The SN Ia Rate In0.5<z<0.9 ClustersThe SN Ia Rate In

0.5<z<0.9 Clusters

Keren Sharon

Tel Aviv University

Keren Sharon

Tel Aviv University

Avishay Gal-Yam, Dani Maoz, Alex Filippenko, Ryan Foley, Jeff Silverman, Harald Ebeling, C.J. Ma, Eran Ofek, Megan Donahue, Richard Ellis,Robert Kirshner, Thomas Matheson, John Mulchaey, Vicki Sarajedini, Mark Voit

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Gal-Yam et al. (2002)

Sharon et al. (2007)Mannucci et al. (2007)

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Overview

15 Clusters at 0.5< z <0.9 HST imaging (PI Gal-Yam)

Follow-up & luminosity from ground (@Keck, Palomar, Subaru)

Found ~10 cluster candidates

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The Cluster Sample0.5>z>0.9

x-ray luminous

Were previously observed by HST/ACS 1 epoch for free

Figure: redshift distribution

Lx distribution of MACS clusters,

Ebeling et al. (2007)

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The Cluster Sample Cluster z

MACS0911 0.504MACS2214 0.504MACS0257 0.506MACS0018 0.540 (aka CL0016) MACS1149 0.544MACS1423 0.545MACS0717 0.548 MACS0454 0.550 (aka MS0451) MACS2129 0.570MACS0647 0.584SDSS1004 0.680MACS0744 0.686MS1054 0.830CL0152 0.831CL1226 0.888

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HST imaging

Epoch 1: Archival, ≥1 orbit in I814 or i775(and additional bands for some clusters)

Epoch 2: cycle 14, 1 orbit/cluster (4x~500s)

Epoch 3: cycle 15, 1 orbit/cluster (but 6 clusters not observed due to ACS’ untimely death)

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Search

Promptly after observation

Image subtraction

All by human (i.e., me )

Total search area:340 arcmin2

37 candidates

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Hosts Redshifts

Keck Sprctroscopy w/ LRIS or DEIMOS

1’’ Longslit / multislit mask

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Spectra examples

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Hosts Redshifts

Keck Sprctroscopy w/ LRIS or DEIMOS1’’ Longslit / multislit mask

9* hosts @cluster z (*one via sdss photo-z)2 hostless8 BG8 FG3 AGN7 ???

8-16 cluster events (?)

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SN Candidates – examples1. cluster events

z=0.55

z=0.54

z=0.89 z=0.83

z=0.55

z=0.83

4.4’’

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SN Candidates – examples2. field events

z=0.87(bg)

z=0.49(fg)

z=0.23(fg) z=0.62(bg)

z=0.75(bg)

z=0.58(bg)

4.4’’

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SN Candidates – examples3. hostless

Cluster z=0.504

Cluster z=0.570

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Numbers to rates:

iibandiLt

SNeRateSN

,

#

Sum over all images Control time

Cluster stellar-luminosity enclosed in search area

*

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Stellar Luminosity

Subaru photometry in BVRIz’ (Ebeling et al.)

0.5x0.5 deg centered on cluster

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Stellar Luminosity

Subaru photometry in BVRIz’ (Ebeling et al.)

0.5x0.5 deg centered on cluster

Star / galaxy separation light profile / half-light radius scales with

magnitude stars and other point sources populate a well-defined locus in this plot, and can be separated from galaxies.

● MU_MAX = peak surface brightness above the background level. (SExtractor)

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Stellar Luminosity

Subaru photometry in BVRIz’ (Ebeling et al.)

0.5x0.5 deg centered on clusterStar / galaxy separation

Net flux inside search area = total flux in area – sky flux density x area ‘cluster SED’

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Stellar Luminosity

(E Spec. Template: Kinney et al. 1996)

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Stellar Luminosity

(Spec. Template: Kinney et al. 1996)

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Stellar Luminosity

(Spec. Template: Kinney et al. 1996)

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Stellar Luminosity

(Spec. Template: Kinney et al. 1996)

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Stellar Luminosity

Convert VRIz’ to restframe B / g

Correct for faint end of luminosity function, due to magnitude limit (usually m~25)

Results: enclosed B-band stellar luminosity, typically ~ 2-5 x1012 LB

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Numbers to rates:

iibandiLt

SNeRateSN

,

#

Sum over all images Control time

Cluster stellar-luminosity enclosed in search area

*

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Search Efficiency Simulations

>120 Fake SNe were blindly added to each image

Reduction and search as in real data

Recovery rate noted as function of magnitude

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Search Efficiency Simulations

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Search Efficiency Simulations

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Uncertainties

Statistical: Poisson errors of order 30%

Systematic: rate estimated many times by Monte-Carlo simulation, drawing:

Stretch factor from Sullivan et al. (2006)Luminosity, efficiency from their distributions (e.g., see Sharon et al. 2007)

Classification uncertainty (in progress)

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Results

Gal-Yam et al. (2002)

Sharon et al. (2007)Mannucci et al. (2008)

SNuB ~ 0.5 SNe/(100yr 1010 LB)

SNuM ~ 0.12 SNe/(100yr 1010 M)

PRELIMINARY