Supernovae in Deep Hubble Space Telescope Galaxy Cluster Fields: Cluster Rates and Field Counts

We have searched for high-redshift supernova (SN) candidates in multiple deep Hubble Space Telescope (HST) archival images of nine galaxy-cluster fields. We detect six apparent SNe, with I814 between 21.6 and 28.4 mag. There is roughly 1 SN per deep (flux limit I814 > 26 mag), doubly-imaged, WFPC2 cluster field. Two SNe are associated with cluster galaxies (at redshifts z=0.18 and z=0.83), three are probably in galaxies not in the clusters (at z=0.49, z=0.60, and z=0.98), and one is at unknown z. After accounting for observational efficiencies and uncertainties (statistical and systematic) we derive the rate of type-Ia SNe within the projected central 500 kpc of rich clusters: R=0.20(+0.84)(-0.19) SNu in clusters at z=0.18 to 0.37, and R=0.41(+1.23)(-0.39) SNu in clusters at z=0.83 to 1.27 (95 per cent confidence interval; H_0=50; 1 SNu = 1 SN per century per 10^10 L_B_sun). Combining the two redshift bins, the SN rate at a mean redshift of z=0.41 is R(z=0.41) = 0.30(+0.58)(-0.28) SNu. The upper bounds argue against SNe-Ia being the dominant source of the large iron mass observed in the intra-cluster medium. We also compare our observed counts of field SNe (i.e., non-cluster SNe of all types) to recent model predictions. The observed field count is zero or one SN with I814 < 26 mag, and 1 to 3 SNe with I814 < 27 mag. These counts are about two times lower than some of the predictions. Since the counts at these magnitudes are likely dominated by type-II SNe, our observations may suggest obscuration of distant SNe-II, or a SN-II luminosity distribution devoid of a large high-luminosity tail.Comment: MNRAS, in press. Small modifications in final version include redshifts for all five detected SN host galaxies, upward revision of cluster SN-Ia rates, and some changes in field SN count

Discovery of Multiply Imaged Galaxies behind the Cluster and Lensed Quasar SDSS J1004+4112

We have identified three multiply imaged galaxies in Hubble Space Telescope images of the redshift z=0.68 cluster responsible for the large-separation quadruply lensed quasar, SDSS J1004+4112. Spectroscopic redshifts have been secured for two of these systems using the Keck I 10m telescope. The most distant lensed galaxy, at z=3.332, forms at least four images, and an Einstein ring encompassing 3.1 times more area than the Einstein ring of the lensed QSO images at z=1.74, due to the greater source distance. For a second multiply imaged galaxy, we identify Ly_alpha emission at a redshift of z=2.74. The cluster mass profile can be constrained from near the center of the brightest cluster galaxy, where we observe both a radial arc and the fifth image of the lensed quasar, to the Einstein radius of the highest redshift galaxy, ~110 kpc. Our preliminary modeling indicates that the mass approximates an elliptical body, with an average projected logarithmic gradient of ~-0.5. The system is potentially useful for a direct measurement of world models in a previously untested redshift range.Comment: 5 pages, 3 figures. Accepted by ApJL. High resolution version of the paper can be found at: http://wise-obs.tau.ac.il/~kerens/papers.htm

Supernovae in Low-Redshift Galaxy Clusters: the Type-Ia Supernova Rate

Supernova (SN) rates are a potentially powerful diagnostic of star formation history (SFH), metal enrichment, and SN physics, particularly in galaxy clusters with their deep, metal-retaining potentials, and simple SFH. However, a low-redshift cluster SN rate has never been published. We derive the SN rate in galaxy clusters at 0.06<z<0.19, based on type Ia supernovae (SNe Ia) that were discovered by the Wise Observatory Optical Transient Survey. As described in a separate paper, a sample of 140 rich Abell clusters was monitored, in which six cluster SNe Ia were found and confirmed spectroscopically. Here, we determine the SN detection efficiencies of the individual survey images, and combine the efficiencies with the known spectral properties of SNe Ia to calculate the effective visibility time of the survey. The cluster stellar luminosities are measured from the Sloan Digital Sky Survey (SDSS) database in the griz SDSS bands. Uncertainties are estimated using Monte-Carlo simulations in which all input parameters are allowed to vary over their known distributions. We derive SN rates normalized by stellar luminosity, in SNU units (SNe per century per 10^10 L_sun) in five photometric bandpasses, of 0.36+/-(0.22,0.14)+/-0.02 (B), 0.351+/-(0.210,0.139)+/-0.020 (g), 0.288+/-(0.172,0.114)+/-0.018 (r), 0.229+/-(0.137,0.091)+/-0.014 (i), 0.186+/-(0.111,0.074)+/-0.010 (z), where the quoted errors are statistical and systematic, respectively. The SN rate per stellar mass unit, derived using a color-luminosity-mass relation, is 0.098+/-(0.059,0.039)+/-0.009 SNe (century 10^10 M_sun)^-1. The low cluster SN rates we find are similar to, and consistent with, the SN Ia rate in local elliptical galaxies.Comment: Revised version following referee's comments; Accepted by Ap

Supernovae in the Subaru Deep Field: An Initial Sample, and Type Ia Rate, out to Redshift 1.6

Large samples of high-redshift supernovae (SNe) are potentially powerful probes of cosmic star formation, metal enrichment, and SN physics. We present initial results from a new deep SN survey, based on re-imaging in the R, i', z' bands, of the 0.25 deg2 Subaru Deep Field (SDF), with the 8.2-m Subaru telescope and Suprime-Cam. In a single new epoch consisting of two nights of observations, we have discovered 33 candidate SNe, down to a z'-band magnitude of 26.3 (AB). We have measured the photometric redshifts of the SN host galaxies, obtained Keck spectroscopic redshifts for 17 of the host galaxies, and classified the SNe using the Bayesian photometric algorithm of Poznanski et al. (2007) that relies on template matching. After correcting for biases in the classification, 55% of our sample consists of Type Ia supernovae and 45% of core-collapse SNe. The redshift distribution of the SNe Ia reaches z ~ 1.6, with a median of z ~ 1.2. The core-collapse SNe reach z ~ 1.0, with a median of z ~ 0.5. Our SN sample is comparable to the Hubble Space Telescope/GOODS sample both in size and redshift range. The redshift distributions of the SNe in the SDF and in GOODS are consistent, but there is a trend (which requires confirmation using a larger sample) for more high-z SNe Ia in the SDF. This trend is also apparent when comparing the SN Ia rates we derive to those based on GOODS data. Our results suggest a fairly constant rate at high redshift that could be tracking the star-formation rate. Additional epochs on this field, already being obtained, will enlarge our SN sample to the hundreds, and determine whether or not there is a decline in the SN Ia rate at z >~ 1.Comment: 20 pages, 8 figures, MNRAS accepte

The Type Ia Supernova Rate in Redshift 0.5--0.9 Galaxy Clusters

Supernova (SN) rates are potentially powerful diagnostics of metal enrichment and SN physics, particularly in galaxy clusters with their deep, metal-retaining potentials and relatively simple star-formation histories. We have carried out a survey for supernovae (SNe) in galaxy clusters, at a redshift range 0.5<z<0.9, using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. We reimaged a sample of 15 clusters that were previously imaged by ACS, thus obtaining two to three epochs per cluster, in which we discovered five likely cluster SNe, six possible cluster SNe Ia, two hostless SN candidates, and several background and foreground events. Keck spectra of the host galaxies were obtained to establish cluster membership. We conducted detailed efficiency simulations, and measured the stellar luminosities of the clusters using Subaru images. We derive a cluster SN rate of 0.35 SNuB +0.17/-0.12 (statistical) \pm0.13 (classification) \pm0.01 (systematic) [where SNuB = SNe (100 yr 10^10 L_B_sun)^-1] and 0.112 SNuM +0.055/-0.039 (statistical) \pm0.042 (classification) \pm0.005 (systematic) [where SNuM = SNe (100 yr 10^10 M_sun)^-1]. As in previous measurements of cluster SN rates, the uncertainties are dominated by small-number statistics. The SN rate in this redshift bin is consistent with the SN rate in clusters at lower redshifts (to within the uncertainties), and shows that there is, at most, only a slight increase of cluster SN rate with increasing redshift. The low and fairly constant SN Ia rate out to z~1 implies that the bulk of the iron mass in clusters was already in place by z~1. The recently observed doubling of iron abundances in the intracluster medium between z=1 and 0, if real, is likely the result of redistribution of existing iron, rather than new production of iron.Comment: Accepted to ApJ. Full resolution version available at http://kicp.uchicago.edu/~kerens/HSTclusterSNe

An Open Pilot Study of Training Hostile Interpretation Bias to Treat Disruptive Mood Dysregulation Disorder

Objective: Irritability in disruptive mood dysregulation disorder (DMDD) may be associated with a biased tendency to judge ambiguous facial expressions as angry. We conducted three experiments to explore this bias as a treatment target. We tested: 1) whether youth with DMDD express this bias; 2) whether judgment of ambiguous faces can be altered in healthy youth by training; and 3) whether such training in youth with DMDD is associated with reduced irritability and associated changes in brain function. Methods: Participants in all experiments made happy versus angry judgments of faces that varied along a happy to angry continuum. These judgments were used to quantify a “balance point,” the facial expression at which a participant's judgment switches from predominantly happy to predominantly angry. We first compared balance points in youth with DMDD (n = 63) versus healthy youth (n = 26). We then conducted a double-blind, randomized controlled trial of active versus sham balance-point training in 19 healthy youth. Finally, we piloted open, active balance-point training in 14 youth with DMDD, with 10 completing an implicit functional MRI (fMRI) face-emotion processing task. Results: Relative to healthy youth, DMDD youth manifested a shifted balance point, expressed as a tendency to classify ambiguous faces as angry rather than happy. In both healthy and DMDD youth, active training is associated with a shift in balance point toward more happy judgments. In DMDD, evidence suggests that active training may be associated with decreased irritability and changes in activation in the lateral orbitofrontal cortex. Conclusions:These results set the stage for further research on computer-based treatment targeting interpretation bias of angry faces in DMDD. Such treatment may decrease irritability and alter neural responses to subtle expressions of happiness and anger

The Cytosolic Tail of the Golgi Apyrase Ynd1 Mediates E4orf4-Induced Toxicity in Saccharomyces cerevisiae

The adenovirus E4 open reading frame 4 (E4orf4) protein contributes to regulation of the progression of virus infection. When expressed individually, E4orf4 was shown to induce non-classical transformed cell-specific apoptosis in mammalian cells. At least some of the mechanisms underlying E4orf4-induced toxicity are conserved from yeast to mammals, including the requirement for an interaction of E4orf4 with protein phosphatase 2A (PP2A). A genetic screen in yeast revealed that the Golgi apyrase Ynd1 associates with E4orf4 and contributes to E4orf4-induced toxicity, independently of Ynd1 apyrase activity. Ynd1 and PP2A were shown to contribute additively to E4orf4-induced toxicity in yeast, and to interact genetically and physically. A mammalian orthologue of Ynd1 was shown to bind E4orf4 in mammalian cells, confirming the evolutionary conservation of this interaction. Here, we use mutation analysis to identify the cytosolic tail of Ynd1 as the protein domain required for mediation of the E4orf4 toxic signal and for the interaction with E4orf4. We also show that E4orf4 associates with cellular membranes in yeast and is localized at their cytoplasmic face. However, E4orf4 is membrane-associated even in the absence of Ynd1, suggesting that additional membrane proteins may mediate E4orf4 localization. Based on our results and on a previous report describing a collection of Ynd1 protein partners, we propose that the Ynd1 cytoplasmic tail acts as a scaffold, interacting with a multi-protein complex, whose targeting by E4orf4 leads to cell death

Coimmunoprecipitation of E4orf4 with WT and mutant Ynd1 proteins.

<p>E4orf4 was immunoprecipitated from <i>ynd1Δ</i> yeast cells expressing the indicated Ynd1 proteins. Western blots of the immune complexes (IP) and input lysates (10% of IP) were stained with the indicated antibodies.</p

Transduction of E4orf4 toxicity by WT and mutant Ynd1 constructs.

<p><b>A</b>. <i>ynd1Δ</i> cells transformed with WT Ynd1 or mutant Ynd1 constructs in the presence or absence of E4orf4 were serially diluted (1∶5) and grown on glucose and galactose plates. <b>B</b>. <i>ynd1Δ</i> cells were transformed with WT Ynd1 or mutant constructs in the presence or absence of E4orf4. Yeast cell concentrations were equalized according to OD measurements, and equal amounts of yeast were grown on glucose and galactose plates. A quantitative comparison of the ability of WT and mutant Ynd1 constructs to mediate the E4orf4 toxic signal was performed as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0015539#s2" target="_blank">Materials and Methods</a> section, and reflects relative colony sizes in the presence and absence of E4orf4. The activity of WT Ynd1 was defined as 1. Three experiments were carried out containing 2 duplicates each. Error bars represent the standard error.</p