SOCIAL ACTIVISM: TEACHING ACTIVISM THROUGH SOCIALLY CONSCIOUS PLAYS

Students derived numerous benefits while participating in theater by gaining confidence and social skills. To help navigate these skills, this thesis showed that using a socially conscious play helped participants gain empathy, an understanding of their community, and an interest in social activism. This protocol outlined the process of producing And a Child Shall Lead, by Michael Slade. The entire process of working on Slade’s play allowed students in middle school to gain an understanding of the Holocaust and helped them appreciate how social activism can shape communities

Strong Evolution of X-Ray Absorption in the Type IIn Supernova SN 2010jl

We report two epochs of Chandra-ACIS X-ray imaging spectroscopy of the nearby bright Type IIn supernova SN 2010jl, taken around 2 months and then a year after the explosion. The majority of the X-ray emission in both the spectra is characterized by a high temperature (\ga 10 keV) and is likely to be from the forward shocked region resulting from circumstellar interaction. The absorption column density in the first spectrum is high, ~ 10^{24} cm^{-2}, more than 3 orders of magnitude higher than the Galactic absorption column, and we attribute it to absorption by circumstellar matter. In the second epoch observation, the column density has decreased by a factor of 3, as expected for shock propagation in the circumstellar medium. The unabsorbed 0.2-10 keV luminosity at both epochs is ~7 x 10^{41} erg/s. The 6.4 keV Fe line clearly present in the first spectrum is not detected in the second spectrum. The strength of the fluorescent line is roughly that expected for the column density of circumstellar gas, provided the Fe is not highly ionized. There is also evidence for an absorbed power law component in both the spectra, which we attribute to a background ultraluminous X-ray source.Comment: 14 pages, 4 figures, resubmitted to ApJL after responding to referee's comment

Common Envelope Evolution Leading to Supernovae with Dense Interaction

A variety of supernova events, including Type IIn supernovae and ultraluminous supernovae, appear to have lost up to solar masses of their envelopes in 10's to 100's of years leading up to the explosion. In order to explain the close timing of the mass loss and supernova events, we explore the possibility that the mass loss is driven by common envelope evolution of a compact object (neutron star or black hole) in the envelope of a massive star and the supernova is triggered by the inspiral of the compact object to the central core of the companion star. The expected rate of such events is smaller than the observed rate of Type IIn supernovae but the rates may agree within the uncertainties. The mass loss velocity is related to the escape velocity from the common envelope system and is comparable to the observed velocity of 100's of km s$^{-1}$ in Type IIn events. The mass loss is expected to be denser near the equatorial plane of the binary system and there is good evidence that the circumstellar media in Type IIn supernovae are asymmetric. Some of these supernova types show evidence for energies in excess of the canonical $10^{51}$ ergs, which might be the result of explosions from rapid accretion onto a compact object through a disk.Comment: Small changes to agree with published version: ApJ Letters, 752, L2 (2012

Caltech Core-Collapse Project (CCCP) Observations of Type II Supernovae: Evidence for Three Distinct Photometric Subtypes

We present R-Band light curves of Type II supernovae (SNe) from the Caltech Core Collapse Project (CCCP). With the exception of interacting (Type IIn) SNe and rare events with long rise times, we find that most light curve shapes belong to one of three distinct classes: plateau, slowly declining and rapidly declining events. The last class is composed solely of Type IIb SNe which present similar light curve shapes to those of SNe Ib, suggesting, perhaps, similar progenitor channels. We do not find any intermediate light curves, implying that these subclasses are unlikely to reflect variance of continuous parameters, but rather might result from physically distinct progenitor systems, strengthening the suggestion of a binary origin for at least some stripped SNe. We find a large plateau luminosity range for SNe IIP, while the plateau lengths seem rather uniform at approximately 100 days. As analysis of additional CCCP data goes on and larger samples are collected, demographic studies of core collapse SNe will likely continue to provide new constraints on progenitor scenarios.Comment: Submitted to ApJ

Wave-Driven Mass Loss in the Last Year of Stellar Evolution: Setting the Stage for the Most Luminous Core-Collapse Supernovae

During the late stages of stellar evolution in massive stars (C fusion and later), the fusion luminosity in the core of the star exceeds the star's Eddington luminosity. This can drive vigorous convective motions which in turn excite internal gravity waves. The local wave energy flux excited by convection is itself well above Eddington during the last few years in the life of the star. We suggest that an interesting fraction of the energy in gravity waves can, in some cases, convert into sound waves as the gravity waves propagate (tunnel) towards the stellar surface. The subsequent dissipation of the sound waves can unbind up to several $M_\odot$ of the stellar envelope. This wave-driven mass loss can explain the existence of extremely large stellar mass loss rates just prior to core-collapse, which are inferred via circumstellar interaction in some core-collapse supernovae (e.g., SNe 2006gy and PTF 09uj, and even Type IIn supernovae more generally). An outstanding question is understanding what stellar parameters (mass, rotation, metallicity, age) are the most susceptible to wave-driven mass loss. This depends on the precise internal structure of massive stars and the power-spectrum of internal gravity waves excited by stellar convection.Comment: Version accepted to MNRA

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

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

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

Type IIn Supernova SN 2010jl: Optical Observations for Over 500 Days After Explosion

We present extensive optical observations of a Type IIn supernova (SN) 2010jl for the first 1.5 years after the discovery. The UBVRI light curves demonstrated an interesting two-stage evolution during the nebular phase, which almost flatten out after about 90 days from the optical maximum. SN 2010jl has one of the highest intrinsic H_alpha luminosity ever recorded for a SN IIn, especially at late phase, suggesting a strong interaction of SN ejecta with the dense circumstellar material (CSM) ejected by the progenitor. This is also indicated by the remarkably strong Balmer lines persisting in the optical spectra. One interesting spectral evolution about SN 2010jl is the appearance of asymmetry of the Balmer lines. These lines can be well decomposed into a narrow component and an intermediate-width component. The intermediate-width component showed a steady increase in both strength and blueshift with time until t ~ 400 days after maximum, but it became less blueshifted at t ~ 500 days when the line profile appeared relatively symmetric again. Owing to that a pure reddening effect will lead to a sudden decline of the light curves and a progressive blueshift of the spectral lines, we therefore propose that the asymmetric profiles of H lines seen in SN 2010jl is unlikely due to the extinction by newly formed dust inside the ejecta, contrary to the explanation by some early studies. Based on a simple CSM-interaction model, we speculate that the progenitor of SN 2010jl may suffer a gigantic mass loss (~ 30-50 M_sun) in a few decades before explosion. Considering a slow moving stellar wind (e.g., ~ 28 km/s) inferred for the preexisting, dense CSM shell and the extremely high mass-loss rate (1-2 M_sun per yr), we suggest that the progenitor of SN 2010jl might have experienced a red supergiant stage and explode finally as a post-red supergiant star with an initial mass above 30-40 M_sun.Comment: 34 pages, 9 figures, accepted for publication in A

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