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The SDSS-V Local Volume Mapper (LVM): Data Analysis Pipeline

T0 review · 3 major / 4 minor · reviewed 2026-08-12 · deepseek-v4-flash

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Pith's one-line read The SDSS-V Local Volume Mapper's new data analysis pipeline separates starlight from ionized-gas emission in spectra whose apertures contain anywhere from zero to thousands of stars, and recovers emission-line fluxes, equivalent widths…

desk verdict A genuinely new RSP template method wrapped in a partly self-referential validation; the emission-line accuracy claims outrun what the simulations can test. read the letter →

arxiv 2411.09729 v1 pith:CCHZU6GO submitted 2024-11-14 astro-ph.IM astro-ph.GA

Sebastian F. Sanchez , Alfredo Mejía-Narvaez , Oleg V. Egorov , Kathryn Kreckel , Niv Drory , Guillermo A. Blanc , J. Eduardo Méndez-Delgado , Jorge K. Barrera-Ballesteros
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Hector Ibarra Dmitry Bizyaev Pablo García Aida Wofford Alejandra Z. Lugo-Aranda
This is my paper · ORCID
classification astro-ph.IMastro-ph.GA
keywords integralfieldspectroscopydataanalysispipelineemissionlinemeasurementsstellarcontinuumsubtractionresolvedpopulationsspectraltemplatelibraryLocalVolumeMapperfeedback
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper presents the first operational data analysis pipeline for the Local Volume Mapper, an integral-field spectroscopic survey that will collect over fifty million spectra spanning physical resolutions from roughly 0.05 pc to 100 pc. The central claim is that the pipeline can separate the stellar continuum from ionized-gas emission lines even when an aperture contains only one star, a few stars, or thousands, which is the regime where classical stellar-population synthesis does not apply. Using a template library of resolved stellar populations built from an empirical stellar library, the pipeline recovers emission-line fluxes, equivalent widths, systemic velocities, and velocity dispersions with precision and accuracy adequate for quantifying stellar feedback. Stellar parameters are recovered reliably for single stars, while luminosity-weighted averages for mixed populations are less precise but carry constant, correctable biases. The authors demonstrate the pipeline on idealized and realistic simulations and on a deep Orion Nebula exposure, and they publicly distribute the code and data products.

What carries the argument

The central object is the RSP template library: 1235 templates formed by clustering roughly 19,000 stars from an empirical stellar library in the space of effective temperature, surface gravity, metallicity, and alpha-enhancement, then further clustered by spectral similarity into 108 representative spectra. Each RSP carries a probability distribution function over stellar parameters, and the pipeline fits each observed spectrum as a dust-attenuated, kinematically broadened linear combination of these templates. A two-stage fitting loop first derives stellar kinematics and dust attenuation from a small subset of templates while masking emission lines, then performs a full Monte Carlo linear decomposition of the gas-free spectrum; the residual of the subtraction is smoothed to a low-order component so the emission-line fit sees an almost zero background. The mechanism carries the argument because it is what lets continuum subtraction work in apertures containing too few stars for classical stellar synthesis, and it is what lets the pipeline report not just one stellar model but a probability distribution for the stellar content.

What would settle it

Take a set of LVM apertures whose continua are dominated by stars outside the template library's coverage, such as hot OB stars or regions with strong nebular continuum like the core of Orion, and compare the DAP emission-line fluxes, velocities, and dispersions against independent measurements from high-resolution, high-signal-to-noise spectroscopy of the same regions; if the recovered emission-line parameters shift systematically with the continuum mismatch, for example with the Paschen jump at roughly 8200 Angstroms, the central claim fails. A simpler decisive test is to run the DAP on the Orion deep exposure with the nebular continuum subtracted by an independent method and check whether the faint auroral line fluxes change by more than the quoted Monte Carlo errors.

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Extended reading notes

Core claim

The authors claim that the LVM-DAP robustly corrects for stellar continuum features and recovers emission-line parameters, namely flux, equivalent width, systemic velocity, and velocity dispersion, with precision and accuracy that fulfill the primary goal of the LVM analysis, while the recovered stellar parameters are reliable when the spectrum is dominated by a single star but less precise for integrated populations. The load-bearing novelty is the resolved stellar population (RSP) approach: instead of modeling each aperture with single stellar populations that assume a fully sampled initial mass function, the pipeline decomposes the continuum into a linear combination of 108 representative stellar spectra, each carrying a probability distribution over effective temperature, surface gravity, metallicity, and alpha-element abundance. After subtracting the best stellar model and a low-order residual correction, emission lines are measured twice, parametrically with Gaussians and non-parametrically with weighted moments, with Monte Carlo error propagation. Quantitative tests on simulations show flux recovery within roughly ten percent for the majority of lines above a signal-to-noise ratio of about ten, with kinematics accurate to a few kilometers per second for the strongest lines; the authors explicitly note that the stellar library does not cover hot OB stars or nebular continuum, and that the integrated stellar parameters of mixed populations show offsets that follow linear trends and can be corrected statistically.

Load-bearing premise

The whole analysis rests on the assumption that the stellar and nebular continuum in every LVM aperture can be represented well enough by a linear combination of the 108 empirical RSP templates, plus a low-order residual adjustment, so that subtracting that model does not bias the measured emission lines.

Editorial extensions

If this is right

  • The pipeline makes it possible to process the LVM's roughly 55 million spectra automatically, fiber by fiber, without spatial binning, producing emission-line maps at physical scales from 0.05 pc to 100 pc.
  • Emission-line diagnostics such as BPT-style line ratios, electron density from the [S II] doublet, and temperature from auroral lines can be measured across resolved H II regions and stellar clusters, directly serving the survey's stellar-feedback science.
  • For single-star-dominated apertures, the recovered effective temperature, gravity, metallicity, and alpha abundance are reliable enough to characterize the stellar content, with effective temperature recovered to about five percent, though low-gravity and metallicity are less precise.
  • For mixed-population apertures, the constant biases in the recovered average stellar parameters can be corrected statistically, allowing approximate stellar population properties even when classical synthesis is invalid.
  • Public release of the DAP code and data products starting with SDSS DR20 lets other surveys with high spatial resolution per spaxel adopt the RSP decomposition approach.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • If the RSP decomposition is as robust as the simulations suggest, the same template-plus-PDF approach could be applied to other integral-field surveys whose spaxels resolve stellar populations, replacing the need to bin spatially before synthesis.
  • The admitted failure to fit the Orion continuum, including the blue-end mismatch and the Paschen jump from nebular continuum, implies that adding nebular continuum models and hotter OB-star templates to the RSP library would materially improve both stellar parameter recovery and the accuracy of weak emission lines in bright H II regions; this is a testable upgrade rather than a fundamental limit.
  • Because each RSP template carries a PDF rather than a point value, the pipeline's output is naturally suited to hierarchical or Bayesian population inference, allowing users to combine fiber PDFs into spatially resolved stellar parameter distributions with quantified degeneracies.
  • A practical caution follows from the paper's own finding that the non-parametric moment method fails on strongly blended lines like the [O II] doublet: final science catalogs should merge parametric and non-parametric outputs line by line rather than treating one method as uniformly superior.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 4 minor

Summary. The paper introduces version 1.0.0 of the SDSS-V Local Volume Mapper Data Analysis Pipeline (LVM-DAP), which separates stellar and ionized-gas components in LVM integral-field spectra. The pipeline first fits non-linear stellar parameters (v_star, sigma_star, A_V), then performs parametric and non-parametric emission-line fits, and finally synthesizes the stellar continuum using a new library of Resolved Stellar Population (RSP) templates built from the MaStar library, each carrying a PDF of physical parameters. The accuracy of the pipeline is assessed with idealized simulations (Cloudy/MAPPINGS plus Pollux stars), empirical 'realistic' simulations, single-star fits of MaStar spectra, and an application to a deep Orion Nebula exposure. The authors conclude that emission-line fluxes, equivalent widths, velocities, and dispersions are recovered with accuracy sufficient for the LVM primary goal, while stellar parameters are reliable for single stars but less precise for integrated populations.

Significance. If the central accuracy claims hold, the paper is a valuable methods contribution: it provides a working, publicly distributed pipeline for a major survey, introduces the RSP concept with associated PDFs for partially resolved stellar populations, and includes validation against physically motivated photoionization simulations. The decision to release code, templates, and example data products is a concrete strength that aids reproducibility. The idealized simulations with Cloudy and MAPPINGS truth, and the Orion comparison against multiple literature datasets, are also strong features. The main significance risk is that the quantitative accuracy claims in Table 3 rest largely on the self-referential realistic simulations, while the independent idealized simulations are presented only qualitatively; this needs to be addressed before the headline accuracy statement is fully supported.

major comments (3)
  1. [Sec. 4.2, 4.3, Table 3] The quantitative emission-line recovery statistics in Table 3 are derived from the realistic simulations described in Sec. 4.2, but those simulations use the DAP's own outputs as input truth: stellar continua are drawn from the same RSP library used in the fit, and emission-line fluxes are taken from the DAP analysis of the reference frame. This makes the quoted precision and accuracy partly a measure of the pipeline's ability to reproduce its own outputs. The idealized simulations in Sec. 4.1 use external truth (Cloudy and MAPPINGS line fluxes, Pollux stellar spectra) and are therefore not circular, but the paper only states that 'similar results' were found without quantitative tables or figures for these simulations. Please add a quantitative idealized-simulation accuracy table parallel to Table 3, or explicitly restrict the central accuracy claim to the self-consistent case and justify why the residual-based noise model is representative.
  2. [Sec. 3.1, Sec. 5.4, Fig. 15] The continuum-representation assumption is load-bearing but not independently tested. The residual-correction step in Sec. 3.1 subtracts a smoothed low-order component from the stellar-subtracted spectrum and forces a zero background before emission-line fitting; this can absorb real continuum structure and bias line fluxes and equivalent widths. Section 5.4 documents exactly the relevant failure mode: with the Orion integrated spectrum, the RSP library cannot fit the blue continuum near 3700-4000 Å or the Paschen jump at ~8200 Å, and the paper attributes part of the residual to nebular continuum and broad line wings. Since the realistic simulations cannot produce such template mismatch, the impact of this mismatch on recovered line parameters is never quantified. Please add a test that injects synthetic emission lines into spectra containing non-RSP continuum components (e.g., an OB-star continuum or a nebular-continuum model with the Paschen jump) and reports the resulting biases in flux, EW, velocity, and dispersion.
  3. [Sec. 4.4, Fig. 8] The single-star validation fits MaStar spectra with the RSP library generated from the same MaStar spectra, so it is an internal-consistency test rather than an external accuracy test. The paper acknowledges this limitation in the text, but the abstract and Sec. 7 state that the recovered stellar parameters are 'reliable for single stars' without this caveat. The claim would be strengthened by validating against at least a subset of stars from an independent library outside MaStar, such as the Pollux stars already used in the idealized simulations or model-atmosphere grids; otherwise the statement should be softened to say that the method is internally consistent within the parameter space covered by the library.
minor comments (4)
  1. [Abstract and Sec. 1] The abstract contains typos: 'systemtic velocity' should be 'systemic velocity', and 'robustly correct' should be 'robustly corrects'. Similar typographical issues appear elsewhere, e.g., 'poitings' in Sec. 5, 'origion' in Sec. 5.4, and 'descrived' in Sec. 5.5.
  2. [Sec. 4.5, Fig. 11 caption] Figure 11 caption says 'the RSP template comprising 1253 stars', but the text consistently states that the RSP library contains 1235 templates. Please correct the number.
  3. [Sec. 3.3.1] The resolution mismatch between MaStar (R~1800) and LVM (R~4000) is mentioned, but the paper does not quantify how this affects the stellar velocity dispersion recovery or the effective spectral binning used in the non-linear fit. A sentence giving the expected systematic floor on sigma_star from this mismatch would help users interpret the values in the data products.
  4. [Sec. 4.5, Fig. 10] The text reports offsets and corrected fractions for the stellar population recovery, but the definition of 'corrected' is not explicit in the text near Fig. 10. Please state whether the corrections are simple additive offsets and whether they are derived from the same simulations or from independent data.

Circularity Check

3 steps flagged · score 6.0 of 10

Continuum-representation accuracy is partly self-referential: realistic simulations draw both stellar continua and emission-line truth from the DAP's own outputs and RSP library.

  1. fitted input called prediction [Sec. 4.2, 'Realistic simulations', first paragraph]
    "The second set of simulations, which we will call 'realistic', uses the outputs of the DAP analysis on real LVM observations. Essentially, it uses the properties of the emission lines extracted by the DAP based on the weighted-moment analysis on a real LVM frame (reference frame) to generate RSS spectra of the ionized gas emission... By construction, the spatial distribution of the flux intensities of the simulated emission lines is the same as the spatial distribution of those properties in the reference frame."

    The 'true' emission-line fluxes injected into the realistic simulations are the DAP's own weighted-moment measurements from the reference frame. The recovery statistics in Sec. 4.3 and Table 3 therefore measure how well the DAP reproduces its own outputs under added noise and randomized kinematics, not how well it recovers independent physical truth. The claimed accuracy for emission-line fluxes, EWs, velocities, and dispersions is thus partly a self-consistency check rather than an external validation of the continuum subtraction on which those measurements depend.

  2. fitted input called prediction [Sec. 4.2, 'Realistic simulations', second paragraph; and Sec. 4.5]
    "in addition, for each fiber, a stellar spectrum is simulated by randomly combining spectra from a selected RSP-template, adding a certain dust attenuation (AV,star), and applying certain kinematics (vel_star, sigma_star)."

    The simulated stellar continua are built by linearly combining spectra from the same RSP template library that the DAP later fits (Sec. 3.3). Input continua therefore lie inside the span of the fitting basis by construction, so template mismatch cannot appear in the quoted accuracies. The realistic simulations never exercise the failure mode documented in Sec. 5.4, where the adopted templates cannot fit the Orion continuum around 3700-4000 Å or the Paschen jump at ~8200 Å. The central claim that the DAP 'robustly correct[s] for stellar continuum features' is consequently not independently established by these simulations.

1 more flagged steps
  1. fitted input called prediction [Sec. 4.4, 'Recovery of the parameters for a single star', final paragraph]
    "Another important remark regarding the current exploration is that we have performed this test using the same stellar library and spectra adopted to generate the RSP templates used in the fitting process. Therefore, we are not fully testing the ability of the procedure to recover physical properties of individual stars in the most general sense, but rather exploring the ability to recover them within the boundaries of properties covered by the MaStar library."

    The single-star validation fits the very MaStar spectra from which the RSP templates were constructed (Sec. 3.3.1), so good recovery of Teff, log(g), [Fe/H], and [alpha/Fe] partly confirms that the template-building procedure preserved information about its own training set. This is a training-set validation, not an independent test against external stellar labels. The paper honestly discloses this, but the abstract's statement that 'the recovered stellar parameters are reliable for single stars' is weaker than an external validation would support.

full rationale

The paper is transparent about its limitations, but the central accuracy claim for continuum subtraction and emission-line recovery rests partly on simulations whose inputs are the DAP's own outputs or its own template library. The realistic simulations (Sec. 4.2) generate emission-line truth from the DAP's weighted-moment measurements and generate stellar continua by randomly combining RSP templates from the same library used in the fit; thus Table 3's precision and accuracy figures are partly a self-consistency test, not an external test of template mismatch. The single-star validation (Sec. 4.4) is likewise performed on the MaStar library used to build the RSP templates, a disclosed training-set validation. Independently, the idealized simulations (Sec. 4.1) use Cloudy/MAPPINGS emission models and Pollux stellar atmosphere spectra, which are external to the RSP library, and the Orion application (Sec. 5) compares line ratios to O92, B00, and S07, providing some external benchmark. However, Sec. 5.4 explicitly documents that the adopted templates cannot reproduce the real Orion continuum (blue-end mismatch and Paschen jump), and the low-order residual correction that absorbs this mismatch is inherited from prior work by the same group (Sanchez et al. 2016a; Lacerda et al. 2022). Because the realistic validation cannot expose this failure mode, the robustness claim is partially circular. There is no imported 'uniqueness theorem' and no hidden self-citation chain; the partial circularity is confined to the validation strategy. Score 6 reflects a central claim that is partly forced by construction but retains independent content from the idealized simulations and the external Orion comparison.

Assumptions & free parameters 9 free parameters · 6 assumptions · 0 invented entities

The central claim rests on the representativeness of the RSP template library and the noise model. The free parameters are hand-chosen hyperparameters of the clustering and analysis thresholds, which directly shape the template library and the conditions under which stellar products are produced. The axioms are standard domain assumptions about the data reduction, stellar parameter catalog, photoionization models, and linearity of the continuum decomposition. No new physical entities are introduced.

free parameters (9)
  • Physical parameter bin sizes for RSP clustering = Δlog(Teff)=0.03, Δlog(g)=0.03, Δ[Fe/H]=0.2, Δ[α/Fe]=0.15
    Chosen by hand to balance the homogeneity of the template library against the number of stars per bin; affects the resolution and coverage of the final templates.
  • Minimum stars per bin = 3
    Selected to ensure enough S/N per RSP template while retaining as much parameter coverage as possible; it sets the threshold for including a bin in the library.
  • S/N threshold for MaStar library inclusion = S/N>5 in blue range 3980-4090 Å
    Applied to select MaStar spectra for template construction, directly shaping the stellar parameter coverage of the library.
  • Number of RSP clusters (ncl) = 108
    Chosen after testing 4, 12, 36, 108, 342; balances spectral degeneracies against computational cost and is a key hyperparameter of the final template library.
  • k-neighbor for spectral clustering = 3
    An input parameter for scikit-learn's SpectralClustering; set by hand to define the similarity graph.
  • Normalization window for clustering = 50 Å around 5000 Å
    Used to scale RSP spectra before clustering, affecting the definition of spectral similarity.
  • S/N threshold for full stellar decomposition = 20
    Above this continuum S/N the DAP performs multi-RSP fitting; below it selects a single template or none, so it governs which stellar products are produced.
  • Dust attenuation bin width = 75 Å
    Smoothing scale adopted for the AV derivation, following Wilkinson et al.; it speeds computation and changes the derived AV values.
  • Kinematic spectral binning = 3 pixels
    Used to match the observed spectral sampling to the template resolution (about 1.5 Å); affects recovered v* and sigma*.
assumptions (6)
  • domain assumption CoSha-assigned stellar parameters (Teff, log g, [Fe/H], [α/Fe]) for MaStar stars are accurate and can be propagated into RSP template PDFs.
    Section 3.3.1 builds the RSP library from these values; any systematic error in CoSha propagates into the template PDFs and the recovered stellar parameters.
  • domain assumption The LVM data reduction pipeline correctly performs sky subtraction, flux calibration, wavelength calibration, and error propagation.
    Section 2 summarizes the DRP and the DAP takes its outputs as input; errors in the DRP affect all DAP measurements and the noise model in realistic simulations.
  • domain assumption A linear combination of a small number of RSP templates can represent the stellar continuum in any LVM aperture.
    Section 3.1 assumes this to separate stellar and gas components; if not true, the continuum subtraction leaves residuals that bias emission-line parameters.
  • domain assumption Photoionization models (Cloudy, MAPPINGS) used in idealized simulations produce realistic emission-line spectra for testing.
    Section 4.1 relies on these models to define the true input for the idealized simulations; their accuracy determines how meaningful that test is.
  • ad hoc to paper Residuals from the DAP fit to a real frame are a representative noise model for constructing realistic simulations.
    Section 4.2 uses these residuals to generate noise spectra; this is a convenient but self-referential choice, since the residuals depend on the DAP's own fit quality.
  • domain assumption Gaussian line profiles are adequate for the parametric emission-line fits.
    Section 3.1 fits emission lines as Gaussians; non-Gaussian profiles (e.g., wings) could bias flux and kinematics, as acknowledged in Sec. 5.4.

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Cite this review

Pith. "Pith review of The SDSS-V Local Volume Mapper (LVM): Data Analysis Pipeline." pith.science (2026). https://pith.science/paper/CCHZU6GO

@misc{pith2026241109729,
  author       = {Pith},
  title        = {Pith review of: The SDSS-V Local Volume Mapper (LVM): Data Analysis Pipeline},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/CCHZU6GO}},
  note         = {Machine review of arXiv:2411.09729}
}
read the original abstract

We introduce the Data Analysis Pipeline (DAP) for the Sloan Digital Sky Survey V (SDSS-V) Local Volume Mapper (LVM) project, referred to as the LVM-DAP. We outline our methods for recovering both stellar and emission line components from the optical integral field spectroscopy, highlighting the developments and changes implemented to address specific challenges of the data set. The observations from the LVM project are unique because they cover a wide range of physical resolutions, from approximately 0.05 pc to 100 pc, depending on the distance to the targets. This, along with the varying number of stars sampled in each aperture (ranging from zero, just one of a few, to thousands), presents challenges in using previous spectral synthesis methods and interpreting the spectral fits. We provide a detailed explanation of how we model the stellar content and separate it from the ionized gas emission lines. To assess the accuracy of our results, we compare them with both idealized and more realistic simulations, highlighting the limitations of our methods. We find that the DAP robustly correct for stellar continuum features and recover emission line parameters (e.g. flux, equivalent width, systemtic velocity and velocity dispersion) with a precision and accuracy that fulfill the requirements of the primary goal of the analysis. In addition, the recovered stellar parameters are reliable for single stars, the recovery of integrated populations is less precise. We conclude with a description of the data products we provide, instructions for downloading and using our software, and a showcase illustrating the quality of the data and the analysis on a deep exposure taken on the Huygens region at the center of the Orion Nebula.

Figures

Figures reproduced from arXiv: 2411.09729 by the authors.

Figure 1
Figure 1. Scheme of the LVM-dap analysis flow for a single fiber spectrum, including the main procedures: (i) derivation of the non-linear parameters of the stellar spectrum (v⋆, σ⋆ and AV,⋆), (ii) parametric derivation of the properties of the ionized gas emission lines (EL), including the flux intensity (fEL), velocity (vEL) and velocity dispersion (σEL), (iii) stellar component synthesis, i.e., decomposition into a set of … view at source ↗
Figure 2
Figure 2. Distribution of the physical properties derived using CoSha for 22773 stars extracted from the MaStar stellar library (grey-solid line and density contours), together with the average properties for the 1235 RSPs created by clustering those MaStar stars in the space of physical properties using a regular grid (colored stars). Left (right) panel shows the distribution in the log(g)-Te f f ([α/Fe]-[Fe/H]) plane, with … view at source ↗
Figure 3
Figure 3. Sub-set of the spectra included in the template comprising 108 RSPs created by clustering in the observational space the 1235 RSPs which properties are shown in [PITH_FULL_IMAGE:figures/full_fig_p009_3.png] view at source ↗
Figures from the paper (14 more)
Figure 4
Figure 4. Figure 4: Probability distribution function of the physical proper￾ties of stars (Te f f , log(g), [Fe/H] and [α/Fe]) for the full template comprising 108 RSPs (black contours), together with the same dis￾tribution for three selected RSPs within the template (colour con￾tours) s…
Figure 5
Figure 5. Figure 5: Upper-panels: Spatial distribution of the input (left panel) and recovered (right panel) fluxes of the [O iii]5007 (blue), Hα (green) and [N ii]6583 (red) emission lines in an arbitrary scale. Lower-panel: Example of the spectral modelling, showing the spectrum integra…
Figure 6
Figure 6. Figure 6: Similar figure as the one shown in [PITH_FULL_IMAGE:figures/full_fig_p013_6.png]
Figure 7
Figure 7. Figure 7: Comparison between the simulated and recovered parameters for the emission lines based on the non-parametric analysis described in Sec. 3.1, for the ad-hoc realistic simulations described in Sec. 4.2. A total of 326400 emission lines were included in the simulation. We…
Figure 8
Figure 8. Figure 8: Comparison between the stellar physical parameters (Te f f : top-left, log(g): top-right ,[Fe/H]: bottom-left, and [α/Fe]: bottom-right) estimated by the LVM-DAP using a RSP-library with just 108 templates, and the values reported by CoSha for the ∼19,000 individual Ma…
Figure 9
Figure 9. Figure 9: Comparison between the value of the physical proper￾ties (Te f f , log(g), [Fe/H], and [α/Fe]) of one arbitrarily selected star of within MaStar catalog as derived by CoSha (blue star) and the PDF recovered by the DAP (red contours). The PDFs for the full template comp…
Figure 10
Figure 10. Figure 10: Comparison between the recovered and simulated stellar physical parameters (Te f f : top-left, log(g): top-right, [Fe/H]: bottom-left, and [α/Fe]: bottom-right) using LVM-DAP for a set of 1700 realistic simulations in which it was a assumed a number of stars between 5…
Figure 11
Figure 11. Figure 11: Comparison between the simulated (blue contours) and recovered (red contours) PDF of the physical properties of stars (Te f f , log(g), [Fe/H], and [α/Fe]) derived for one of the 1700 simu￾lations generated by mixing randomly the spectra of 5 stars within the RSP temp…
Figure 12
Figure 12. Figure 12: Comparison between the recovered and simulated non-linear parameters of the stellar component: v⋆ (left panel), σ⋆ (middel panel) and AV,⋆ (right panel). Contours, symbols and lines in each panel have the same meaning as those in [PITH_FULL_IMAGE:figures/full_fig_p02…
Figure 13
Figure 13. Figure 13: Normalized histograms of the distribution of S/N ratios (top panels) and cumulative distributions (bottom panels) for three representative emission lines (Hα: black, [O iii]5007: blue, and [N ii]5755: cyan) and the stellar continuum around ∼5000Å (red) for ∼7 million …
Figure 14
Figure 14. Figure 14: Spatial distribution of fluxes recovered by the DAP of the [O iii]5007 (blue), Hα (green), and [N ii]6583 (red) emission lines for the combination of un-saturated pointings covering the cen￾tral region of the Orion nebulae described in the text, using an arbi￾trary sc…
Figure 15
Figure 15. Figure 15: Integrated spectrum of the central 5’×6’ region of the Orion Nebula (black solid line), together with the best-fitted stellar model (red solid line), the model of the strongest emission lines fitted with Gaussian functions (blue solid line), and the residual after sub…
Figure 16
Figure 16. Figure 16: Example of the analysis performed by LVM-DAP to recover the properties of the ionized gas emission lines. Each panel shows the distribution across the FoV of the LVM IFU of the flux intensity estimated by the weighted-moment procedure for the 20 brightest emission lin…
Figure 17
Figure 17. Figure 17: Comparison between the flux intensities for the emission lines derived using the non-parametric (NP ELINES) and parametric (PM ELINES) procedures described in Sec. 3.1, for the ad-hoc realistic simulations described in Sec. 4.2 (left panel) and the Orion data discusse…

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Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. The Twentieth Data Release of the Sloan Digital Sky Survey: First All-Sky BOSS Spectra, eROSITA-SDSS-V Mapper Coordinated Observations, and a Preview of the Local Volume Mapper

    astro-ph.GA 2026-07 accept novelty 6.0 of 10

    DR20 releases over three million BOSS spectra (first southern-hemisphere SDSS-V optical data), 169 LVM integral-field tiles over six targets, and eighteen value-added catalogs.

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