The connection between galaxies and quasar absorption lines

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


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)


4.12 ]yr/kpc/[M sfr)( NSchmidt-Kennicutt law:



Luminosity selected galaxiesLilly et al. 1995, Steidel et al. 1999


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?

Documents

The connection between galaxies and quasar absorption lines