Why do we need a vlst for studying qso absorption lines
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Why do we need a VLST for studying QSO absorption lines?. So that we can go deeper…. Brilliant!. A Genius!!. sublime…. The Critics agree…. QSO absorption lines and a VLST. My top-three topics for QAL studies in the UV: {detailed probing of the `cosmic web’ (Ly a , weak metal lines)} 

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Brilliant!

A Genius!!

sublime….

The Critics agree….


Qso absorption lines and a vlst
QSO absorption lines and a VLST

My top-three topics for QAL studies in the UV:

{detailed probing of the `cosmic web’ (Lya, weak metal lines)} 

metallicity of nearby galaxies

QSO absorption lines from QSOs (briefly)


What about metallicity
What about metallicity?

  • Measurements from QSO absorption lines show little evolution from z=4 to ~1

  • The lack of evolution appears to be largely independent of column density

    • from Lya-forest clouds to Damped Lya systems (DLAs)


What about metallicity1

13.5-5.8 Gyr

5.8 – 1.2 Gyr

Pettini (2003)

What about metallicity?

Kinda surprising…. expect `gas’ in the universe to be getting more enriched with time as galaxies evolve and pollute

  • DLAs in particular don’t approach solar at z=0


Let’s measure metallicities from nearby galaxies…

  • Advantages of looking at nearby galaxies:

  • determine wide range of galaxy properties (21cm, X-ray, etc.)

  • select low luminosity galaxies that are hard to see at higher-z

  • check for fainter interlopers close to any selected galaxy

  • easier to examine the galaxy’s environment (isolated, group, cluster)


NGC 4319, v=1405 km s-1

QSO absorption lines from nearby galaxies

Mrk 205, z=0.071


Time for one example to show what can be done and how far we ve got
Time for one example…… to show what can be done and how far we’ve got

Used HST + STIS to measure abundances towards

HS1543+5921 / SBS1543+593

With:

Ed Jenkins,

Todd Tripp,

Max Pettini


10

DSS image

SBS1543+593

HS 1543+5921

z=0.807


QSO

star

HII region,

z=0.009

(2700 km s-1)

APO 3.5m, R, 15 min

Reimers

& Hagen 98


QSO

star

HST STIS (clear), 800s


Spectroscopy
Spectroscopy

F(1200) = 2.6x10-15 pretty hard even with first-order gratings; fortunately CVZ object (15 orbits)

[S/H] = -0.4

Higher than

expected?


HS1543+5921

PG1543+489

Pettini (2003)

Compare Zs with DLA samples



What could we do with a vlst
What could we do with a VLST? spectral resolution with HST:

  • There are plenty of QSO-galaxy pairs in the sky! Just too faint!

  • Go deeper, the number of interesting pairs becomes substantial


STIS echelle spectral resolution with HST:


What could we do with a vlst1
What could we do with a VLST? spectral resolution with HST:

  • There are plenty of QSO-galaxy pairs in the sky! Just too faint!

  • Go deeper, the number of interesting pairs becomes substantial

  • Already know some QSO intercept large N(H I) from 21cm maps [knowing HI a priori helps choose a target to measure Z]

  • Four examples, just to show what we’re missing out on….

    • VLA maps from Womble (1993)

    • optical images from DSS


Gal: IC1746 spectral resolution with HST:

cz = 5201 km/s

QSO: 0151+045

sep = 10 kpc

V=14.8?

F(1220)=3e-15

==30 STIS orbits

Nice edge-on galaxy probe outer disk


N(H I) ~ 7-13 e19 cm/2 spectral resolution with HST:

CaII: 


Gal: NGC3184 spectral resolution with HST:

cz = 592 km/s

QSO: 1015+416

sep = 11 kpc

V=17.7 – 19.1?

F(1220)=?

chance to probe edge of huge HI envelope…

…compare to metallicties from HII regions…


N(H I) ~ 4e19 cm/2 spectral resolution with HST:

CaII: 


Gal: NGC470 spectral resolution with HST:

cz = 2374 km/s

QSO: Q0117+031

sep = 10 kpc

V=18.2

F(1220)=?

NGC 474

19.9


N(H I) ~ 6-10 e20 cm/2 spectral resolution with HST:

CaII: 


Gal: NGC3079 spectral resolution with HST:

cz = 1125 km/s

QSO: Q0957+558

sep = 8 kpc

V=17.4

F(1220)=1e-15


2.5 hrs, F658N, WFPC2 spectral resolution with HST:

Great way to study outflows!


N(H I) ~ 3 e20 cm/2 spectral resolution with HST:

CaII: 


Or multiple qsos
…or multiple QSOs! spectral resolution with HST:

NGC 3628

(cz=843 km/s)

QSOs have ‘O’ mags between 18.7 and 20.7

4 X-ray sources

near M65

Arp et al 2002


…or multiple multiple QSOs! spectral resolution with HST:

(narrow metal lines

instead of DLAs)


Summary
Summary spectral resolution with HST:

  • There are plenty of QSO-galaxy pairs known:

    • though number with 21cm maps and/or CaII/NaI observations is smaller

    • more behind galaxy disks to appear with GALEX presumably

    • … and using SDSS photo-z techniques

  • Need UV telescope that can:

    • reach 10 km/s resolution down to 20 mag

      • factor of 250 in flux over STIS G140M echelle

    • large wavelength range to cover many lines

      • important for ionization corrections

      • …. and for studying relative abundunace patterns which can be used to infer history of metal production

    • how about…. a LiF coated mirror and do < 1100A as well? i.e. HST+FUSE

  • Payoff:

    • detailed inventory of galaxy metallicities in the local universe

    • for individual galaxies:

      • ability to compare ISM abundances with values from HII regions

      • variations of metallicities as a function of radius if multiple sightlines available

      • kinematics and ionization structure of gas in the outer regions of galaxies

    • probes of the interface between a galaxy and the IGM


Qso absorption lines from qsos
QSO absorption lines from QSOs spectral resolution with HST:

Suppose instead of probing galaxies, could probe QSOs instead.

  • QSOs are ejecting large amounts of metal-enriched gas into the IGM  might expect:

    • metallicity of the gas around a QSO to be high

    • ionization of the gas to be high

    • absorption to be complex from outflows mixing with the IGM

  • By observing many QSO-QSO pairs, should be able to track the enrichment of the IGM with radius

  • Compare absorption from a f/g QSO with associated absorption (zabs ~ zem) in the QSO’s spectrum

    • learn more about associated systems, compare structure, ionization, and metallicity variations over small scales.


Available qso qso pairs
Available QSO-QSO pairs spectral resolution with HST:

  • SDSS provides a large # of QSO pair candidates with the b/g QSO < 20th

  • Often require follow-up spectra of one of the pairs from the ground

    • both from collaborators: Joe Hannawi, Gordon Richards and Michael Strauss


J0836 4841

4.1”, spectral resolution with HST:

19 h-1 kpc

J0836+4841

z=0.66

z=1.71


J0836 48411
J0836+4841 spectral resolution with HST:

  • zabs = zQSO = 0.66 in SDSS spec

  • Likely to be a DLA!

  • Probably host galaxy

  • Perhaps high metallicity?


J2313 1445

3e-16 spectral resolution with HST:

J2313+1445

zbg = 1.52

zfg = 0.79

sep = 6.4” or

32 h-1 kpc

  • - outflowing gas from jet

  • companion fuelling QSO

  • unrelated galaxy in

  • QSO cluster


A future project
A future project spectral resolution with HST:

  • QSOs appear to cause the same kinds of MgII systems that field galaxies cause

  • Will need a VLST to do the kinds of spectroscopy of interest….


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