Spectral Mapping Reconstruction of Extended Sources

Smith, J. D.; Armus, L.; Dale, Daniel A.; Roussel, Hervé; Sheth, Kartik; Buckalew, B.; Jarrett, T. H.; Hélou, G.; Kennicutt, Robert C.

doi:10.1086/522634

Cited by 244 publications

(212 citation statements)

References 31 publications

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“…This conservative regridding method is a similar approach to the variable-pixel linear reconstruction algorithm used in the astronomy community, which was developed to preserve photometry and resolution for the Hubble Space Telescope [41]. We used subroutines from the Cube Builder for IRS Spectra Maps (CUBISM) [42] based on the Sutherland-Hodgman polygon clipping algorithm [43] for the efficient calculation of overlapped fractions. More details are available in the documentation of the development of the IDL-based Geospatial Data Processor (IGDP) [44].…”

Section: Conservative Regriddingmentioning

confidence: 99%

A Conservative Downscaling of Satellite-Detected Chemical Compositions: NO2 Column Densities of OMI, GOME-2, and CMAQ

et al. 2018

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A conservative downscaling technique was applied when comparing nitrogen dioxide (NO 2 ) column densities from space-borne observations and a fine-scale regional model. The conservative downscaling was designed to enhance the spatial resolution of satellite measurements by applying the fine-scale spatial structure from the model, with strict mass conservation at each satellite footprint pixel level. With the downscaling approach, NO 2 column densities from the Ozone Monitoring Instrument (OMI; 13 × 24 km nadir footprint resolution) and the Global Ozone Monitoring Experiment-2 (GOME-2; 40 × 80 km) show excellent agreement with the Community Multiscale Air Quality (CMAQ; 4 × 4 km) NO 2 column densities, with R = 0.96 for OMI and R = 0.97 for GOME-2. We further introduce an approach to reconstruct surface NO 2 concentrations by combining satellite column densities and simulated surface-to-column ratios from the model. Compared with the Environmental Protection Agency's (EPA) Air Quality System (AQS) surface observations, the reconstructed surface concentrations show a good agreement; R = 0.86 for both OMI and GOME-2. This study demonstrates that the conservative downscaling approach is a useful tool to compare coarse-scale satellites with fine-scale models or observations in urban areas for air quality and emissions studies. The reconstructed fine-scale surface concentration field could be used for future epidemiology and urbanization studies.

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Section: Conservative Regriddingmentioning

confidence: 99%

A Conservative Downscaling of Satellite-Detected Chemical Compositions: NO2 Column Densities of OMI, GOME-2, and CMAQ

et al. 2018

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“…The slit width (comparable to angular resolution) is 3.6 for the SL and 10.5 for the LL modules. Data reduction was performed with the CUBISM software (Smith et al 2007) and consisted in cube assembling, calibration, flux correction for extended sources and bad pixel removal. From the LL data cube we extracted maps integrated in the H 2 line at 17.0 μm, the PAH band in Fig.…”

Section: Observationsmentioning

confidence: 99%

Interstellar C₆₀⁺

Berné¹,

Mulas²,

Joblin³

2013

A&A

117

113

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Buckminsterfullerene (C 60 ) has recently been detected through its infrared emission bands in the interstellar medium (ISM), including in the proximity of massive stars, where physical conditions could favor the formation of the cationic form, C + 60 . In addition, C + 60 was proposed as the carrier of two diffuse interstellar bands in the near-IR, although a firm identification still awaits gas-phase spectroscopic data. We examined in detail the Spitzer IRS spectra of the NGC 7023 reflection nebula, at a position close (7.5 ) to the illuminating B star HD 200775, and found four previously unreported bands at 6.4, 7.1, 8.2, and 10.5 μm, in addition to the classical bands attributed to polycylic aromatic hydrocarbons (PAHs) and neutral C 60 . These 4 bands are observed only in this region of the nebula, while C 60 emission is still present slightly farther away from the star, and PAH emission even farther away. Based on this observation, on theoretical calculations we perform, and on laboratory studies, we attribute these bands to C + 60 . The detection of C + 60 confirms the idea that large carbon molecules exist in the gas phase in these environments. In addition, the relative variation in the C 60 and C + 60 band intensities constitutes a potentially powerful probe of the physical conditions in highly UV-irradiated regions.

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“…Initial data processing was performed with version S18.7 of the Spitzer Science Center pipeline. Spectral data cubes were compiled using the CUBISM software (Smith et al 2007), and bad/rogue pixels were masked by visual inspection. As in the case of PACS, emission line maps were constructed through customized procedures.…”

Section: Spitzer/irsmentioning

confidence: 99%

Dust, ice and gas in time (DIGIT):HerschelandSpitzerspectro-imaging of SMM3 and SMM4 in Serpens

Dionatos

Jørgensen

Green

et al. 2013

A&A

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Context. Mid-and far-infrared observations of the environment around embedded protostars reveal a plethora of high excitation molecular and atomic emission lines. Different mechanisms for the origin of these lines have been proposed, including shocks induced by protostellar jets and radiation or heating by the embedded protostar of its immediate surroundings. Aims. By studying of the most important molecular and atomic coolants, we aim at constraining the physical conditions around the embedded protostars SMM3 and SMM4 in the Serpens molecular cloud core and measuring the CO/H 2 ratio in warm gas. The excitation conditions for molecular species are assessed through rotational diagrams. Emission lines from major coolants are compared to the results of steady-state C-and J-type shock models. Results. Line emission tends to peak at distances of ∼10-20 from the protostellar sources with all but [CII] peaking at the positions of outflow shocks seen in near-IR and sub-millimeter interferometric observations. The [CII] emission pattern suggests that it is most likely excited from energetic UV radiation originating from the nearby flat-spectrum source SMM6. Excitation analysis indicates that H 2 and CO originate in gas at two distinct rotational temperatures of ∼300 K and 1000 K, while the excitation temperature for H 2 O and OH is ∼100-200 K. The morphological and physical association between CO and H 2 suggests a common excitation mechanism, which allows direct comparisons between the two molecules. The CO/H 2 abundance ratio varies from ∼10 −5 in the warmer gas up to ∼10 −4 in the hotter regions. Shock models indicate that C-shocks can account for the observed line intensities if a beam filling factor and a temperature stratification in the shock front are considered. C-type shocks can best explain the emission from H 2 O. The existence of J-shocks is suggested by the strong atomic/ionic (except for [CII]) emission and a number of line ratio diagnostics. Dissociative shocks can account for the CO and H 2 emission in a single excitation temperature structure. Conclusions. The bulk of cooling from molecular and atomic lines is associated with gas excited in outflow shocks. The strong association between H 2 and CO constrain their abundance ratio in warm gas. Both C-and J-type shocks can account for the observed molecular emission; however, J-shocks are strongly suggested by the atomic emission and provide simpler and more homogeneous solutions for CO and H 2 . The variations in the CO/H 2 abundance ratio for gas at different temperatures can be interpreted by their reformation rates in dissociative J-type shocks, or the influence of both C and J shocks.

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Spectral Mapping Reconstruction of Extended Sources

Cited by 244 publications

References 31 publications

A Conservative Downscaling of Satellite-Detected Chemical Compositions: NO2 Column Densities of OMI, GOME-2, and CMAQ

A Conservative Downscaling of Satellite-Detected Chemical Compositions: NO2 Column Densities of OMI, GOME-2, and CMAQ

Interstellar C₆₀⁺

Dust, ice and gas in time (DIGIT):HerschelandSpitzerspectro-imaging of SMM3 and SMM4 in Serpens

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Spectral Mapping Reconstruction of Extended Sources

Cited by 244 publications

References 31 publications

A Conservative Downscaling of Satellite-Detected Chemical Compositions: NO2 Column Densities of OMI, GOME-2, and CMAQ

A Conservative Downscaling of Satellite-Detected Chemical Compositions: NO2 Column Densities of OMI, GOME-2, and CMAQ

Interstellar C60+

Dust, ice and gas in time (DIGIT):HerschelandSpitzerspectro-imaging of SMM3 and SMM4 in Serpens

Contact Info

Product

Resources

About

Interstellar C₆₀⁺