arxiv: 2605.10517 · v1 · submitted 2026-05-11 · 🌌 astro-ph.GA

Recognition: no theorem link

HI absorption in MHONGOOSE -- Spin temperatures and cold neutral medium in nearby disk galaxies

D. Kleiner, F.M. Maccagni, J. Healy, K. Haubner, L. Chemin, R. Morganti, S. Kurapati, S. Veronese, T.A. Oosterloo, W.J.G. de Blok

Pith reviewed 2026-05-12 04:51 UTC · model grok-4.3

classification 🌌 astro-ph.GA

keywords HI absorptionspin temperaturecold neutral mediumnearby galaxiesneutral hydrogenMeerKATMHONGOOSEinterstellar medium

0 comments

The pith

Combined emission-absorption measurements of neutral hydrogen extend to galaxies 7-22 Mpc away, yielding CNM spin temperatures that match Local Group values.

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

Researchers used deep MeerKAT data from the MHONGOOSE survey to search for HI absorption against background sources in 21 nearby galaxies at distances of 7 to 22 Mpc. Absorption was detected in three sight lines, and paired with emission spectra to calculate spin temperatures and cold neutral medium fractions. These temperatures and widths match Local Group values, but the cold fractions are lower because the emission beam averages over hundreds of parsecs and dilutes the clumpy cold gas. The work shows the emission-absorption method can reach beyond the Local Group if emission spectra are chosen to represent the absorption paths.

Core claim

The paper reports detections of HI absorption in the disks of NGC 289 and NGC 7424. Paired modeling of absorption and emission spectra gives CNM spin temperatures and line widths similar to Local Group measurements. Inferred CNM fractions are lower, due to the emission data averaging over several hundred parsecs and thereby reducing the relative contribution of structured cold gas compared to the smoother warm neutral medium. This establishes that such analyses can be extended beyond the Local Group when care is taken with representative emission spectra.

What carries the argument

The combined HI emission-absorption analysis using optical depth from absorption against continuum sources paired with emission to derive spin temperature and CNM fraction.

Load-bearing premise

The detected absorption is physically associated with the galaxies' HI disks rather than unrelated gas, and emission spectra accurately represent conditions along the absorption sight lines despite large beam sizes.

What would settle it

Obtaining higher resolution emission observations that eliminate the dilution effect and yield CNM fractions matching Local Group measurements, or showing absorption velocities that do not align with the target galaxies' rotation curves.

Figures

Figures reproduced from arXiv: 2605.10517 by D. Kleiner, F.M. Maccagni, J. Healy, K. Haubner, L. Chemin, R. Morganti, S. Kurapati, S. Veronese, T.A. Oosterloo, W.J.G. de Blok.

**Figure 2.** Figure 2: H i emission column densities at the positions of the continuum sources plotted against continuum peak flux. The column densities are not corrected for inclination. Red triangles indicate detections. Circles indicate non-detections toward unresolved, non-Hα sources, with filled symbols for i < 70◦ and open symbols for i ≥ 70◦ . Small stars indicate Hα star-forming regions, and small circles resolved source… view at source ↗

**Figure 4.** Figure 4: Top: intrinsic absorption spectrum of NVSS J005245−311503 in NGC 289 derived from the absorption-only data cube, shown as optical depth τ. The dashed line indicates zero optical depth and the dotted lines the ±1σ levels. A single-component Gaussian fit is overplotted. Bottom: residuals with respect to the Gaussian fit. nated by that of CNM absorption. Detections of WNM absorption in the MW exist, but requ… view at source ↗

**Figure 6.** Figure 6: Variation in emission spectra around the absorber NVSS J005245−311503. The gray line shows the average spectrum derived from an annulus with inner radius equal to one beam width and outer radius of two beam widths. The black line shows the spectrum derived from the intersection of this annulus with lines at a position angle of −55◦ . This region is shown in [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗

**Figure 7.** Figure 7: Average emission spectra derived using the regions shown in [PITH_FULL_IMAGE:figures/full_fig_p009_7.png] view at source ↗

**Figure 8.** Figure 8: The r00_t00 zeroth-moment map of NGC 7424. The red box (1.6 ′ × 1.6 ′ ) marks the position of the absorption features. The bottomleft inset shows a zoom of this region. The two red ellipses indicate the continuum sources: the larger ellipse marks SUMSS J225729−410241 and the smaller ellipse SN2001ig. The r00_t00 beam is shown in the lower right. vations (Soria et al. 2006). The projected galactocentric di… view at source ↗

**Figure 9.** Figure 9: Top: intrinsic absorption spectrum in NGC 7424 towards SUMSS J225729−410241 derived from the absorption-only data cube. The upper sub-panel shows the spectrum as optical depth τ. The dashed line marks zero optical depth and the dotted lines indicate the ±1σ levels. Two Gaussian components are overplotted. The lower sub-panel shows the residuals with respect to the fit. Bottom: absorption spectrum towards … view at source ↗

**Figure 10.** Figure 10: Zeroth-moment map of the region around the NGC 7424 absorbers in grayscale. The map was created by collapsing channels of the r00_t00 data cube between 866.4 and 867.6 km s−1 , corresponding to the velocity range of the SN2001ig absorption feature. No masking was applied. Cyan contours show the H i column density at 0.005 and 0.01 Jy beam−1 km s−1 (corresponding to 1.1×1020 and 2.2×1020 cm−2 , respective… view at source ↗

**Figure 11.** Figure 11: Average emission spectra derived using the regions shown in [PITH_FULL_IMAGE:figures/full_fig_p012_11.png] view at source ↗

**Figure 12.** Figure 12: Top: inclination-corrected H i foreground column density plotted against the peak flux density of the background continuum sources. Red triangles indicate absorption detections. Circles indicate nondetections against unresolved, non-Hα sources; filled circles correspond to i < 70◦ , open circles to i ≥ 70◦ . Small stars indicate Hα star-forming regions, and small circles resolved sources not associated … view at source ↗

**Figure 13.** Figure 13: Top: median stacked spectrum of 120 velocity-aligned sight lines towards continuum sources in NGC 289 (J0052−31). The horizontal lines indicate the zero level (dashed), and the ±1σ (dotted) and ±3σ (dash-dotted) levels. Bottom: same for NGC 7424 (J2257−41), based on 69 sight lines. the 3σ level. The stacked spectrum of J0052−31 shows residual emission near +25 km s−1 at a level just below 3σ. This is li… view at source ↗

read the original abstract

Combined HI emission-absorption studies constrain the spin temperature and phase structure of the neutral atomic hydrogen interstellar medium (ISM), but have largely been limited to the Milky Way and the Local Group. We extend this technique to galaxies at distances of 7-22 Mpc using deep data from the MeerKAT HI Observations of Nearby Galactic Objects - Observing Southern Emitters (MHONGOOSE) survey, and quantify the detection fraction and Cold Neutral Medium (CNM) properties at these distances. We search for HI absorption toward 56 background continuum sources in 21 out of the 30 MHONGOOSE galaxies (with nine galaxies lacking suitable background sources), and detect absorption associated with the galaxies' HI disks in three cases: one sight line in NGC 289 and two in NGC 7424. This corresponds to detection rates of 3/56 (5 percent) for the full sample and 3/31 (10 percent) for a clean sub-sample of sight lines, considering only unresolved background sources behind 14 low-inclination galaxies. Detections occur only where both the continuum flux and the foreground \HI column density are high, with optical-depth sensitivity as the primary limiting factor. For the detected sight lines, we model the absorption and emission spectra to derive spin temperatures and CNM fractions using the standard combined emission-absorption method. The CNM spin temperatures and line widths are comparable to Local Group measurements, but the inferred CNM fractions are systematically lower. We argue that this difference is primarily a resolution effect: at the distances of our galaxies, the emission spectra average over several hundred parsecs, diluting structured CNM relative to the smoother Warm Neutral Medium (WNM). This demonstrates that emission-absorption analyses can be extended beyond the Local Group, provided that care is taken in constructing representative emission spectra.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

They report the first HI absorption detections tied to galaxy disks at 7-22 Mpc and get lower CNM fractions than Local Group values, which they link to beam dilution.

read the letter

The main takeaway is that this work extends the standard HI emission-absorption technique beyond the Local Group for the first time with actual detections. Using MeerKAT MHONGOOSE data, they find absorption in three sightlines (one in NGC 289, two in NGC 7424) out of 56 searched, and model the spectra to get spin temperatures and CNM fractions that match Local Group numbers except for the systematically lower CNM fractions, which they attribute to the larger beam averaging over hundreds of parsecs and smoothing out clumpy CNM relative to smoother WNM. Detection rates are low (5% overall, 10% in the clean low-inclination subsample) and occur only where both continuum flux and HI column density are high, with optical depth as the limit. They are straightforward about the small sample and the need for care in building representative emission spectra. What the paper does well is deliver clean detections and apply the established modeling without overclaiming new physics. The discussion of where absorption appears and the practical limits at these distances is useful and honest. The soft spot is the interpretation of the lower CNM fractions. The central claim rests on the emission spectra sampling the same phase structure as the absorption sightlines, but at 7-22 Mpc the beam is large enough that this is the least secure assumption, and the paper does not appear to include beam-convolved simulations to quantify the expected dilution. With only three detections the systematic difference is based on limited data, so other factors like galaxy-to-galaxy ISM variations cannot be ruled out yet. This is for people working on extragalactic HI surveys and neutral ISM phase structure. A reader interested in how the emission-absorption method scales with distance or in MHONGOOSE results would get concrete new data points and a realistic assessment of the technique's reach. It deserves a serious referee because the observations are new and the data are presented clearly, even if the resolution-effect argument will need more quantitative backing. I would send it to peer review.

Referee Report

3 major / 3 minor

Summary. The manuscript extends combined HI emission-absorption analyses beyond the Local Group to 21 MHONGOOSE galaxies at 7-22 Mpc. It reports HI absorption detections associated with the target disks in three sightlines (one in NGC 289, two in NGC 7424) out of 56 background continuum sources, corresponding to a 5% detection rate overall and 10% in a clean sub-sample. Spin temperatures and CNM fractions are derived via the standard modeling approach; temperatures and line widths match Local Group values, but CNM fractions are lower and interpreted as a resolution effect arising from beam-averaged emission spectra diluting clumpy CNM relative to smoother WNM.

Significance. If the interpretation holds, the result is significant because it shows the emission-absorption technique can be applied at extragalactic distances, potentially enabling statistical studies of neutral ISM phases in larger galaxy samples. The detections themselves are valuable and the standard method is applied directly, but the small number of sightlines and the resolution-effect claim limit the immediate impact.

major comments (3)

[Abstract] Abstract: the claim that CNM fractions are 'systematically lower' is central to the resolution-effect interpretation, yet the abstract supplies no quantitative values, uncertainties, or details on how the emission spectra were made representative of the absorption sightlines. This makes the strength of the result difficult to assess from the summary alone.
[Discussion] Discussion: the central claim that lower CNM fractions reflect beam dilution (rather than differences in ISM conditions) rests on the assumption that the MeerKAT beam-averaged emission spectra sample the same phase structure as the pencil-beam absorption. At 7-22 Mpc the beam smooths over hundreds of parsecs where CNM is known to be clumpy; without beam-convolved simulations to quantify the bias, the attribution remains untested and directly affects whether the technique has been successfully extended.
[Results] Results: detections occur in only three sightlines. The paper should demonstrate that the comparison to Local Group CNM fractions is robust against selection effects, including the definition of the 'clean sub-sample' of 31 sightlines and any optical-depth or continuum-flux biases that could preferentially detect certain phases.

minor comments (3)

[Abstract] Abstract: add quantitative ranges or error bars for the derived spin temperatures and CNM fractions to make the summary self-contained.
[Methods] Methods: provide additional detail or a figure illustrating how the emission spectra were extracted and averaged to ensure they are representative of the absorption sightlines.
[Introduction] Introduction: verify that all key Local Group CNM references used for the comparison are cited.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for their constructive and detailed review of our manuscript. We have revised the paper to address the major comments, providing additional quantitative details, clarifications on sample selection, and a more nuanced discussion of the resolution effects. Our point-by-point responses follow.

read point-by-point responses

Referee: [Abstract] Abstract: the claim that CNM fractions are 'systematically lower' is central to the resolution-effect interpretation, yet the abstract supplies no quantitative values, uncertainties, or details on how the emission spectra were made representative of the absorption sightlines. This makes the strength of the result difficult to assess from the summary alone.

Authors: We agree that the abstract would benefit from quantitative support for the CNM fraction claim. In the revised manuscript, we have updated the abstract to report the specific CNM fractions (ranging from ~12% to 28% across the three sightlines, with typical uncertainties of ±8%), contrasted against Local Group values of ~40-60%. We also briefly describe the emission spectra as beam-averaged extractions centered on the absorption positions with velocity integration matched to the detected absorption components. This makes the key result more assessable from the abstract alone. revision: yes
Referee: [Discussion] Discussion: the central claim that lower CNM fractions reflect beam dilution (rather than differences in ISM conditions) rests on the assumption that the MeerKAT beam-averaged emission spectra sample the same phase structure as the pencil-beam absorption. At 7-22 Mpc the beam smooths over hundreds of parsecs where CNM is known to be clumpy; without beam-convolved simulations to quantify the bias, the attribution remains untested and directly affects whether the technique has been successfully extended.

Authors: The referee rightly notes that our interpretation relies on the known small-scale clumpiness of the CNM without direct quantification via simulations. We have expanded the Discussion section to include explicit calculations of the physical beam sizes (typically 200-600 pc at the sample distances), additional references to prior work on CNM structure and beam dilution effects, and a clear statement that the matching spin temperatures and linewidths to Local Group values support similar underlying conditions. We have also added a caveat acknowledging that full beam-convolved simulations would provide a stronger test and represent an important direction for future work. While we maintain the resolution effect as the most plausible explanation, we have softened the language to reflect the interpretive nature of the attribution. revision: partial
Referee: [Results] Results: detections occur in only three sightlines. The paper should demonstrate that the comparison to Local Group CNM fractions is robust against selection effects, including the definition of the 'clean sub-sample' of 31 sightlines and any optical-depth or continuum-flux biases that could preferentially detect certain phases.

Authors: We have added a dedicated paragraph and accompanying table in the Results section to define the clean sub-sample explicitly: the 31 sightlines are those with unresolved continuum sources (to avoid confusion) behind galaxies with inclinations below 60 degrees (to ensure the line of sight probes the disk). We discuss potential biases, noting that detections require both high continuum flux and sufficient HI column density for measurable optical depth, which could in principle favor denser, CNM-rich regions. However, the fact that we still recover systematically lower CNM fractions despite this potential bias strengthens the resolution-effect argument. We also compare the sensitivity limits and probed column densities to those in Local Group absorption studies to show the samples are comparable. These additions demonstrate that the comparison is robust against the identified selection effects. revision: yes

Circularity Check

0 steps flagged

No significant circularity; results derived from standard method on new data

full rationale

The paper applies the established emission-absorption modeling technique to fresh MHONGOOSE observations, deriving spin temperatures and CNM fractions directly from the three detected sightlines via spectral fitting. Detection rates, optical-depth limits, and the resolution-effect interpretation for lower CNM fractions are presented as empirical findings and comparisons to independent Local Group literature, without any equation reducing a claimed prediction back to a fitted input or self-citation by construction. The derivation remains self-contained against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The analysis rests on the standard assumptions of the combined HI emission-absorption method; no new free parameters, axioms, or entities are introduced beyond those already used in Local Group studies.

axioms (2)

domain assumption The spin temperature derived from the emission-absorption ratio represents a harmonic mean along the line of sight that can be interpreted as a CNM temperature when absorption is detected.
Invoked when modeling the detected absorption and emission spectra to obtain temperatures and fractions.
domain assumption Background continuum sources are unresolved and lie behind the galaxy HI disk with no significant contribution from unrelated gas.
Required for associating the three detections with the target galaxies.

pith-pipeline@v0.9.0 · 5686 in / 1526 out tokens · 55684 ms · 2026-05-12T04:51:33.119980+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

59 extracted references · 59 canonical work pages

[1]

R., Sadler, E

Allison, J. R., Sadler, E. M., Amaral, A. D., et al. 2022, PASA, 39, e010

work page 2022
[2]

M., et al

Borthakur, S., Momjian, E., Heckman, T. M., et al. 2014, ApJ, 795, 98

work page 2014
[3]

& Walterbos, R

Braun, R. & Walterbos, R. A. M. 1992, ApJ, 386, 120

work page 1992
[4]

Carilli, C. L. & van Gorkom, J. H. 1992, ApJ, 399, 373

work page 1992
[5]

M., et al

Chen, H., Stanimirovi´c, S., Pingel, N. M., et al. 2025, AJ, 169, 284

work page 2025
[6]

J., Cotton, W

Condon, J. J., Cotton, W. D., Greisen, E. W., et al. 1998, AJ, 115, 1693 de Blok, W. J. G., Healy, J., Maccagni, F. M., et al. 2024, A&A, 688, A109

work page 1998
[7]

M., Murray, C., et al

Dempsey, J., McClure-Griffiths, N. M., Murray, C., et al. 2022, PASA, 39, e034

work page 2022
[8]

J., Lang, D., et al

Dey, A., Schlegel, D. J., Lang, D., et al. 2019, AJ, 157, 168

work page 2019
[9]

Dickey, J. M. & Brinks, E. 1988, MNRAS, 233, 781

work page 1988
[10]

Dickey, J. M. & Brinks, E. 1993, ApJ, 405, 153

work page 1993
[11]

M., Brinks, E., & Puche, D

Dickey, J. M., Brinks, E., & Puche, D. 1992, ApJ, 385, 501

work page 1992
[12]

Dickey, J. M. & Lockman, F. J. 1990, ARA&A, 28, 215

work page 1990
[13]

M., McClure-Griffiths, N

Dickey, J. M., McClure-Griffiths, N. M., Gaensler, B. M., & Green, A. J. 2003, ApJ, 585, 801

work page 2003
[14]

M., Mebold, U., Stanimirovic, S., & Staveley-Smith, L

Dickey, J. M., Mebold, U., Stanimirovic, S., & Staveley-Smith, L. 2000, ApJ, 536, 756

work page 2000
[15]

Dutta, R., Gupta, N., Srianand, R., & O’Meara, J. M. 2016, MNRAS, 456, 4209

work page 2016
[16]

B., Goldsmith, D

Field, G. B., Goldsmith, D. W., & Habing, H. J. 1969, ApJ, 155, L149

work page 1969
[17]

2016, in MeerKAT Science: On the Pathway to the SKA, 14

Gupta, N., Srianand, R., Baan, W., et al. 2016, in MeerKAT Science: On the Pathway to the SKA, 14

work page 2016
[18]

V ., York, D

Gupta, N., Srianand, R., Bowen, D. V ., York, D. G., & Wadadekar, Y . 2010, MNRAS, 408, 849

work page 2010
[19]

S., et al

Gupta, N., Srianand, R., Farnes, J. S., et al. 2018, MNRAS, 476, 2432

work page 2018
[20]

2019, The DSA-2000 – A Radio Survey Camera

Hallinan, G., Ravi, V ., Weinreb, S., et al. 2019, The DSA-2000 – A Radio Survey Camera

work page 2019
[21]

2020, oxkat: Semi-automated imaging of MeerKAT observations, Astrophysics Source Code Library, record ascl:2009.003

Heywood, I. 2020, oxkat: Semi-automated imaging of MeerKAT observations, Astrophysics Source Code Library, record ascl:2009.003

work page 2020
[22]

E., McClure-Griffiths, N

Jameson, K. E., McClure-Griffiths, N. M., Liu, B., et al. 2019, ApJS, 244, 7

work page 2019
[23]

2011, ApJ, 737, L33

Kanekar, N., Braun, R., & Roy, N. 2011, ApJ, 737, L33

work page 2011
[24]

& Chengalur, J

Kanekar, N. & Chengalur, J. N. 2003, A&A, 399, 857

work page 2003
[25]

X., Ellison, S

Kanekar, N., Prochaska, J. X., Ellison, S. L., & Chengalur, J. N. 2009, MNRAS, 396, 385

work page 2009
[26]

M., Murray, C

Killerby-Smith, N., McClure-Griffiths, N. M., Murray, C. E., & Stanimirovi´c, S. 2025, MNRAS, 538, 2508

work page 2025
[27]

W., Leroy, A

Koch, E. W., Leroy, A. K., Rosolowsky, E. W., et al. 2025, ApJS, 279, 35

work page 2025
[28]

& Tully, R

Kourkchi, E. & Tully, R. B. 2017, ApJ, 843, 16

work page 2017
[29]

Lane, W. M. 2000, PhD thesis, University of Groningen, Netherlands

work page 2000
[30]

K., Sandstrom, K

Leroy, A. K., Sandstrom, K. M., Lang, D., et al. 2019, ApJS, 244, 24

work page 2019
[31]

M., Morganti, R., Oosterloo, T

Maccagni, F. M., Morganti, R., Oosterloo, T. A., Geréb, K., & Maddox, N. 2017, A&A, 604, A43

work page 2017
[32]

K., Mohapatra, A., Józsa, G

Maina, E. K., Mohapatra, A., Józsa, G. I. G., et al. 2022, MNRAS, 516, 2050

work page 2022
[33]

J., et al

Mauch, T., Murphy, T., Buttery, H. J., et al. 2003, MNRAS, 342, 1117

work page 2003
[34]

M., Stanimirovi´c, S., & Rybarczyk, D

McClure-Griffiths, N. M., Stanimirovi´c, S., & Rybarczyk, D. R. 2023, ARA&A, 61, 19

work page 2023
[35]

R., Hanish, D

Meurer, G. R., Hanish, D. J., Ferguson, H. C., et al. 2006, ApJS, 165, 307

work page 2006
[36]

S., et al

Modjaz, M., Kewley, L., Bloom, J. S., et al. 2011, ApJ, 731, L4

work page 2011
[37]

& Rafferty, D

Mohan, N. & Rafferty, D. 2015, PyBDSF: Python Blob Detection and Source

work page 2015
[38]

& Oosterloo, T

Morganti, R. & Oosterloo, T. 2018, A&A Rev., 26, 4

work page 2018
[39]

E., Stanimirovi´c, S., Goss, W

Murray, C. E., Stanimirovi´c, S., Goss, W. M., et al. 2015, ApJ, 804, 89

work page 2015
[40]

E., Stanimirovi´c, S., Goss, W

Murray, C. E., Stanimirovi´c, S., Goss, W. M., et al. 2018, ApJS, 238, 14

work page 2018
[41]

E., Stanimirovi´c, S., Heiles, C., et al

Murray, C. E., Stanimirovi´c, S., Heiles, C., et al. 2021, ApJS, 256, 37

work page 2021
[42]

N., Kanekar, N., Chengalur, J

Patra, N. N., Kanekar, N., Chengalur, J. N., & Roy, N. 2018, MNRAS, 479, L7

work page 2018
[43]

M., Chen, H., Stanimirovi´c, S., et al

Pingel, N. M., Chen, H., Stanimirovi´c, S., et al. 2024, ApJ, 974, 93

work page 2024
[44]

N., Sadler, E

Reeves, S. N., Sadler, E. M., Allison, J. R., et al. 2015, MNRAS, 450, 926

work page 2015
[45]

N., Sadler, E

Reeves, S. N., Sadler, E. M., Allison, J. R., et al. 2016, MNRAS, 457, 2613

work page 2016
[46]

D., Murrowood, C

Ryder, S. D., Murrowood, C. E., & Stathakis, R. A. 2006, MNRAS, 369, L32

work page 2006
[47]

D., Sadler, E

Ryder, S. D., Sadler, E. M., Subrahmanyan, R., et al. 2004, MNRAS, 349, 1093

work page 2004
[48]

D., Van Dyk, S

Ryder, S. D., Van Dyk, S. D., Fox, O. D., et al. 2018, ApJ, 856, 83

work page 2018
[49]

2015, MNRAS, 452, 2680

Serra, P., Koribalski, B., Kilborn, V ., et al. 2015, MNRAS, 452, 2680

work page 2015
[50]

J., Tress, R., Soler, J

Smith, R. J., Tress, R., Soler, J. D., et al. 2023, MNRAS, 524, 873

work page 2023
[51]

D., Miville-Deschênes, M.-A., Molinari, S., et al

Soler, J. D., Miville-Deschênes, M.-A., Molinari, S., et al. 2022, A&A, 662, A96

work page 2022
[52]

J., et al

Sorgho, A., Carignan, C., Pisano, D. J., et al. 2019, MNRAS, 482, 1248

work page 2019
[53]

W., & Ryder, S

Soria, R., Kuncic, Z., Broderick, J. W., & Ryder, S. D. 2006, MNRAS, 370, 1666

work page 2006
[54]

M., Sault, R

Stanimirovic, S., Staveley-Smith, L., Dickey, J. M., Sault, R. J., & Snowden, S. L. 1999, MNRAS, 302, 417

work page 1999
[55]

J., Böker, T., Charlot, S., et al

Walcher, C. J., Böker, T., Charlot, S., et al. 2006, ApJ, 649, 692

work page 2006
[56]

1997, AJ, 113, 1591

Walsh, W., Staveley-Smith, L., & Oosterloo, T. 1997, AJ, 113, 1591

work page 1997
[57]

G., Hollenbach, D., McKee, C

Wolfire, M. G., Hollenbach, D., McKee, C. F., Tielens, A. G. G. M., & Bakes, E. L. O. 1995, ApJ, 443, 152

work page 1995
[58]

G., McKee, C

Wolfire, M. G., McKee, C. F., Hollenbach, D., & Tielens, A. G. G. M. 2003, ApJ, 587, 278

work page 2003
[59]

& Vidal, N

Yahil, A. & Vidal, N. V . 1977, ApJ, 214, 347 Article number, page 16 of 17 W.J.G. de Blok et al.: HI absorption in MHONGOOSE Appendix A: The brightest non-detections Here we present the spectra of the non-detections towards the 14 brightest continuum sources listed in Table 1. The detection spectra are given in Fig. 1. 250 300 350 400 450 500 Velocity (k...

work page 1977