The Host Galaxies of Extremely Strong DLAs - … · The Host Galaxies of Extremely Strong DLAs Pasquier Noterdaeme Institut d'Astrophysique de Paris Galaxies in absorption - Marseille,

The Host Galaxies of Extremely Strong DLAs

Pasquier Noterdaeme Institut d'Astrophysique de Paris

Galaxies in absorption - Marseille, Dec. 2-4, 2013


P. Noterdaeme - The host galaxies of extremely strong DLAs

Outline

High-z galaxies in emission

Host galaxies of QSO absorbers?

DLA galaxies

Extremely strong DLAs - distribution - metals - link with GRB-DLAs? - reddening - host galaxy

Conclusions



→ Lyman-Break Galaxies (Steidel+96)

→ Lyman-α emitters (LAEs) - Narrow-band filters around Lyα line (e.g. Ouchi+08) - Long-slit spectroscopy (e.g. Rauch+08, Cassata+11) - IFU (e.g. Adams+11)

→ IR/mm (e.g. Daddi+09)

→ Absorption

Stellar continuum: bright, massive galaxies (Shapley+03)

Faint in broad-band imaging: low mass systems on average, little dust (Gawiser+07)

Probes the overall luminosity function (e.g. Cen+12)

High SFR, dust

High-z Galaxies (z>2)

Absorption is great but...



Pune rabbit



Host galaxies of absorption systems?

→ Most absorbing galaxies are expected to be intrinsically faint

→ Quasar is bright

→ We don't know where to look (how far is the galaxy from the l.o.s?)

→ Hard to associate galaxy with absorber

Need improved observational strategies/efficient instrumentation

low-z: Absorbers-galaxies (e.g. Bergeron & Boissé 1991, Le Brun+97, Turnshek+01, Rao+03, etc.) Galaxies-absorbers (e.g. Noterdaeme+10, York+12, Straka+13). Lorrie's talk

high-z:

Deep, multi-wavelength, long-slit spectroscopy (VLT/Xshooter): get all at once. (e.g. Fynbo+) Integral field spectroscopy: quite large spatial coverage (Céline's talk).

λ → Link gas and galaxy (e.g. Nicolas).

DLA galaxies

Neutral gas cross-section larger than star-light emitting regions → DLA hosts can be found relatively far from the QSO line of sight

Kashikawa+13

→ Wish to go at small impact parameter to probe ISM that directly feeds star-formation → Select very high N(HI). rare!

21cm local Universe (Zwaan+05) high-z (simulations: Pontzen+08)

Fynbo+10

Christensen+

Bouché+12

Fynbo+11

Krogager+12

Bunker+

Moller+93

Moller+04 Noterdaeme+12a Fynbo+13


P. Noterdaeme - The host galaxies of extremely strong DLAs Also at z<1: Rao+11

Extremely strong DLAs: f(NHI)

→ small incidence compensated by huge number of QSO lines of sight → ~120 000 QSO spectra in BOSS DR10 (Paris+12,+13) → automatic search for DLAs (Noterdaeme+09,+12, *)

Petitjean+93

Noterdaeme+14

→ Using DR11: ~ 100 DLAs with N(HI) = [½ – 2] x 1022 cm-2


P. Noterdaeme - The host galaxies of extremely strong DLAs * SDSS DLAs: www.iap.fr/users/noterdae/DLA/DLA.html

Extremely strong DLAs: metals

Stack EWs

Δv

N, b



Extremely strong DLAs: metals

→ Average metallicity ~ 1/20th solar

→ Depletion ~ SMC / MW-Halo

→ Dv ~ 120 km/s

Molecules? (see also Balashev+13)

Ledoux+06



Extremely strong DLAs: GRBs

Neutral hydrogen

Metals

Differences explained by: - excitation by source? - orientation? - sample size?



Extremely strong DLAs: QSO colours

→ Ly-α absorption → continuum: some dust?



Extremely strong DLAs: dust

→ SMC type in most cases (~ most absorbers, York+06, but molecular-rich, cold gas, Noterdaeme+09b, Srianand+08b, Ledoux+, in prep.) → E(B-V) ~ 0.02-0.03 → AV/NHI ~ 10-23 mag cm-2 (~ overall DLA pop, Vladilo+08) → extinction increases with metal EW (~ Khare+12)



Extremely strong DLAs: Ly-α emission

→ ~ 0.6 x 1042 erg/s

→ idea: light from DLA-galaxy emitted within the fibre, at wavelength where QSO is absorbed Rahmani+10 → observational advantage of ESDLAs: very wide dark core



weighted


Distribution

→ mean value (stack / individual) matches that of LAEs with L>0.1x1042 erg s-1

→ distributions match

→ expect ~1/100 with L>5x1042 erg s-1

Noterdaeme+12a, Kulkarni+12




Distribution





BOSS




Distribution





BOSS



MagE


Distribution





BOSS

Xshooter



MagE


Kinematics



Extremely strong DLAs / LAEs: incidence

Incidence of ESDLAs:

Incidence of L>1041 erg/s LAEs:

→ rgas ~ 2.5 kpc i.e. well with the fibre (1” or 8 kpc)



ESDLAs (from Lyα):

Extremely strong DLAs: SFR

Star-formation rate

(Kennicutt+98)

Kennicutt-Schmidt law: relates surface density and SFR

fesc from 0.05 global galaxy pop. (Hayes+10) to 0.30 in LAEs (e.g. Blanc+11, Nakajima+12). ESDLA observed with Xshooter: fesc~0.20 (Noterdaeme+12a). → SFR ~ 2-3 Msun yr-1

→ rgal ~ 2.5 kpc



Extremely strong DLAs: Ly-α escape

Dependence on dust?



Summary/Conclusions

Recall on DLA history: “threshold (log NHI=20.3) ensures neutrality and found similar to local disks. But 5 times larger cross-section at high-z → Early view of √5 times larger galaxies?”

At log NHI~20.3, we don't know where we are.

Locally: 21-cm maps shows that high NHI (~1022 cm-2) probe small b (<5kpc).

High-z: Simulations do show the same (Altay+13, Rahmati+13, Alireza's talk) Observations: relation b vs NHI (for DLAs: Krogager+12)

ESDLAs: Now possible thanks to SDSS-III

1. Absorption properties similar to that of the overall DLA population, integrated properties more similar to that of GRB-DLAs, with some differences that could be explained by geometry (NHI) and excitation (metals).

2. Ly-α in emission. - May be surprising as Ly-α photons need to scatter out the line centre → importance of clumpiness, geometry, viewing angle (Kulas+12, Noterdaeme+12a, Lausen+13, Zheng & Wallace+13). - Luminosity distribution, kinematics and incidence match that of LAEs with L>1041 erg/s from emission- selected surveys. → Similar to the population found by Rauch+08. SFRs ~ 2-3 Msun yr-1

High-metallicity DLAs (Fynbo+): galaxies higher SFRs but larger b. Outskirts of LBGs?

Starting to get a consistent picture of DLAs vs emission-selected galaxy population. Next step: deep, multi-wavelength spectroscopic follow-up!

Thank you!



DLA galaxies

Kashikawa+13

21cm local Universe (Zwaan+05) high-z (simulations: Pontzen+08)

Fynbo+10

Christensen+

Bouché+12

Fynbo+11

Krogager+12

Bunker+

Moller+93

Moller+04 Noterdaeme+12a Fynbo+13



Documents

The Host Galaxies of Extremely Strong DLAs - … · The Host Galaxies of Extremely Strong DLAs Pasquier Noterdaeme Institut d'Astrophysique de Paris Galaxies in absorption - Marseille,