Observational constraints to boxy/peanut bulge formation time

Isabel Pérez Departamento Física Teórica y del Cosmos, Universidad de Granada

I. Martinez-Valpuesta(IAC), T. Ruiz-Lara(IAC), A. de Lorenzo-Caceres(IAC)), J. Falcón-Barroso (IAC), Estrella Florido (UGR),R.M. Gonzalez-Delgado (IAA), M. Lyubenova (RUG), R.A. Marino (ETH), S.F. Sanchez (UAM), P. Sánchez-Bláquez (U. autóma de Madrid), G. van de Ven (MPI), A. Zurita (UGR)

Observations trace a boxy/peanut structure in the MW

Valenti, et al. (2016)

based on RC stars from VVV

Boxy/peanut are ubiquitous

Martinez-Valpuesta et al. 2006

Boxy/peanut shape bulges in more than 40% of disc galaxies (Lutticke et al . 2000).

Simulations show that boxy peanut bulges are bars (Combes & Sanders 1981; Athanassoula et al. 2002, Debattista et al. 2006, etc)

Observational evidence from spectroscopy of edge-on galaxies (e.g. Kuijken & Merrifield 1995; Bureau & Freeman 1999; Chung & Bureau 2004)

How do B/P bulges look like in less inclined galaxies?

Boxy/peanut shape bulges related to bar/lense structures seen face-on (Debattista et al. 2013, Laurikainen et al. 2017, 2014, Athanassoula et al 2015)

When and how bars and boxy/peanut bulges form?

- resolved star formation histories (near-field cosmology)

CALIFA survey PMAS (Ppak configuration) 3400-7300 ÅFinal spectral resolution FWHM ~ 6 Å and spatial resolutiion 1”

Subsample of 20 barred spirals beloging to size outliers such as NGC6032

When and how bars and boxy/peanut bulges form?

- star formation histories: Integrated spectra from elliptical annuli bins

Stellar content analysis different approaches:● Colours

● Line indices

● Full spectral fitting

Sanchez-Blazquez et al. 2011

``STEllar Content and Kinematics via Maximum A Posteriori likelihood''STECKMAP (Ocvirk 2006)

Stellar Population models: MILES (Vazdekis et al. 2010: http://miles.iac.es)

Comparison between CMD and integrated stellar populations: LMC

Ruiz-Lara, Pérez, Gallart et al. 2015

Comparison between CMD and integrated stellar populations: LMC

WFPC2, reaching the oldest MS turn-offAparicio & Gallart 2004

EFOSC2 Ruiz-Lara et al. 2015

Comparison between CMD and integrated stellar populations: LMC

Good agreement between state-of-the-art resolved stellar analysis and full spectral fitting (Ruiz-Lara, Pérez et al 2015)

When and how bars and boxy/peanut bulges form from star formation histories

Integrated spectra from elliptical annuli bins

Snapshot of bar and bulge formation from the SFH of NGC6032

Pérez, Martinez-Valpuesta et al. 2017.

Pérez, Martinez-Valpuesta et al. 2017.

Snapshot of bar and bulge formation from the SFH of NGC6032

Pérez, Martinez-Valpuesta et al. 2017.

Pérez, Martinez-Valpuesta et al. 2017.

Quenching of the SF in the 'inner' bar: bar as a conveyor belt

Pérez, Martinez-Valpuesta et al. 2017.

Bar grows from disc material

Pérez, Martinez-Valpuesta et al. 2017.

Pérez, Martinez-Valpuesta et al. 2017.

Snapshot of bar and bulge formation from numerical simulations: bar formation and buckling period

Pérez, Martinez-Valpuesta et al. 2017.

Summary

● The close relation between morphological features and SFHs suggest a long-lasting bar

● The enhancement of star formation in the inner bar suggests, based on the new simulation a relation with the bar formation and main growth, right before the buckling event. In this way we can estimate the buckling occurring around 8 Gyrs ago. We can also infer the formation of the stable disc and the bar at least before 10 Gyrs.

● After the event of the B/P formation, the bar grows again mainly from disc material

● When the bar forms there is a quenching in the star formation of the inner bar, suggesting that the bar can act as a conveyor belt, transferring material to the centre from the disc without forming stars within it.

● Sanchez-Menguiano, Sanchez, Perez et al 2017 accepted (Today!)● 102 spiral galaxies with MUSE (part of the AMUSING project) 2D distributions Gas

abundances, stellar properties, kinematics, physical properties of HII regions