Adam G. Riess
Space 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
dust
Bright=near
dim=far
dim & red=closer!
Expansion History of the Universe
(redshift)
,
,
,
(Distance)
M
M
M
1
1
1
Mass is
destiny
The Accelerating Universe
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
Searching for the Epoch of
…a required feature of a mixed dark matter/dark energy Universe
z
0.0
0.4
0.8
1.2
1.7
0.4
1.0
2.3
4.3
8.0
Searching for the Epoch of
z
0.0
0.4
0.8
1.2
1.7
0.4
1.0
2.3
4.3
8.0
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
Effect
geometrical dilution
Factors of (1+z)
2
redshift of energy density
1
dilation of integration time
1
Decline of SN Ia SED
~0.9-1.0
~1
Decline in QE of detectors
~0.9-1.0
~1
Total=6
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 ToO
Riess (STScI)
Strolger (STScI)
for 6-8 SNe Ia
Tonry (UH)
at 1.2<z<1.8
Filippenko (UCB)
Kirshner, (CfA)
Challis, (CfA)
Casertano, (STScI)
Dickinson (STScI)
Giavalisco (STScI)
Ferguson (STScI)
399 orbits
of deep imaging
for extragalactic
studies
Searching for SNe Ia with ACS
5 z-band epochs, spaced by 45 days, simultaneous v,i band, 120 tiles
CDFS=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
i
v
Most Common SN types: type Ia and type II
z
Color Discrimination
Our first higher-z SN Ia, Aphrodite
Aphrodite (1<z<1.5)
ACS F850lp
ACS grism spectrum
NICMOS F110W
viz
The Rise and Fall of Aphrodite
Oct
Oct
20
Nov
Aug
Oct
Sept
Oct
Nov
Oct517
30
31
1110
25
22
Our Second Higher-z SN Ia, Thoth
Epoch 2
Epoch 3
Epoch 3-2
red, elliptical
host
Keck
VLT
z=1.3
Our Third Higher-z SN Ia, Nanna
Epoch 1
Epoch 2
OII, Keck
difference
And Some Even More Distant…
Athena: phot-z: 1.8<z<2.2
Colors, mag
SN Ia at z~1.8
Osiris: Colors, mag
SN Ia at 1.5<z<1.8
ACS f850lp
viz
We are off to a great start…results coming soon to a journal near you…
Dilution of Light or Gravity Depends on
the Number of Dimensions Either “Sees”
Number of Dimensions
Intensity/Distance Law
1
Independent of Distance
(I ~ 1/R0)
2
Reciprocal of Distance
I ~ 1/R1
3
Inverse Square Law
I ~ 1/R2
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 2002hq
SN Ia 2002hp
SN Ia 2002fw
The New Cosmological Model;
circa 2002
?
??
SN Ia Host Morphology
z<0.7
high fraction of hosts with well-defined structure
z>1.3
high fraction of irregulars and ERO hosts