Re: Cluster science status

From: Tony Spadafora (ALSpadafora@lbl.gov)
Date: Mon Jul 03 2006 - 13:14:36 PDT

  • Next message: Chris Lidman: "Re: Cluster science status"

    HI all,

    Proposed dates for a teleconference are:
    Tues Jul 11
    Wed Jul 12
    Tues Jul 18
    Wed Jul 19

    Proposed start time is 10:00 PDT. With updates on progress from the
    cluster groups and discussion of new ideas, we might plan on 1.5-2
    hrs. Please let me know if you are available at these times (and if
    not, please suggest alternative times - preferably during the weeks
    of July 10 or July 17).

    Regards,
    -Tony

    On Jun 28, 2006, at 6:17 PM, Saul Perlmutter wrote:

    > ...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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