Expanded Very Large Array and the Plateau de Bure Interferometer.
- The large molecular gas reservoir is spatially resolved into two CO(J = 1→0) components (northeast and southwest; previously identified in CO J = 3→2 emission) with respective gas masses of 4.3 and 3.5×1010 (αCO/0.8) M sun. We thus find that the optically invisible northeast component slightly dominates the gas mass in this system.
Riechers et al. 2011, ApJ, 724, L153†
http://adsabs.harvard.edu/abs/2010ApJ...724L.153R
- We report the detection of CO(J = 1 → 0) emission toward the lensed L sstarf UV Lyman-break galaxies (LBGs) MS 1512-cB58 (z = 2.73) and the Cosmic Eye (z = 3.07), using the Expanded Very Large Array.
- The CO(J = 1 → 0) emission in the Cosmic Eye is slightly resolved on scales of 4farcs5 ± 1farcs5, consistent with previous studies of nebular emission lines. This suggests that the molecular gas is associated with the most intensely star-forming regions seen in the ultraviolet (UV).
Ivison et al. 2011, MNRAS, 412, 1913†
http://adsabs.harvard.edu/abs/2011MNRAS.412.1913I
- We report the results of a pilot study with the Expanded Very Large Array (EVLA) of 12CO J= 1-0 emission from four submillimetre-selected galaxies at z= 2.2-2.5, each with an existing detection of 12CO J= 3-2, one of which comprises two distinct spatial components.
- Using the EVLA's most compact configuration, we detect strong, broad [medians: 990 km s-1 full width at zero intensity; 540 km s-1 full width at half-maximum (FWHM)]J= 1-0 line emission from all of our targets - coincident in position and velocity with their J= 3-2 emission.
- The median linewidth ratio, σ1-0/σ3-2= 1.15 ± 0.06, suggests that the J= 1-0 is more spatially extended than the J= 3-2 emission, a situation confirmed by our maps which reveal velocity structure in several cases and typical sizes of ˜16 kpc FWHM.
- The median brightness temperature (Tb) ratio is r3-2/1-0= 0.55 ± 0.05, consistent with local galaxies with LIR > 1011 Lȯ, noting that our value may be biased high because of the J= 3-2 based sample selection.
CO(1-0) in quasars†
Riechers et al., 2006, ApJ, 650, 604†
http://adsabs.harvard.edu/abs/2006ApJ...650..604R
- We present 12CO(J=1-->0) observations of the high-redshift quasi-stellar objects (QSOs) BR 1202-0725 (z=4.69), PSS J2322+1944 (z=4.12), and APM 08279+5255 (z=3.91) using the NRAO Green Bank Telescope (GBT) and the MPIfR Effelsberg 100 m telescope.
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