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Paper   IPM / Astronomy / 17601
School of Astronomy
  Title:   The stratification of ISM properties in the edge-on galaxy NGC 891 revealed by NIKA2
1.  S. Katsiol
2.  E. M. Xilouris
3.  C. Kramer
4.  R. Adam
5.  P. Ade
6.  H. Ajeddig
7.  P. André
8.  E. Artis
9.  H. Aussel
10.  M. Baes
11.  A. Beelen
12.  A. Benoît
13.  S. Berta
14.  L. Bing
15.  O. Bourrion
16.  M. Calvo
17.  A. Catalano
18.  C. J. R. Clark
19.  I. . De Looze
20.  M. De Petris
21.  F.-X. Désert
22.  S. Doyle
23.  E. F. C. Driessen
24.  G. Ejlali
25.  M. Galametz
26.  F. Galliano
27.  A. Gomez
28.  J. Goupy
29.  C. Hanser
30.  A. Hughes
31.  A. P. Jones
32.  F. Kéruzoré
33.  B. Ladjelate
34.  G. Leclercq
35.  S. Leclercq
36.  J.-F. Lestrade
37.  J.-F. Macías-Pérez
38.  S. C. Madden
39.  A. Maury
40.  P. Mauskopf
41.  F. Mayet
42.  A. Monfardini
43.  M. Muñoz-Echeverría
44.  A. Nersesian
45.  L . Pantoni
46.  D. Paradis
47.  L. Perotto
48.  G. Pisano
49.  N. Ponthieu
50.  V. Revéret
51.  A. J. Rigby
52.  A. Ritacco
53.  C. Romero
54.  H. Roussel
55.  F. Ruppin
56.  K. Schuster
57.  A. Sievers
58.  M. W. L. Smith
59.  J. . Tedros
60.  F. Tabatabaei
61.  C. Tucker
62.  N. Ysard
63.  R. Zylka
  Status:   Published
  Journal: Astronomy & Astrophysics
  Vol.:  679
  Year:  2023
  Supported by:            ipm IPM
Context. As the millimeter wavelength range remains a largely unexplored spectral region for galaxies, the IMEGIN large program aims to map the millimeter continuum emission of 22 nearby galaxies at 1.15 and 2 mm. Aims. Using the high-resolution maps produced by the NIKA2 camera, we explore the existence of very cold dust and take possible contamination by free–free and synchrotron emission into account. We study the IR-to-radio emission coming from different regions along the galactic plane and at large vertical distances. Methods. New observations of NGC 891, using the NIKA2 camera on the IRAM 30 m telescope, along with a suite of observations at other wavelengths were used to perform a multiwavelength study of the spectral energy distribution in the interstellar medium in this galaxy. This analysis was performed globally and locally, using the advanced hierarchical Bayesian fitting code, HerBIE, coupled with the THEMIS dust model. Results. Our dust modeling is able to reproduce the near-IR to millimeter emission of NGC 891, with the exception of an excess at a level of 25% obtained by the NIKA2 observations in the outermost parts of the disk. The radio continuum and thermal dust emission are distributed differently in the disk and galaxy halo. Different dusty environments are also revealed by a multiwavelength investigation of the emission features. Our detailed decomposition at millimeter and centimeter wavelengths shows that emission at 1 mm is purely originated by dust. Radio components become progressively important with increasing wavelengths. Finally, we find that emission arising from small dust grains accounts for ∼9.5% of the total dust mass, reaching up to 20% at large galactic latitudes. Shock waves in the outflows that shatter the dust grains might explain this higher fraction of small grains in the halo. Conclusions. NIKA2 observations have proven essential for a complete characterization of the interstellar medium in NGC 891. They have been critical to separate the dust, free–free, and synchrotron emission in the various emitting regions within the galaxy.

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