nigel douglas university of groningennigel douglas university of groningen

measuring kinematics in elliptical galaxiesmeasuring kinematics in elliptical galaxies

(spiral) galaxy dynamics

(spiral) galaxy dynamics

neutral gas

(stars, HII regions)

Braun 2002

rotation curve decomposition rotation curve decomposition

RotCurve (cwru.edu)RotCurve (cwru.edu)

early-type galaxy dynamics early-type galaxy dynamics stellar spectroscopy

Statler et al 99

IFU (integral field unit)

IFU (integral field unit)

Oosterloo priv comm

discrete tracers of kinematics

discrete tracers of kinematics

• globular clusters

• satellites

• PNe

• stars

• globular clusters

• satellites

• PNe

• stars

stellar streamsstellar streams

Ibata et al. 2004Ibata et al. 2004

PNe • easy to detect

• easy to measure radial velocity

linewidth 21 km/s

• ubiquitous at 2.5 20 per 109 LB

e.g. 750 for NGC 3379

PNe v stars

• by assumption PNe follow stars

• how true is this?

• PNe age and population synthesis

techniques for acquiring PNe radial velocities:

techniques for acquiring PNe radial velocities:

• imaging+spectroscopy

• perot-fabry

• slitless spectroscopy

imaging + spectroscopyngc 5128

Hui, Ford, Ciardullo, Jacoby 1993Hui, Ford, Freeman, Dopita 1995Peng, Ford, Freeman 2004

fabry-perot ngc 3384

fabry-perot ngc 3384

Tremblay, Merritt, Wiilliams 1995

68 PNe68 PNe

slitless spectroscopy:the PN spectrum

Slitless spectroscopy(1)Slitless spectroscopy(1)

trials at AAT 1995trials at AAT 1995

slitless spectroscopy NGC 5128 slitless spectroscopy NGC 5128

Slitless spectroscopy(2)Slitless spectroscopy(2)

cf Hui et al 1995

24 PNe compared

cf Hui et al 1995

24 PNe compared

Slitless spectroscopy(3)Slitless spectroscopy(3)

Fehrenbach 1947

Douglas & Taylor 1999

Fehrenbach 1947

Douglas & Taylor 1999

CDI at WHT: M94

modified ISIS

1997-2001

NGC 7457

NGC 5866

Douglas et al. 2000

MB = -19.8

D = 10.5 Mpc

UT1 + FORS1

1999/2000

14 hrs:

535 PN to 3 Reff

CDI at VLT: NGC 4697

Méndez et al. 2001

Bibliography: PNe velocitieswith slitless spectroscopy

Bibliography: PNe velocitieswith slitless spectroscopy

CDI (rotating spectrograph):

Douglas & Taylor 1999

Douglas, Gerssen et al 2000

CDI (mirror and grism):

Méndez, Riffeser et al 2001

PN.S (simultaneous CDI):

Douglas, Arnaboldi et al 2002

Romanowsky, Douglas et al 2003

CDI (rotating spectrograph):

Douglas & Taylor 1999

Douglas, Gerssen et al 2000

CDI (mirror and grism):

Méndez, Riffeser et al 2001

PN.S (simultaneous CDI):

Douglas, Arnaboldi et al 2002

Romanowsky, Douglas et al 2003

PN.S design

PN.S grating

PN.S mask

• instrument efficiency = 72% total system efficiency = 33%

three 36 Å [O III] filters ( -1400 .. +3400 km/s)

• field of view = 11.4’ x 10.3’ • dispersion 1.29 pxl/Å • built by prime optics, RSAA, ASTRON

Douglas et al 2002Douglas et al 2002

sample data

5’ x 2’ field in M31 (H. Merrett et al.)

pn.spectrograph projectpn.spectrograph project

pn.s team:

n. douglas, n. napolitano (groningen)

k. kuijken (leiden)

a. romanowsky, m. merrifield,

h. merrett (nottingham)

m. arnaboldi (turin)

m. capaccioli (naples)

k. freeman (rsaa)

o. gerhard (basel)

pn.s team:

n. douglas, n. napolitano (groningen)

k. kuijken (leiden)

a. romanowsky, m. merrifield,

h. merrett (nottingham)

m. arnaboldi (turin)

m. capaccioli (naples)

k. freeman (rsaa)

o. gerhard (basel)

sample of 12 bright, round E galaxies:

B 12.5, E2 or rounder,

v < 1300 km/s

100 - 400 PNe per galaxy, to 5-15 Reff

~ 8 hours to reach m5007 = 28.0

PN.S programme

WHT+PN.S:

March 2002

3 hrs :

197 PN velocities

to 7 Reff ,

v = 20 km/s

E1 , MB = -20.0

D = 11 Mpc

NGC 3379

Surface brightness profiles

PNe

stars(Capaccioli et al. 1990)

NGC 3379: Dispersion profile

isotropic constant-M/L Hernquist model

110 PNe

Isotropic singular isothermal halo

197 PNe

long-slit data(Statler & Smecker-Hane 1999)

29 PNe (Ciardullo, Jacoby & Dejonghe 1993)

Sluis et al. also confirmed with ~60 PNe

“Science three” dispersion profiles

isotropic

constant-M/L

Hernquist model

Romanowsky et al. 2003

(refs for long-slit:

Bender et al 1994)

Romanowsky et al. 2003

(refs for long-slit:

Bender et al 1994)

- single wavelength:

poor discrimination

utilises 0.1% of spectrum

+ undispersed H-alpha camera

PN.S limitations

M-CDI: masked counter-dispersed imaging

M-CDI: masked counter-dispersed imaging

past narrow band surveys at D > 10 Mpc: poor returns in follow-up spectroscopy

apply counter-dispersed imaging

(don’t need good astrometry)

but utilise all information

Ciardullo et al. 1998

UT2+FORS2/MXU:28-30 Apr 2001

MCDI

1400B VPH grism

6 fields @ 1 hr each:

200 PN velocities

to 5 Reff ,

v =15 km/s

PNe in M87

NGC3377

future developments:

NGC3377

future developments:

wavelength tagging detectors

NGC3377

future developments:

spectrum of an entire galaxy

NGC3377

future developments:

non-radial velocities