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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20140212T123000
DTEND;TZID=Atlantic/Canary:20140212T133000
UID:iactalks-610
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/610
CREATED:2014-02-12T12:30:00+00:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:Bar characterization from S4G imaging: Gaining insight into the sec
 ular evolution of disc galaxies
DESCRIPTION:Bar characterization from S4G imaging: Gaining insight into the
  secular evolution of disc galaxies\nMr. Simon Diaz Garcia\n\n\nThe &Lambd
 a;CDM model predicts that galaxies originate in dark matter haloes, underg
 oing in their early age a process of continuous merges with other galaxies
  that determines the first part of their evolution. The frequency of these
  events decreases with time and their gradual change turns to be internall
 y driven, becoming much slower. Bars, elongated stellar structures in the 
 central regions of galaxies, are known to play an active role in this phas
 e of their evolution, so-called secular. \nBars are fundamentally responsi
 ble for the redistribution of matter and the angular momentum of the baryo
 nic and dark matter components of disc galaxies. Different simulations pre
 dict that bars get stronger and longer in time, slowing down their rotatio
 n speed. \nBased on the Spitzer Survey of Stellar Structure in Galaxies (S
 4G) 3.6 μm imaging, we aim to study the secular evolution of disc galax
 ies by focusing on their stellar bar parameters. We take a large well-defi
 ned sample of about 650 nearby barred galaxies and we infer the gravitatio
 nal potential from 3.6 μm images. We calculate gravitational torques, t
 he ratio of the maximal tangential force to the mean axisymmetric radial f
 orce, in order to obtain a quantitative measure of the bar-induced perturb
 ation strengths. In addition, we estimate the bar strength from the m=2 no
 rmalized Fourier density amplitudes and determine bar lengths both visuall
 y and by using an ellipse fitting method. Bar morphology and the interplay
  with spiral arms are studied via image-stacking methods as well. \nIn thi
 s talk I will present the statistical results derived from our measurement
 s, providing observational evidence for the evolution of bars in accordanc
 e with the current theoretical predictions. We study bar parameters as a f
 unction of the Hubble type, addressing how the different measurements of t
 he bar strength correlate with each other and with the galactic mass. The 
 quality of our data allows us to probe the properties of bars in the Local
  Universe and connect them to the evolution of other galactic structures. 
 \n
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