J/ApJ/954/141 The MADGICS 8621{AA} DIB cat. from GaiaDR3 RVS (Saydjari+, 2023) ================================================================================ Measuring the 8621{AA} Diffuse Interstellar Band in Gaia DR3 RVS spectra: obtaining a clean catalog by marginalizing over stellar types. Saydjari A.K., Uzsoy A.S. M, Zucker C., Peek J.E.G., Finkbeiner D.P. =2023ApJ...954..141S ================================================================================ ADC_Keywords: Interstellar medium; Spectra, optical; Equivalent widths; Space velocities; Reddening; Stars, distances; Parallaxes, trigonometric Keywords: Diffuse interstellar bands ; Astronomy data reduction ; Catalogs Abstract: Diffuse interstellar bands (DIBs) are broad absorption features associated with interstellar dust and can serve as chemical and kinematic tracers. Conventional measurements of DIBs in stellar spectra are complicated by residuals between observations and best-fit stellar models. To overcome this, we simultaneously model the spectrum as a combination of stellar, dust, and residual components, with full posteriors on the joint distribution of the components. This decomposition is obtained by modeling each component as a draw from a high-dimensional Gaussian distribution in the data space (the observed spectrum)-a method we call "Marginalized Analytic Data-space Gaussian Inference for Component Separation" (MADGICS). We use a data-driven prior for the stellar component, which avoids missing stellar features not well modeled by synthetic spectra. This technique provides statistically rigorous uncertainties and detection thresholds, which are required to work in the low signal-to-noise regime that is commonplace for dusty lines of sight. We reprocess all public Gaia DR3 RVS spectra and present an improved 8621{AA} DIB catalog, free of detectable stellar line contamination. We constrain the rest-frame wavelength to 8623.14+/-0.087{AA} (vacuum), find no significant evidence for DIBs in the Local Bubble from the 1/6th of RVS spectra that are public, and show unprecedented correlation with kinematic substructure in Galactic CO maps. We validate the catalog, its reported uncertainties, and biases using synthetic injection tests. We believe MADGICS provides a viable path forward for large-scale spectral line measurements in the presence of complex spectral contamination. Description: The primary data used in this work are the Gaia DR3 RVS spectra, which were obtained from the Gaia archive (Gaia Col. 2016A&A...595A...1G ; see I/337, superseded by I/355). These are optical spectra spanning 8460-8700{AA}. The primary Gaia analysis of these spectra falls under the General Stellar Parameteriser-spectroscopy (GSP-Spec) module, which is a purely spectroscopic analysis to obtain chemophysical stellar parameters from combined RVS spectra (Recio-Blanco+ 2023A&A...674A..29R). See Section 2. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file madgics.dat 498 7789 *MADGICS 8621{AA} Diffuse Interstellar Band (DIB) catalog -------------------------------------------------------------------------------- Note on madgics.dat: Along with the main catalog file including the MADGICS ("Marginalized Analytic Data-space Gaussian Inference for Component Separation") method output, we also provide a subset of values in the Gaia DR3 catalog (see I/355), the Gaia DR3 DIB cat. (2023A&A...674A..40G), the Bailer-Jones distance catalog (CBJ; see I/352), and the result of dustmap queries along the lines of sight. Any other value desired from external catalogs can be obtain by cross-match or using the Gaia source ID. -------------------------------------------------------------------------------- See also: I/337 : Gaia DR1 (Gaia Collaboration, 2016) V/146 : LAMOST DR1 catalogs (Luo+, 2015) I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021) I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022) J/A+A/550/A103 : Model 1D (LHD) and 3D (CO5BOLD) sp. (Allende Prieto+, 2013) J/ApJ/774/72 : 19 DIBs and 8 other interstellar lines (Kos+, 2013) J/A+A/550/A108 : DIB in VLT-FLAMES Tarantula Survey (van Loon+, 2013) J/A+A/585/A12 : Nearby early-type stars spectroscopic survey (Bailey+, 2016) J/ApJ/885/131 : ~200 high-mass SFR plx & PMs with VLBI (Reid+, 2019) J/MNRAS/506/150 : The GALAH+ Survey DR3 (Buder+, 2021) J/A+A/654/A130 : GSP-spec line list (Contursi+, 2021) J/A+A/654/A116 : Measured DIB 8620 (Zhao+, 2021) http://faun.rc.fas.harvard.edu/saydjari/GaiaDIB/ : Online data access http://zenodo.org/record/8303423 : Associated data to the paper http://www.cosmos.esa.int/web/gaia : Gaia home page Byte-by-byte Description of file: madgics.dat -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 1- 19 I19 --- GaiaDR3 Gaia DR3 source ID (gaia_source_id) 21- 26 I6 --- Seq [529/998803] Index of public RVS spectra, sorted on Gaia source ID (linear_indx) 28- 36 F9.4 --- sSNR [15/1346.4] SNR of the spectrum (stellar_snr) 38- 52 F15.11 deg RAdeg [0/360] Gaia DR3 right ascension (ICRS) at Ep=2016.0 (ra) 54- 68 F15.11 deg DEdeg [-85.82/79.36] Gaia DR3 declination (ICRS) at Ep=2016.0 (dec) 70- 81 F12.8 deg GLON [0/360] Galactic longitude 83- 94 F12.8 deg GLAT [-78/71] Galactic latitude 96-106 F11.7 kpc X [-11.43/11.6]? Galactic cartesian coordinate X 108-118 F11.7 kpc Y [-15.17/10.23]? Galactic cartesian coordinate Y 120-129 F10.7 kpc Z [-5.6/3.6]? Galactic cartesian coordinate Z 131-139 F9.6 --- U [-1/1] Galactic cartesian X-coordinate direction (unit direction vector) 141-149 F9.6 --- V [-1/1] Galactic cartesian Y-coordinate direction (unit direction vector) 151-159 F9.6 --- W [-0.98/0.95] Galactic cartesian Z-coordinate direction (unit direction vector) -------------------------------------------------------------------------------- 161-167 F7.4 0.1nm EW [-1.1/1] MADGICS DIB equivalent width in {AA} 169-174 F6.4 0.1nm e_EW [0.0018/0.2] EW uncertainty (ew_err) 176-183 F8.3 0.1nm lambda [8613.6/8633.4] MADGICS DIB center wavelength (stellar frame) in {AA} (lam) 185-189 F5.3 0.1nm e_lambda [0.08/1.8] lambda uncertainty (lam_err) 191-195 F5.3 0.1nm sig [0.5/4] MADGICS DIB width in {AA} 197-201 F5.3 0.1nm e_sig [0.09/2.8] sig uncertainty (sig_err) 203-209 F7.2 km/s VdLSR [-427/383] MADGICS DIB velocity in LSR (v_dust_lsr) 211-215 F5.2 km/s e_VdLSR [2.7/62] VdLSR uncertainty (v_dust_lsr_err) (1) 217-223 F7.2 km/s VdLSRCO [-427/381] MADGICS DIB velocity in LSR (of Dame+ 2001ApJ...547..792D CO map) (v_dust_lsr_COframe) 225-231 F7.5 [-] logdChi2 [1.6/2.6] MADGICS log of change in {chi}^2^ from adding DIB component (log10delchisq) 233-239 F7.4 --- dibSNR [3.79/13.56] MADGICS DIB signal-to-noise ratio (significance of detection) (dib_snr) (2) 241-246 F6.4 --- Chi2 [0.005/0.4] Total {chi}^2^ per degree of freedom for MADGICS component model (totchisqperdof) -------------------------------------------------------------------------------- 248-255 F8.5 mas Plx [-1.1/27.9]? Gaia DR3 parallax of background star (parallax) 257-263 F7.5 mas e_Plx [0.008/0.8]? Plx uncertainty (parallax_error) 265-271 F7.2 km/s RV [-340/379] Gaia DR3 radial velocity of background star (solar barycentric) (v_star_bary) 273-277 F5.2 km/s e_RV [0.1/32] RV uncertainty (v_star_bary_error) 279-284 F6.4 mag E(BP-RP) [0.0002/4.1]? E(BP-RP), color excess modeled by Gaia (ebpminrp_gspphot) 286-292 F7.4 mag E(B-V)sfd [0.0048/73.1] Reddening E(B-V) along line of sight, according to SFD dustmap (Schlegel+ 1998ApJ...500..525S) (sfd) 294-299 F6.4 mag E(B-V)B19 [0/3.48]? Reddening E(B-V) at location of background star, according to Bayestar19 (Green+ 2019ApJ...887...93G) 3D dust map (bayestar19) 301-305 F5.3 0.1nm EWGSP [0.013/0.46]? GSP-spec DIB equivalent width in {AA} (dibew_gspspec) 307-314 F8.6 0.1nm e_EWGSP [0/0.24]? EWgsp uncertainty (dibew_gspspec_uncertainty) 316-324 F9.6 0.1nm erEWNGSP [-1/0.11]? Uncertainty on DIB equivalent width value occuring from noise part (dibewnoise_gspspec_uncertainty) 326-332 F7.3 0.1nm lamGSP [861.3/862.8]? GSP-spec DIB center wavelength (stellar frame) in {AA} (dib_gspspec_lambda) 334-341 F8.6 0.1nm e_lamGSP [0.001/0.4]? lamGSP uncertainty (dib_gspspec_lambda_uncertainty) 343-348 F6.4 0.1nm p2GSP [0.2/3.5]? GSP-spec DIB width of the Gaussian profile (p2) in {AA} (dibp2_gspspec) 350-355 F6.4 0.1nm e_p2GSP [0.01/1.7]? p2GSP uncertainty (dibp2_gspspec_uncertainty) 357-363 F7.4 --- p0GSP [-0.074/-0.0092]? GSP-spec DIB Gaussian amplitude (depth; p0) (dibp0_gspspec) 365-375 I11 --- QFGSP [-2/5]?=-2147483648 GSP-spec DIB pipeline quality factor, QF (dibqf_gspspec) (3) 377-384 F8.5 [-] logChi2GSP [-4.5/-1.2]? Log of GSP-Spec {chi}^2^ for stellar fit (logchisq_gspspec) 386-426 A41 --- FlGSP GSP-Spec quality flag string chain (flags_gspspec) (4) 428-437 F10.4 pc rgeoCBJ [35.7/17697]? CBJ median geometric distance (r_med_geo) 439-448 F10.4 pc b_rgeoCBJ [35.6/15310]? 16th-percentile geometric distance (r_lo_geo) 450-459 F10.4 pc B_rgeoCBJ [35.8/21086]? 84th-percentile geometric distance (r_hi_geo) 461-470 F10.4 pc rpgeoCBJ [35.7/16376]? CBJ median photo-geometric distance (r_med_photogeo) 472-481 F10.4 pc b_rpgeoCBJ [35.6/13131]? 16th-percentile photo-geometric distance (CBJ) (r_lo_photogeo) 483-492 F10.4 pc B_rpgeoCBJ [35.8/19078]? 84th-percentile photo-geometric distance (CBJ) (r_hi_photogeo) 494-498 I5 --- FlCBJ [10000/11133]? CBJ distance inference flags (flag_cbj) (5) -------------------------------------------------------------------------------- Note (1): This uncertainty does not include uncertainty in the stellar frame, which should be added in quadrature to obtain the true uncertainty. Note (2): This is a continuous quality metric that can be used as a cut to obtain cleaner catalogs. Note (3): Quality flags from Gaia Col. 2023A&A...674A..40G (Table 2). Code as follows: -------------------------------------------------------------- QF {rho}_0_ {rho}_2_ ({AA}) -------------------------------------------------------------- 0 <0.15 AND >max(R_A_,R_B_) 1.2-3.2 1 <0.15 AND R_B_ 1.2-3.2 2 <0.15 AND >max(R_A_,R_B_) 0.6-1.2 3 <0.15 AND R_B_ 0.6-1.2 4 <0.15 AND Glim B : Hartigan dip test for unimodality. Left digit geometric, right digit photogeometric 0 = unimodal hypothesis okay 1 = possible evidence for multimodality C : QG models used in prior. Left digit bluer model, right digit redder model 0 = null (no model) 1 = one-component Gaussian 2 = two-component Gaussian 3 = smoothing spline -------------------------------------------------------------------------------- Acknowledgements: Saydjari Andrew [andrew.saydjari _at_ cfa.harvard.edu] ================================================================================ (End) Emmanuelle Perret [CDS] 14-Sep-2023