Bulge

Transcription

Bulge

Using 3D Spectroscopy to Probe
the Orbital Structure of
Composite Bulges
Peter Erwin
MPE
with: Roberto Saglia, Jens Thomas, Max Fabricius, Ralf Bender,
Stephanie Rusli (MPE); Nina Nowak (U. Stockholm); John E. Beckman,
Juan Carlos Vega Beltrán (IAC)
Vienna IAU Symposium: July 2014
Bulges in Disk Galaxies: The Traditional Picture
The New Picture: Many galaxies have “pseudobulges”
M33: inner few hundred pc =
spiral arms, star formation,
flattened isophotes, rapid
rotation — just like rest of disk!
Nuclear!
Cluster
“Bulge”
Disk
(2MASS Large Galaxy Atlas K-band profile)
NGC 3945 (SB0): Photometric Bulge is Flattened
Photometric bulge: r < 17 arcsec (1.6 kpc)
“Bulge” isophotes very elliptical
(similar to outer disk)
-20.
-10.
0.
10.
20.
arc sec
-20.
-10.
0.
10.
20.
arc sec
Partial nuclear ring + inner
(nuclear) bar
unsharp mask
-20.
-10.
0.
10.
20.
arc sec
Partial nuclear ring + inner
(nuclear) bar
Photometric bulge has
same flattening as disk;
disky substructure
(nuclear bar + ring)
!
Pseudobulge?
unsharp mask
NGC 3945: Kinematics in Photometric Bulge
HET kinematics from !
Fabricius+2012
NGC 3945: Kinematics in Photometric Bulge
HET kinematics from !
Fabricius+2012
Vdeproj. /σ rises to > 2 in photometric bulge region:
kinematically cool pseudobulge, not a classical bulge!
NGC 3945: Inner Morphology
-20.
-10.
0.
10.
20.
arc sec
Ellipse Fits
Ellipse fits (R-band + HST)
inner bar
-20.
-10.
0.
10.
20.
arc sec
Ellipse Fits
inner bar
Major-axis profile
(HST F814w)
Sersic: n = 2.02, Re = 120 pc
-20.
-10.
0.
10.
20.
arc sec
Ellipse Fits
inner bar
Major-axis profile
(HST F814w)
Sersic: n = 2.02, Re = 120 pc
-20.
-10.
0.
10.
20.
arc sec
Ellipse Fits
inner bar
Rounder isophotes (ell = 0.2) inside disky/ring
isophotes (ell = 0.35): r < 1.5 arcsec (150 pc)
!
Central photometric excess:
B/D decomposition Sérsic component
dominates for r < 1 arcsec (100 pc)
!
What are the kinematics of this inner region?
Kinematics of the Central Region
“Classical bulge” region
“Pseudobulge” !
region
HST-STIS data (Gültekin+2009)
Vdeproj. /σ < 1 in central bulge region: kinematically hot!
(Compact) classical bulge
Other Examples (Nine found so far)
NGC 1068
Vdp /𝜎
Vdp /𝜎
NGC 3368
Davies+2007 (SINFONI AO)
Shapiro+2003
SINFONI AO data
Fabricius+2012
Gerssen+2006
NGC 4699
Vdp /𝜎
Vdp /𝜎
NGC 2859
SINFONI AO data
Erwin+2014 (WHT-ISIS)
Bower+1993
de Lorenzo-Cáceres+2008
(SAURON)
S3BH: SINFONI Search for Supermassive
Black Holes
•
VLT-SINFONI AO observations of ~ 30 galaxies in Kband for stellar kinematics
•
•
15 disk galaxies — includes 3 composite bulges
Schwarzschild modeling to measure SMBH masses
•
e.g. Nowak+2007, 2008, 2010; Rusli+2011, 2013;
Erwin+2014 (in prep), Bender+2014 (in prep)
•
Stellar orbital structure as a byproduct
Stellar Velocity & Dispersion Fields for
Composite-Bulge Galaxies
NGC 3368
NGC 4371
𝜎
V
-80
V
+80
h3
𝜎
3˝
𝜎
3˝
60-130
MBH = 1.5 ⇥ 107 M
h4
NGC 4699
+60
V
MBH = 7.5 ⇥ 106 M
Nowak+2010
-60
160-220
MBH = 9.0 ⇥ 107 M
Stellar Dynamics from Schwarzschild Modeling
of SINFONI Data
Classical Bulge
Composite Bulges
Vertical!
anisotropy
Isotropic
Planar!
anisotropy
z
23º
R
Mass-weighted average of orbits within
±23º of equatorial plane
!
Anisotropy defined using ratio of “equatorial”
(radial+azimuthal) to vertical velocity
dispersions:
2
2
1
e/ z
Classical bulges are isotropic; disky pseudobulges are anisotropic (as expected for flattened disk)
Summary
•
Composite Bulges: S0–Sab galaxies with both classical
bulges and disky pseudobulges
•
SINFONI AO K-band data for stellar kinematics +
Schwarzschild modeling:
•
SMBH masses
•
Stellar orbital structure in classical and pseudobulge
regions — consistent with classical vs disky
classifications from morphology

Bulge

Transcription

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