Re: Cluster science status

From: Saul Perlmutter (saul@lbl.gov)
Date: Wed Jun 28 2006 - 18:17:18 PDT

  • Next message: Marc Postman: "Fwd: ACS Status and Plan for the Next Few Days"

    ...One extra note to add to the status report: Tony will be trying to
    set up a conference call in the next few weeks for discussion of plans,
    so watch for email from ALSpadafora@lbl.gov

    --Saul

    Kyle S Dawson wrote:

    >Hi All,
    >
    >I also feel that I have not done a good job updating everyone with the
    >status of the SN search, so let me take this oppurtunity to do so. I'll
    >start with a simple laundry list of what we've found, and then summarize
    >our initial interpretations and some issues yet unresolved.
    >
    >There are now 25 clusters in the program. Three of these were added in
    >Dec-Apr using free orbits from supernova-less clusters. All three of
    >these new clusters come from archival XMM data. Observations are
    >complete for 19 clusters. If I remember correctly, the search for SNe
    >in 5 of the remaining 6 clusters will end in late July, and the last
    >cluster search will end in late Aug. Those dates need to be double checked.
    >
    >The full cluster list, images of SNe, etc can be found on the TWiki:
    >http://hstclustersn.lbl.gov:8081/twiki/bin/view/Supernovae/WebHome
    >usrname: TWikiGuest
    >passwd: hstclustersn
    >
    >Current status:
    >
    >Orbits used: 158 ACS, 21 NICMOS
    >Remaining UNscheduled orbits: 7 ACS, 9 NICMOS
    >
    >***BEGIN LAUNDRY LIST*******
    >
    >SNe discovered:
    >
    >Active:
    >A-004: Awaiting spectroscopy using Subaru and VLT this week. Host is
    >red, possible early type, but SN is too bright to be associated with
    >z=1.4 cluster. SN color/mag, consistent with z~1.0-1.2.
    >
    >Cluster E hosts:
    >O-000: z=1.01
    >K-000: z=1.41???Waiting better spectroscopy, hopefully tonight
    >H-005: z=1.23
    >
    >Other cluster SNe
    >C-001: z=0.98, spectroscopically confirmed Ia, host faint and uncertain
    >
    >SNe hosted by E type galaxies with no emission lines in background of
    >clusters:
    >O-006: z=1.31
    >C-000: z=1.09
    >G-004: z=1.35
    >
    >low z field SNe (probably not useful for cosmology, maybe for rates)
    >N-010: z=0.203, type unknown
    >P-001: z=0.92, type unknown
    >P-009: z=0.821, Ia
    >X-027: z=0.4, type unknown (probably core collapse)
    >C-007: host uncertain, type unknown
    >G-003: z=0.963, type unknown
    >F-008: host uncertain, type unknown
    >H-003: z=0.851, Ia
    >Z-005: z=0.624, Ia
    >
    >possible z>1.5 SNe (based on SNe color/mag, host color/mag):
    >X-018: one epoch, faint red host
    >X-026: two epochs, faint red host
    >T-001: one epoch, faint red host
    >
    >undetermined redshift, discovered this week in reverse subtractions
    >(last epoch as ref, first epoch as search). Three have faint hosts that
    >appear spiral or irregular, with SNe and host consistent with z>1. We
    >hope to find emission lines in spectroscopic observations next spring.
    >E-012: faint host
    >F-012: faint host, SNe color, lightcurve consistent with z>1 Ia
    >K-018: possible cluster E, z=1.41, SN probably not useful for cosmology
    >due to poorly sampled lightcurve, very good for rates, spectroscopy of
    >host tonight, weather permitting
    >L-021: faint host
    >
    >And finally, one mystery object:
    >F-006: galactic, extragalactic, z=0.54, quasar, SNIc, hypernova, pop
    >III SN, star??????? Nothing in the lightcurve or spectrum resembles
    >anything this group has seen before. The transient is hostless to a
    >limiting mag z'>26.5, i'>26.5. At max, the transient has z'=21.2 and
    >i'=21.1.
    >The lightcurve has a risetime of 100 days with no evolution in color.
    >The spectrum has features semi-consistent with a SNIc at z=0.54, but
    >lacks key Fe features. We posted an IAUC, or CBET as they are now
    >called, and have an article written about it here:
    >http://www.newscientistspace.com/article/dn9360-enigmatic-object-baffles-supernova-team.html
    >We got more data on this in poor conditions Sunday night at Keck and
    >last night at Subaru, there is clear continuum but the spectra are still
    >waiting to be reduced.
    >
    >Unresolved issues: several SNe hosts have not been observed. We got
    >murdered with Mauna Kea weather this spring and lost almost all of our
    >time. We will try to pick up these redshifts in spring 2007.
    >
    >*******END LAUNDRY LIST************
    >
    >Now, as it stands we do have unscheduled orbits. If these orbits are
    >still free in Aug, we plan to return to the 5 RCS clusters in the 02-04
    >hr range for a second round of searching. We will have deep references
    >from the 2005 data for the search, and have Keck DEIMOS time scheduled
    >to coincide with these HST visits. We will use 5-10 orbits, depending
    >on how many are free. If a SN is found, we will follow the lightcurve
    >using the remaining unscheduled orbits. If no SN is found, we will
    >preserve those last orbits to use as ToO for a SN search using time
    >awarded to PRME et al in cycle 15 for observations of a new set of IRAC
    >clusters.
    >
    >One thing that is very interesting to note is that we have a fairly high
    >rate of SNe with z>1 E hosts, but a low rate of late type hosts at this
    >redshift. This is very surprising and we do not have an answer for the
    >low rate of late type hosts. In terms of cosmology, the z>1 E hosts
    >should be extremely useful. The SN are often un-typed, but we plan to
    >obtain deep spectroscopy of the hosts in order to place constraints on
    >star forming and argue for Ia SNe. We believe these SNe should be
    >dust-free as well, but this clearly needs to be explored. These SNe are
    >also in the background of massive clusters, and are therefore subject to
    >magnification via lensing. In order to use these for cosmology, we will
    >need to remove this bias using estimates of cluster masses. We have two
    >students working on this, and I'd like them to explore different
    >techniques of measuring cluster mass. We may be asking for some help
    >with that. For the purposes of cosmology, a 2\sigma measurement of mass
    >through weak lensing is probably fine, but it will be very good for the
    >two students to learn the other methods as well.
    >
    >And finally, we plan to perform a rates analysis. This is the best data
    >set of high z cluster SNe, and the measurement of rates in the cluster
    >environment should be a very good result. To do so, we will need to
    >come to some consensus on how to define the cluster environment. The
    >cluster sample is clearly inhomogeneous so this may require a bit of
    >work. Something to think about for this telecon Marc Postman suggests.
    >
    >-Kyle
    >
    >
    >----- Original Message -----
    >From: Marc Postman <postman@stsci.edu>
    >Date: Wednesday, June 28, 2006 9:13 am
    >Subject: Cluster science status
    >
    >
    >
    >>Saul, Mike, et al.,
    >>
    >>I am wondering if others feel as out of the loop as I on what's
    >>happening with the cluster science part of the program and who is
    >>doing what now. If I am not alone in this, it might be time for a
    >>telecon to at least get an update on progress and discussion of
    >>possible new ideas to pursue with the data.
    >>
    >>-Marc
    >>
    >>-----------------------------------------------------------------
    >>Marc Postman Email: postman@stsci.edu
    >>STScI - CMO Phone: +1-410-338-4340
    >>3700 San Martin Drive Fax: +1-410-338-4796
    >>Baltimore, MD 21218 U.S.A. http://www.stsci.edu/~postman
    >>
    >>
    >>
    >>
    >>



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