Issue |
A&A
Volume 567, July 2014
|
|
---|---|---|
Article Number | A132 | |
Number of page(s) | 21 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201321624 | |
Published online | 28 July 2014 |
The Mice at play in the CALIFA survey
A case study of a gas-rich major merger between first passage and coalescence
1
School of Physics and Astronomy, University of St Andrews, North
Haugh, St Andrews,
KY16 9SS, UK (SUPA)
2
Institute for Astronomy, University of Edinburgh, Royal
Observatory, Blackford
Hill, Edinburgh,
EH9 3HJ, UK (SUPA)
3
Departamento de Física Teórica, Universidad Autónoma de
Madrid, 28049
Madrid,
Spain
4
Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis E. Erro 1,
72840
Tonantzintla, Puebla, Mexico
5
Instituto de Astrofísica de Canarias (IAC),
38205, La Laguna, Tenerife, Spain
6
Depto. Astrofísica, Universidad de La Laguna (ULL),
38206, La Laguna, Tenerife, Spain
7
Instituto de Astrofísica de Andalucía (CSIC),
C/Camino Bajo de Huétor, 50,
18008
Granada,
Spain
8
Leibniz-Institut für Astrophysik Potsdam (AIP),
An der Sternwarte 16,
14482
Potsdam,
Germany
9
European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, 85748
Garching b. Muenchen,
Germany
10
Astronomisches Rechen-Institut, Zentrum für Astronomie der
Universität Heidelberg, Mönchhofstr. 12−14,
69120
Heidelberg,
Germany
11
INAF − Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5,
50125
Firenze,
Italy
12
Dark Cosmology Centre, Niels Bohr Institute, University of
Copenhagen, Juliane Mariesvej
30, 2100
Copenhagen,
Denmark
13
Department of Physics, University of Helsinki,
Gustaf Hällströmin katu 2a,
00014
Helsinki,
Finland
14
Max Planck Institute for Astronomy, Königstuhl 17, 69117
Heidelberg,
Germany
15
GEPI Observatoire de Paris, CNRS, Université Paris
Diderot, Place Jules
Janssen, 92190
Meudon,
France
16
Departamento de Fisica, Universidade Federal de Santa
Catarina, 88040-900
Floriano polis,
Brazil
17
Centro Astronómico Hispano Alemán, C/ Jesús Durbán Remón
2-2, 04004
Almería,
Spain
18
Astronomical Institute of the Ruhr-University Bochum,
Universitätsstr. 150, 44580
Bochum,
Germany
19
RUB Research Department “Plasmas with Complex Interactions”,
Universitätsstr. 150, 44580
Bochum,
Germany
20
Institut d’Astrophysique de Paris, CNRS UMR 7095, Université
Pierre et Marie Curie, 98bis Bd
Arago, 75014
Paris,
France
21
Institute of Astronomy, University of Cambridge,
Madingly Road, Cambridge, CB3 0HA, UK
22
Instituto de Astronomía,Universidad Nacional Autonóma de
Mexico, A.P.
70-264, 04510
México, D.F., México
23
Instituto de Cosmologia, Relatividade e Astrofísica −
ICRA, Centro Brasileiro de Pesquisas Físicas, Rua Dr.Xavier Sigaud 150, CEP
22290-180
Rio de Janeiro, RJ, Brazil
24
University of Vienna, Türkenschanzstrasse 17, 1180
Vienna,
Austria
25
Instituto de Fisica de Cantabria, CSIC-UC, Avenida de los Castros s/n,
39006
Santander,
Spain
26
Sydney Institute for Astronomy, School of Physics A28, The
University of Sydney, NSW,
2006
Sydney,
Australia
27
Departamento de Astrofísica y CC. de la Atmósfera, Universidad
Complutense de Madrid, 28040
Madrid,
Spain
28
Departamento de Física Teórica y del Cosmos, Universidad de
Granada,
18071
Granada,
Spain
29
Centro de Astrofísica and Faculdade de Ciências, Universidade do
Porto, Rua das Estrelas, 4150-762 Porto, PortugalCEI Campus Moncloa, UCM-UPM,
Departamento de Astrofísica y CC. de la Atmósfera, Facultad de CC. Físicas, Universidad Complutense de Madrid, Avda. Complutense s/n, 28040
Madrid,
Spain
30
Landessternwarte, Zentrum für Astronomie der Universität
Heidelberg (ZAH), Königstuhl
12, 69117
Heidelberg,
Germany
31
Australian Astronomical Observatory, PO Box 915, North Ryde, NSW
1670
Sydney,
Australia
32
Department of Physics and Astronomy, Macquarie
University, NSW,
2109
Sydney,
Australia
Received:
2
April
2013
Accepted:
27
May
2014
We present optical integral field spectroscopy (IFS) observations of the Mice, a major merger between two massive (≳1011 M⊙) gas-rich spirals NGC 4676A and B, observed between first passage and final coalescence. The spectra provide stellar and gas kinematics, ionised gas properties, and stellar population diagnostics, over the full optical extent of both galaxies with ~1.6 kpc spatial resolution. The Mice galaxies provide a perfect case study that highlights the importance of IFS data for improving our understanding of local galaxies. The impact of first passage on the kinematics of the stars and gas has been significant, with strong bars most likely induced in both galaxies. The barred spiral NGC 4676B exhibits a strong twist in both its stellar and ionised gas disk. The edge-on disk galaxy NGC 4676A appears to be bulge free, with a strong bar causing its “boxy” light profile. On the other hand, the impact of the merger on the stellar populations has been minimal thus far. By combining the IFS data with archival multiwavelength observations we show that star formation induced by the recent close passage has not contributed significantly to the total star formation rate or stellar mass of the galaxies. Both galaxies show bicones of high ionisation gas extending along their minor axes. In NGC 4676A the high gas velocity dispersion and Seyfert-like line ratios at large scaleheight indicate a powerful outflow. Fast shocks (vs ~ 350 km s-1) extend to ~6.6 kpc above the disk plane. The measured ram pressure (P/k = 4.8 × 106 K cm-3) and mass outflow rate (~8−20 M⊙ yr-1) are similar to superwinds from local ultra-luminous infrared galaxies, although NGC 4676A only has a moderate infrared luminosity of 3 × 1010 L⊙. Energy beyond what is provided by the mechanical energy of the starburst appears to be required to drive the outflow. Finally, we compare the observations to mock kinematic and stellar population maps extracted from a hydrodynamical merger simulation. The models show little enhancement in star formation during and following first passage, in agreement with the observations. We highlight areas where IFS data could help further constrain the models.
Key words: galaxies: kinematics and dynamics / galaxies: interactions / galaxies: evolution / galaxies: stellar content / galaxies: Seyfert / techniques: integral field spectroscopy
© ESO, 2014
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