The Mice at play in the CALIFA survey. A case study of a gas-rich major merger between first passage and coalescence
Loading...
Download
Official URL
Full text at PDC
Publication date
2014
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
EDP Sciencies
Citations
Exportar
Citation
Abstract
We present optical integral field spectroscopy (IFS) observations of the Mice, a major merger between two massive (≳10^11 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 × 10^6 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 × 10^10 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.
Description
© ESO, 2014. Artículo firmado por 46 autores. This study makes use of the data provided by the Calar Alto Legacy Integral Field Area (CALIFA) survey (http://www.califa.caha.es). Based on Observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut fur Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). CALIFA is the first legacy survey being performed at Calar Alto. The CALIFA collaboration would like to thank the IAA-CSIC and MPIA-MPG as major partners of the observatory, and CAHA itself, for the unique access to telescope time and support in manpower and infrastructures. The CALIFA collaboration thanks also the CAR staff for the dedication to this project, The authors would like to thank the anonymous referee for comments that significantly improved the paper, Dimitri Gadotti for providing extersive help and advice with the image decomposition; Mike Dopita and Tim Heckman for their patience explaining the effects of shocks in superwinds; Daria Dubinoyska for creating undistorted ACS PSF images from the Tiny Tim images and Carotin Villforth for further help with the ACS PSF; Lia Athanassoula for help interpeting the kinematic maps: Daniel Pomarede for help getting SDvision running; Jeremy Sanders and Roderik Johnstone for help interpreting( the X-ray observations: Eva Schinnerer for pointing out the effect of beam smearing; all other interested researchers who have contributed with questions and comments following discussions and presentations of this work over the last 2 years. The numerical simulations were performed on facilities hosted by the CSC-IT Center for Science in Espoo. Finland, which are financed by the Finnish ministry of education. Funding and financial support acknowledgements.: V. W. from the European Research Council Starting Grant (RI, Wild SEDmorph), European Research Council Advanced Grant (RI. J. Dunlop) and Marie Curie Career Reintegration Grant (RI. Wild Phiz-ev): J. M. A. from the European Research Council Starting Grant (RI. Wild SEDmorph); E. F. R. G. from the Mexican National Council for Science and Technology (CONACYT); A. G. from the European Union Seventh Framework Programme (FP7/2007 under grant agreement n. 267251. The Dark Cosmology Centre is funded by the Danish National Research Foundation. R H. J. from the Research Funds of the University of Helsinki: J. F. B. from the Ramón y Cajal Programme, grants AYA2010-21322-C03-02 and AIB-2010-DE-00227 from the Spanish Ministry of Economy and Competitiveness (MINECO), as well as from the FP7 Marie Curie Actions of the European Commission, via the Initial Training Network DAGAL under REA grant agreement no. 289313; R. G. D. and R. G. B. from the Spanish project AYA2010-15081: A. M. I. from the Agence Nationale de la Recherche through the STILISM project (ANR-12-BS05-0016-02) and from BMBF through the Erasmus-F project (grant number 05 A12BA1). R. A. M. from the Spanish programme of International Campus of Excellence Moncloa (CEI), K. J. from the Emmy Noether-Programme a the German Science Foundation (DIG) under grant Ja 1114/3-2; P. R. & J. M. G. from the Fundacao para a Ciencia e a Tecnologia (FCT) under project FCOMP-01-0124-FEDER-029170 (Reference FCT PTDC/FIS-AST/3214/2012). funded by FCT-MEC (PIDDAC) and FEDER (COMPETE). I. M. P, from Spanish grant AYA2010-15169 and the Junta de Andalucía through TIC 114 and the Excellence Project P08-TIC-03531 C. J. W. from the Marie Curie Career Integration Grant 303912; J. I. R and J, V M. from the Spanish MINECO under grant AYA2010-21887-C04-01.and from Junta de Andalucía Excellence Project PEX2011-FQM7058: E. M. Q. from the European Research Council via the award of a Consolidator Grant (PI McLure): M. P. from the Marie Curie Career Reintegration Grant (P.I. Wild Phiz-ev). This work was supported in part by the National Science Foundation under Grant No. PHYS-1066293 and the hospitality of the Aspen Center for Physics.