Re: Cluster science status

From: Chris Lidman (clidman@eso.org)
Date: Mon Jul 10 2006 - 07:55:19 PDT

  • Next message: Tony Spadafora: "Cluster conference call July 19"

    Hi Tony,
       I can make it for the 18th and 19th. The 11th and 12th are too
    difficult for me.

    Regards,

    Chris.

    On Jul 3, 2006, at 4:14 PM, Tony Spadafora wrote:

    > 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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    CHILE

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