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Abstract Cool, dusty interstellar material plays an important role in the chemical evolution of galaxies. We present an analysis of this material across galaxy type through a spatially resolved spectral stacking analysis of galaxies from the MaNGA survey. With stellar population synthesis, we isolate neutral gas signals from resonance lines, comparing outcomes across model types, galactic geometry, and host stellar mass and age. We find that both synthetic and empirical models fail to capture the range of galactic chemical abundances. There is also notable Naicontamination from the Galaxy’s interstellar medium (ISM) in the MILES empirical stellar library. We are unable to reliably determine the column density of the gas due to the accuracy of absorption measurements, but differential analysis across radius and inclination reveals consistent and significant path-length dependent absorption in the equivalent width of Nai. We note similar but lesser trends in a narrow Caiiindex. We find no trends in Caior in a broad Caiiindex, indicating its ISM insensitivity and providing evidence in favor of its utility in determining the age and chemical content of stellar populations. Our data shows there is a cool ISM component in most external galaxies withD_n(4000) < 1.7 that can be traced by Nai. Lastly, we caution that the characterization of gas kinematics traced by Naiin such low-resolution spectra is subject to systematic effects due to the chosen approach to stellar population modeling. 

Abstract We assess the impact of Caiiλλ3934, 3969 and Naiλλ5891, 5897 absorption arising in the interstellar medium (ISM) on the Sloan Digital Sky Survey-IV MaNGA Stellar Library (MaStar) and produce corrected spectroscopy for 80% of the 24,162-star catalog. We model the absorption strength of these transitions as a function of the stellar distance, Galactic latitude, and dust reddening based on high-spectral resolution studies. With this model, we identify 6342 MaStar stars that have negligible ISM absorption (W^ISM(CaiiK) < 0.07 Å andW^ISM(Nai5891) < 0.05 Å). For 12,110 of the remaining stars, we replace their NaiD profile (and their Caiiprofile for effective temperaturesT_eff> 9000 K) with a coadded spectrum of low-ISM stars with similarT_eff, surface gravity, and metallicity. For 738 additional stars withT_eff> 9000 K, we replace these spectral regions with a matching ATLAS9-based BOSZ model. This results in a mean reduction inW(CaiiK) (W(NaiD)) of 0.4–0.7 Å (0.6–1.1 Å) for hot stars (T_eff> 7610 K), and a mean reduction inW(NaiD) of 0.1–0.2 Å for cooler stars. We show that interstellar absorption in the simple stellar population (SSP) model spectra constructed from the original library artificially enhancesW(CaiiK) by ≳20% at young ages (<400 Myr); dramatically enhances the strength of stellar NaiD in starbursting systems (by ≳50%); and enhances stellar NaiD in older stellar populations (≳10 Gyr) by ≳10%. We provide SSP spectra constructed from the cleaned library and discuss the implications of these effects for stellar population synthesis analyses constraining the stellar age, [Na/Fe] abundance, and initial mass function. 

Abstract We present an analysis of Hubble Space Telescope COS/G160M observations of CIVin the inner circumgalactic medium (CGM) of a novel sample of eightz∼ 0,L≈L^⋆galaxies, paired with UV-bright QSOs at impact parameters (R_proj) between 25 and 130 kpc. The galaxies in this stellar-mass-controlled sample (log₁₀M_⋆/M_⊙∼ 10.2–10.9M_⊙) host supermassive black holes (SMBHs) with dynamically measured masses spanning log₁₀M_BH/M_⊙∼ 6.8–8.4; this allows us to compare our results with models of galaxy formation where the integrated feedback history from the SMBH alters the CGM over long timescales. We find that the CIVcolumn density measurements (N_{C IV}; average log₁₀N_{C IV,CH}= 13.94 ± 0.09 cm⁻²) are largely consistent with existing measurements from other surveys ofN_{C IV}in the CGM (average log₁₀N_{C IV,Lit}= 13.90 ± 0.08 cm⁻²), but do not show obvious variation as a function of the SMBH mass. By contrast, specific star formation rate (sSFR) is highly correlated with the ionized content of the CGM. We find a large spread in sSFR for galaxies with log₁₀M_BH/M_⊙> 7.0, where the CGM CIVcontent shows a clear dependence on galaxy sSFR but notM_BH. Our results do not indicate an obvious causal link between CGM CIVand the mass of the galaxy’s SMBH; however, through comparisons to the EAGLE, Romulus25, and IllustrisTNG simulations, we find that our sample is likely too small to constrain such causality. 

{"Abstract":["This file contains a version of the SDSS-IV MaNGA Stellar Library (MaStar) which has been corrected for the effects of absorption in the CaII 3934, 3969 and NaI D 5891, 5897 transitions arising in the Milky Way's interstellar medium (ISM).  These corrections are described in full in Rubin et al. (2025).  In brief, we first develop a model of the absorption strengths of these transitions as a function of stellar distance, Galactic latitude, and dust reddening based upon high-spectral resolution studies.  We use this model to identify 6342 MaStar stars with negligible ISM absorption.  For 12110 of the remaining stars, we replace their NaI D profile (and their CaII profile for effective temperatures > 9000 K) with a coadded spectrum of low-ISM stars with similar effective temperature, surface gravity, and metallicity.  For 738 additional stars with effective temperatures > 9000 K, we replace these spectral regions with a matching ATLAS9-based BOSZ model.  This procedure yields corrected spectroscopy for 80% of the 24162-star catalog.\n\nThe spectra in this file are identical to those which have been unified to the 99.5th-percentile spectral resolution curve for MaStar and made available at https://www.sdss4.org/dr17/mastar/mastar-spectra (with the exception of the corrected spectral regions described above).  The datamodel is described below.    \n\nMANGAID - The XX-XXXXXX format MaNGA IDWAVE - Vacuum wavelength grid. The wavelength sampling is logarithmic (Angstroms)FLUX - Observed flux, corrected for Milky Way ISM contamination.  Extinction-corrected to above the Earth's atmosphere but not corrected for Galactic extinction (10^-17 erg/s/cm^2/Ang)IVAR - Inverse variance of the flux (10^34 s^2cm^4Ang^2/erg^2)PREDISP - Instrumental broadening sigma.  Does not include the effect of pixel integration (Angstroms)SRES - Spectral resolution = WAVE/(sqrt(8*ln(2)) * PREDISP)REPLACEMENT_CAII_FLG - Flag indicating treatment of the CaII spectral region.  Described in Table 3REPLACEMENT_NAID_FLG - Flag indicating treatment of the NaID spectral region.  Described in Table 3NSIG_THRESH - Maximum 3D distance in stellar parameter space from stars included in empirical replacement stack, if one was constructed.  Described in Sec. 3.1 and 3.2 (Psi_thresh)ewCaIIK_pred - Interstellar CaII K EW predicted by model described in Sec. 2.2 (Angstroms)ewNaI5891_pred - Interstellar NaI D 5891 EW predicted by model described in Sec. 2.2 (Angstroms)ewNaI5897_pred - Interstellar NaI D 5897 EW predicted by model described in Sec. 2.2 (Angstroms)"],"Other":["Preferred Citation\n\nIf you use these library spectra in your research, we ask that you please cite our article, "Sloan Digital Sky Survey IV MaStar: Quantification and Abatement of Interstellar Absorption in the Largest Empirical Stellar Spectral Library," Rubin et al. (2025), ApJ, 981 31, doi:10.3847/1538-4357/ad8eb6.  Please also cite this Zenodo deposit."]} 

ABSTRACT We have re-observed $$\rm \sim$$40 low-inclination, star-forming galaxies from the MaNGA survey (σ ∼ 65 km s−1) at ∼6.5 times higher spectral resolution (σ ∼ 10 km s−1) using the HexPak integral field unit on the WIYN 3.5-m telescope. The aim of these observations is to calibrate MaNGA’s instrumental resolution and to characterize turbulence in the warm interstellar medium and ionized galactic outflows. Here we report the results for the Hα region observations as they pertain to the calibration of MaNGA’s spectral resolution. Remarkably, we find that the previously reported MaNGA line-spread-function (LSF) Gaussian width is systematically underestimated by only 1 per cent. The LSF increase modestly reduces the characteristic dispersion of H ii regions-dominated spectra sampled at 1–2 kpc spatial scales from 23 to 20 km s−1 in our sample, or a 25 per cent decrease in the random-motion kinetic energy. This commensurately lowers the dispersion zeropoint in the relation between line-width and star-formation rate surface-density in galaxies sampled on the same spatial scale. This modest zero-point shift does not appear to alter the power-law slope in the relation between line-width and star-formation rate surface-density. We also show that adopting a scheme whereby corrected line-widths are computed as the square root of the median of the difference in the squared measured line width and the squared LSF Gaussian avoids biases and allows for lower signal-to-noise data to be used reliably.