Person: Stubbs, Christopher
Loading...
Email Address
AA Acceptance Date
Birth Date
Research Projects
Organizational Units
Job Title
Last Name
Stubbs
First Name
Christopher
Name
Stubbs, Christopher
56 results
Search Results
Now showing 1 - 10 of 56
Publication Cosmological Constraints from Measurements of Type Ia Supernovae Discovered during the First 1.5 yr of the Pan-STARRS1 Survey(IOP Publishing, 2014) Rest, Armin; Scolnic, D.; Foley, R. J.; Huber, M. E.; Chornock, R.; Narayan, Gautham; Tonry, J. L.; Berger, Edo; Soderberg, Alicia; Stubbs, Christopher; Riess, A.; Kirshner, Robert; Smartt, S. J.; Schlafly, E.; Rodney, S.; Botticella, M. T.; Brout, D.; Challis, P.; Czekala, Ian; Drout, Maria Rebecca; Hudson, M. J.; Kotak, R.; Leibler, C.; Lunnan, R; Marion, G. H.; McCrum, M.; Milisavljevic, D.; Pastorello, A.; Sanders, Nathan Edward; Smith, K.; Stafford, E.; Thilker, D.; Valenti, S.; Wood-Vasey, W. M.; Zheng, Z.; Burgett, W. S.; Chambers, K. C.; Denneau, L.; Draper, P. W.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Metcalfe, N.; Price, P. A.; Sweeney, W.; Wainscoat, R.; Waters, C.We present griz P1 light curves of 146 spectroscopically confirmed Type Ia supernovae (SNe Ia; 0.03 < z < 0.65) discovered during the first 1.5 yr of the Pan-STARRS1 Medium Deep Survey. The Pan-STARRS1 natural photometric system is determined by a combination of on-site measurements of the instrument response function and observations of spectrophotometric standard stars. We find that the systematic uncertainties in the photometric system are currently 1.2% without accounting for the uncertainty in the Hubble Space Telescope Calspec definition of the AB system. A Hubble diagram is constructed with a subset of 113 out of 146 SNe Ia that pass our light curve quality cuts. The cosmological fit to 310 SNe Ia (113 PS1 SNe Ia + 222 light curves from 197 low-z SNe Ia), using only supernovae (SNe) and assuming a constant dark energy equation of state and flatness, yields $w=-1.120^{+0.360}_{-0.206}\hbox{(Stat)} ^{+0.269}_{-0.291}\hbox{(Sys)}$. When combined with BAO+CMB(Planck)+H 0, the analysis yields $\Omega _{\rm M}=0.280^{+0.013}_{-0.012}$ and $w=-1.166^{+0.072}_{-0.069}$ including all identified systematics. The value of w is inconsistent with the cosmological constant value of –1 at the 2.3σ level. Tension endures after removing either the baryon acoustic oscillation (BAO) or the H 0 constraint, though it is strongest when including the H 0 constraint. If we include WMAP9 cosmic microwave background (CMB) constraints instead of those from Planck, we find $w=-1.124^{+0.083}_{-0.065}$, which diminishes the discord to <2σ. We cannot conclude whether the tension with flat ΛCDM is a feature of dark energy, new physics, or a combination of chance and systematic errors. The full Pan-STARRS1 SN sample with ~three times as many SNe should provide more conclusive results.Publication A Robust Quantification of Galaxy Cluster Morphology Using Asymmetry and Central Concentration(American Astronomical Society, 2013) Nurgaliev, Daniyar Rashidovich; McDonald, M.; Benson, B. A.; Miller, E. D.; Stubbs, Christopher; Viklinin, AlexeyWe present a novel quantitative scheme of cluster classification based on the morphological properties that are manifested in X-ray images. We use a conventional radial surface brightness concentration parameter (c_SB) as defined previously by others and a new asymmetry parameter, which we define in this paper. Our asymmetry parameter, which we refer to as photon asymmetry (A_phot), was developed as a robust substructure statistic for cluster observations with only a few thousand counts. To demonstrate that photon asymmetry exhibits better stability than currently popular power ratios and centroid shifts, we artificially degrade the X-ray image quality by (1) adding extra background counts, (2) eliminating a fraction of the counts, (3) increasing the width of the smoothing kernel, and (4) simulating cluster observations at higher redshift. The asymmetry statistic presented here has a smaller statistical uncertainty than competing substructure parameters, allowing for low levels of substructure to be measured with confidence. A phot is less sensitive to the total number of counts than competing substructure statistics, making it an ideal candidate for quantifying substructure in samples of distant clusters covering a wide range of observational signal-to-noise ratios. Additionally, we show that the asymmetry-concentration classification separates relaxed, cool-core clusters from morphologically disturbed mergers, in agreement with by-eye classifications. Our algorithms, freely available as Python scripts (https://github.com/ndaniyar/aphot), are completely automatic and can be used to rapidly classify galaxy cluster morphology for large numbers of clusters without human intervention.Publication WISE J233237.05–505643.5: A Double-peaked, Broad-lined Active Galactic Nucleus with a Spiral-shaped Radio Morphology.(American Astronomical Society, 2013) Tsai, Chao-Wei; Jarrett, T. H.; Stern, Daniel; Emonts, Bjorn; Barrows, R. Scott; Assef, Roberto J.; Norris, Ray P.; Eisenhardt, Peter R. M.; Lonsdale, Carol; Blain, Andrew W.; Benford, Dominic J.; Wu, Jingwen; Stalder, Brian; Stubbs, Christopher; High, F. William; Li, K. L.; Kong, Albert K. H.We present radio continuum mapping, optical imaging, and spectroscopy of the newly discovered double-peaked, broad-lined active galactic nucleus (AGN) WISE J233237.05–505643.5 at redshift z = 0.3447. This source exhibits an FR-I and FR-II hybrid morphology, characterized by a bright core, jet, and Doppler-boosted lobe structures in Australian Telescope Compact Array continuum maps at 1.5, 5.6, and 9 GHz. Unlike most FR-II objects, W2332–5056 is hosted by a disk-like galaxy. The core has a projected 5'' linear radio feature that is perpendicular to the curved primary jet, hinting at unusual and complex activity within the inner 25 kpc. The multi-epoch, optical-near-IR photometric measurements indicate significant variability over a 3-20 yr baseline from the AGN component. Gemini South optical data show unusual double-peaked emission-line features: the centroids of the broad-lined components of H-alpha and H-beta are blueshifted with respect to the narrow lines and host galaxy by ~3800 km s–1. We examine possible cases that involve single or double supermassive black holes in the system and discuss the required future investigations to disentangle the mysterious nature of this system.Publication A Search for Fast Optical Transients in the Pan-STARRS1 Medium-Deep Survey: M-Dwarf Flares, Asteroids, Limits on Extragalactic Rates, and Implications for LSST(American Astronomical Society, 2013) Berger, Edo; Leibler, C. N.; Chornock, R; Rest, A.; Foley, R. J.; Soderberg, Alicia; Price, P. A.; Burgett, W. S.; Chambers, K. C.; Flewelling, H.; Huber, M. E.; Magnier, E. A.; Metcalfe, N.; Stubbs, Christopher; Tonry, J. L.We present a search for fast optical transients (τ ~ 0.5 hr-1 day) using repeated observations of the Pan-STARRS1 Medium-Deep Survey (PS1/MDS) fields. Our search takes advantage of the consecutive g P1 r P1 observations (16.5 minutes in each filter), by requiring detections in both bands, with non-detections on preceding and subsequent nights. We identify 19 transients brighter than 22.5 AB mag (S/N gsim 10). Of these, 11 events exhibit quiescent counterparts in the deep PS1/MDS templates that we identify as M4-M9 dwarfs at d ≈ 0.2-1.2 kpc. The remaining eight transients lack quiescent counterparts, exhibit mild but significant astrometric shifts between the g P1 and r P1 images, colors of (g – r)P1 ≈ 0.5-0.8 mag, non-varying light curves, and locations near the ecliptic plane with solar elongations of about 130°, which are all indicative of main-belt asteroids near the stationary point of their orbits. With identifications for all 19 transients, we place an upper limit of R FOT(τ ~ 0.5 hr) lsim 0.12 deg–2 day–1 (95% confidence level) on the sky-projected rate of extragalactic fast transients at lsim 22.5 mag, a factor of 30-50 times lower than previous limits; the limit for a timescale of ~1 day is R FOT lsim 2.4 × 10–3 deg–2 day–1. To convert these sky-projected rates to volumetric rates, we explore the expected peak luminosities of fast optical transients powered by various mechanisms, and find that non-relativistic events are limited to M ≈ –10 to ≈ – 14 mag for a timescale of ~0.5 hr to ~1 day, while relativistic sources (e.g., gamma-ray bursts, magnetar-powered transients) can reach much larger luminosities. The resulting volumetric rates are lsim 13 Mpc–3 yr–1 (M ≈ –10 mag), lsim 0.05 Mpc–3 yr–1 (M ≈ –14 mag), and lsim 10–6 Mpc–3 yr–1 (M ≈ –24 mag), significantly above the nova, supernova, and gamma-ray burst rates, respectively, indicating that much larger surveys are required to provide meaningful constraints. Motivated by the results of our search, we discuss strategies for identifying fast optical transients in the Large Synoptic Survey Telescope main survey, and reach the optimistic conclusion that the veil of foreground contaminants can be lifted with the survey data, without the need for expensive follow-up observations.Publication Slowly Fading Super-Luminous Supernovae That Are Not Pair-Instability Explosions(Nature Publishing Group, 2013) Nicholl, M.; Smartt, S. J.; Jerkstrand, A.; Inserra, C.; McCrum, M.; Kotak, R.; Fraser, M.; Wright, D.; Chen, T.-W.; Smith, K.; Young, D. R.; Sim, S. A.; Valenti, S.; Howell, D. A.; Bresolin, F.; Kudritzki, R. P.; Tonry, J. L.; Huber, M. E.; Rest, A.; Pastorello, A.; Tomasella, L.; Cappellaro, E.; Benetti, S.; Mattila, S.; Kankare, E.; Kangas, T.; Leloudas, G.; Sollerman, J.; Taddia, F.; Berger, E.; Chornock, R; Narayan, Gautham; Stubbs, Christopher; Foley, R. J.; Lunnan, R; Soderberg, Alicia; Sanders, Nathan Edward; Milisavljevic, Danny; Margutti, Raffaella; Kirshner, Robert; Elias-Rosa, N.; Morales-Garoffolo, A.; Taubenberger, S.; Botticella, M. T.; Gezari, S.; Urata, Y.; Rodney, S.; Riess, A. G.; Scolnic, D.; Wood-Vasey, W. M.; Burgett, W. S.; Chambers, K.; Flewelling, H. A.; Magnier, E. A.; Kaiser, N.; Metcalfe, N.; Morgan, J.; Price, P. A.; Sweeney, W.; Waters, C.Super-luminous supernovae that radiate more than 10\(^{44}\) ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1–4. Some evolve slowly, resembling models of ‘pair-instability’ supernovae. Such models involve stars with original masses 140–260 times that of the Sun that now have carbon–oxygen cores of 65–130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron–positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of \(^{56}\)Ni are synthesized; this isotope decays to \(^{56}\)Fe via \(^{56}\)Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10–16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10\(^{−6}\) times that of the core-collapse rate.Publication PS1-10afx at z = 1.388: Pan-STARRS1 Discovery of a New Type of Superluminous Supernova(American Astronomical Society, 2013) Chornock, R; Berger, Edo; Rest, A.; Milisavljevic, Danny; Lunnan, R; Foley, R. J.; Soderberg, Alicia; Smartt, S. J.; Burgasser, A. J.; Challis, Peter; Chomiuk, L.; Czekala, Ian; Drout, Maria Rebecca; Fong, W; Huber, M. E.; Kirshner, Robert; Leibler, C.; McLeod, Brian; Marion, G. H.; Narayan, Gautham; Riess, A. G.; Roth, K. C.; Sanders, Nathan Edward; Scolnic, D.; Smith, K.; Stubbs, Christopher; Tonry, J. L.; Valenti, S.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Magnier, E. A.; Price, P. A.We present the Pan-STARRS1 discovery of PS1-10afx, a unique hydrogen-deficient superluminous supernova (SLSN) at redshift z = 1.388. The light curve peaked at z P1 = 21.7 mag, making PS1-10afx comparable to the most luminous known SNe, with Mu = –22.3 mag. Our extensive optical and near-infrared observations indicate that the bolometric light curve of PS1-10afx rose on the unusually fast timescale of ~12 days to the extraordinary peak luminosity of 4.1 × 1044 erg s–1 (M bol = –22.8 mag) and subsequently faded rapidly. Equally important, the spectral energy distribution is unusually red for an SLSN, with a color temperature of ~6800 K near maximum light, in contrast to previous hydrogen-poor SLSNe, which are bright in the ultraviolet (UV). The spectra more closely resemble those of a normal SN Ic than any known SLSN, with a photospheric velocity of ~11, 000 km s–1 and evidence for line blanketing in the rest-frame UV. Despite the fast rise, these parameters imply a very large emitting radius (gsim 5 × 1015 cm). We demonstrate that no existing theoretical model can satisfactorily explain this combination of properties: (1) a nickel-powered light curve cannot match the combination of high peak luminosity with the fast timescale; (2) models powered by the spindown energy of a rapidly rotating magnetar predict significantly hotter and faster ejecta; and (3) models invoking shock breakout through a dense circumstellar medium cannot explain the observed spectra or color evolution. The host galaxy is well detected in pre-explosion imaging with a luminosity near L*, a star formation rate of ~15 M ☉ yr–1, and is fairly massive (~2 × 1010 M ☉), with a stellar population age of ~108 yr, also in contrast to the young dwarf hosts of known hydrogen-poor SLSNe. PS1-10afx is distinct from known examples of SLSNe in its spectra, colors, light-curve shape, and host galaxy properties, suggesting that it resulted from a different channel than other hydrogen-poor SLSNe.Publication The Pan-STARRS 1 Photometric Reference Ladder, Release 12.0(IOP Publishing, 2013) Magnier, E. A.; Schlafly, E.; Finkbeiner, Douglas; Juric, M.; Tonry, J. L.; Burgett, W. S.; Chambers, K. C.; Flewelling, H. A.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Price, P. A.; Sweeney, W. E.; Stubbs, ChristopherAs of 2012 Jan 21, the Pan-STARRS1 \(3\pi\) Survey has observed the 3/4 of the sky visible from Hawaii with a minimum of 2 and mean of 7.6 observations in 5 filters, \(g_{\rm P1},r_{\rm P1},i_{\rm P1},z_{\rm P1},y_{\rm P1}\). Now at the end of the second year of the mission, we are in a position to make an initial public release of a portion of this unprecedented dataset. This article describes the PS1 Photometric Ladder, Release 12.01 This is the first of a series of data releases to be generated as the survey coverage increases and the data analysis improves. The Photometric Ladder has rungs every hour in RA and at 4 intervals in declination. We will release updates with increased area coverage (more rungs) from the latest dataset until the PS1 survey and the final re-reduction are completed. The currently released catalog presents photometry of \(\sim 1000\) objects per square degree in the rungs of the ladder. Saturation occurs at \(g_{\rm P1}, r_{\rm P1}, i_{\rm P1} \sim 13.5; z_{\rm P1} \sim 13.0;\) and \(y_{\rm P1} \sim 12.0\). Photometry is provided for stars down to \(g_{\rm P1}, r_{\rm P1}, i_{\rm P1} \sim 19.1\) in the AB system. This data release depends on the rigid `Ubercal' photometric calibration using only the photometric nights, with systematic uncertainties of (8.0, 7.0, 9.0, 10.7, 12.4) millimags in \((g_{\rm P1},r_{\rm P1},i_{\rm P1},z_{\rm P1},y_{\rm P1})\). Areas covered only with lower quality nights are also included, and have been tied to the Ubercal solution via relative photometry; photometric accuracy of the non-photometric regions is lower and should be used with caution.Publication Galaxy clusters discovered via the Sunyaev-Zel'dovich effect in the first 720 square degrees of the South Pole Telescope survey(American Astronomical Society, 2013) Reichardt, C. L.; Stalder, B.; Bleem, L. E.; Montroy, T. E.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, M. L. N.; Bautz, M.; Bayliss, Matthew; Bazin, G.; Benson, B. A.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Rest, A.; Ruel, J.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Staniszewski, Z.; Stark, A. A.; Story, K.; Stubbs, Christopher; Suhada, R.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.We present a catalog of galaxy cluster candidates, selected through their Sunyaev-Zel'dovich (SZ) effect signature in the first 720 deg2 of the South Pole Telescope (SPT) survey. This area was mapped with the SPT in the 2008 and 2009 austral winters to a depth of ~18 μKCMB-arcmin at 150 GHz; 550 deg2 of it was also mapped to ~44 μKCMB-arcmin at 95 GHz. Based on optical imaging of all 224 candidates and near-infrared imaging of the majority of candidates, we have found optical and/or infrared counterparts for 158, which we then classify as confirmed galaxy clusters. Of these 158 clusters, 135 were first identified as clusters in SPT data, including 117 new discoveries reported in this work. This catalog triples the number of confirmed galaxy clusters discovered through the SZ effect. We report photometrically derived (and in some cases spectroscopic) redshifts for confirmed clusters and redshift lower limits for the remaining candidates. The catalog extends to high redshift with a median redshift of z = 0.55 and maximum confirmed redshift of z = 1.37. Forty-five of the clusters have counterparts in the ROSAT bright or faint source catalogs from which we estimate X-ray fluxes. Based on simulations, we expect the catalog to be nearly 100% complete above M 500 ≈ 5 × 1014 M ☉ h –1 70 at z gsim 0.6. There are 121 candidates detected at signal-to-noise ratio greater than five, at which the catalog purity is measured to be 95%. From this high-purity subsample, we exclude the z < 0.3 clusters and use the remaining 100 candidates to improve cosmological constraints following the method presented by Benson et al. Adding the cluster data to CMB + BAO + H 0 data leads to a preference for non-zero neutrino masses while only slightly reducing the upper limit on the sum of neutrino masses to ∑m ν < 0.38 eV (95% CL). For a spatially flat wCDM cosmological model, the addition of this catalog to the CMB + BAO + H 0 + SNe results yields σ8 = 0.807 ± 0.027 and w = –1.010 ± 0.058, improving the constraints on these parameters by a factor of 1.4 and 1.3, respectively. The larger cluster catalog presented in this work leads to slight improvements in cosmological constraints from those presented by Benson et al. These cosmological constraints are currently limited by uncertainty in the cluster mass calibration, not the size or quality of the cluster catalog. A multi-wavelength observation program to improve the cluster mass calibration will make it possible to realize the full potential of the final 2500 deg2 SPT cluster catalog to constrain cosmology.Publication Cosmological Constraints from Sunyaev-Zel'dovich-selected Clusters with X-Ray Observations in the First 178 deg2 of the South Pole Telescope Survey(American Astronomical Society, 2013) Benson, B. A.; de Haan, T.; Dudley, J. P.; Reichardt, C. L.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, Matthew; Bautz, M.; Bayliss, Matthew; Bazin, G.; Bleem, L. E.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; Desai, S.; Dobbs, M. A.; Foley, R. J.; Forman, William; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Murray, S. S.; Natoli, T.; Padin, S.; Plagge, T.; Pryke, C.; Rest, A.; Ruel, Jonathan; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, Brian; Staniszewski, Z.; Stark, Antony; Story, K.; Stubbs, Christopher; Suhada, R.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Viklinin, Alexey; Williamson, R.; Zahn, O.; Zenteno, A.We use measurements from the South Pole Telescope (SPT) Sunyaev-Zel'dovich (SZ) cluster survey in combination with X-ray measurements to constrain cosmological parameters. We present a statistical method that fits for the scaling relations of the SZ and X-ray cluster observables with mass while jointly fitting for cosmology. The method is generalizable to multiple cluster observables, and self-consistently accounts for the effects of the cluster selection and uncertainties in cluster mass calibration on the derived cosmological constraints. We apply this method to a data set consisting of an SZ-selected catalog of 18 galaxy clusters at z > 0.3 from the first 178 deg2 of the 2500 deg2 SPT-SZ survey, with 14 clusters having X-ray observations from either Chandra or XMM-Newton. Assuming a spatially flat ΛCDM cosmological model, we find the SPT cluster sample constrains σ8(Ω m /0.25)0.30 = 0.785 ± 0.037. In combination with measurements of the cosmic microwave background (CMB) power spectrum from the SPT and the seven-year Wilkinson Microwave Anisotropy Probe data, the SPT cluster sample constrains σ8 = 0.795 ± 0.016 and Ω m = 0.255 ± 0.016, a factor of 1.5 improvement on each parameter over the CMB data alone. We consider several extensions beyond the ΛCDM model by including the following as free parameters: the dark energy equation of state (w), the sum of the neutrino masses (Σm ν), the effective number of relativistic species (N eff), and a primordial non-Gaussianity (f NL). We find that adding the SPT cluster data significantly improves the constraints on w and Σm ν beyond those found when using measurements of the CMB, supernovae, baryon acoustic oscillations, and the Hubble constant. Considering each extension independently, we best constrain w = –0.973 ± 0.063 and the sum of neutrino masses Σm ν < 0.28 eV at 95% confidence, a factor of 1.25 and 1.4 improvement, respectively, over the constraints without clusters. Assuming a ΛCDM model with a free N eff and Σm ν, we measure N eff = 3.91 ± 0.42 and constrain Σm ν < 0.63 eV at 95% confidence. We also use the SPT cluster sample to constrain f NL = –220 ± 317, consistent with zero primordial non-Gaussianity. Finally, we discuss the current systematic limitations due to the cluster mass calibration, and future improvements for the recently completed 2500 deg2 SPT-SZ survey. The survey has detected ~500 clusters with a median redshift of ~0.5 and a median mass of ~2.3 × 1014 M ☉ h –1 and, when combined with an improved cluster mass calibration and existing external cosmological data sets will significantly improve constraints on w.Publication SPT-CL J0205–5829: A z = 1.32 Evolved Massive Galaxy Cluster in the South Pole Telescope Sunyaev-Zel'dovich Effect Survey(American Astronomical Society / IOP Publishing, 2013) Stalder, Brian; Ruel, Jonathan; Šuhada, R.; Brodwin, M.; Aird, K. A.; Andersson, K.; Armstrong, R.; Ashby, Matthew; Bautz, M.; Bayliss, Matthew; Bazin, G.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H. M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Desai, S.; Dobbs, M. A.; Dudley, J. P.; Foley, R. J.; Forman, William; George, E. M.; Gettings, D.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; High, F. W.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hrubes, J. D.; Jones, C.; Joy, M.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Mohr, J. J.; Montroy, T. E.; Murray, Stephen; Natoli, T.; Nurgaliev, Daniyar Rashidovich; Padin, S.; Plagge, T.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shaw, L.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stanford, S. A.; Staniszewski, Z.; Stark, Antony; Story, K.; Stubbs, Christopher; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Viklinin, Alexey; Williamson, R.; Zahn, O.; Zenteno, A.The galaxy cluster SPT-CL J0205–5829 currently has the highest spectroscopically confirmed redshift, z = 1.322, in the South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. XMM-Newton observations measure a core-excluded temperature of TX = 8.7+1.0 –0.8 keV producing a mass estimate that is consistent with the Sunyaev-Zel'dovich-derived mass. The combined SZ and X-ray mass estimate of M 500 = (4.8 ± 0.8) × 1014 h –1 70 M ☉ makes it the most massive known SZ-selected galaxy cluster at z > 1.2 and the second most massive at z > 1. Using optical and infrared observations, we find that the brightest galaxies in SPT-CL J0205–5829 are already well evolved by the time the universe was <5 Gyr old, with stellar population ages >≈ Gyr, and low rates of star formation (<0.5 M ☉ yr–1). We find that, despite the high redshift and mass, the existence of SPT-CL J0205–5829 is not surprising given a flat ΛCDM cosmology with Gaussian initial perturbations. The a priori chance of finding a cluster of similar rarity (or rarer) in a survey the size of the 2500 deg2 SPT-SZ survey is 69%.