A search for supernovae A search for supernovae in galaxy clusters at 0.1 < in galaxy clusters at 0.1 <

z < 0.2z < 0.2

David J SandDavid J SandCollaborators: Dennis Zaritsky, Stephane Collaborators: Dennis Zaritsky, Stephane Herbert-Fort, Suresh Sivanandam, Doug Herbert-Fort, Suresh Sivanandam, Doug

CloweCloweChandra Fellows Symposium 2006

SNe in clustersSNe in clusters

The metal enrichment of the ICM, SNIa rate in clusters, and the amount of stellar mass in intracluster light are intimately

related subjects

Enrichment of the Enrichment of the intracluster mediumintracluster medium

SNIa provide ~0.7 Msun of iron per event (e.g. Tsujimoto et al. 1995)

Clusters are excellent for studying metal enrichment -- they have a simple SFH and deep potential from which material cannot escape. Can be measured from the iron-K complex at ~7 keV.

Renzini 2003; see also Tozzi et al. 2003

Is there some way to separate the Is there some way to separate the two populations?two populations?

Perhaps in galaxy clusters -- Perhaps in galaxy clusters -- simple SFH and dominated by simple SFH and dominated by

ellipticals ?ellipticals ?

SN Ia progenitorsSN Ia progenitors

SNIa are common in both old, evolved stellar systems and in regions of high star formation (e.g. Mannucci et al.

2005; Sullivan et al. 2006) -- Two populations of progenitors??? Possible singly degenerate and double degenerate systems

Log SFR

SNR

Gonzalez et al. (2005) Gonzalez et al. (2005) have shown that the ICL have shown that the ICL is well fit by a separate ris well fit by a separate r1/4 1/4

profile and has a radial profile and has a radial extent of ~100s of kpc extent of ~100s of kpc

Different measurements Different measurements have suggested that the have suggested that the ICL makes up ~10-20% of ICL makes up ~10-20% of the total stellar budget the total stellar budget

Can intracluster SN be Can intracluster SN be enriching the ICM in situ? enriching the ICM in situ? -- preliminary calculations -- preliminary calculations suggest up to 50% of suggest up to 50% of metals come from IC SN metals come from IC SN (Zaritsky et al. 2004)(Zaritsky et al. 2004)

Content and quantity of Content and quantity of intracluster lightintracluster light

The ratio of hostless to hosted SN Ia gives a measurement of the mean ICL fraction (see also Gal-Yam et al. 2003)

Arizona cluster Arizona cluster supernovae searchsupernovae search

~60 X-ray selected galaxy clusters at 0.1 < z < 0.2

Revisit fields monthly in the g-band at the 90-inch

Follow-up spectroscopy at the MMT within 5 days to weed out foregrounds and core-collapse SN

Goal: Find 15-30 SN-Ia

Three principle goals:Three principle goals:1. Determine the mean fraction of intracluster

star light.

2. Determine the Sne-Ia rate to place clear constraints on the SN-Ia ‘delay time’ -- the time between formation of a stellar system and the eventual explosion of some of its members as SN-Ia. This may be a clean way to probe the ‘older’ progenitor population in clusters

3. Combine these two measurements to determine the contribution of intracluster Sne to the global chemical enrichment of clusters

Three principle goals:Three principle goals:1. Determine the mean fraction of intracluster

star light.

2. Determine the Sne-Ia rate to place clear constraints on the SN-Ia ‘delay time’ -- the time between formation of a stellar system and the eventual explosion of some of its members as SN-Ia. This may be a clean way to probe the ‘older’ progenitor population in clusters

3. Combine these two measurements to determine the contribution of intracluster Sne to the global chemical enrichment of clusters

90 Prime on the 2.3m 90 Prime on the 2.3m Bok TelescopeBok Telescope

Blue sensitive, 1 degree FOV, 0.45”/pixel

We center each cluster on chip 1 (30’ FOV) and use the other chips as a control -- each chip is separated by ~500 arcsec

Typical seeing: ~2 arcsec

The complete initial photometric campaign

Received 11 nights of Bok time to write an image pipeline and demonstrate that we can ID transients on <1 day time scales. -- DONE

Science

Basically impossible to calculate a SN-Ia rate from single-band, single-epoch photometry alone

BUT, some limits can still be put on the fraction of IC SN to hosted SN -- Using the control field chips

SNe detection in real timeSNe detection in real time

Automated pipeline developed to reduce data, difference images with best archived reference image (using Alard’s algorithm), detect potential transients and post them to a group web site for human review.

Typically ~10 candidates; 1 real

Human confirmed transients are batch submitted to NED and GCVS to screen out known AGN/QSOs and variable stars

Transient detection efficiencyTransient detection efficiency

Place fake point source ‘SN’ into images to understand detection efficiency as a function of seeing, AM, and

background (in galaxy vs. hostless)

Typically 75% detection efficiency from g~18-22

The TallyThe TallyNot reduced yet!

Cluster chip

92 candidate SN

9 hostless

~50 candidate SN

3 hostless

Scaled to match detection eff of cluster chip!

~60 candidate SN

2 hostless90 - 55 = 35 9 -3 =6

ICL FractionICL FractionIf we assume that the other chips accurately account for the background transient rate and that all the remaining SN candidates are Ia’s in the cluster, then we get an ICL fraction of ~15%, consistent with other results and techniques.

All ICL-SN candidates are within ~400 kpc of BCG

There is still definitely some level of contamination -- possibly large -- we need spectra for conclusive results!!

The Rare CatchThe Rare CatchWe are sensitive to ~400-1000 s scale transients in the range g~17-21 -- with 50 sq deg this is a new domain in transient phase space

Most flaring objects are likely M dwarfs -- but there is a chance for new science

Also, we are keeping an eye out for SN strongly lensed by the cluster

RecapRecap•We have begun a SN search in ~60 X-ray selected galaxy clusters at 0.1<z<0.2 with the 1 degree imager on the UA 2.3m

•An automated transient detection pipeline is in place, and our detection efficiencies are well understood

•It seems as if ~15% of our cluster SN candidates are hostless, suggesting a similar ICL fraction. But this result must be confirmed with spectroscopy, which we are in the process of acquiring

•Once the survey is complete, we will be able to place constraints on the SNIa ‘delay time’ and the metal enrichment of the ICM

The Near and Far FutureThe Near and Far FutureWe have been allocated 12 Bok and 5 MMT spectroscopy nights this fall!!

First run is in <10 days -- stay tuned -- with spectra, definitive statements can be made about the ICL and the SNR in clusters

Expansion of the survey to higher redshifts -- only way to probe the delay time is by measuring SNR at a variety of redshifts

A measurement of the SNIa as a function of redshift will shed light on the metal enrichment of the ICM

Teaming up with the Catalina Sky Teaming up with the Catalina Sky SurveySurvey

Catalina Sky Survey is a nearly all-sky dedicated search for near-earth asteroids. They throw out all of their stationary transients!!

We will soon be monitoring nearby groups and clusters for hosted and hostless SN and novae. Stay tuned….

Also following up short time ‘flaring’ transients