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Galaxies and Other Gaseous Structures Through Quasar Absorption Lines. Jane Charlton Penn State.

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Galaxies and other gaseous structures through quasar absorption lines

Galaxies and Other GaseousStructures Through QuasarAbsorption Lines

Jane Charlton

Penn State

Collaborators: Chris Churchill (NMSU), Jie Ding (NYU), Anand Naryanan (PSU), Nikola Milni (PSU), Jane Rigby (UofA), Stephanie Zonak (Maryland), Nick Bond (Princeton), Rick Mellon (Virginia), Rajib Ganguly (STScI), Ryan Lynch (PSU), Toru Misawa (PSU)


Unbiased probes of almost all gas
Unbiased Probes of Almost All Gas

  • Giant spiral galaxies (halos, disks, cold clouds, debris).

  • Elliptical and S0 galaxies.

  • Dwarf galaxies.

  • Intragroup medium.

  • Intergalactic filaments and sheets.

    All have some absorption cross section.


A common theme
A Common Theme

Where is the boundary between what is left behind from galaxy formation and what is ejected from galaxies?



Outline classes of mgii absorbers1
Outline: Classes of MgII Absorbers

  • Strong >0.3A

  • Super Strong >1.5A


Outline classes of mgii absorbers2
Outline: Classes of MgII Absorbers

  • Strong >0.3A

  • Super Strong >1.5A

  • DLAs N(HI)>1020.3


Outline classes of mgii absorbers3
Outline: Classes of MgII Absorbers

  • Strong >0.3A

  • Super Strong >1.5A

  • DLAs N(HI)>1020.3

  • Weak <0.3A


Strong mgii absorbers arise near giant galaxies
Strong MgII Absorbers AriseNear Giant Galaxies

  • Within 38h-1 kpc of a >0.08 LK* galaxy.

  • Rarely found outside this “boundary”.

  • Most produce Lyman limit breaks.

Steidel 1996



Kinematic models of strong mg ii absorbers halos and disks
Kinematic Models of Strong Mg II Absorbers: Halos and Disks

  • Halos - cloud components spread out in velocity

  • Disks - cloud components clustered within 10’s of km/s


Kinematic models of strong mg ii absorbers halos and disks1
Kinematic Models of Strong Mg II Absorbers: Halos and Disks

Observed profiles

Pure disk model

Charlton and Churchill 1998



Kinematic models of strong mg ii absorbers halos and disks3
Kinematic Models of Strong Mg II Absorbers: Halos and Disks

Observed profiles

75% disk 25% halo model


Direct information about relationship to galaxies
Direct Information About Relationship to Galaxies

Rotation curve shows MgII profile at velocity consistent with extended disk.

Some halo contribution needed as well.

Steidel et al. 2001


Absorption signatures of coronae
Absorption Signatures of Coronae?

Some strong MgII systems have strong, broad CIV profiles that encompass the dominant MgII absorption in velocity.

The CIV cannot arise in the same phase of gas as the MgII, but is rather in a lower density, “diffuse” region.

Ding et al. 2003


Absorption signatures of coronae1
Absorption Signatures of Coronae?

Churchill

et al. 2001

Systems with satellite clouds in MgII have stronger CIV


Civ deficient systems
CIV Deficient Systems

  • Systems below the CIV absorption strength vs. MgII kinematics correlation line, members of the “CIV deficient class”, tend to have red galaxy hosts.

  • However, some are early type spirals rather than ellipticals.

  • Lack of CIV absorption may signify weak or absent corona.


High velocity clouds
High Velocity Clouds

  • Satellite clouds in z~1 MgII absorbers are similar to HVCs seen around the Milky Way

  • The CIV absorption related to z=0 HVCs may be systematically weaker than at z=1,but beware of systematic effects!

NGC2155



A gallery of superwinds at z 1 5
A Gallery of Superwinds at z=1.5?

  • 4/4 of the strongest MgII absorbers have these distinctive kinematics

  • Subcomponents are apparent in the weaker FeII and MgI transitions

  • Separation between saturated MgII troughs 100-300 km/s

Bond et al. 2001


Multiphase superwinds and expected evolution
Multiphase Superwinds and Expected Evolution

  • Predict kinematic similarities between MgII and CIV, perhaps with velocity shifts from multiphase wind model (Martin et al., in prep).

  • The number of >1A MgII systems is seen to decrease with increasing z for z>2; but not for >1.5A systems (Prochter et al., submitted).


What are dlas
What Are DLAs?

  • About half of z<1 DLAs are associated with dwarf or low surface brightness galaxies.

  • Other than that, very few of the z<1 Lyman limit systems are associated with dwarfs or low surface brightness galaxies.

Why do dwarf and low surface brightness galaxies present a significant cross-section for damped Lyman-alpha absorption but not for N(HI) = 1017 - 1020 cm-2 absorption?


What are dlas1
What Are DLAs?

  • In some DLAs a phase is apparent in 21-cm that gives rise to a very narrow (< few km/s) profile.

  • Mg I is not consistent with arising in the same phase of gas as Mg II. Small parsec scale pockets (~1 km/s velocity spreads) are consistent with the Mg I. Consistent with detailed work by Wolfe et al. 2003

DLAs may be small, star forming pockets and their surroundings, located in a variety of environments.

In dwarfs and LSBGs the surrounding gas may escape such that sub-DLA Lyman limit systems are rare.

Lane et al. 2000


Multiple and single cloud weak mgii absorbers separate populations
Multiple and Single Cloud Weak MgII Absorbers: Separate Populations

  • Some weak MgII absorbers are likely to be an extension of the strong MgII absorber population.

  • However, there is an excess of single-cloud, weak MgII systems: separate population

Rigby et al. 2003


Two populations of multiple cloud weak mgii absorbers
Two Populations of Multiple Cloud Weak MgII Absorbers? Populations

Ding et al. 2004

Extensions of strong MgII absorber population and absorbers related to dwarf galaxies and their winds (Stocke et al. 2004).


Single cloud weak mgii absorbers
Single-Cloud Weak MgII Absorbers Populations

  • Comprise most of N(HI)>1015.5cm-2 forest

  • Not within ~50h-1kpc of a >0.1L* galaxy

  • MgII profile is unresolved at 6km/s.

  • Metallicity >0.1 solar and in some cases solar.

  • Size of MgII phase ~10pc

  • Density of MgII phase ~0.1 cm-3

  • CIV must arise in a separate, lower density phase, ~10-3 cm-3


Surprising implications
Surprising Implications Populations

  • Cover same area of sky as bright galaxies. If spherical that would imply a ratio of more than a million to one for the structures producing this absorption relative to L* galaxies. But geometry is unlikely to be spherical.

  • Single-cloud, weak MgII absorbers could arise in Population III star clusters or shell fragments of supernovae in dwarf galaxies.

  • They could be small metal-enriched pockets in the elusive, small-mass, dark matter halos predicted by cold dark matter scenarios.

Rigby et al. 2003


Evolution of single cloud weak mgii absorbers to z 0
Evolution of Single-cloud Weak MgII Absorbers to z=0 Populations

  • Survey of E140M spectra from STIS, using SiII1260 and CII1335 as tracers of weak, low ionization systems.

  • Finds dN/dz consistent with no evolution to z=0.

Narayanan et al. 2004


Expected evolution due to decline in extragalactic background radiation
Expected Evolution Due to Decline in Extragalactic Background Radiation

  • Increase in equivalent width of MgII from high density phase.

  • Significant increase in MgII from low density phase, easily detectable at z=0.


Expected evolution due to decline in extragalactic background radiation1
Expected Evolution Due to Decline in Extragalactic Background Radiation

  • Single-cloud weak MgII absorber at z=1 will become a multiple-cloud weak MgII absorber at z=0.

  • CIV significantly weaker at z=0.


Expected evolution due to decline in extragalactic background radiation2
Expected Evolution Due to Decline in Extragalactic Background Radiation

  • This absorber was not quite detected in a survey of <z>=0.9 absorbers. It would be a “CIV-only” system at that time.

  • At z=0 it would be easily detected, with multiple MgII components.



Evolution of single cloud weak mgii absorbers to z 01
Evolution of Single-cloud Weak MgII Absorbers to z=0 Background Radiation

  • Expect dN/dz~1 for evolved MgII phase of z=1 population.

  • But also expect dN/dz~5 for MgII from “CIV-only” clouds at z=1.

  • Conclude some structures are evolving away between z=1 and z=0

  • Related to decline in star formation rate?

Narayanan et al. 2004


Constraints on geometry of single cloud weak mgii absorbers
Constraints on Geometry of Single-Cloud Weak MgII Absorbers Background Radiation

  • Fewer “CIV-only” systems found than “low+high” systems.

  • Multiple CIV components in about half the “low+high” systems.

Milni et al. 2004


Constraints on geometry of single cloud weak mgii absorbers1
Constraints on Geometry of Single-Cloud Weak MgII Absorbers Background Radiation

  • CIV component centered on low ionization gas stronger than others.

  • “CIV-only” systems have N(CIV) similar to offset CIV in “low+high” systems.


Constraints on geometry of single cloud weak mgii absorbers2
Constraints on Geometry of Single-Cloud Weak MgII Absorbers Background Radiation

  • Cannot have single small MgII cloud within large CIV “halo” or would observe far too many “CIV-only” systems.

  • For thousands of spherical MgII clouds in large CIV “halos” the offset CIV components do not arise within overproducing “CIV-only” systems.

  • Flattened MgII clouds can give rise to large covering factor, small thickness, and not too many “CIV-only” systems.

  • Could these arise as collapsed, star-forming regions in the cosmic web, or from multiphase layers from supernova-related processes?


Possible geometric models for single cloud weak mgii absorbers
Possible Geometric Models for Single-Cloud Weak MgII Absorbers

  • Need many thousands of small, high density clouds within larger, low density halo - doesn’t seem plausible.

  • Need to find a way to produce offset CIV components.


Possible geometric models for single cloud weak mgii absorbers1
Possible Geometric Models for Single-Cloud Weak MgII Absorbers

  • Need many thousands of high density spheres inside larger, low density halo.

  • Additional low density spheres can produce offset CIV, but would also produce a large number of “CIV-only” systems.

  • Ruled out.


Constraints on geometry of single cloud weak mgii absorbers3
Constraints on Geometry of Single-Cloud Weak MgII Absorbers Absorbers

  • Flattened low ionization condensations inside filaments.

  • Surrounding network of filaments give rise to offset CIV.

  • Low ionization condensations can be transient but then there must be more of them.

  • Reasonable model.


What are civ absorption systems
What Are CIV Absorption Systems? Absorbers

  • CIV is found within 100kpc of L* galaxies and seldom outside that radius.

  • Statistically, weak MgII is found in a fair fraction of these.

  • Hypothesized related to infalling material/satellites.

Chen et al. 2001


What are civ absorption systems1
What Are CIV Absorption Systems? Absorbers

  • CIV is found within 100kpc of L* galaxies and seldom outside that radius.

  • Statistically, weak MgII is found in a fair fraction of these.

  • Hypothesized related to infalling material/satellites.

Chen et al. 2001


Summary and future work
Summary and Future Work Absorbers

  • Strong MgII absorbers arise from multiphase medium of many types of giant galaxies.

  • Superwinds could produce the very strongest MgII absorption.

  • DLAs are likely to be special little regions relating to star formation in a variety of environments.

  • Some multiple-cloud, weak MgII absorbers could be related to dwarf galaxies/winds.

  • Single-cloud weak MgII absorbers seem to be a significant population of self-enriching region in the intergalactic medium.

  • Plan to model >100 absorbers at z<1 and 100 absorbers at 1<z<2 to establish trends in the midst of large variety.


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