Supernovae and Dark Energy

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Supernovae and Dark Energy
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SNIa Similarity and Diversity
SN1a are standardizable candles Bright
slow Dim fast One parameter yields
10 luminosity distances
B V I
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Luminosity Distance and Cosmological Parameters
(Impress the ignorant)
(See whats going on)
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Luminosity Distances 0.5 lt z lt 1.5
Z ? (m-M) 0.5 0.13 /- 0.05 1.0 0.00
/- 0.08 1.5 -0.10 /- 0.10 (speculative!)
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SNIa Results in 1998
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Fall 2001 Continuous Search
Barris et al. 2004
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SNIa - Results in 2003
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Constraints on ?M, ??, and w
2dF ?Mh 0.2 0.03 KP h 0.72 0.08
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Higher z with ACS and GOODS
(Adam Riess, PI)
5 z-band epochs, spaced by 45 days, simultaneous
v,i band, 120 tiles
CDFS08/02-02/03
HDFN11/02-05/03
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CDFS
2002kc (0.214)
2002fw (1.3)
2002hq (0.74)
2002kb (0.474)
2002fz (0.839)
2002hr (0.526)
2003ak (1.57)
2002lg (0.61)
2002kd (0.735)
2003aj (1.4)
2002fy (0.88)
2002hp (1.3)
2002ga (0.988)
2002ht (?)
2002hs (0.388)
2002fv (1.0)
2002fx (1.8)
2003al (0.91)
2002ke (0.578)
HDFN
2003eq (0.85)
2003dz (0.48)
2003en (0.54)
Vilas (0.86)
2003dy (1.37)
2002kl (0.39)
2003er (0.63)
2003be (0.64)
2003dx (0.46)
2003bd (0.67)
2003ea (0.89)
2003bb (0.89)
2003bc (0.51)
2003eb (0.92)
2003ew (0.66)
2003es (0.968)
2003eu (0.76)
2003az (1.27)
2003en (0.54)
2003ba (0.47)
2002ki (1.14)
2002kh (0.71)
2003et (0.83)
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Aphrodite ACS Delivers!
Aphrodite (z1.3)
ACS F850lp
ACS grism spectrum
NICMOS F110W
viz
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Thoth Hidden by its Host
red, elliptical host
z1.3
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Gilgamesh z1.6
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HST Crucial for z gt 1!
HSTACS z1.30
Ground-based
z1.06
z1.20
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The New SN Ia Hubble Diagram
6 of the 7 highest redshift SNIa
97ff
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The Cosmic Acceleration Persists
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and the Contours for ? Shrink.
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The Nature of Dark Energy

• What is this stuff???
• Three clues
• Quantity ? (flat?)
• Quality w (-1?)
• Constancy dw/dt (0?)

w
w
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SNIa Progenitors and Gestation
Still a big mystery!
Dahlen et al. 2004
Strolger et al. 2004
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Progress on Dark Energy using SNIa
z gt 1 HST only
z lt 1 Ground based

• Essential for
• w0, w constraints
• Progess in systematics
• Host galaxies
• Colors (rest frame UV)
• SNxx contamination
• Spectra
• Evolution
• Progenitors and ICs
• Want gt10,000, need 1000
• Wide field, optical colors

• Essential for
• w0, w constraints
• Immunity to systematics
• Want 300, need 30
• Use z, J, H, and grism
• Challenge is improving search efficiency

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Ground-based Searches
Project Start - End GPix Harvest Clrs Sampling
Essence CTIO 4m 2001 - 2005 0.06 40 per yr 2 2 week campaign
CFHTLS CFHT 3.6m 2003 - 2008 0.4 200 per yr 3 2 week campaign
Pan-STARRS Telescope 1 2006 - 2007 1 100 per mo 5 Every 4 days
Pan-STARRS 2007 - 4 1000 per mo 5 Every 4 days
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Pan-STARRS Survey Comparison
Coverage log(deg2)
Limiting magnitude
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Constraints on w
Pan-STARRS 1 year
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SNIa Distances without Redshifts
Barris et al. 2004
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SNIa Distances without Redshifts
Barris et al. 2004
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Distance and Redshift from SNIa Photometry Alone
Barris et al. 2004
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The Nature of Dark Energy, II

• Cosmological Constant
• Consistent with the observations at 1-?
• All theorists hate it

w
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Supernova Systematics

• Uninteresting (avoidable)
• Photometry error (0.03 ? 0.01)
• UV SEDs (0.05 ? 0.00)
• Poor LC coverage (0.04 ? 0.00)
• Host extinction (0.06 ? 0.03)

• Interesting (intrinsic)
• SN1a progenitor, initial conditions, trigger (z)
• Host extinction and properties (z)
• Gravitational lensing (z)
• Transparency of IGM (z)

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Theoretical Models for SNIa
Luminosity-decline rate
Turbulent flame consuming a white dwarf
Spectra
Niemeyer et al.
Hoeflich et al.
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What Causes the Diversity?

• Progenitors may have different
• Mass (luminosity 56Ni mass)
• Metallicity (Z ? ? n ? ? 56Ni ?)
• Age (22Ne sedimentation?)
• Binary companion (???)
• Mass transfer mechanism (???)
• Explosion may have different
• Trigger mechanism (???)
• Propagation (deflagration/detonation, weather,
  etc)
• Good news
• Chandresekhar mass and NSE make explosions quite
  uniform (50 and 1 parameter gets us to 20)
• Bad news
• Plenty of room for unknown systematics at the 2
  level

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Models are Un(der)constrained

• Understanding the explosion is not enough
• Need explosion mechanism and initial conditions
• A small fraction of WD explode
• WDs which do explode wait a long time
• Initial conditions could easily depend on z
• Age of the Universe
• Galaxy interaction rate
• Star formation rate
• Metallicity

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Constraints on w
Pan-STARRS 1 year
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Constraints on w
0.01, 0.02, 0.04 mag systematic