dimitri gadotti (max planck institute for astrophysics – garching) magpop network meeting what can...
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Dimitri Gadotti(Max Planck Institute for Astrophysics – Garching)
MAGPOP Network Meeting
What can we learn from imaging and spectroscopy of well-resolved galaxies?
1. The BUDDA code:
- from bulge/disk decomposition to multi-component decomposition
2. Dating secular evolution:
- the ages of bars
3. On bars and haloes:
- inferring halo properties from bar properties
The BUDDA Code(de Souza, Gadotti & dos Anjos 2004)
• BUlge/Disk Decomposition Analysis (http://www.mpa-garching.mpg.de/~dimitri/budda.html)
• 2D (Image Fitting)• reliable results (de Jong 1995) for galaxies with different components (constraints from PA and ellipticity)• discrepancies among 1D fits can be as large as 100% (Baggett, Baggett & Anderson 1998)
• Bulge (Sérsic 1968)
• Disk (Freeman 1970)
• Residual Images (sub-structures)
Dimitri Gadotti (MPA – Garching)
A Structural Analysis of 51 Early-Type Galaxies
• R-band images
• Structural parameters
• Inner disks in ~ 1/3 of Es• merger signature (see Burstein et al. 2001)?
direct image residual image
NGC 1052 (E4 – Sey2)
Dimitri Gadotti (MPA – Garching)
IC 1459
direct image
residual image
A Structural Analysis of 51 Early-Type Galaxies
• Classified as E3 (RC3) but has a disk! It’s an S0! Also a LINER…
• Wrong morphological classification in ~ 1/3 of Es and S0s
Dimitri Gadotti (MPA – Garching)
NGC 1291
Residual Images and Sub-StructuresN
GC
22
17NGC 4314 (B band – Steward Obs.)
(Gadotti & de Souza 2006)
NG
C 5850 (K
s – Kitt Peak)
(Gadotti &
de Souza 2005, 2006)
Dimitri Gadotti (MPA – Garching)
The New BUDDA:Generalized Ellipses
Pure Boxy
Disky
(e.g., Athanassoula et al. 1990)
• Boxy Es emit strongly in radio/X-ray, are more luminous & massive, and show slow rotation compared to disky Es (e.g., Bender et al. 1989)
• Different formation histories (Naab & Burkert 2003)?
Dimitri Gadotti (MPA – Garching)
The New BUDDA:Double Exponential Disks
• Truncation (Freeman 1970 type II - e.g., Pohlen 2002)
• Anti-truncation (Erwin, Beckman & Pohlen 2005)
Origin: bars, spirals, interactions…???
?3-5 h0 3-5 h0
Dimitri Gadotti (MPA – Garching)
The New BUDDA:Four Components
• Central Source• Moffat (1969) profile: fits better seeing effects (see Trujillo et al. 2001a,b)
• Bar• Sérsic profile• n=1: late-type bars• n=0.5-1: early-type bars
Dimitri Gadotti (MPA – Garching)
Dimitri Gadotti (MPA – Garching)
Bars and Secular Evolution
Bars are to a large extent shaping the physical properties of galaxies (see Kormendy & Kennicutt 2004):
- creating rings & spirals arms
- attenuating metallicity & color gradients
- fueling AGN & central star formation
- building bulges
Questions
- When did the first bars appear?
- How fast bars drive gas to the center?
- For how long a bar modifies the evolution of its host galaxy?
- What is the fraction of pseudo-bulge stars?
- Are bars really recurrent?
Dimitri Gadotti (MPA – Garching)
Estimating the Ages of Bars(see Gadotti & de Souza 2005)
y
xσz
- Thin bars ↔ recently-formed; thick bars ↔ evolved
- Measure the stellar vertical velocity dispersion
Dimitri Gadotti (MPA – Garching)
Spectroscopy
- 14 face-on barred galaxies: Kitt Peak (2.3m) & La Silla (1.5m)- Diversified sample: morphology, AGN and environment
Dimitri Gadotti (MPA – Garching)
Gauss-Hermite series (van der Marel & Franx 93)
K0III stars
Determining the LOSVDs
Dimitri Gadotti (MPA – Garching)
Radial Profiles of σz
r
σz
r
σz
Young bar
Old bar
Central drop in σz (inner disk?)
Dimitri Gadotti (MPA – Garching)
Let’s Quantify
- σZ,bar: at 50%-60% of bar semi-major length
σZ: difference to σZ in the disk at same distance
- Young bars: σZ,bar ~ 30 Km/s and σZ ~ 5 Km/s
- Old bars: σZ,bar ~ 100 Km/s and σZ ~ 40 Km/s
- Statistical tests indicate different populations at the 98% confidence level
Dimitri Gadotti (MPA – Garching)
Some Results
- AGN activity seems to be found preferentially in young bars (timescale for AGN fueling is short):- 2/8 (25%) of old bars have AGN, but 3/5 (60%) of young bars
show activity- Better bar x AGN correlation with young bars!
- Bar recurrence may be more frequent in late-type galaxies:- 7/8 (88%) of old bars are early-type, but only 2/5 (40%) of
young bars are early-type
Dimitri Gadotti (MPA – Garching)
On Bars and Haloes
• Previous studies concluded that haloes are against bars (Ostriker & Peebles 1973)
• Using live haloes the truth is the opposite (Athanassoula & Misiriotis 2002; see also Athanassoula 2003)!
• Angular momentum transfer between halo and disk makes stronger bars• Depends on halo properties like mass and velocity distribution
MH | MD
Dimitri Gadotti (MPA – Garching)
On Bars and Haloes
J and Ks near-infrared observations at the Cananea 2.1-m telescope
• Compare the properties of N-body models and real barred galaxies
N-body simulations
MH | MD
Dimitri Gadotti (MPA – Garching)