Evidence for Pre-Existing Dust in the Bright Type IIn SN 2010jl

SN 2010jl was an extremely bright, Type IIn SNe which showed a significant IR excess no later than 90 days after explosion. We have obtained Spitzer 3.6 and 4.5 \mum and JHK observations of SN 2010jl \sim90 days post explosion. Little to no reddening in the host galaxy indicated that the circumstellar material lost from the progenitor must lie in a torus inclined out of the plane of the sky. The likely cause of the high mid-IR flux is the reprocessing of the initial flash of the SN by pre-existing circumstellar dust. Using a 3D Monte Carlo Radiative Transfer code, we have estimated that between 0.03-0.35 Msun of dust exists in a circumstellar torus around the SN located 6 \times 10 ^17 cm away from the SN and inclined between 60-80\cdot to the plane of the sky. On day 90, we are only seeing the illumination of approximately 5% of this torus, and expect to see an elevated IR flux from this material up until day \sim 450. It is likely this dust was created in an LBV-like mass loss event of more than 3 Msun, which is large but consistent with other LBV progenitors such as {\eta} Carinae.Comment: Accepted in A

Phase II trial of temsirolimus for relapsed/refractory primary CNS lymphoma

Purpose: In this phase II study (NCT00942747), temsirolimus was tested in patients with relapsed or refractory primary CNS lymphoma (PCNSL). Patients and Methods: Immunocompetent adults with histologically confirmed PCNSL after experiencing high-dose methotrexate-based chemotherapy failure who were not eligible for or had experienced high-dose chemotherapy with autologous stem-cell transplant failure were included. The first cohort (n = 6) received 25 mg temsirolimus intravenously once per week. All consecutive patients received 75 mg intravenously once per week. Results: Thirty-seven eligible patients (median age, 70 years) were included whose median time since their last treatment was 3.9 months (range, 0.1 to 14.6 months). Complete response was seen in five patients (13.5%), complete response unconfirmed in three (8%), and partial response in 12 (32.4%) for an overall response rate of 54%. Median progression-free survival was 2.1 months (95% CI, 1.1 to 3.0 months). The most frequent Common Toxicity Criteria ≥ 3° adverse event was hyperglycemia in 11 (29.7%) patients, thrombocytopenia in eight (21.6%), infection in seven (19%), anemia in four (10.8%), and rash in three (8.1%). Fourteen blood/CSF pairs were collected in nine patients (10 pairs in five patients in the 25-mg cohort and four pairs in four patients in the 75-mg cohort). The mean maximum blood concentration was 292 ng/mL for temsirolimus and 37.2 ng/mL for its metabolite sirolimus in the 25-mg cohort and 484 ng/mL and 91.1 ng/mL, respectively, in the 75-mg cohort. Temsirolimus CSF concentration was 2 ng/mL in one patient in the 75-mg cohort; in all others, no drug was found in their CSF. Conclusion: Single-agent temsirolimus at a weekly dose of 75 mg was found to be active in relapsed/refractory patients with PCNSL; however, responses were usually short lived

A Massive Progenitor of the Luminous Type IIn Supernova 2010jl

The bright, nearby, recently discovered supernova SN2010jl is a member of the rare class of relatively luminous Type~IIn events. Here we report archival HST observations of its host galaxy UGC5189A taken roughly 10yr prior to explosion, as well as early-time optical spectra of the SN. The HST images reveal a bright, blue point source at the position of the SN, with an absolute magnitude of -12.0 in the F300W filter. If it is not just a chance alignment, the source at the SN position could be (1) a massive young (less than 6 Myr) star cluster in which the SN resided, (2) a quiescent, luminous blue star with an apparent temperature around 14,000K, (3) a star caught during a bright outburst akin to those of LBVs, or (4) a combination of option 1 and options 2 or 3. Although we cannot confidently choose between these possibilities with the present data, any of them imply that the progenitor of SN2010jl had an initial mass above 30Msun. This reinforces mounting evidence that many SNe IIn result from very massive stars, that massive stars can produce visible SNe without collapsing quietly to black holes, and that massive stars can retain their H envelopes until shortly before explosion. Standard stellar evolution models fail to account for these observed properties.Comment: 6 pages, 4 figures, submitted to Ap

SN 2010jl in UGC 5189: Yet another luminous type IIn supernova in a metal-poor galaxy

We present ASAS data starting 25 days before the discovery of the recent type IIn SN 2010jl, and we compare its light curve to other luminous IIn SNe, showing that it is a luminous (M_I ~ -20.5) event. Its host galaxy, UGC 5189, has a low gas-phase oxygen abundance (12 + log(O/H) = 8.2), which reinforces the emerging trend that over-luminous core-collapse supernovae are found in the low-metallicity tail of the galaxy distribution, similar to the known trend for the hosts of long GRBs. We compile oxygen abundances from the literature and from our own observations of UGC 5189, and we present an unpublished spectrum of the luminous type Ic SN 2010gx that we use to estimate its host metallicity. We discuss these in the context of host metallicity trends for different classes of core-collapse objects. The earliest generations of stars are known to be enhanced in [O/Fe] relative to the Solar mixture; it is therefore likely that the stellar progenitors of these overluminous supernovae are even more iron-poor than they are oxygen-poor. A number of mechanisms and massive star progenitor systems have been proposed to explain the most luminous core-collapse supernovae; any successful theory will need to include the emerging trend that points towards low-metallicity for the massive progenitor stars. This trend for very luminous supernovae to strongly prefer low-metallicity galaxies should be taken into account when considering various aspects of the evolution of the metal-poor early universe. (abridged)Comment: 27 pages, 7 figures, 2 tables. Accepted for publication in Ap

Caltech Core-Collapse Project (CCCP) observations of type IIn supernovae: typical properties and implications for their progenitor stars

Type IIn Supernovae (SNe IIn) are rare events, constituting only a few percent of all core-collapse SNe, and the current sample of well observed SNe IIn is small. Here, we study the four SNe IIn observed by the Caltech Core-Collapse Project (CCCP). The CCCP SN sample is unbiased to the extent that object selection was not influenced by target SN properties. Therefore, these events are representative of the observed population of SNe IIn. We find that a narrow P-Cygni profile in the hydrogen Balmer lines appears to be a ubiquitous feature of SNe IIn. Our light curves show a relatively long rise time (>20 days) followed by a slow decline stage (0.01 to 0.15 mag/day), and a typical V-band peak magnitude of M_V=-18.4 +/- 1.0 mag. We measure the progenitor star wind velocities (600 - 1400 km/s) for the SNe in our sample and derive pre-explosion mass loss rates (0.026 - 0.12 solar masses per year). We compile similar data for SNe IIn from the literature, and discuss our results in the context of this larger sample. Our results indicate that typical SNe IIn arise from progenitor stars that undergo LBV-like mass-loss shortly before they explode.Comment: ApJ, submitte

A Spitzer Survey for Dust in Type IIn Supernovae

Recent observations suggest that Type IIn supernovae (SNe IIn) may exhibit late-time (>100 days) infrared (IR) emission from warm dust more than other types of core-collapse SNe. Mid-IR observations, which span the peak of the thermal spectral energy distribution, provide useful constraints on the properties of the dust and, ultimately, the circumstellar environment, explosion mechanism, and progenitor system. Due to the low SN IIn rate (<10% of all core-collapse SNe), few IR observations exist for this subclass. The handful of isolated studies, however, show late-time IR emission from warm dust that, in some cases, extends for five or six years post-discovery. While previous Spitzer/IRAC surveys have searched for dust in SNe, none have targeted the Type IIn subclass. This article presents results from a warm Spitzer/IRAC survey of the positions of all 68 known SNe IIn within a distance of 250 Mpc between 1999 and 2008 that have remained unobserved by Spitzer more than 100 days post-discovery. The detection of late-time emission from ten targets (~15%) nearly doubles the database of existing mid-IR observations of SNe IIn. Although optical spectra show evidence for new dust formation in some cases, the data show that in most cases the likely origin of the mid-IR emission is pre-existing dust, which is continuously heated by optical emission generated by ongoing circumstellar interaction between the forward shock and circumstellar medium. Furthermore, an emerging trend suggests that these SNe decline at ~1000--2000 days post-discovery once the forward shock overruns the dust shell. The mass-loss rates associated with these dust shells are consistent with luminous blue variable (LBV) progenitors.Comment: Accepted for publication to ApJ, 17 pages, 10 figures, 10 table

Use of bioanalyzer electropherograms for quality control and target evaluation in microarray expression profiling studies of ocular tissues

Expression profiling with DNA microarrays has been used to examine the transcriptome of a wide spectrum of vertebrate cells and tissues. The sensitivity and accuracy of the data generated is dependent on the quality and composition of the input RNA. In this report, we examine the quality and array performance of over 200 total RNA samples extracted from ocular tissues and cells that have been processed in a microarray core laboratory over a 7-year period. Total RNA integrity and cRNA target size distribution were assessed using the 2100 Bioanalyzer. We present Affymetrix GeneChip array performance metrics for different ocular samples processed according to a standard microarray assay workflow including several quality control checkpoints. Our review of ocular sample performance in the microarray assay demonstrates the value of considering tissue-specific characteristics in evaluating array data. Specifically, we show that Bioanalyzer electropherograms reveal highly abundant mRNAs in lacrimal gland targets that are correlated with variation in array assay performance. Our results provide useful benchmarks for other gene expression studies of ocular systems

SN 2011ht: Confirming a Class of Interacting Supernovae with Plateau Light Curves (Type IIn-P)

We present photometry and spectroscopy of the Type IIn supernova (SN) 2011ht, identified previously as a SN impostor. The light curve exhibits an abrupt transition from a well-defined ~120 day plateau to a steep bolometric decline. Leading up to peak brightness, a hot emission-line spectrum exhibits signs of interaction with circumstellar material (CSM), in the form of relatively narrow P-Cygni features of H I and He I superimposed on broad Lorentzian wings. For the remainder of the plateau phase the spectrum exhibits strengthening P-Cygni profiles of Fe II, Ca II, and H-alpha. By day 147, after the plateau has ended, the SN entered the nebular phase, heralded by the appearance of forbidden transitions of [O I], [O II], and [Ca II] over a weak continuum. At this stage, the light curve exhibits a low luminosity that is comparable to that sub-luminous Type II-P supernovae, and a relatively fast visual-wavelength decline that is significantly steeper than the Co-56 decay rate. However, the total bolometric decline, including the IR luminosity, is consistent with Co-56 decay, and implies a low Ni-56 mass of ~0.01 M(Sun). We therefore characterize SN 2011ht as a bona-fide core-collapse SN very similar to the peculiar SNe IIn 1994W and 2009kn. These three SNe define a subclass, which are Type IIn based on their spectrum, but that also exhibit well-defined plateaus and produce low Ni-56 yields. We therefore suggest Type IIn-P as a name for this subclass. Possible progenitors of SNe IIn-P, consistent with the available data, include 8-10 M(Sun) stars, which undergo core collapse as a result of electron capture after a brief phase of enhanced mass loss, or more massive M>25 M(Sun) progenitors, which experience substantial fallback of the metal-rich radioactive ejecta. In either case, the energy radiated by these three SNe during their plateau must be dominated by CSM interaction (abridged).Comment: accepted, post-proof version (includes new data

A Central Excess of Stripped-Envelope Supernovae within Disturbed Galaxies

This paper presents an analysis of core-collapse supernova distributions in isolated and interacting host galaxies, paying close attention to the selection effects involved in conducting host galaxy supernova studies. When taking into account all of the selection effects within our host galaxy sample, we draw the following conclusions: i) Within interacting, or 'disturbed', systems there is a real, and statistically significant, increase in the fraction of stripped-envelope supernovae in the central regions. A discussion into what may cause this increased fraction, compared to the more common type IIP supernovae, and type II supernovae without sub-classifications, is presented. Selection effects are shown not to drive this result, and so we propose that this study provides direct evidence for a high-mass weighted initial mass function within the central regions of disturbed galaxies. ii) Within 'undisturbed' spiral galaxies the radial distribution of type Ib and type Ic supernovae is statistically very different, with the latter showing a more centrally concentrated distribution. This could be driven by metallicity gradients in these undisturbed galaxies, or radial variations in other properties (binarity or stellar rotation) driving envelope loss in progenitor stars. This result is not found in 'disturbed' systems, where the distributions of type Ib and Ic supernovae are consistent.Comment: Accepted for publication in MNRA

The Unusual Temporal and Spectral Evolution of SN2011ht. II. Peculiar Type IIn or Impostor?

SN2011ht has been described both as a true supernova and as an impostor. In this paper, we conclude that it does not match some basic expectations for a core-collapse event. We discuss SN2011ht's spectral evolution from a hot dense wind to a cool dense wind, followed by the post-plateau appearance of a faster low density wind during a rapid decline in luminosity. We identify a slow dense wind expanding at only 500--600 km/s, present throughout the eruption. A faster wind speed V ~ 900 km/s may be identified with a second phase of the outburst. There is no direct or significant evidence for any flow speed above 1000 km/s; the broad asymmetric wings of Balmer emission lines in the hot wind phase were due to Thomson scattering, not bulk motion. We estimate a mass loss rate of order 0.04 Msun/yr during the hot dense wind phase of the event. There is no evidence that the kinetic energy substantially exceeded the luminous energy, roughly 2 X 10^49 ergs; so the total energy was far less than a true SN. We suggest that SN2011ht was a giant eruption driven by super-Eddington radiation pressure, perhaps beginning about 6 months before the discovery. A strongly non-spherical SN might also account for the data, at the cost of more free parameters.Comment: To appear in the Astrophysical Journal, Nov. 20 issue. Expanded discussion re SN impostors and Type IIn SNe plus two new figure