Upload
amethyst-reid
View
40
Download
1
Tags:
Embed Size (px)
DESCRIPTION
The connection between galaxies and quasar absorption lines. Lise Christensen. Quasar absorption lines. Ly a forest. Metal lines. LLS. DLA. Types of systems. Ly a forest : N (H I ) < 10 17 cm -2 LLS : 10 17 < N (H I ) < 2*10 20 cm -2 - PowerPoint PPT Presentation
Citation preview
The connection between galaxies and quasar absorption lines
Lise Christensen
Quasar absorption lines
DLALLS
Ly forest
Metal lines
Types of systems
Charlton, 2000
Ly forest : N(H I) < 1017 cm-2
LLS : 1017 < N(H I) < 2*1020 cm-2
DLA : N(H I) > 2*1020 cm-2
Column density distribution
NdN
dn
Petitjean et al. 1993
is roughly =1.5 over 10 decades
most mass is contained in high N systems
(neutral gas only)
Evidence for a steeper slope at DLA column densities
DLA
evolution with z ? DLA stars DLAs are reservoirs
for galaxy formation?
dNzNNfc
mH
crit
Hg ),(0
Mass in stars (SDSS)
Rao et al. 2005Prochaska et al. 2005Zwaan et al. 2005
21 cm observations
Neutral gas density
Metal lines- from high resolution observations
DLA metallicities
Prochaska et al. 2003
What we know about DLAs:
N(H I) as galaxy disks – but are they disks?
Metal enriched – star formation has taken place
[M/H] between halo and disk stars
Slow evolution
Reservoirs for star formation?
In what type of galaxies do DLAs reside?
Purpose of the integral field spectroscopic survey
What types of galaxies harbor DLAs?Large disks or small dwarfs?Understand proto-galaxies
DLA galaxies present an alternative selection to flux limited surveysLook for emission lines from the galaxies hosting DLAsSFRs, Impact parameters, and sizes
Main parts:
1. Low redshift: Search for optical emission lines
2. High redshift (z > 2): search for Lyman- emission
The PMAS instrument
Observations are done with:
PMAS= Potsdam Multi
Aperture Spectrophotometer
16*16 fibres connected to lens
array (no loss between fibres)
8”*8” field of view ( in our
setup)
3.5 m telescope at Calar Alto,
Spain
IFS advantages:
Imaging and
spectroscopy
simultaneously
No slit-losses
Pointing less crucial
Spectral resolution
independent on spatial
sampling and seeing
Method
Method
Previous low-z studies:
Low-z : ~30 known DLA systems – 14 confirmed DLA galaxies
3C 336, z = 0.927
DLA at z = 0.656
24000 s WFPC2archive image(Steidel et al 1997)
z=0.8908R=23.5
z =0.931R=24.5
But where is the z=0.656DLA galaxy?
[O II] atz=0.656
Abundances
PHL 1226 – subDLA at z=0.16 projected distance: 18 kpc
(Bergeron et al. 1988)
Christensen et al. 2005
Abundances
Figure from Pettini et al, 2004G4: Christensen et al. 2005
DLA metallicities could be biased by gradient compare metallicities from
emission and absorption
DLAs at high redshifts (z>2)
>500 DLA systems known – 6 confirmed…(3 intervening)
Q2233+131, z = 3.3
Sub-DLA at z = 3.15
m~25
Djorgovski et al 1996,Christensen et al. 2004
Visualisation – long slits
Visualisation – narrow bands - cubes
Movies
Looping through a cube ofQ2233+131,Sub-DLA @ z =3.15
Candidate DLA galaxies
Results: high-z DLA survey14 DLAs (+ 8 sub-DLAs) towards 9 QSOs
8 good candidates found – but only detected at the 3-
4 levels
Line flux in the range 3-10*10-17erg cm-2 s-1
Impact parameters from 1 - 4” (10 - 40 kpc)
DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs
Red symbols from compilation inMoeller et al. 2002
DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRsExponential fit
Scale length
kpc
kpc
)/exp(0 hrNN
+low-z data from Chen et al. 2005
DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs
Aver a
ge p
redic
t ed
im
pac t
par a
met e
r s f
r om
sim
ula
tions
M102
dr exp(-r/5) 102 M
9
21.7
r
This mass is in neutral gas; M(H I) (MW has 3*109 M )
Does this imply that DLA galaxies are L* galaxies? No. This is neutral gas mass only. MW mass ~1011 M (in stars) Numerical simulations by Nagamine et al. 2004 suggest M*/Mgas=3 at z=3
M(DLA gal) = 1010 M ~10% M(MW)
DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs
4.12 ]yr/kpc/[M sfr)( NSchmidt-Kennicutt law:
DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs
DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs
Luminosity selected galaxiesLilly et al. 1995, Steidel et al. 1999
DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs
Com
ovin
g
SFR
DLAs: Wolfe et al. 2005, Storrie-Lombardi et al. 2000, Peroux et al 2003, Prochaska et al 2005
Dust obscuration bias?
Summary
1. IFS able to identify faint emission lines
independent confirmation is needed
Ly properties consistent with known DLA galaxies
2. Impact parameters indicate large disks
large impact parameters at high and low-z
3. Disks are massive, but not necessarily luminous
4. Average SFR consistent with a Schmidt-Kennicutt law
assuming radial sizes of 10 kpc
5. DLAs do not dominate the comoving SFR
missing very high N(HI) DLAs in surveys ?
6. DLA metallicities biased by gradients?