Type Ia Supernovae in Galaxy Clusters from the CFHT Supernova

Legacy Survey (SNLS).

Melissa L. Graham, C. J. Pritchet, and the SNLS Team

University of Victoria, Canada.

SkiLS/AstroSki, January 2007, Mt Washington

Galaxy Cluster Abell 1689: N.Benitez, T.Broadhurst, H.Ford, M.Clampin, G.Hartig, G.Illingworth, ACS Science Team, ESA, NASA (APOD)SNIa diagram: Scott Hilditch, Lancaster University, http://www.lancs.ac.uk/ug/hilditch and also http://astro.berkeley.edu/~ehuff/cosmology_files

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Why SNIa in Galaxy Clusters?1) Evidence that SNIa rate per unit mass low in clusters

2) SNIa rate per unit mass now known to be an order of magnitude lower in early type galaxies

So, is morphology-density relation the sole affect on the SNIa rate per unit mass in clusters?

SNIaThe SNLS SNIa Cataloghttp://legacy.astro.utoronto.ca

GalaxiesThe Ilbert Photo-z CatalogIlbert et al. 2006, A&A 457 3 841. - restricted to i' < 24.0

ClustersThe Olsen Optical Cluster CatalogOlsen et al. 2007, A&A 461 1 81.

Data from CFHTLS.

MegaCamCFHT

current total = 278+

Olsen cluster catalog complete to redshift approx. 0.7, so all catalogs restricted to z<0.8.

Field SNeIa Galaxies Clusters

D1 57 31364 13

D2 44 35679 9

D3 57 34337 13

D4 48 27003 6

All 206 128383 41

SNIa rate in a galaxy is the sum of two components:

SNRIa = (A x M) + (B x SFR) [# SNIa per year]

A = (5.3 ± 1.1) x 10-14 SNIa/year/unit stellar massB = (3.9 ± 0.7) x10-4 SNIa/year/unit star formation rate

(Sullivan et al. 2006, ApJ 648 868.)

Expected SNIa Rate for Galaxies.

SNRIa normalized to make the total number expected in the field equal to the total number observed.

Identify SNIa and Galaxies in Clusters.- consider diameters 400kpc and 800kpc- environment depth used was ±0.05(1+z) of the cluster's redshift

Diameter 0.4 MpcCluster z=0.503D1ax, z=0.496

Diameter 0.4 MpcCluster z=0.305D3mq, z=0.246

Diameter 0.8 MpcCluster z=0.405D3mx, z=0.47

Diameter 0.8 MpcCluster z=0.6505D4ef, z=0.606

Probability of observing x SNIa in clusters given the expected number µ :

For x > µ

Or, for x < u

Summed Poisson Probabilities

xx

x

SUM x

exP

'

'

!');,(

x

x

x

SUM x

exP

0'

'

!');,0(

Comparing # SNeIa Observed to Expected in Clusters

Using both A+B rate components:Diameter# SNIa # SNIa Sum Poisson # For A Significant. [Mpc] Observed ExpectedProbability Result (P<5%)0.4 2 2.80 0.47 70.8 4 4.19 0.59 0, 9

Using rate component A only:Diameter# SNIa # SNIa Sum Poisson [Mpc] Observed ExpectedProbability0.4 2 3.70 0.290.8 4 5.31 0.39

03D1ax at z=0.496

Completeness Issues:1) Detection efficiency drops in brighter galaxies, and early types are brighter and more likely to be in clusters2) Detection efficiency drops for fainter SNIa, and Sullivan et al. 2006 show that fainter SNIa occur more often in early type galaxies Conclusions:1) SNIa rate per unit mass in clusters consistent with rate in field galaxies, to within a factor of 2, with 95% confidence2) SNIa rate per unit mass in cluster and field early type galaxies is also consistent.3) With a cluster sample 3 times the CFHTLS sample size, rate affects outside the morphology-density relation can be detected

Other Work:1) Use of clustering parameter significance to compare rates on continuous clustering scale. (Ask me how!)2) Use of detection efficiencies from Neill et al. 2006 to correct number of SNeIa observed in field and clusters, and derive a SNIa rate per unit mass in clusters.

Observational Program:- deep component of CFHT Legacy Survey- MegaCam images four 1 sq.deg. fields spread out in RA in u*g’r’i’z’- images every two to three days (rest frame)- depth of approximately i’<25, so SNeIa to z=1.0+

Science Goals:- constrain w, the equation-of-state-parameter for dark energy- derive rates and evaluate properties of SNeIa to constrain their progenitor scenarios

Collaborators:Victoria, Canada: Chris Pritchet, Dave Balam, Don Neill, Eric Hsiao, MeToronto, Canda: Ray Carlberg, Mark Sullivan, Andy Howell, Kathy Perrett, Alex ConleyFrance: Reynald Pain, Pierre Astier, Julien Guy, Nicolas Regnault, and more.Other: Isobel Hook, Saul Perlmutter, and more.http://

legacy.astro.utoronto.ca

Significance Parameter

F

EF

F

EFE

AA

N

AA

NN

redshift depth±0.05(1+z)

AE

For a cylidrical volume centered on galaxy or SNIa:

NE = number in environmentNF = number in fieldAE = area of environmentAF = area of field

The significance (Σ) of clustering in its environment is:

Environment depth represents photometric redshift uncertainty of Ilbert Galaxy Catalog.

Intermediate environment diameter of 0.6 Mpc adopted for following experiment.

Significance Parameter

Significance Parameter

Significance Parameter

Evaulating SNIa Rate per Unit Mass in Olsen Clusters

]1[/

, VSPECyr

IaIacorr z

C

SNN

Ncorr,Ia = number of SNIa per yea r in deep fields

NIa = number of observed SNIa in deep fields

S = number of seasons of SNLS observing

εyr = detection and identification efficiency of SNeIa

CSPEC = fraction of unidentified SNeIa which have spectra

<z>V = volume-weighted average redshift of survey

Evaulating SNIa Rate per Unit Mass in Olsen Clusters

Ncorr,Ia

(SNIa/year)

Mass(1013 M⊙)

Rate(10-14 SNIa/year/M⊙)

Clusters 5.6±2.8 8.17 6.86±3.5

Field 414.7±29 490 8.46±0.6

SNRIa in E/S0 = (5.3 ± 1.1) x 10-14 SNIa/year/M⊙

(Sullivan et al. 2006)

SNRIa in low redshift clusters = 7.4(+4.4-2.9 ±2.1) x 10-14

SNIa/year/M⊙

(Sharon et al. 2006)