High%20Resolution%20X-Ray/UV%20Spectroscopy%20of%20the%20Intergalactic%20Medium:%20Hunting%20and%20Modeling%20the%20Missing%20Baryons%20in%20the%20WHIM

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High Resolution X-Ray/UV Spectroscopy of the
Intergalactic MediumHunting and Modeling the
Missing Baryons in the WHIM
Fabrizio Nicastro (Harvard-Smithsonian Center for
Astrophysics)
Collaborators S. Mathur, M. Elvis, J. Drake, F.
Fiore, T. Fang. J. Bergeron, H. Marshall, Y.
Krongold, D. Weinberg, A. Fruscione The
XTE-ASM Team R. Remillard, A. Levine, H. Bradt,
E. Morgan
(Nicastro et al., 2005, Nature, 433, 495 Nicastro
et al., 2005, ApJ, in press Nicastro et al.,
2005, ASR, in press Williams et al., 2005, ApJ,
in press Nicastro et al., 2003, Nature, 421, 719)
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Overview

• Missing Baryons and the Warm-Hot Intergalactic
  Medium
• The Local Group WHIM (Nicastro et al., 2002, ApJ,
  573, 157 Nicastro et al., 2003, Nature, 421,
  729 Williams et al., 2005, ApJ, in press,
  astro-ph/0504558)
• The WHIM at z gt 0 First Measurement (Nicastro et
  al., 2005, Nature, 433, 495 Nicastro et al.,
  2005, ApJ, in press, astro-ph/0504187)
• Future Prospects

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What is the WHIM?
A mixture of primordial but progressively
enriched baryonic matter forming a very tenuous
(? 5-50) web of filaments connecting deep
dark-matter potential wells in the Universe, and
shock-heated to T 105-107 K during the
continuous process of structure formation
(Cen Ostriker, 1999, ApJ, 514, 1)
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The WHIM Filaments
350 h-1 Mpc
64 h-1 Mpc
NOVII 1015 cm-2 NOVIII 1015 cm-2 Z/Z?
0.05-0.3 T 105 - 107 K nb 10-6-10-5 cm-3
(Hellsten et al., 1998)
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The WHIM Filament in the Local Supercluster
Environment
0.5-2 keV Brightness in ph/s/cm2/sr
OVI column density in cm-2
OVIII column density in cm-2
OVII column density in cm-2
(Kravtsov, Klypin Hoffman, 2002)
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Why Should we Care? The Global Picture A Flat
Universe O? OM 1
WMAP Picture
(Science cover, 19 Dec. 2003)
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Concordance Cosmology
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Missing Baryons
(Nicastro et al., 2005, Nature, 433, 495)
of b
gt76 5.7 1.7 4.6 29 4.8 46 54
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Why?
(54 ? 9) of Baryons are missing!

• Verify Theory and Find Missing Baryons
• Ecology of the Universe (Metal Pollution)
• Absolute (e.g. trigger star formation near
  super-massive BH seeds) and Relative (e.g. Model
  for Sun structure vs recent revised O, N
  measurements) Metallicities.
• Galaxy Superwinds (SN) vs AGN winds
• Nucleosynthesis
• Cosmological parameters from density fluctuations
  of WHIM filaments (1-10 Mpc at z0-2)
• Pilot Tech and Feasibility Studies for Pop-3
  Stars and Re-ionizaton

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How to detect the WHIM
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Chandra and XMM-Newton Gratings

• Launched on July 1999 and December 1999 (when the
  existence of the WHIM was first predicted)
• gt 70 ? better than any previous X-ray
  spectrometer R1000 (MEG) and R400 (LEG/RGS)
• Small Effective Area 5 cm2 (MEG), 40 cm2 (LEG/RGS)

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WHIM is Faint

• NOVII lt 1016 cm-2 ? EW(OVII) lt 40 mÅ. Requires gt
  100 ct/res.el. In Chandra-LETG or XMM-RGS
• Brightest nearby Seyferts1-2 mCrab
• Exceptionally high quality X-ray spectra of
  background AGN are needed, implying either very
  large exposures or bright states, or both.

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Our Strategy
(Chandra Cycles 4-5-6 and Newton-XMM Cycles 2-3)

• Blazars flare to gt 10 times normal
• Trigger ToO (from Rossi-XTE ASM)
• Outbursts last 1-2 weeks

• 1st TOO on 2002 October 27 100 ks ACIS-LETG
• 2nd TOO on 2003 June 6 100 ks HRC-LETG
• Spectacular Results!

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WHIM and ISM Absorption
(Nicastro et al., 2005, Nature, 433,495 Nicastro
et al., 2005, ApJ, in press Williams et al.,
2005, ApJ, in press)
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The z0 AbsorberHot Galactic Corona or Local
Group WHIM?
1
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Z0 Absorption
Chandra
(Williams et al., 2005, ApJ, in press)
FUSE
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Doppler ParameterOVII Gas ?LV-OVI Gas
(Williams et al., 2005, ApJ, submitted)
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Ionization Balance
For 2 ions from the same element
For 2 ions from different elements
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Low-Density SolutionThe OVI Problem
(Williams et al., 2005, ApJ, submitted)
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The Ne/O Problem
Ne/O 1
Ne/O 0
(Williams et al., 2005, ApJ, submitted)
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Sun Structure and Metallicity
22 nearby stars observed with Chandra-HETG
(Drake Testa, 2005, Nature, submitted)
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High- and Low-Velocity OVI
FUSE spectrum of PKS 2155-304
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Velocity Segregation
(Nicastro et al., 2003, Nature, 421, 719)
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2
WHIM at Cosmological Distances ?b Estimate
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WHIM at Cosmological Distances
(1.2-1.6)
(Nicastro et al., 2005, ASR, in press,
astro-ph/0501126)
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OVII WHIM Number Density
Cf. with (Danforth Shull, 2005)
(Nicastro et al., 2005, ASR, in press,
astro-ph/0501126)
Derived from Fang, Bryan Canizares, 2002
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Ob(NOVIIgt7x1014 cm-2)

• Mkn 421 (2 Filaments.) z0.03
• Combined Mkn4211ES1028511 (3 Filaments)
  zeq(1ES1028511) 0.023
• THE MISSING BARYONS HAVE BEEN FOUND

(Nicastro et al., 2005, Nature, 433, 495
Nicastro et al., ASR, in press, astro-ph/0501126)
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Summary

• z0 Absorber
• OVII-OVIII and NeIX trace a low-density medium ?
  Local WHIM Filament?
• HV-OVI at rest in the LGSR
• WHIM at zgt0
• 4 detections so far (2 lines of sight)
• First Estimates of dN/dz and ?b consistent with
  predictions and with the total number of missing
  baryons (within large uncertainties due to the
  low statistics)

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3
Short and Long Term Prospects for the WHIM
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Awarded Programs Grants to Study the WHIM

• Long-Term-Space Astrophysics (LTSA) funded for
  2004-2009 (PI)
• Chandra Archival funded in cycle 6 (Co-I)
• 4 Chandra TOOs in cycle 4, 5 (PI)
• 2 XMM TOOs in cycle 2 and 3 (PI)
• 2 Chandra TOOs in cycle 6 (PI)
• XMM 300 ks in cycle 4 (PI)
• Chandra 850 ks proposed in cycle 7 (PI)

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Short-Term Prospects 1

• GOAL Reduce ?b and dN/dz uncertainties down to
  35 (level of the other baryonic components in
  the Universe), from current (140,-70)

Chandra approved up to 2010 TOOs key strategy
to detect the WHIM and identify promising high-z
sighlines But
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Deep In Redshift
Proposed 850 ks Chandra (AO7) Approved 300 ks
XMM (AO4)
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Long-Term Prospects

• Long Term mapping the WHIM up to z1-2 needs
  high throughput and spectral resolution in X-ray
  Constellation-X (R gt 2.5 x LETG, A 50 x LETG),
  XEUS (R 2.5 x LETG, A 750 x LETG)
• ? Hundreds to Thousands of Systems
• Cosmological Parameters (density fluctuations)
• Dark-Matter Maps
• Metallicity History (Ecology of the Universe)
• IGM/galaxy/AGN Feedback
• Heating History of the Universe (dT/dz)

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High Spectral Resolution Low-Energy Coverage
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R300 vs R3000OVII Forest
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Pharos
Pharos (Elvis, Fiore et al. 2002 SPIE,
astro-ph/0303444) Midex concept (CfA, Obs. Rome,
MIT, JHU) R gt 3000 _at_ 1 keV
A 25 x LETG Coverage
12-150 Å. Slew on source in lt 1-3 min
about 10 Soft-GRB per year with F 10-5 erg
cm-2 (gt 0.5 years on the brightest QSOs at z
1-2).
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Baryonic Matter Where did we get it from I
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Baryonic Matter Where did we get it from II
Missing Matter Found Iran's Got It By Daniel H.
Blazejewski (Glossynews.com)Feb 14, 2005,
0927 Fabrizio Nicastro of the
Harvard-Smithsonian Center for Astrophysics in
Cambridge, Massachusetts, and his colleagues
looked at X-rays from a distant quasar called
Markarian 421 as they passed through a region of
warm gas and determined that the other 97.5
percent of matter in the universe is being
hoarded by Iran after being shipped out of Iraq
shortly before the commencement of the 2003
liberation of the country. "It is difficult
to know whether this region is typical of the
entire Axis of Evil," said Michael Shull of the
University of Colorado in a separate commentary
in this week's Nature. Scientific models predict
that 95 percent of the universe is composed of
dark matter and energy, the effects of which can
be discerned from the gravitational motion of
stars and galaxies. It is in these forms of
matter that Iran has taken a strategic leap
forward in weapons technology. Back at the
White House, President George W. Bush continued
to pester Vice President Dick Cheney about
blowing up the newly discovered matter. Cmon,
Dick, one MOAB, itd be fun, wouldnt it? Pretty
lights, and a great big noise? You gotta admit,
you wanna do it, dont ya, Dickster? Well, maybe
if I had included it in my inauguraleratory
speech or state of the onion address, we wouldnt
be in this mess right now. Its your fault,
Cheney!
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Pharos
distant beacons as cosmological probes A
MIDEX mission concept
The Pharos of Alexandria, one of the Seven
Wonders of the ancient world, was the
tallest building on Earth (120m). Its
mysterious mirror, whose reflection could be
seen more than 55 km off-shore fascinated
scientists for centuries.
Martin Elvis
(CfA) In collaboration with F. Fiore, F.
Nicastro, V. DElia, S. Savaglio, L. Sbordone, G.
Stratta, A. Fontana, L. Stella, C Norman, A.
Fruchter, and others
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Pharos Mission Concept

• Goal R6000 (50 km s-1) soft (lt1 keV) X-ray
  spectroscopy
• Physics driver resolve thermal widths of X-ray
  lines
• Astronomy driver resolve internal galaxy motions

• Gamma-ray Burst (GRB) afterglows produce many
  more X-ray photons than any other high redshift
  source (i.e. quasars).
• Requires acquisition within 10 minutes of GRB
• 1 minute goal, as Swift

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4 themes of early 21st Century astrophysics
converge on Gamma ray bursts
The most energetic events in the Universe 1997
1st GRB redshift

• The fate of the baryons
• Large Scale Structure
• 1998 1st WHIM simulations
• 2002 1st WHIM detection

Galaxies in the Age of Star Formation 1997
Hubble Deep Field GRB hosts
GRB X-ray afterglows
The Reionization Epoch 2000 Gunn-Peterson trough
_at_ z6
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X-raying the WHIM GRB afterglows are better
than AGN

• 7/11 bright SAX GRBs have X-ray afterglows
  fluencegt 1x10-5 erg s-1 0.5-2keV
• HETE-2 also finds many bright X-ray afterglows

• 100 GRB/yr at fluencegt1x10-7 erg cm-2
• Detect X-ray forest.
• 40 GRB/yr at fluencegt1x10-6 erg cm-2
• Resolve lines, detect faint lines -gt abundances
• 1-2 GRB/yr at fluencegt1x10-5 erg cm-2
• Resolve faint lines

A high orbit would double the number of bright
bursts available
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Pharos Galaxies in the Age of Star Formation
GRBs also probe normal high z galaxies

• Star formation in the Universe peaked at z2

• Studies of zgt1-2 galaxies are biased against
  dusty environments.

• GRB hosts are normal galaxies

Mann et al. 2002 MNRAS, 332, 549

• GRB afterglows will reveal host
• Galaxy dynamics, abundances, dust content at
  zgt1

X-ray high resolution spectroscopy Optical-near
infrared high resolution spectroscopy
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Pharos Beacons of the Reionization Era
GRBs may be the only bright zgt6 sources

• Gunn-Peterson trough found in z6.28 quasar
  Epoch of reionization
• Becker et al., Djorgovski et al.

• Primordial star formation (PopIII) may create
  100-1000s Msol stars Madau, Norman et al.

• Quickly produce hypernovae GRBs?

• 10 of GRBs may be at zgt6
• Bromm Loeb
• First metal production, snapshot of IGM

• No quasars at zgtgt6?
• GRBs a unique probe of reionization epoch?

HST Deep Field (http//www.stsci.edu/ftp/science/h
df/hdf/html)
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Pharos Rapid GRB Trigger Location

• Problem require lt1armin location acquisition
  in 1-10 minutes and require quasi-4p coverage
  conflicting goals
• Solution divide GRB trigger from location (as on
  BeppoSAX)

t0s
20cm dia x 50cm length
t3s
t30s
Trigger faceted CsI solid 1o in seconds
Rapid rough slew to 1o location
Location small X-ray coded mask eg XMM pn chip
with 10ox10o fov to obtain arcmin location in a
few seconds

• short focal length reduces moment of inertia,
  ImR2
• (factor 25 for 2 meters vs. 10 meters)

GRB trigger must be on-board autonomous
t40s
Fine slew to lt1 arcmin position
t60s
X-ray spectrometer starts to take data
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How to detect the WHIM
Background QSO
Emission (lines) A 2x2x5 Mpc3 Filament (4.5 x
11, at z1) L 6 x 1039 erg/s/sr at z 1 ? F
10-24 erg/s/cm2 Cf. Chandra limit 10-18 in
2-4 months for point source
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WHIM Solutions
NVI-NVII-based
OVII-based
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Voigt Profiles

• Convolution of Natural and Doppler Broadening
• Voigt Parameter
• a ? G/??
• Not relevant in other bands
• a ltlt 1
• Relevant in X-rays
• a gt 1
• (Inner shell Transitions)
• Affects the Depth at the core of the line
• ?o?Niful?o

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Fe Inner Shell vs. Outer Shell

• ?o?Niful?o