Published on August 29, 2007
The connection between galaxies and quasar absorption lines: The connection between galaxies and quasar absorption lines Lise Christensen Quasar absorption lines: Quasar absorption lines DLA LLS Lya forest Metal lines Types of systems: Types of systems Charlton, 2000 Lya forest : N(H I) andlt; 1017 cm-2 LLS : 1017 andlt; N(H I) andlt; 2*1020 cm-2 DLA : N(H I) andgt; 2*1020 cm-2 Column density distribution: Column density distribution Petitjean et al. 1993 b 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: DLA evolution with z ? DLA stars DLAs are reservoirs for galaxy formation? Mass in stars (SDSS) Rao et al. 2005 Prochaska et al. 2005 Zwaan et al. 2005 21 cm observations Neutral gas density Slide6: Constant density ? SDSS data at zandgt; 2.2 Prochaska et al 2005: Statistical significant decrease in the line density l (z) is constant at zandlt;2.2 n(z) is constant Then A(z) must decrease Low-z data from Rao et al. 2005 Zwaan et al. 2005 Metal lines- from high resolution observations: Metal lines- from high resolution observations DLA metallicities: DLA metallicities Prochaska et al. 2003 What we know about DLAs:: 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: 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 surveys Look for emission lines from the galaxies hosting DLAs SFRs, Impact parameters, and sizes Main parts: Low redshift: Search for optical emission lines High redshift (z andgt; 2): search for Lyman-a emission The PMAS instrument : 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 Method: Method a d l Slide14: 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 WFPC2 archive image (Steidel et al 1997) Slide15: z=0.8908 R=23.5 z =0.931 R=24.5 But where is the z=0.656 DLA galaxy? [O II] at z=0.656 Abundances: Abundances PHL 1226 – subDLA at z=0.16 projected distance: 18 kpc (Bergeron et al. 1988) Christensen et al. 2005 Abundances: Abundances Figure from Pettini et al, 2004 G4: Christensen et al. 2005 DLA metallicities could be biased by gradient compare metallicities from emission and absorption DLAs at high redshifts (z>2): DLAs at high redshifts (zandgt;2) andgt;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 – long slits Visualisation – narrow bands - cubes: Visualisation – narrow bands - cubes l l Movies: Movies Looping through a cube of Q2233+131, Sub-DLA @ z =3.15 Candidate DLA galaxies: Candidate DLA galaxies Results: high-z DLA survey 14 DLAs (+ 8 sub-DLAs) towards 9 QSOs 8 good candidates found – but only detected at the 3-4s levels Line flux in the range 3-10*10-17erg cm-2 s-1 Impact parameters from 1 - 4' (10 - 40 kpc) Slide23: DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs Red symbols from compilation in Moeller et al. 2002 Slide24: DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs Exponential fit Scale length 30+/-16 kpc 5+/-2 kpc Slide25: +low-z data from Chen et al. 2005 DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs Average predicted impact parameters from simulations Slide26: 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 Slide27: Schmidt-Kennicutt law: DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs Slide28: DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs Luminosity selected galaxies Lilly et al. 1995, Steidel et al. 1999 Slide29: DLA galaxy; Line fluxes ; Impact parameters ; masses ; SFRs Comoving SFR DLAs: Wolfe et al. 2005, Storrie-Lombardi et al. 2000, Peroux et al 2003, Prochaska et al 2005 Dust obscuration bias? Summary : Summary IFS able to identify faint emission lines independent confirmation is needed Lya properties consistent with known DLA galaxies Impact parameters indicate large disks large impact parameters at high and low-z Disks are massive, but not necessarily luminous Average SFR consistent with a Schmidt-Kennicutt law assuming radial sizes of 10 kpc DLAs do not dominate the comoving SFR missing very high N(HI) DLAs in surveys ? 6. DLA metallicities biased by gradients?