Erratum for: A&A, 695, A202 (2025), https://doi.org/10.1051/0004-6361/202553891

1. Introduction

This erratum addresses the incorrect derivation of the CO(1-0) intensity map originally included in Villanueva et al. (2025), which did not consider the proper combination of the Northern Extended Millimetre Array (NOEMA) inteferometric CO(1-0) data with available Institut de radioastronomie millimétrique (IRAM) 30 m CO(1-0) observations (as originally included in Krieger et al. 2021). With the inclusion of the new, well-combined full set of the CO(1-0) emission line data, fluxes of the CO clouds are ∼1.0–1.5 orders of magnitude higher than in the previous version.

The revision impacts some aspects regarding the number of cloud-like structures identified, best-linear fit parameters, and conclusions. As a consequence, figures and equations have been updated according to the new version of the CO data presented here; on average, the results are in agreement with both those included in Villanueva et al. (2025) and similar upcoming studies (e.g., Lopez et al. in prep.).

2. Updated sections

2.1. Abstract

To perform our analysis, we identified CO clouds using the archival ¹²CO(J = 1-0) NOEMA+IRAM moment 0 map within 2 kpc of the center of M 82, with sizes ranging between ∼31 and 400 pc. Then, we computed the CO-to-polycyclic aromatic hydrocarbon (PAH) relations for the 413 validated CO clouds.

2.2. CO NOEMA data

As explained in Lopez et al. (in prep.), the CO(1-0) data include both IRAM 30 m single-dish and NOEMA interferometric observations originally included in Krieger et al. (2021). Briefly, the two datasets were first combined using the Common Astronomy Software Applications (CASA) task feather to ensure that the final products include zero spacing data, and then convolved to obtain a round synthesized beam. Finally, the CO intensity map (moment 0) was produced by integrating the emission comprised in velocity-range based masks constructed from Karl Jansky Very Large Array (VLA) 21 cm emission line observations (Martini et al. 2018), and both archival IRAM 30 m CO(2-1) map (Leroy et al. 2015) and CO(1-0) data (Krieger et al. 2021). This resulted in a 2.2″ resolution CO(1-0) intensity map that covers the inner ∼2 kpc of the starburst galaxy M 82 (see the left panel of Fig. 1).

Fig. 1. Corrected M 82 CO(J = 1-0) map derived by combining IRAM observations with NOEMA observations (left), MIRI-F770W images (middle), and MIRI-F1130W images (right) in cutouts of 5′×4.2′. The new version of the left panel contains the updated set of 413 CO clouds identified here (white contours).

2.3. Cloud identification

Using the new version of the CO(1-0) intensity map and QUICKCLUMP¹ (Sidorin 2017), and following the procedure described in Sect. 2.2 and Appendix B in Villanueva et al. (2025), we validated 413 CO clouds (white contours in the left panel of Fig. 1); their sizes range between ∼31 and 400 pc (see Fig. 2). We now find larger CO cloud sizes than in the original study (57.6 versus 41.3 pc).

Fig. 2. Distribution of sizes of the 413 CO clouds we identified in the updated NOEMA+IRAM map using QUICKCLUMP.

We obtain the following updated distributions: disk (DISK; 22 clouds), streamer east (SE; 87 clouds), streamer west (SW; 90 clouds), outflow north (ON; 95 clouds), and outflow south (OS; 119 clouds).

2.4. CO versus PAH relations

We computed the relations between CO and mid-IR PAH emission for the 413 molecular clouds identified in Sect. 2.3. The new best-linear fit relation for the data binned in I_MIRI770 values is given by

$$\begin{array}{cc}\hfill log(I_{\mathrm{CO}(1-0)}/[\mathrm{K}\mathrm{km}/\mathrm{s}])=(0.59\pm 0.16)\times & log(I_{\mathrm{MIRI}770}/[\mathrm{MJy}{\mathrm{sr}}^{-1}])\hfill \\ \hfill & -(0.92\pm 0.32).\hfill \end{array}$$(1)

We note that the slope for the entire cloud sample is slightly lower than that of the previous version (m = 0.74 ± 0.19), although still within the uncertainties. However, we obtain different Pearson r_p values for the CO-F770W relation when dividing the cloud sample by regions. While the CO-F770W relation is still tight in the disk, ON and OS (r_p ∼ 0.7 − 0.9), the rest of the groups now have significantly lower r_p values (with an almost null correlation for SE; see Table 1).

The bottom-left panel of Fig. 3 shows the new version of the I_{CO(1 − 0)}-F1130W relation. We computed the updated best-linear relation for the data binned in I_MIRI1130 values as follows:

Fig. 3. Updated version of the relations between ICO(1 − 0) versus IMIRI770 (top), and IMIRI1130 (bottom).

$$\begin{array}{cc}\hfill log(I_{\mathrm{CO}(1-0)}/[\mathrm{K}\mathrm{km}/\mathrm{s}])=(0.68\pm 0.16)\times & log(I_{\mathrm{MIRI}1130}/[\mathrm{MJy}{\mathrm{sr}}^{-1}])\hfill \\ \hfill & -(0.91\pm 0.34).\hfill \end{array}$$(2)

We note that the CO-F1130W best fit has a slightly lower slope compared to that found in the previous version (m = 0.8 ± 0.25). Likewise, when splitting the clouds into the regions of M 82, we find that the updated CO-F1130W relation remains only tight for ON; the rest of the groups have a poor or null correlation (see Table 1).

When we compare the x₀ = −b/m values (i.e., the x value where the best linear relation intercepts the x-axis) for the two relations with the previous versions, we find that M 82 now has slightly higher x₀ values (∼1.1–1.2 times higher than those for PHANGS galaxies). Although now there are smaller discrepancies in the linear parameters for the CO-F770W and CO-F1130W relations in the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) survey and M 82, they still appear to reflect differences in the mechanisms of PAH emission.

The right panels of Fig. 3 show that we still find tighter CO-F770W (top) and CO-F1130W (bottom) relations in clouds larger than 100 pc (now the Pearson r_p ∼ 0.5 − 0.6; previously was r_p ∼ 0.7) compared to those with shorter diameters (now is ≲0.3 compared to ∼0.1–0.4). The updated results still indicate that larger clouds have more significant CO detections than smaller structures.

2.5. CO versus F770W/F1130W

The top panel of Fig. 4 presents the new relation between CO and the I_MIRI770/I_MIRI1130 ratio. Interestingly, the CO-F770W/F1130W relation is now tighter for the disk and ON than in the previous version (r_p ≳ 0.5 − 0.7). When analyzing the projected distances of the CO clouds with respect to the optical center (bottom panel), we note that now small clouds (≲50 pc) from both SE and SW (i.e., those with low r_p in the top panel of Fig. 4), and at distances greater than 1 kpc from the optical center contribute significantly to the scatter of the CO-F770W/F1130W relation at log(I_MIRI770/I_MIRI1130) ∼ 0.56.

Fig. 4. New version of the ICO(1 − 0) versus IMIRI770/IMIRI1130 ratio.

In summary, despite a rescaling of the integrated fluxes of the CO line for the new set of 413 clouds identified, our new results are on average in agreement with the main findings included in Villanueva et al. (2025) and the upcoming follow-up studies based on the CO-PAH relations in M 82 (e.g., Lopez et al. in prep.).

References

© The Authors 2025

All Tables

All Figures

	Fig. 1. Corrected M 82 CO(J = 1-0) map derived by combining IRAM observations with NOEMA observations (left), MIRI-F770W images (middle), and MIRI-F1130W images (right) in cutouts of 5′×4.2′. The new version of the left panel contains the updated set of 413 CO clouds identified here (white contours).
In the text

	Fig. 2. Distribution of sizes of the 413 CO clouds we identified in the updated NOEMA+IRAM map using QUICKCLUMP.
In the text

	Fig. 3. Updated version of the relations between ICO(1 − 0) versus IMIRI770 (top), and IMIRI1130 (bottom).
In the text

	Fig. 4. New version of the ICO(1 − 0) versus IMIRI770/IMIRI1130 ratio.
In the text