arXiv subjects

D. Brisbin

Publications and source records attributed to D. Brisbin.

At least 19 recordsLinked to original sources

arXiv2022

An extended [CII] halo around a massive star-forming galaxy at z = 5.3

High-redshift observations are often biased towards massive and bright galaxies that are not necessarily representative of the full population. In order to accurately study galaxy evolution and mass assembly at these redshifts, observations of ``normal'' main sequence galaxies are required. Here we present Atacama Large Millimeter/Submillimeter Array (ALMA) 0.3" resolution observations of the [CII] emission line at 158$\mu$m of HZ7, a main sequence galaxy at $z=5.25$. Comparing to archival rest-frame UV observations taken by the Hubble Space Telescope (HST), we find strong evidence of the existence of extended [CII] emission, which we estimate to be twice the size of the rest-frame UV emission, yielding one of the first high-redshift objects where a clear signature of a [CII] ``Halo'' has been detected to date. For a matched S\'ersic profile with n = 1, we measured a [CII] effective radius of $0.50\pm 0.04$" (3.07$\pm 0.25$ kpc) and an average rest-frame UV effective radius of $0.2\pm0.04$" ($1.48\pm0.16$ kpc). The [CII] morphology and kinematics of the system suggest a merging event resulting in a non rotating disk system. This event could be responsible for the extended [CII] emission. Alternatively, some potential obscured emission could also explain the [CII] to UV size ratio. These results contribute to the growing consensus with respect to the existence of extended [CII] emission around galaxies.

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arXiv2022

Structure and kinematics of a massive galaxy at z ~ 7

Observations of the rest-frame UV emission of high-redshift galaxies suggest that the early stages of galaxy formation involve disturbed structures. Imaging the cold interstellar medium can provide a unique view of the kinematics associated with the assembly of galaxies. In this paper, we analyzed the spatial distribution and kinematics of the cold ionized gas of the normal star-forming galaxy COS-2987030247 at z = 6.8076, based on new high-resolution observations of the [C II] 158um line emission obtained with the Atacama Large Millimeter/submillimeter Array. These observations allowed us to compare the spatial distribution and extension of the [C II] and rest-frame UV emission, model the [C II] line data-cube using 3DBarolo, and measure the [C II] luminosity and star formation rate (SFR) surface densities in the galaxy subregions. The system is found to be composed of a main central source, a fainter north extension, and candidate [C II] companions located 10-kpc away. We find similar rest-frame UV and [C II] spatial distributions, suggesting that the [C II] emission emerges from the star-forming regions. The agreement between the UV and [C II] surface brightness radial profiles rules out diffuse, extended [C II] emission in the main galaxy component. The [C II] velocity map reveals a velocity gradient in the north-south direction suggesting ordered motion, as commonly found in rotating-disk galaxies. But higher-resolution observations would be needed to rule out a compact merger scenario. Our model indicates a low average velocity dispersion, $\sigma$ < 30 km s$^{-1}$. This result implies a dispersion lower than the expected value from observations and semi-analytic models of high redshift galaxies. We argue that COS-2987030247 is a candidate rotating disk experiencing a short period of stability which will be possibly perturbed at later times by accreting sources.

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arXiv2020

Observations of [OI]63micron line emission in main-sequence galaxies at z~1.5

We present Herschel-PACS spectroscopy of four main-sequence star-forming galaxies at z~1.5. We detect [OI]63micron line emission in BzK-21000 at z=1.5213, and measure a line luminosity, L([OI]63micron) = (3.9+/-0.7)x1.E+9 Lsun. Our PDR modelling of the interstellar medium in BzK-21000 suggests a UV radiation field strength, G~320 G0, and gas density, n~1800 cm-3, consistent with previous LVG modelling of the molecular CO line excitation. The other three targets in our sample are individually undetected in these data, and we perform a spectral stacking analysis which yields a detection of their average emission and an [OI]63micron line luminosity, L([OI]63micron) =(1.1+/-0.2)x1E+9 Lsun. We find that the implied luminosity ratio, L([OI]63micron)/L(IR), of the undetected BzK-selected star-forming galaxies broadly agrees with that of low-redshift star-forming galaxies, while BzK-21000 has a similar ratio to that of a dusty star-forming galaxy at z~6. The high [OI]63micron line luminosities observed in BzK-21000 and the $z \sim 1 -3$ dusty and submm luminous star-forming galaxies may be associated with extended reservoirs of low density, cool neutral gas.

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arXiv2019

CO and Fine-Structure Lines Reveal Low Metallicity in a Stellar-Mass-Rich Galaxy at z ~ 1?

We present detections of the CO(4-3) and [C I] 609 $\mu$m spectral lines, as well as the dust continuum at 480.5 GHz (rest-frame), in 3C 368, a Fanaroff-Riley class II (FR-II) galaxy at redshift (z) 1.131. 3C 368 has a large stellar mass, ~ 3.6 x 10$^{11}$ M$_\odot$, and is undergoing an episode of vigorous star formation, at a rate of ~ 350 M$_\odot$/yr, and active galactic nucleus (AGN) activity, with radio-emitting lobes extended over ~ 73 kpc. Our observations allow us to inventory the molecular-gas reservoirs in 3C 368 by applying three independent methods: (1) using the CO(4-3)-line luminosity, excitation state of the gas, and an $\alpha_{CO}$ conversion factor, (2) scaling from the [C I]-line luminosity, and (3) adopting a gas-to-dust conversion factor. We also present gas-phase metallicity estimates in this source, both using far-infrared (FIR) fine-structure lines together with radio free-free continuum emission and independently employing the optical [O III] 5007 A and [O II] 3727 A lines (R$_{23}$ method). Both methods agree on a sub-solar gas-phase metallicity of ~ 0.3 Z$_\odot$. Intriguingly, comparing the molecular-gas mass estimated using this sub-solar metallicity, M$_{gas}$ ~ 6.4 x 10$^{10}$ M$_\odot$, to dust-mass estimates from multi-component spectral energy distribution (SED) modeling, M$_{dust}$ ~ 1.4 x 10$^8$ M$_\odot$, yields a gas-to-dust ratio within ~ 15% of the accepted value for a metallicity of 0.3 Z$_\odot$. The derived gas-mass puts 3C 368 on par with other galaxies at z ~ 1 in terms of specific star-formation rate and gas fraction. However, it does not explain how a galaxy can amass such a large stellar population while maintaining such a low gas-phase metallicity. Perhaps 3C 368 has recently undergone a merger, accreting pristine molecular gas from an external source.

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arXiv2018

Resolving Star Formation on Sub-Kiloparsec Scales in the High-Redshift Galaxy SDP.11 Using Gravitational Lensing

We investigate the properties of the interstellar medium, star formation, and the current-day stellar population in the strongly-lensed star-forming galaxy H-ATLAS J091043.1-000321 (SDP.11), at z = 1.7830, using new Herschel and ALMA observations of far-infrared fine-structure lines of carbon, oxygen and nitrogen. We report detections of the [O III] 52 um, [N III] 57 um, and [O I] 63 um lines from Herschel/PACS, and present high-resolution imaging of the [C II] 158 um line, and underlying continuum, using ALMA. We resolve the [C II] line emission into two spatially-offset Einstein rings, tracing the red- and blue-velocity components of the line, in the ALMA/Band-9 observations at 0.2" resolution. The values seen in the [C II]/FIR ratio map, as low as ~ 0.02% at the peak of the dust continuum, are similar to those of local ULIRGs, suggesting an intense starburst in this source. This is consistent with the high intrinsic FIR luminosity (~ 3 x 10^12 Lo), ~ 16 Myr gas depletion timescale, and < 8 Myr timescale since the last starburst episode, estimated from the hardness of the UV radiation field. By applying gravitational lensing models to the visibilities in the uv-plane, we find that the lensing magnification factor varies by a factor of two across SDP.11, affecting the observed line profiles. After correcting for the effects of differential lensing, a symmetric line profile is recovered, suggesting that the starburst present here may not be the result of a major merger, as is the case for local ULIRGs, but instead could be powered by star-formation activity spread across a 3-5 kpc rotating disk.

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arXiv2017

CO-Dark Star Formation and Black Hole Activity in 3C 368 at z = 1.131: Coeval Growth of Stellar and Supermassive Black Hole Masses

We present the detection of four far-infrared fine-structure oxygen lines, as well as strong upper limits for the CO(2-1) and [N II] 205 um lines, in 3C 368, a well-studied radio-loud galaxy at z = 1.131. These new oxygen lines, taken in conjunction with previously observed neon and carbon fine-structure lines, suggest a powerful active galactic nucleus (AGN), accompanied by vigorous and extended star formation. A starburst dominated by O8 stars, with an age of ~6.5 Myr, provides a good fit to the fine-structure line data. This estimated age of the starburst makes it nearly concurrent with the latest episode of AGN activity, suggesting a link between the growth of the supermassive black hole and stellar population in this source. We do not detect the CO(2-1) line, down to a level twelve times lower than the expected value for star forming galaxies. This lack of CO line emission is consistent with recent star formation activity if the star-forming molecular gas has low metallicity, is highly fractionated (such that CO is photodissociated through much of the clouds), or is chemically very young (such that CO has not yet had time to form). It is also possible, though we argue unlikely, that the ensemble of fine structure lines are emitted from the region heated by the AGN.

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arXiv2013

Panchromatic spectral energy distributions of Herschel sources

(abridged) Far-infrared Herschel photometry from the PEP and HerMES programs is combined with ancillary datasets in the GOODS-N, GOODS-S, and COSMOS fields. Based on this rich dataset, we reproduce the restframe UV to FIR ten-colors distribution of galaxies using a superposition of multi-variate Gaussian modes. The median SED of each mode is then fitted with a modified version of the MAGPHYS code that combines stellar light, emission from dust heated by stars and a possible warm dust contribution heated by an AGN. The defined Gaussian grouping is also used to identify rare sources. The zoology of outliers includes Herschel-detected ellipticals, very blue z~1 Ly-break galaxies, quiescent spirals, and torus-dominated AGN with star formation. Out of these groups and outliers, a new template library is assembled, consisting of 32 SEDs describing the intrinsic scatter in the restframe UV-to-submm colors of infrared galaxies. This library is tested against L(IR) estimates with and without Herschel data included, and compared to eight other popular methods often adopted in the literature. When implementing Herschel photometry, these approaches produce L(IR) values consistent with each other within a median absolute deviation of 10-20%, the scatter being dominated more by fine tuning of the codes, rather than by the choice of SED templates. Finally, the library is used to classify 24 micron detected sources in PEP GOODS fields. AGN appear to be distributed in the stellar mass (M*) vs. star formation rate (SFR) space along with all other galaxies, regardless of the amount of infrared luminosity they are powering, with the tendency to lie on the high SFR side of the "main sequence". The incidence of warmer star-forming sources grows for objects with higher specific star formation rates (sSFR), and they tend to populate the "off-sequence" region of the M*-SFR-z space.

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arXiv2012

The Herschel Multi-tiered Extragalactic Survey: HerMES

The Herschel Multi-tiered Extragalactic Survey, HerMES, is a legacy program designed to map a set of nested fields totalling ~380 deg^2. Fields range in size from 0.01 to ~20 deg^2, using Herschel-SPIRE (at 250, 350 and 500 μm), and Herschel-PACS (at 100 and 160 μm), with an additional wider component of 270 deg^2 with SPIRE alone. These bands cover the peak of the redshifted thermal spectral energy distribution from interstellar dust and thus capture the re-processed optical and ultra-violet radiation from star formation that has been absorbed by dust, and are critical for forming a complete multi-wavelength understanding of galaxy formation and evolution. The survey will detect of order 100,000 galaxies at 5σin some of the best studied fields in the sky. Additionally, HerMES is closely coordinated with the PACS Evolutionary Probe survey. Making maximum use of the full spectrum of ancillary data, from radio to X-ray wavelengths, it is designed to: facilitate redshift determination; rapidly identify unusual objects; and understand the relationships between thermal emission from dust and other processes. Scientific questions HerMES will be used to answer include: the total infrared emission of galaxies; the evolution of the luminosity function; the clustering properties of dusty galaxies; and the properties of populations of galaxies which lie below the confusion limit through lensing and statistical techniques. This paper defines the survey observations and data products, outlines the primary scientific goals of the HerMES team, and reviews some of the early results.

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arXiv2011

The Herschel Multi-Tiered Extragalactic Survey: SPIRE-mm Photometric Redshifts

We investigate the potential of submm-mm and submm-mm-radio photometric redshifts using a sample of mm-selected sources as seen at 250, 350 and 500 μm by the SPIRE instrument on Herschel. From a sample of 63 previously identified mm-sources with reliable radio identifications in the GOODS-N and Lockman Hole North fields 46 (73 per cent) are found to have detections in at least one SPIRE band. We explore the observed submm/mm colour evolution with redshift, finding that the colours of mm-sources are adequately described by a modified blackbody with constant optical depth τ = (ν/ν0)^β where β = +1.8 and ν0 = c/100 μm. We find a tight correlation between dust temperature and IR luminosity. Using a single model of the dust temperature and IR luminosity relation we derive photometric redshift estimates for the 46 SPIRE detected mm-sources. Testing against the 22 sources with known spectroscopic, or good quality optical/near-IR photometric, redshifts we find submm/mm photometric redshifts offer a redshift accuracy of |z|/(1+z) = 0.16 (< |z| >= 0.51). Including constraints from the radio-far IR correlation the accuracy is improved to |z|/(1 + z) = 0.15 (< |z| >= 0.45). We estimate the redshift distribution of mm-selected sources finding a significant excess at z > 3 when compared to ~ 850 μm selected samples.

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arXiv2011

HerMES: point source catalogues from deep Herschel-SPIRE observations

We describe the generation of single-band point source catalogues from submillimetre Herschel-SPIRE observations taken as part of the Science Demonstration Phase of the Herschel Multi-tiered Extragalactic Survey (HerMES). Flux densities are found by means of peak-finding and the fitting of a Gaussian point-response function. With highly-confused images, careful checks must be made on the completeness and flux density accuracy of the detected sources. This is done by injecting artificial sources into the images and analysing the resulting catalogues. Measured flux densities at which 50 per cent of injected sources result in good detections at (250, 350, 500) μm range from (11.6, 13.2, 13.1) mJy to (25.7, 27.1, 35.8) mJy, depending on the depth of the observation (where a `good' detection is taken to be one with positional offset less than one full-width half-maximum of the point-response function, and with the measured flux density within a factor of 2 of the flux density of the injected source). This paper acts as a reference for the 2010 July HerMES public data release.

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arXiv2011

Mid-J CO Emission From NGC 891: Microturbulent Molecular Shocks in Normal Star Forming Galaxies

We have detected the CO(6-5), CO(7-6), and [CI] 370 micron lines from the nuclear region of NGC 891 with our submillimeter grating spectrometer ZEUS on the CSO. These lines provide constraints on photodissociation region (PDR) and shock models that have been invoked to explain the H_2 S(0), S(1), and S(2) lines observed with Spitzer. We analyze our data together with the H_2 lines, CO(3-2), and IR continuum from the literature using a combined PDR/shock model. We find that the mid-J CO originates almost entirely from shock-excited warm molecular gas; contributions from PDRs are negligible. Also, almost all the H_2 S(2) and half of the S(1) line is predicted to emerge from shocks. Shocks with a pre-shock density of 2x10^4 cm^-3 and velocities of 10 km/s and 20 km/s for C-shocks and J-shocks, respectively, provide the best fit. In contrast, the [CI] line emission arises exclusively from the PDR component, which is best parameterized by a density of 3.2x10^3 cm^-3 and a FUV field of G_o = 100 for both PDR/shock-type combinations. Our mid-J CO observations show that turbulence is a very important heating source in molecular clouds, even in normal quiescent galaxies. The most likely energy sources for the shocks are supernovae or outflows from YSOs. The energetics of these shock sources favor C-shock excitation of the lines.

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arXiv2011

Herschel/HerMES: The X-ray - Infrared correlation for star-forming galaxies at z~1

For the first time, we investigate the X-ray/infrared (IR) correlation for star-forming galaxies at z~1, using SPIRE submm data from the recently-launched Herschel Space Observatory and deep X-ray data from the 2Ms Chandra deep field north (CDFN) survey. We examine the X-ray/IR correlation in the soft X-ray (SX, 0.5-2 keV) and hard X-ray (HX, 2-10 keV) bands by comparing our z~1 SPIRE-detected star-forming galaxies (SFGs) to equivalently IR-luminous (L_IR >10^10 L_sun) samples in the local/low redshift Universe. Our results suggest that the X-ray/IR properties of the SPIRE SFGs are on average similar to those of their local counterparts, as we find no evidence for evolution in the L_SX/L_IR and L_HX/L_IR ratios with redshift. We note however, that at all redshifts, both L_SX/L_IR and L_HX/L_IR are strongly dependent on IR luminosity, with luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs,L_IR >10^11 L_sun) having up to an order of magnitude lower values than normal infrared galaxies (L_IR <10^11 L_sun). We derive a L_SX-L_IR relation and confirm the applicability of an existing L_HX-L_IR relation for both local and distant LIRGs and ULIRGs, consistent with a scenario where X-ray luminosity is correlated with the star-formation rate (SFR).

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arXiv2011

PACS Evolutionary Probe (PEP) - A Herschel Key Program

Deep far-infrared photometric surveys studying galaxy evolution and the nature of the cosmic infrared background are a key strength of the Herschel mission. We describe the scientific motivation for the PACS Evolutionary Probe (PEP) guaranteed time key program and its role in the complement of Herschel surveys, and the field selection which includes popular multiwavelength fields such as GOODS, COSMOS, Lockman Hole, ECDFS, EGS. We provide an account of the observing strategies and data reduction methods used. An overview of first science results illustrates the potential of PEP in providing calorimetric star formation rates for high redshift galaxy populations, thus testing and superseeding previous extrapolations from other wavelengths, and enabling a wide range of galaxy evolution studies.

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arXiv2011

HerMES: Lyman Break Galaxies individually detected at 0.7 < z < 2.0 in GOODS-N with Herschel/SPIRE

As part of the Herschel Multi-tiered Extragalactic Survey we have investigated the rest-frame far-infrared (FIR) properties of a sample of more than 4800 Lyman Break Galaxies (LBGs) in the Great Observatories Origins Deep Survey North field. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 < z < 1.6 and one object at z ~ 2.0. The ones detected by Herschel SPIRE have redder observed NUV-U and U-R colors than the others, while the undetected ones have colors consistent with average LBGs at z > 2.5. The UV-to-FIR spectral energy distributions of the objects detected in the rest-frame FIR are investigated using the code CIGALE to estimate physical parameters. We find that LBGs detected by SPIRE are high mass, luminous infrared galaxies. It appears that LBGs are located in a triangle-shaped region in the A_FUV vs. Log L_FUV diagram limited by A_FUV=0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom-right to the top-left of the diagram. This upper envelop can be used as upper limits for the UV dust attenuation as a function of L_FUV}. The limits of this region are well explained using a closed-box model, where the chemical evolution of galaxies produces metals, which in turn lead to higher dust attenuation when the galaxies age.

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arXiv2011

Redshift Determination and CO Line Excitation Modeling for the Multiply-Lensed Galaxy HLSW-01

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.

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arXiv2011

Modeling of the HERMES J105751.1+573027 submillimeter source lensed by a dark matter dominated foreground group of galaxies

We present the results of a gravitational lensing analysis of the bright $\zs=2.957$ sub-millimeter galaxy (SMG), HERMES J105751.1+573027 found in {\it Herschel}/SPIRE Science Demonstration Phase data from the Herschel Multi-tiered Extragalactic Survey (HerMES) project. The high resolution imaging available in optical and Near-IR channels, along with CO emission obtained with the Plateau de Bure Interferometer, allow us to precisely estimate the intrinsic source extension and hence estimate the total lensing magnification to be $μ=10.9\pm 0.7$. We measure the half-light radius $R_{\rm eff}$ of the source in the rest-frame Near-UV and $V$ bands that characterize the unobscured light coming from stars and find $R_{\rm eff,*}= [2.0 \pm 0.1]$ kpc, in good agreement with recent studies on the Submillimeter Galaxy population. This lens model is also used to estimate the size of the gas distribution ($R_{\rm eff,gas}= [1.1\pm0.5]$) kpc by mapping back in the source plane the CO (J=5-4) transition line emission. The lens modeling yields a relatively large Einstein radius $R_{\rm Ein}= 4\farcs10 \pm 0\farcs02$, corresponding to a deflector velocity dispersion of [$483\pm 16] \,\kms$. This shows that HERMES J105751.1+573027 is lensed by a {\it galaxy group-size} dark matter halo at redshift $\zl\sim 0.6$. The projected dark matter contribution largely dominates the mass budget within the Einstein radius with $f_{\rm dm}(<R_{\rm Ein})\sim 80%$. This fraction reduces to $f_{\rm dm}(<R_{\rm eff,G1}\simeq 4.5\kpc)\sim 47%$ within the effective radius of the main deflecting galaxy of stellar mass $M_{\rm *,G1}=[8.5\pm 1.6] \times 10^{11}\msun$. At this smaller scale the dark matter fraction is consistent with results already found for massive lensing ellipticals at $z\sim0.2$ from the SLACS survey.

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arXiv2011

Discovery of a Multiply-Lensed Submillimeter Galaxy in Early HerMES Herschel/SPIRE Data

We report the discovery of a bright ($f(250\mum) > 400$ mJy), multiply-lensed submillimeter galaxy \obj\ in {\it Herschel}/SPIRE Science Demonstration Phase data from the HerMES project. Interferometric 880\mum\ Submillimeter Array observations resolve at least four images with a large separation of $\sim 9\arcsec$. A high-resolution adaptive optics $K_p$ image with Keck/NIRC2 clearly shows strong lensing arcs. Follow-up spectroscopy gives a redshift of $z=2.9575$, and the lensing model gives a total magnification of $μ\sim 11 \pm 1$. The large image separation allows us to study the multi-wavelength spectral energy distribution (SED) of the lensed source unobscured by the central lensing mass. The far-IR/millimeter-wave SED is well described by a modified blackbody fit with an unusually warm dust temperature, $88 \pm 3$ K. We derive a lensing-corrected total IR luminosity of $(1.43 \pm 0.09) \times 10^{13}\, \mathrm{L}_{\odot}$, implying a star formation rate of $\sim 2500\, \mathrm{M}_{\odot}\, \mathrm{yr}^{-1}$. However, models primarily developed from brighter galaxies selected at longer wavelengths are a poor fit to the full optical-to-millimeter SED. A number of other strongly lensed systems have already been discovered in early {\it Herschel} data, and many more are expected as additional data are collected.

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arXiv2011

Dynamical Structure of the Molecular Interstellar Medium in an Extremely Bright, Multiply Lensed z~3 Submillimeter Galaxy Discovered with Herschel

We report the detection of CO 5-4, 3-2, and 1-0 emission in the strongly lensed, Herschel/SPIRE-selected submillimeter galaxy (SMG) HLSW-01 at z=2.9574+/-0.0001, using the Plateau de Bure Interferometer, the Combined Array for Research in Millimeter-wave Astronomy, and the Green Bank Telescope. The observations spatially resolve the molecular gas into four lensed images with a maximum separation of ~9", and reveal the internal gas dynamics in this system. We derive lensing-corrected CO line luminosities of L'(CO 1-0) = (4.17+/-0.41), L'(CO 3-2) = (3.96+/-0.20) and L'(CO 5-4) = (3.45+/-0.20) x 10^10 (mu_L/10.9)^-1 Kkm/s pc^2, corresponding to luminosity ratios of r_31 = 0.95+/-0.10, r_53 = 0.87+/-0.06, and r_51 = 0.83+/-0.09. This suggests a total molecular gas mass of Mgas = 3.3 x 10^10 (alpha_CO/0.8) (mu_L/10.9)^-1 Msun. The gas mass, gas mass fraction, gas depletion timescale, star formation efficiency, and specific star formation rate are typical for an SMG. The velocity structure of the gas reservoir suggests that the brightest two lensed images are dynamically resolved projections of the same dust-obscured region in the galaxy that are kinematically offset from the unresolved fainter images. The resolved kinematics appear consistent with the complex velocity structure observed in major, `wet' (i.e., gas-rich) mergers. Major mergers are commonly observed in SMGs, and are likely to be responsible for fueling their intense starbursts at high gas consumption rates. This study demonstrates the level of detail to which galaxies in the early universe can be studied by utilizing the increase in effective spatial resolution and sensitivity provided by gravitational lensing.

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