TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a...
-
Upload
brianne-oconnor -
Category
Documents
-
view
214 -
download
0
Transcript of TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a...
![Page 1: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/1.jpg)
Twenty-five Years of QSO Absorption Studies with HST: A Windfall of Missing Baryons, Gastrophysical Diagnostics, and Puzzles
Todd M. Tripp, University of Massachusetts
![Page 2: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/2.jpg)
From Day 1, HST has produced spectacular and entirely unique results via point-source spectroscopy.
This talk: a highly biased and incomplete discussion of HST QSO absorber studies − historical results, puzzles, and potential .
![Page 3: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/3.jpg)
HST does QSO Absorption Lines: A Windfall of Missing Baryons• Jan. 14-16, 1991, Feb. 23, 1991: UV spectroscopy of
3C273 with HST (Morris et al. 1991; Bahcall et al. 1991)
GHRS data (Morris et al. 1991)
• Extrapolation from high redshift predicted: 0.9 – 2.3 Lyα lines (EQW > 25 mÅ); Morris et al. detected 14!
![Page 4: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/4.jpg)
The COS Absorption Survey of Baryon Harbors (CASBaH)
1. Probing warm-hot intergalactic gas at 0.5 < z < 1.3 with a blind Survey for O VI, NeVIII, Mg X, and Si XII Absorption Systems (and lots of other goodies)
2. CASBaH-x: Near-UV extension to completely cover Lyα (and other key species, e.g., O VI) from z = 0 to z(QSO)
COS vitals High spectral resolution: 15 km/s FWHM FUV+NUV coverage: observed λ = 1150 – 3000 Å Sensitivity: 20x previous HST spectrographs
![Page 5: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/5.jpg)
An Untapped Discovery Space: The Extreme UV
The high density of lines in the EUV provides anextraordinary array of gas diagnostics.
See seminal papers of Verner, Tytler, & Barthel (1994a,b)
Fan et al.
![Page 6: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/6.jpg)
Diagnostic Power of the Extreme UVThe high densityof lines in the FUVand EUV provides an extraordinaryarray of gasdiagnostics.
![Page 7: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/7.jpg)
Data Quality (CASBaH Program)
![Page 8: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/8.jpg)
Data Quality (CASBaH Program)
This sight line reveals:• COS FUV spectrum only: 803 absorption lines• FUV+NUV data: 1078 absorption lines, and we don’t have all of the NUV data yet!• Species detected in this single sight line:
– H I Lyα up to Lyτ (i.e., H19)– He I– C II, C III, C IV– N II, N III, N IV, N V– O II, O III, O IV, O V, O VI– Ne V, Ne VIII– Mg II– Al II, Al III– Si II, Si III, Si IV– Fe II, Fe III
![Page 9: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/9.jpg)
Data Quality (CASBaH Program)
Publications so far:
• Our group: Ribaudo et al. 2011; Tripp et al. 2011; Lehner et al. 2012,2013; Meiring et al. 2013; Fox et al. 2013; Burchett et al. 2013; Johnson et al. 2014
• Archival researchers: Shull et al. 2012; Muzahid et al. 2013; Stevans et al. 2014; Hussain et al. 2015; Johnson et al. 2015
![Page 10: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/10.jpg)
HST does QSO Absorption Lines: A Windfall of Missing Baryons
• Weymann et al. (1998): number of Lyα lines per unit redshift as a function of redshift
Log (1+z)
Log
(dN/dz)
(i.e.
, num
ber p
er u
nit r
edsh
ift)
987 Lyα lines from HST
![Page 11: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/11.jpg)
HST does QSO Absorption Lines: A Windfall of Missing Baryons
• Weymann et al. (1998): number of Lyα lines per unit redshift as a function of redshift
Log (1+z)
Log
(dN/dz)
(i.e.
, num
ber p
er u
nit r
edsh
ift)
High redshiftdecline drivenby expansion ofthe universe
At low z, decline is mitigated by disappearance of QSOs and decline of UV bkg.
![Page 12: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/12.jpg)
A Sea Change in Theoretical Astrophysics: The Rise of the Cosmological Simulations
Mpc
Mpc
BARYONS DARK MATTER GAS TEMP.
![Page 13: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/13.jpg)
• At the present epoch, stars account for a tiny fraction of the baryons, ≤ 10% (Persic & Salucci 1992; Gnedin & Ostriker 1992, Fukugita et al. 1998, Bell et al. 2003)
Cosmological simulation(Oppenheimer et al.)
HST does QSO Absorption Lines: A Windfall of Missing Baryons
![Page 14: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/14.jpg)
HST does QSO Absorption Lines: A Windfall of Missing Baryons
• Hydrodynamic cosmological simulations predict that 30 - 50% of the baryons are in low-density, shock-heated gas at 105 - 107 K at z = 0
• WHIM = robust prediction from many studies (e.g., Cen & Ostriker 1999; Davé et al. 2001; Cen & Ostriker 2006; Cen & Chisara et al. 2011; Smith et al. 2011)
Cen & Chisara (2011)
Lyα forest
STARS
“Warm-hot” intergalacticMedium (WHIM)
![Page 15: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/15.jpg)
• OVI: a most excellent WHIM probe
HST does QSO Absorption Lines: A Windfall of Missing Baryons
Non-eq., cooling modelsCollisional eq.
![Page 16: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/16.jpg)
• OVI: a most excellent WHIM probe
HST does QSO Absorption Lines: A Windfall of Missing Baryons
Non-eq., cooling modelsCollisional eq.
Tripp et al. (1998, 2000a, 2000b, 2001, 2003, 2008, 2012)
![Page 17: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/17.jpg)
• OVI: a most excellent WHIM probe
HST does QSO Absorption Lines: A Windfall of Missing Baryons
Non-eq., cooling modelsCollisional eq.
Tripp et al. (1998, 2000a, 2000b, 2001, 2003, 2008, 2012)
![Page 18: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/18.jpg)
HST does QSO Absorption Lines: A Windfall of Missing Baryons
Tripp et al. 2008
Danforth & Shull 2005,2008; Shull et al. 2006; Stocke et al. 2006; Wakker & Savage2009; Prochaska et al. 2004,2006,2011a,b; Thom & Chen 2008a,b; Howk etal. 2009; Lehner et al. 2009; Mulchaey & Chen 2009; Chen & Mulchaey 2009
![Page 19: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/19.jpg)
HST does QSO Absorption Lines: Wait, wut?
Tripp et al. 2008
Aligned OVI absorbersare photoionized?
![Page 20: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/20.jpg)
![Page 21: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/21.jpg)
![Page 22: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/22.jpg)
![Page 23: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/23.jpg)
![Page 24: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/24.jpg)
![Page 25: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/25.jpg)
![Page 26: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/26.jpg)
![Page 27: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/27.jpg)
Ion Xi-1 (eV) Xi (eV)
C III 24.4 47.9
O III 35.1 54.9
O IV 54.9 77.4
S IV 34.9 47.2
S V 47.2 72.6
Ne VIII 207.3 239.1
Ionization Potentials
![Page 28: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/28.jpg)
![Page 29: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/29.jpg)
![Page 30: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/30.jpg)
![Page 31: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/31.jpg)
![Page 32: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/32.jpg)
![Page 33: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/33.jpg)
![Page 34: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/34.jpg)
Tripp et al. (2011)
![Page 35: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/35.jpg)
Cold gas:photoionized
When CLOUDY fits the observed S III/S IV, it slightly underpredictsthe S V and vastly underpredictsthe Ne VIII (off by many orders ofmagnitude). The Ne VIII arises in hot gas.
Hot gas: hot
![Page 36: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/36.jpg)
![Page 37: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/37.jpg)
HST does QSO Absorption Lines: Testing Cosmological Simulations
H I Column Density (cm-2)
b va
lue
(km
s-1
)
High resolution (7 km s-1)STIS observations
Simulation measurements(from mock STIS data)
![Page 38: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/38.jpg)
HST does QSO Absorption Lines: Testing Cosmological Simulations
H I Column Density (cm-2)
b va
lue
(km
s-1
)
High resolution (7 km s-1)STIS observations
Simulation measurements(from mock STIS data)
![Page 39: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/39.jpg)
HST does QSO Absorption Lines: Testing Cosmological Simulations
Colu
mn
Den
sity
D
istrib
ution
log [H I Column Density (cm-2)]
![Page 40: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/40.jpg)
HST does QSO Absorption Lines: Testing Cosmological Simulations
Colu
mn
Den
sity
D
istrib
ution
log [H I Column Density (cm-2)]
Kollmeier et al. (2014)
![Page 41: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/41.jpg)
HST does QSO Absorption Lines: Testing Cosmological Simulations
Colu
mn
Den
sity
D
istrib
ution
log [H I Column Density (cm-2)]
Kollmeier et al. (2014)
Many (most?) of these H I absorbers are NOT
intergalactic; this is gas in the gaseous halos
and circumgalatic media of galaxies.
![Page 42: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/42.jpg)
Result 1: Star-Forming Galaxies Have Huge, Metal-Enriched, Highly Ionized Halos
Tumlinson et al. 2011
Red sequence
BlueCloud
Grayscale: galaxy color-stellar mass data from SDSS+GALEX(Schiminovich et al. 2007)
![Page 43: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/43.jpg)
Result 1: Star-Forming Galaxies Have Huge, Metal-Enriched, Highly Ionized Halos• Are these huge halos substantial mass reservoirs?• A back-of-the envelope calculation:
• To estimate the total mass, we must account for the gas metallicity:
With fhit = 0.8, R = 150 kpc, and <NOVI> = 1014.5 cm-2,
MO ≈ 107 M
With fOVI = 0.2 and solarmetallicity,
Mgas ≈ 109 M
![Page 44: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/44.jpg)
Result 1: However, there are some caveats• Some of the
absorbers show indications of very high metallicities
• OVI system, z=0.70152,
• log N(OVI)=14.42
Meiring, Tripp et al.(2013, in press,arXiv 1209.0939)
-200 +200Absorber Velocity (km/s)
![Page 45: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/45.jpg)
• z=0.70152• Log N(HI) < 13.6
• Z > 1.6 Z
• log N(OVI)=14.42
• Z=0.72152• Log N(HI) < 13.7
• Z > 1.0 Z
• Log N(OVI) = 13.86
Result 1: However, there are some caveats
Meiring, Tripp et al.(2013, in press,arXiv 1209.0939) -200 +200Absorber Velocity (km/s)
![Page 46: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/46.jpg)
• z=0.70152• Log N(HI) < 13.6
• Z > 1.6 Z
• log N(OVI)=14.42
• Z=0.72152• Log N(HI) < 13.7
• Z > 1.0 Z
• Log N(OVI) = 13.86
Result 1: However, there are some caveats
Meiring, Tripp et al.(2013, in press,arXiv 1209.0939) -200 +200Absorber Velocity (km/s)
• Impact parameter = 217 kpc• SFR = 6.4 M yr-1
• [O/H] = +0.22
![Page 47: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/47.jpg)
QSO-Galaxy Connections:Large-Scale Environment is important!
• Survey of very low-z absorbers with 100% completeness for L > 0.01 L*
No. Galaxies within 1500 kpc
log
[C IV
col
umn
dens
ity (c
m-2
)]
![Page 48: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/48.jpg)
C IV DETECTIONS
C IV NON-DETECTIONS
![Page 49: TODAY, 9PM PBS Program synopsis: “But Hubble's early days nearly doomed it to failure: a one-millimeter engineering blunder had turned the billion-dollar.](https://reader033.fdocuments.in/reader033/viewer/2022051517/5697bf811a28abf838c851df/html5/thumbnails/49.jpg)
Some take-aways• High-resolution UV
spectroscopy can yield huge samples of absorbers rich in information; these data will remain uniquely valuable for years/decades
• OVI/NeVIII absorbers are not photoionized and arise in complex, multi-multi phase entities; physics here is poorly understood
• These absorbers sometimes exhibit extremely high metallicities; again, wut?
• Cosmological simulations have difficulty with even the most simple case of intergalactic (?) Lyα clouds