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Mid-Infrared Colors Vary with Galactic Environment: Contrasting Star-Forming Disks, Young Centers, and Quiescent Star-Formation Deserts

T0 review · 3 major / 4 minor · reviewed 2026-08-01 · deepseek-v4-flash

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Pith's one-line read This paper finds that mid-infrared colors of the diffuse interstellar medium in 71 nearby star-forming galaxies stay uniform across normal disks but change measurably in two extreme environments—young star-forming centers and quiescent bulg

desk verdict Solid 71-galaxy taxonomy with a well-validated CMZ story; the bulge neutral-PAH claim is intriguing but rests on a starlight-subtraction systematic the paper itself flags — referee-worthy, but that part should be framed as provisional. read the letter →

arxiv 2607.19512 v1 pith:UJHA27SY submitted 2026-07-21 astro-ph.GA

Debosmita Pathak , Karin M. Sandstrom , Adam K. Leroy , Ryan Chown , Daniel A. Dale , Hannah B. Koziol , Mansi Padave , Jessica Sutter
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Thomas G. Williams Dalya Baron Alberto D. Bolatto Mederic Boquien Oleg V. Egorov Eric Emsellem Simon C. O. Glover Ralf S. Klessen Eva Schinnerer Todd A. Thompson Francesco Belfiore Frank Bigiel Enrico Congiu Ivan Gerasimov Jay Gonzalez Lobos Annie Hughes Laura A. Lopez Justus Neumann Elias K. Oakes Hsi-An Pan Erik Rosolowsky Sumit K. Sarbadhicary
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classification astro-ph.GA
keywords mid-infraredcolorspolycyclicaromatichydrocarbonsdiffuseinterstellarmediumradiationfieldintensitygalacticenvironmentJWSTMIRIstarformationdesertsdustcontinuum
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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 reports that the mid-infrared colors of the diffuse gas between stars in 71 nearby star-forming galaxies are mostly uniform across normal disks, but change sharply in two kinds of special regions. In intensely star-forming galaxy centers, the ratios of PAH emission to hot-dust continuum (e.g., 7.7 µm/21 µm) drop by 0.2–0.4 dex; the paper shows this tracks a more intense radiation field, validated by far-infrared colors and by the 21 µm to molecular-gas ratio. In quiescent bulges and star-formation deserts, only the 7.7 µm PAH feature is suppressed relative to 11.3 µm and 3.3 µm, which the paper interprets as a more neutral PAH population. The result matters because it says environmental state, not just PAH abundance, sets mid-IR colors, with consequences for how infrared emission is used to trace dust and star formation.

What carries the argument

The analysis uses starlight-subtracted MIRI band ratios, especially F770W/F2100W (calibrated to R*_PAH), F770W/F1130W, and F1000W/F2100W, with F300M used as the stellar template. The load-bearing comparisons are (1) far-infrared dust colors and F2100W/ΣMol as independent indicators of radiation intensity U, showing CMZ color suppression tracks U; and (2) the F335M-based 3.3 µm PAH feature plus 11.3 µm to break degeneracies between radiation hardness, PAH charge, and PAH size—this is what isolates neutral PAHs as the bulge explanation.

What would settle it

Take MIRI spectra (or medium-band photometry) of the 7.7, 11.3, and 3.3 µm features in the four bulges with full filter coverage; if the 7.7/11.3 decrement shrinks or vanishes once starlight is subtracted spectrally rather than photometrically via a scaled 3 µm image, the neutral-PAH interpretation fails. Similarly, if far-infrared colors and F2100W/ΣMol were to show CMZ U is not elevated, the radiation-intensity explanation fails.

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Extended reading notes

Core claim

The central claim is that mid-infrared colors of the diffuse ISM are a reliable environmental classification tool: PAH band-ratio colors are nearly constant in normal disks (log F770W/F2100W ≈ 0.52, scatter <0.1 dex), but depart in opposite directions at the two extremes. In central molecular zones the PAH-to-continuum and 10 µm/21 µm colors are depressed by 0.2–0.4 dex because the local radiation intensity U is high, not because PAHs are destroyed; in quiescent bulges and star-formation deserts only the 7.7 µm band is suppressed, indicating more neutral PAHs. The paper also positions F2100W/ΣMol as a practical high-resolution tracer of U and shows a single continuous trend (ρ = 0.86) connec

Load-bearing premise

The claim that bulges host unusually neutral PAHs rests on the model-based starlight subtraction being accurate in exactly the old-stellar regions where the paper states that subtraction is the dominant source of uncertainty.

Editorial extensions

If this is right

  • If correct, mid-IR PAH-band ratios in diffuse disks can serve as a stable baseline; deviations flag extreme environments.
  • In star-forming centers, a depressed 7.7/21 color should not be read as PAH destruction; it mostly records a stronger radiation field.
  • F2100W/ΣMol can be used as a kpc-scale U tracer, validated against far-infrared colors, useful where far-IR data are unavailable.
  • Quiescent bulges join early-type galaxies: low 7.7/11.3 indicates neutral PAHs, so PAH charge must be included to estimate PAH mass in quiescent systems.
  • All environments lie on a single 7.7/11.3 vs sSFR trend, so specific star-formation rate predicts PAH charge state in normal galaxies.

Reading between the lines

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

  • Editorial inference: because the 7.7 µm band is suppressed in quiescent systems, PAH abundances inferred from 7.7 µm alone in bulges or early-type galaxies would be systematically underestimated; an 11.3 µm-based tracer would behave differently.
  • Editorial inference: the F2100W/ΣMol tracer could be ported to high-redshift galaxies where far-IR photometry is absent but CO and mid-IR photometry exist.
  • Editorial inference: the paper's 7.7/11.3–sSFR relation could be tested spectroscopically in individual bulges to see whether the neutral-PAH signature is spatially uniform or confined to the most FUV-poor pockets.
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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. This paper presents JWST/MIRI and NIRCam measurements of diffuse mid-infrared colors in 71 nearby star-forming galaxies from PHANGS-JWST, with a focus on how PAH-related band ratios vary with galactic environment. The authors report that standard PAH ratios are roughly constant across normal star-forming disks (log R*_PAH ≈ 0.52, <0.1 dex scatter), but that young central molecular zones (CMZs) show depressed PAH-to-continuum and 10/21 µm colors, which they attribute to high radiation-field intensity U, and that quiescent bulges/star-formation deserts show selectively low 7.7 µm emission, interpreted as evidence for more neutral PAHs. All environments are claimed to follow a continuous trend between F770W/F1130W and specific star-formation rate. The analysis includes careful treatment of backgrounds, nebular masking, and median-based color definitions, and the paper provides a machine-readable table of environment-integrated measurements.

Significance. If the conclusions hold, this would be an important reference result: the first large-sample JWST/MIRI census of diffuse mid-IR colors across environments, with a public catalog and several cross-checks (ratio-of-medians vs median-of-ratios, nebular masking, anchoring to WISE, far-IR validation). The CMZ interpretation of high U is supported by independent far-IR colors and F2100W/ΣMol, and the disk plateau is a clean, useful benchmark. The bulge neutral-PAH claim is more fragile, however, because it hinges on the starlight subtraction in exactly the regions where that subtraction is acknowledged to dominate the uncertainty, and because the discriminating data exist for only 4 of 13 bulges. The paper is therefore significant but requires a systematic-error demonstration before the bulge interpretation can be accepted.

major comments (3)
  1. [§2.1.2, §3.3.2, §4.4] The bulge-specific result (low F770Wss with normal F1130Wss and F335M_PAH, interpreted as neutral PAHs) rests on the F300M starlight subtraction, which the paper itself identifies as the dominant uncertainty in bulges. Since the F770W correction coefficient (0.22) is twice the F1130W coefficient (0.11), a correlated overestimate of the 7.7 µm stellar component will suppress F770Wss relative to F1130Wss preferentially in F300M-bright bulges. The quoted ±0.08 is CIGALE model scatter, not a systematic error term; if the true old-population SED shifts the factor from 0.22 toward ~0.14, the bulge F770W deficit shrinks substantially and the neutral-PAH signature weakens. I request a systematic-error demonstration: vary the scaling factor within a plausible SED range, or cross-check with an independent stellar template, and show how the bulge F770W/F1130W contrast responds. Without this, the ce
  2. [§2.3, Table 2, Fig. 9] The young-CMZ sample is selected by median F2100W > 10 MJy/sr, and the headline contrasts (R*_PAH, F770W/F2100W, F1130W/F2100W, F1000W/F2100W) all have F2100W in the denominator. A selection cut on a quantity that appears in the measured ratio necessarily contributes to the apparent contrast; the abstract's '0.2–0.4 dex lower' is therefore not an independent measurement of the physical suppression. The supporting far-IR colors (Fig. 12) and F2100W/ΣMol do argue for high U, so this is not fatal, but the paper should quantify the selection covariance—e.g., re-derive the CMZ contrast after selecting centers on ΣSFR or F770W rather than F2100W, and report the induced offset. In addition, the abstract's 0.2–0.4 dex range appears to exceed the environment medians in Table 2 (e.g., log F770Wss/F2100Wss: disks 0.11 vs CMZs −0.03, a 0.14 dex difference); please clarify whether the headline refers
  3. [§4.4, Table 2, Figs. 14–15] The neutral-PAH interpretation rests on a small and partially unpublished dataset: F770Wss/F1130Wss is available for only 4 of 13 bulges, and the F335M_PAH maps (from a submitted paper) are used with a matched-pixel detection criterion of ≥25% coverage. Moreover, the D21 models do not reproduce the observed bulge colors even in the limiting 100%-neutral-PAH case (Figs. 11 and 15), so the model comparison brackets but does not independently confirm the charge interpretation. The claim should be explicitly framed as 'consistent with more neutral PAHs, subject to starlight-subtraction systematics and small-number statistics,' with a clear call for spectroscopic follow-up, rather than presented as a secure physical conclusion.
minor comments (4)
  1. [Abstract, §3.3.1] Please reconcile the stated 0.2–0.4 dex CMZ contrasts with the median values reported in Table 2; if the range applies only to the most extreme dense diffuse regions, state that explicitly.
  2. [§2.4, Fig. 9 captions] For 32 galaxies without MUSE, sSFR is proxied by F2100W/F300M. Since the two populations are plotted together, the figure captions and Table 3 should always flag which sSFR estimator is used for each point.
  3. [§4.4] The F335M_PAH maps from H. Koziol et al. (submitted) are central to the size/charge disentanglement. Please provide public access or a detailed reproducibility statement, since the submitted reference is not yet citable.
  4. [General] The manuscript contains several typographical/layout artifacts (e.g., 'T able', 'Y oung', 'V ary', 'F335MP AH') and should be copy-edited before resubmission.

Circularity Check

2 steps flagged · score 4.0 of 10

CMZ color contrasts are partly built into the F2100W-based selection; bulge neutral-PAH interpretation rests on acknowledged starlight-subtraction systematics but is not a circular reduction.

  1. self definitional [§2.4 (CMZ selection), §3.3.1 and Table 1 (CMZ R*_PAH result), Eq. 1]
    "We select young star-forming centers as galaxy center regions within the M. Querejeta et al. (2021) mask where the median F2100W intensity is >10 MJy sr−1. ... CMZs on average show 0.15 dex lower R∗PAH than normal star-forming disks ... R∗PAH = 2.57 F770Wss/F2100Wss (Eq. 1)."

    The definition of a 'young CMZ' uses exactly the quantity that appears in the denominator of the headline colors. With F2100W > 10 MJy/sr enforced for CMZs while disks have lower F2100W, ratios such as R*_PAH = F770W/F2100W and F1000W/F2100W are depressed even for unchanged PAH/continuum numerators; part of the 0.15–0.4 dex CMZ contrast is therefore a construction of the selection. This is only partial: the numerator bands are independently measured, and the paper's high-U interpretation is additionally validated by Herschel far-IR colors and F2100W/ΣMol.

  2. other [§3.2 and Fig. 9 (R*_PAH–sSFR correlation)]
    "Fig. 9 shows a moderate correlation between environment-integrated sSFR and R∗PAH in ‘normal’ disks (ρ= 0.47). ... log R∗PAH ... as a function of ... log F2100W/F300M (bottom row)."

    For the 32 galaxies without MUSE, sSFR is represented by F2100W/F300M (§2.4), while R*_PAH = 2.57 F770W/F2100W. The shared F2100W factor in the two variables can create or inflate an apparent correlation without any change in PAH physics. This is a secondary, partial artifact: the paper also reports correlations against MUSE sSFR for 42 galaxies, and its headline F770W/F1130W–sSFR trend does not share F2100W.

full rationale

The paper's core claims are observational measurements rather than fitted predictions, and the main physical interpretations are cross-checked with independent data: the high-U attribution for CMZs is validated against Herschel far-IR colors and F2100W/ΣMol, while the bulge neutral-PAH inference is drawn from multiple color ratios (F770W/F1130W, F335M_PAH/F1130W) rather than from a fitted parameter renamed as a result. The starlight-subtraction factors adopted from J. Sutter et al. (2024) are an external CIGALE-based calibration, and the paper itself flags that subtraction is the dominant uncertainty in bulges; a possible systematic error there is a correctness risk, not a circular step. Self-citations (Sutter et al. 2024; Koziol et al. submitted) are used for calibration and maps but do not smuggle in the environment result. The genuine partial circularity is that the CMZ class is selected by F2100W > 10 MJy/sr while the headline colors put F2100W in the denominator, so part of the depression is built into the classification; similarly, the R*_PAH-vs-sSFR correlation shares F2100W when the sSFR proxy is F2100W/F300M. These issues do not collapse the paper: the numerator bands are independently measured, the far-IR checks provide outside support, and the central F770W/F1130W-vs-sSFR trend is not affected by the shared-variable artifact. Score 4 reflects partial, not total, circularity.

Assumptions & free parameters 5 free parameters · 6 assumptions · 0 invented entities

No new physical entities are introduced. The paper's explanatory toolkit is inherited: empirical PAH-to-continuum calibration (Sutter et al. 2024), D21 dust models, α_CO maps (Sun et al. 2025), and morphological masks (Querejeta et al. 2021). The free parameters are analysis/calibration choices rather than physics, but the CMZ selection threshold and starlight-subtraction factors do real work in shaping the headline contrasts; the bulge result couples to the subtraction factors and to unpublished F335M maps.

free parameters (5)
  • R*_PAH scaling constant = 2.57
    Eq. 1 converts F770W/F2100W into the PAH fraction R*_PAH; the factor is an empirical calibration borrowed from Sutter et al. (2024), fitted to diffuse disk data and here applied to all environments including bright centers and faint bulges.
  • Starlight subtraction scaling factors = F770W: 0.22±0.08; F1000W: 0.14±0.02; F1130W: 0.11±0.02; F2100W: 0.032±0.005 (× F300M)
    §2.1.2. CIGALE SED-model-derived factors that predict MIRI starlight from F300M; the dominant systematic in bulges, where stellar contamination reaches ~30% of F770W.
  • Young-center/CMZ selection threshold = median F2100W > 10 MJy/sr (≈ ΣSFR > 0.03 M☉/yr/kpc²)
    §2.3. Hand-chosen F2100W cut to classify young star-forming centers; uses the same 21 µm band that appears in the denominator of the headline color contrasts.
  • Bulge/desert selection threshold = log F2100W/F300M ≤ −0.3 (≈ sSFR ≲ 7×10⁻¹² /yr)
    §2.3. Hand-chosen sSFR-proxy cut for star-formation deserts; calibrations against MUSE for 42/71 galaxies are extrapolated to the full sample.
  • Nebular masking thresholds = F2100W > 3 MJy/sr (non-MUSE galaxies); broken-power-law break x_b fit per CMZ
    §2.5.2–2.5.3. Thresholds used to separate nebular from diffuse pixels; x_b is fitted per galaxy center.
assumptions (6)
  • domain assumption F300M emission is a pure stellar template that can be scaled to predict and remove starlight in F770W, F1000W, F1130W, and F2100W
    §2.1.2. If F300M contains PAH/nebular contamination or the stellar SED extrapolation fails, the starlight-subtracted maps are biased — most consequential in bulges.
  • domain assumption Draine et al. (2021) model SEDs (PAH emission + dust continuum, standard charge/size grids, SB3/mMMP/M31 radiation fields) are a valid grid for interpreting the observed filter ratios
    §4.2, Figs. 11–15. The physical interpretation (U vs PAH charge vs size vs hardness) is read off these grids; the paper finds a 0.1-dex F1000W offset and bulge colors outside the grids.
  • domain assumption F2100W/ΣMol tracks the radiation field intensity U (F2100W ∝ U × N(H) × D/G at U ≲ 10)
    §4.3, Eq. 3. Requires fixed dust-to-gas ratio and the Sun et al. (2025) α_CO prescription; validated only indirectly via ~31-galaxy 16″-resolution Herschel colors (ρ≈0.73).
  • domain assumption Median statistics over 0.″9 pixels suppress HII region contamination in normal disks
    §2.5.1–2.5.2. Tested against MUSE nebular masks (Fig. 3) for a subset; in CMZs the median does not suffice, requiring the broken-power-law diffuse selection.
  • domain assumption The empirical R*_PAH calibration and the 7.7/21-µm-based PAH fraction interpretation extrapolate to extreme environments
    Eq. 1. Calibrated on diffuse disk sightlines (Sutter et al. 2024); its use in CMZs and bulges assumes the continuum under 7.7 µm behaves as in disks.
  • standard math JWST photometric calibration uncertainty ~5% (7% on colors) and Rigby et al. (2023) error model
    §2.5.4. Instrumental uncertainty propagation; standard for the facility.

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Cite this review

Pith. "Pith review of Mid-Infrared Colors Vary with Galactic Environment: Contrasting Star-Forming Disks, Young Centers, and Quiescent Star-Formation Deserts." pith.science (2026). https://pith.science/paper/UJHA27SY

@misc{pith2026260719512,
  author       = {Pith},
  title        = {Pith review of: Mid-Infrared Colors Vary with Galactic Environment: Contrasting Star-Forming Disks, Young Centers, and Quiescent Star-Formation Deserts},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/UJHA27SY}},
  note         = {Machine review of arXiv:2607.19512}
}
abstract

We present $50{-}100\,$pc-resolution JWST/MIRI and NIRCam measurements of mid-infrared (mid-IR) color variations in the diffuse interstellar medium (ISM) of 71 nearby star-forming galaxies from the PHANGS-JWST survey. Mid-IR emission traces the dust column density, intensity ($U$) and hardness of the interstellar radiation field, and the physical state (charge, size) and abundance of polycyclic aromatic hydrocarbons (PAHs). Mid-IR colors that trace PAH band-ratios remain fairly constant in the diffuse ISM of star-forming disks. However, they show stark variations in extreme environments: highly star-forming central molecular zones (CMZs) and star-formation deserts/quiescent bulges. In CMZs, PAH-to-continuum ($3.3/21$, $7.7/21$, and $11.3/21\,\mu$m) and the $10/21\,\mu$m continuum colors are $0.2{-}0.4$ dex lower than in normal disks. We attribute this to higher $U$ based on the far-IR dust colors and the high $21\,\mu{\rm m}/\Sigma_{\rm Mol}$, which we suggest to be a good tracer of $U$ outside star-forming regions. Meanwhile, star-formation deserts show low $7.7\,\mu$m PAH emission, resulting in low $7.7/21\,\mu$m and $7.7/11.3\,\mu$m, while all other mid-IR colors remain typical. This suggests the presence of more neutral PAHs in star-formation deserts, where low $7.7\,\mu$m likely reflects ISM conditions similar to early-type and elliptical galaxies. All environments form part of a continuous trend in $7.7/11.3\,\mu$m vs.\ specific star-formation rate.

Figures

Figures reproduced from arXiv: 2607.19512 by the authors.

Figure 1
Figure 1. Zoom-ins showing a few example galaxies from our sample in F300M, F770Wss, F2100Wss, and R ∗ PAH, with M. Querejeta et al. (2021) morphological environment masks for centers (blue) and bars (red) overlaid for reference [PITH_FULL_IMAGE:figures/full_fig_p005_1.png] view at source ↗
Figure 2
Figure 2. Correlating environment-integrated median ΣSFR (M⊙ yr−1 kpc−1 ; left panel) and sSFR (yr−1 ; right panel) measure￾ments from MUSE with JWST F2100W intensities and F2100W/F300M, respectively, for the 42 galaxies with joint MUSE and JWST coverage. Environments (§2.3) are indicated with colors — old bulges (red), young star-forming centers (blue), normal centers (light blue), and normal disks (light yellow) for targets… view at source ↗
Figure 3
Figure 3. Left: Constructing radial profiles of F770Wss/F2100Wss for NGC1300 as an example. The solid red line shows our fiducial measurement constructed from the ratio of medians taken across the full data set. The other lines show the impact of varying the methodology. Green shows the profile without starlight subtraction for all pixels (solid green), for only diffuse emission (dot-dashed green; see §2.5.2), and constructed… view at source ↗
Figures from the paper (13 more)
Figure 4
Figure 4. Figure 4: The center of NGC7496, an example of galaxy centers removed from analysis due to contamination by prominent diffraction spikes in F2100W. We show maps of contaminated F2100W and resulting R ∗ PAH, blue contours for the center mask from M. Querejeta et al. (2021), and b…
Figure 5
Figure 5. Figure 5: From left to right, F300M, F770Wss, F2100Wss, R ∗ PAH, and resulting masks for diffuse (blue) vs nebular emission (pink) in the center of NGC1512, with dark blue contours for the morphological environment mask for the center of NGC1512 from M. Querejeta et al. (2021). …
Figure 6
Figure 6. Figure 6: Top: Radial profiles of F300M, F770Wss, F2100Wss intensity for all 71 galaxies; F1000Wss and F1130Wss for 20 galaxies, colored by galaxy stellar mass M∗. Bottom: Median (solid lines) and 16th−84th percentile range (shaded region) of radial profiles of F300M, F770Wss, F…
Figure 7
Figure 7. Figure 7: Radial profiles of log R ∗ PAH for individual galaxies colored by total M∗ (left), and then median profiles for groups of galaxies sorted into percentile bins of M∗ (right). All galactocentric distances for the radial profiles are shown in units of the exponential scal…
Figure 8
Figure 8. Figure 8: Plateau value in radial profiles of log R ∗ PAH for each galaxy, measured as the median of all 0.1ℓ∗ annular bins with ℓ∗ ≤ Rgal ≤ 3ℓ∗, points colored by galaxy stellar mass, as a function of global sSFR. Median of 71 galaxies (orange solid line), 1σ scatter (orange ha…
Figure 9
Figure 9. Figure 9: log R ∗ PAH, log F770Wss/F1130Wss, and log F1000Wss/F2100Wss as a function of log ΣSFR (M⊙ yr−1 kpc−2 ; top) and log sSFR = log ΣSFR/Σ∗ (yr−1 ; middle) from MUSE, and log F2100W/F300M (bottom row), split by local environment—old stellar bulges (red), young CMZs (bright…
Figure 10
Figure 10. Figure 10: Mid-IR color-color variation by environment for 20/71 galaxies with full MIRI filter coverage. F770Wss/F2100Wss (or R ∗ PAH) and F770Wss/F1130Wss ratios vs F1000Wss/F2100Wss for bulges (red), CMZs (dark blue), ‘normal’ centers (pale blue), and disks (yellow) shown. th…
Figure 11
Figure 11. Figure 11: B. T. Draine et al. (2021) dust model predic￾tions for varying PAH charge and sizes (‘grids’) assuming three different radiation field hardness models at log U = 1 — modified MMP (black), M31 bulge (red), and a 3 Myr-old starburst (blue); and a 3 Myr-old starburst at …
Figure 12
Figure 12. Figure 12: Correlating far-IR dust temperature tracers with expected tracers of radiation field intensity: Herschel PACS far-IR ratios of specific intensities (Iν) for ∼ 31 galaxies where PACS 70 µm, 100 µm, or 160 µm data are available, with F2100Wss/ICO(2−1) (top row), F2100Ws…
Figure 13
Figure 13. Figure 13: Top: R ∗ PAH, F770Wss/F1130Wss, and F1000Wss/F2100Wss as a function of F2100Wss/ΣMol, which correlates with Tdust (and U). Points colored as in previous figures. Bottom: Predicted variation in R ∗ PAH, F770Wss/F1130Wss, and F1000Wss/F2100Wss with radiation intensity l…
Figure 14
Figure 14. Figure 14: PAH-to-continuum ratios for three PAH-dominated filters for the 19 galaxies from Cycle-1, points colored by environment as in previous figures: F335MPAH (from H. Koziol et al. submitted), F770Wss, and F1130Wss relative to F2100Wss. Dashed lines indicate the predicted …
Figure 15
Figure 15. Figure 15: Mid-IR and near-IR PAH color-color variation by environment. F770Wss/F1130Wss and F335MPAH/F770Wss (small, neutral PAH-to-small, ionized PAH) ratios vs F335MPAH/F1130Wss (small, neutral PAH-to-larger, neutral PAH) ratios. D21 dust model grids at log U = 1 included for…
Figure 16
Figure 16. Figure 16: MUSE sSFR vs median (markers) and 16th−84th percentile scatter (error bars) in Balmer decre￾ment attenuation AV for bulges, centers, and disks in 42 galaxies. Medians and percentiles only measured where both Hα and Hβ are detected within each environment. While most l…

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

  1. Variations in the 3.3 ${\mu}$m Polycyclic Aromatic Hydrocarbon Feature Across Nearby Galaxies Driven by Metallicity and Radiation Field Spectrum

    astro-ph.GA 2026-08 conditional novelty 5.0 of 10

    The 3.3 um PAH feature grows relative to 7.7 and 11.3 um features at low metallicity, with secondary radiation-field-driven variations, indicating smaller PAH populations in low-metallicity environments.

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