Adam G. RiessSpace Telescope Science Institute

How (we think) Nature makes a SN Ia

• Homogeneity: 1.4 Mo, ergs• Negligible hydrogen, lots of IME• Mature progenitors • Models (delayed-detonation) good fit to observations

“Standard” Candles

Bright=near dim=far

dust

dim & red=closer!

Expansion History of the Universe

(reds

hift)

(Distance)

1, M

1, M

1, M

Mass isdestiny

By 1998 two teams measured ~100 SNe Ia at 0.01 <z<1.0 Surprise! The Universe is accelerating, propelled by dark energy.

High-z

SCP

The Accelerating Universe

Searching for the Epoch of

z

0.00.40.81.21.7

0.41.02.34.38.0

…a required feature of a mixed dark matter/dark energy Universe

Searching for the Epoch of

z

0.00.40.81.21.7

0.41.02.34.38.0

Our current goal: 6-8 SNe Ia at 1.2<z<1.8

“Difficulty” Or why its so hard to find type Ia supernovae at z>1.2

EffectEffect Factors of (1+z)Factors of (1+z)geometrical dilutiongeometrical dilution 22

redshift of energy densityredshift of energy density 11

dilation of integration timedilation of integration time 11

Decline of SN Ia SEDDecline of SN Ia SED~0.9-1.0 ~0.9-1.0

~1~1

Decline in QE of detectorsDecline in QE of detectors~0.9-1.0~0.9-1.0

~1~1

Total=6Finding SNe Ia at 1.2<z<1.8 is 10 to 40 times harder than at z=0.5 (a.k.a., 1998)Finding SNe Ia at 1.2<z<1.8 is 10 to 40 times harder than at z=0.5 (a.k.a., 1998)

The GOODs ACS Treasury Program and

The Hubble Higher-z Supernova Search Team

“A Higher-z Supernova Search Piggybacking on the ACS Survey”

134 orbits ToOfor 6-8 SNe Iaat 1.2<z<1.8

Riess (STScI)Strolger (STScI)Tonry (UH)Filippenko (UCB)Kirshner, (CfA)Challis, (CfA)Casertano, (STScI)Dickinson (STScI)Giavalisco (STScI)Ferguson (STScI)

399 orbitsof deep imagingfor extragalacticstudies

Searching for SNe Ia with ACSSearching for SNe Ia with ACS

5 z-band epochs, spaced by 45 days, simultaneous v,i band, 120 tilesCDFS=08/02-02/03 HDFN=11/02-05/03

What we are finding…~5-6 SNe per search epoch (~0.3 SNe/ACS pointing) ~1/2 type Ia, ~1/2 core-collapse, 0.3<z<1.8, <z>=1

SN Color Differences

zi

v

SN Ia UV deficit

Most Common SN types: type Ia and type II

Color Discrimination

Our first higher-z SN Ia, AphroditeAphrodite (1<z<1.5)

ACS grism spectrum

NICMOS F110W

ACS F850lp

viz

The Rise and Fall of Aphrodite

Aug 1Sept 22Oct 1Oct 5Oct 10Oct 20Oct 30Oct 31Nov 17Nov 25

Our Second Higher-z SN Ia, ThothEpoch 3Epoch 2 Epoch 3-2

red, ellipticalhost

Keck

VLT

z=1.3

Our Third Higher-z SN Ia, Nanna

OII, Keck

Epoch 1 Epoch 2 difference

And Some Even More Distant…

We are off to a great start…results coming soon to a journal near you…

Athena: phot-z: 1.8<z<2.2Colors, mag SN Ia at z~1.8

Osiris: Colors, mag SN Ia at 1.5<z<1.8

ACS f850lp

viz

Dilution of Light or Gravity Depends onthe Number of Dimensions Either “Sees”

Number of DimensionsNumber of Dimensions Intensity/Distance LawIntensity/Distance Law

11 Independent of DistanceIndependent of Distance

(I ~ 1/R(I ~ 1/R0)0)

22 Reciprocal of DistanceReciprocal of Distance

I ~ 1/RI ~ 1/R11

33 Inverse Square LawInverse Square Law

I ~ 1/RI ~ 1/R22

Essential component of String Theory: photons move in 3 dimensions, Gravitons leaks into 5,10 or 11 D long-range decay of gravity (Dvali et al 2001)

The Future Is Bright for SNe Ia!

•New tests of the new cosmology (searching for past deceleration)•Deeper understanding of SNe Ia (progenitors)•Probing the nature of Dark Energy

The End

3 SNe Followed in 1 ACS Field !

SN Ia 2002hp

SN 2002hq

SN Ia 2002fw

The New Cosmological Model;circa 2002

?

??

SN Ia Host Morphologyz<0.7

z>1.3

high fraction of hosts with well-defined structure

high fraction of irregulars and ERO hosts