M. Strovink

A NEW DETERMINATION OF THE HIGH-REDSHIFT TYPE Ia SUPERNOVA RATES WITH THE HUBBLE SPACE TELESCOPE ADVANCED CAMERA FOR SURVEYS

A New Determination of the High Redshift Type Ia Supernova Rates with the Hubble Space Telescope Advanced Camera for Surveys. 1 arXiv:0710.3120v1 [astro-ph] 16 Oct 2007 N. Kuznetsova 2,3 , K. Barbary 2,4 , B. Connolly 5 , A. G. Kim 2 , R. Pain 6 , N. A. Roe 2 , G. Aldering 2 , R. Amanullah 7 , K. Dawson 2 , M. Doi 8 V. Fadeyev 9 , A. S. Fruchter 10 , R. Gibbons 11 , G. Goldhaber 2,4 , A. Goobar 12 , A. Gude 4 , R. A. Knop 11 , M. Kowalski 13 , C. Lidman 14 , T. Morokuma 15 J. Meyers 2,4 , S. Perlmutter 2,4 , D. Rubin 2,4 , D. J. Schlegel 2 , A. L. Spadafora 2 , V. Stanishev 12 , M. Strovink 2,4 , N. Suzuki 2 , L. Wang 16 , N. Yasuda 17 (Supernova Cosmology Project) nvkuznetsova@lbl.gov ABSTRACT Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555, under programs GO-9583, GO-9425, GO-9727, and GO-9728. E. O. Lawrence Berkeley National Laboratory, 1 Cyclotron Rd., Berkeley, CA 94720, USA Current address: Physics Department, Hamilton College, Clinton, NY 13323, USA Department of Physics, University of California Berkeley, Berkeley, CA 94720, USA Department of Physics, Columbia University, New York, NY 10027, USA LPNHE, CNRS-IN2P3, University of Paris VI & VII, Paris, France The Space Sciences Laboratory, University of California Berkeley, Berkeley, CA 94720, USA Institute of Astronomy, School of Science, University of Tokyo, Mitaka, Tokyo, 181-0015, Japan Department of Physics, University of California Santa Cruz, Santa Cruz, CA 95064, USA Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37240, USA Department of Physics, Stockholm University,Albanova University Center, S-106 91 Stockholm, Sweden Humboldt Universit¨ t Institut f¨ r Physik, Newtonstrasse 15, Berlin 12489, Germany a u European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago 19, Chile Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, Mitaka, Tokyo, 181-8588, Japan Department of Physics, Texas A&M University, College Station, TX 77843, USA Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, 277 8582, Japan

THE HUBBLE SPACE TELESCOPE * CLUSTER SUPERNOVA SURVEY. II. THE TYPE Ia SUPERNOVA RATE IN HIGH-REDSHIFT GALAXY CLUSTERS

We report a measurement of the Type Ia supernova (SN Ia) rate in galaxy clusters at 0.9 0.9 SNe. Finding 8 +/- 1 cluster SNe Ia, we determine an SN Ia rate of 0.50(-0.19)(+0.23) (stat) (+0.10)(-0.09) (sys) h(70)(2) SNuB (SNuB equivalent to 10(-12) SNe (L-1)circle dot(,B) yr(-1)). In units of stellar mass, this translates to 0.36(-0.13)(+0.16) (stat) (+0.07)(-0.06) (sys) h(70)(2) SNuM (SNuM = 10(-12) SNe M-1 circle dot yr(-1)). This represents a factor of approximate to 5 +/- 2 increase over measurements of the cluster rate at z < 0.2. We parameterize the late-time SN Ia delay time distribution (DTD) with a power law: Psi(t) t(s). Under the approximation of a single-burst cluster formation redshift of z(f) = 3, our rate measurement in combination with lower-redshift cluster SN Ia rates constrains s = -1.41(-0.40)(+0.47), consistent with measurements of the DTD in the field. This measurement is generally consistent with expectations for the double degenerate scenario and inconsistent with some models for the single degenerate scenario predicting a steeper DTD at large delay times. We check for environmental dependence and the influence of younger stellar populations by calculating the rate specifically in cluster red-sequence galaxies and in morphologically early-type galaxies, finding results similar to the full cluster rate. Finally, the upper limit of one hostless cluster SN Ia detected in the survey implies that the fraction of stars in the intra-cluster medium is less than 0.47 (95% confidence), consistent with measurements at lower redshifts.

Nonlinear decline-rate dependence and intrinsic variation of type Ia supernova luminosities

Published B and V fluxes from nearby Type Ia supernovae (SNe) are fitted to light-curve templates with four to six adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a postmaximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B-max and B-BV. Their difference varies systematically with decline-rate Delta m(15) in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of Bmax itself. A Hubble fit to the average of Bmax and BBV requires a systematic correction for observed B-V color that can be described by a linear coefficient R 2:59 +/- 0:24, well below the coefficient R-B approximate to 4:1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, Bmax and BBV exhibit mutual rms intrinsic variation equal to 0:074 +/- 0:019 mag, of which at least an equal share likely belongs to BBV. SN magnitudes measured using maximum luminosity or CMAGIC methods show comparable rms deviations of order approximate to 0.14 mag from the Hubble line. The same fit also establishes a 95% confidence upper limit of 486 km s(-1) on the rms peculiar velocity of nearby SNe relative to the Hubble flow.

Diversity of Decline Rate-corrected Type Ia Supernova Rise Times: One Mode or Two?

To appear in The Astrophysical Journal A Preprint typeset using L TEX style emulateapj v. 03/07/07 DIVERSITY OF DECLINE-RATE-CORRECTED TYPE Ia SUPERNOVA RISE TIMES: ONE MODE OR TWO? Mark Strovink Physics Department and E. O. Lawrence Berkeley National Laboratory University of California, Berkeley, CA 94720 Received 2007 May 4; accepted 2007 August 31 arXiv:0705.0726v2 [astro-ph] 6 Sep 2007 ABSTRACT B-band light-curve rise times for eight unusually well-observed nearby Type Ia supernovae (SNe) are fitted by a newly developed template-building algorithm, using light-curve functions that are smooth, flexible, and free of potential bias from externally derived templates and other prior assumptions. From the available literature, photometric BVRI data collected over many months, including the earliest points, are reconciled, combined, and fitted to a unique time of explosion for each SN. On average, after they are corrected for light-curve decline rate, three SNe rise in 18.81 ± 0.36 days, while five SNe rise in 16.64 ± 0.21 days. If all eight SNe are sampled from a single parent population (a hypothesis not favored by statistical tests), the rms intrinsic scatter of the decline-rate-corrected SN rise time is 0.96 +0.52 days – a first measurement of this dispersion. The corresponding global mean rise time is 17.44 ± 0.39 days, where the uncertainty is dominated by intrinsic variance. This value is ≈2 days shorter than two published averages that nominally are twice as precise, though also based on small samples. When comparing high-z to low-z SN luminosities for determining cosmological parameters, bias can be introduced by use of a light-curve template with an unrealistic rise time. If the period over which light curves are sampled depends on z in a manner typical of current search and measurement strategies, a two-day discrepancy in template rise time can bias the luminosity comparison by ≈0.03 magnitudes. Subject headings: supernovae: general — cosmology: observations — distance scale 1. INTRODUCTION Within a few minutes of explosion, Type Ia supernovae release most of their energy, but due to self-absorption they reach peak luminosity only after 2-3 weeks. During this period of ballistic expansion, while the photosphere grows in radius but shrinks in characteristic velocity as slower, heavier ejecta are revealed, basic properties of the explosion become evident. Spectroscopic signatures of elements intermediate between carbon-oxygen fuel and iron-group ash (Filippenko 1997; Branch et al. 2006) re- veal that burning is incomplete, with deflagration likely playing an early role (Mazzali et al. 2007); nonvanishing polarization measures the progenitor’s asphericity (Wang et al. 2007). After peak brightness, when iron features blanket the spectrum and polarizations wane, SNe be- come more homogeneous. For SN science to progress, therefore, it is crucial to study the period of rising lumi- nosity. In cosmological studies, SNe Ia are prized for their use as standardizable candles to trace the history of cosmic expansion (Riess et al. 1998, 2007; Perlmutter et al. 1999; for a review, see Perlmutter & Schmidt 2003); in this context, periods of greater SN uniformity are of greater value. Indeed, post-maximum luminosity indicators do yield low-dispersion Hubble diagrams (Wang et al. 2003; Wang, X. et al. 2005); post-maximum color measure- ments do solidify the corrections made for absorption by host-galactic dust (Lira 1995; Phillips et al. 1999; Jha et al. 2007). Nevertheless, as ever more ambitious cam- paigns to chronicle the Universe’s expansion history are planned (e.g. Aldering et al. 2002), the fundamental issue Electronic address: strovink@lbl.gov of high z → low z evolution (Howell et al. 2007) keeps SN science in focus. For example, more than one SN Ia progenitor or explosion mechanism might be at work, with progeny neither equally bright nor equally abundant at high vs. low redshift. To secure such understanding, continued study of the rise-time period is essential. The subject of this report is a basic property of this period – the light-curve rise time itself. The B-band rise time is quite sensitive to the main-sequence mass of the white dwarf progenitor and to its carbon/oxygen ratio (see e.g. Dom´ inguez et al. 2001). It is less sensitive to the progenitor’s metallicity. Pskovskii (1984) published the first rise times for classes of type I SNe. In retrospect their range is reason- able, but, oddly, the reported correlation of rise time with decline rate was positive. For individual SNe, the earliest rise-time measurements were made by Leibundgut et al. (1991) (SN 1990N) and by Vacca & Leibundgut (1996) (SN 1994D). For a group of SNe, the earliest measure- ment of the average decline-rate-corrected rise time was reported by Groom (1998) and Goldhaber (1998). They used a model described e.g. by Arnett (1982), in which the initial rise of B flux with time is parabolic. Within ± ≈2 days, these early determinations agree with current values. Soon thereafter, in a definitive paper, Riess et al. (1999b) (henceforth Rie99b) established the presently accepted average rise time to B maximum of 19.5 ± 0.2 days. This was accomplished by ferreting out early unfil- tered photometry for ten nearby SNe and transforming it to standard passbands, to which the parabolic model was applied. Also using this model, Conley et al. (2006) (henceforth Con06) recently confirmed the Rie99b low- redshift average, in addition measuring an average rise

The central tracking detectors for D

Abstract Three types of drift chambers are being constructed for the Fermilab Do experiment. The construction and readout of these chambers stress good spatial resolution, good two hit separation, and d E /d x measurement. A 106 MHz FADC system with hardware zero suppression is being constructed to read out this system.

A search for materials compatible with warm liquids

Abstract This paper reports on the search undertaken since 1987 by a part of the WALIC collaboration to find new materials for the construction of ionizing detectors filled with room temperature liquid hydrocarbons, tetramethylsilane and tetramethylpentane. We have found that several metals, glasses, plastics and glues, very promising for their mechanical, electrical, and radiation hardness properties, can be put into contact with these liquids without observing, during the drift time, any significant decrease in the lifetime of the electrons created by ionization.

Compensation studies of a lead/TMP calorimeter

Abstract We present results from a fully modular lead/TMP calorimeter. In electromagnetic configuration, we have measured the response of 2.5 to 150 GeV/c electrons. The e/π fraction has been determined with electron and pion beams from 5 to 50 GeV/c in hadronic configurations. The modularity of the calorimeter has permitted us to study the compensation for various amounts of hydrogen traversed by the showers. A detailed comparison to a Monte Carlo simulation of all the results is presented.

Test results from a precision drift chamber vertex detector prototype using dimethylether

Abstract Results of beam tests of a prototype drift chamber vertex detector developed for the D-Zero experiment at the Fermilab collider are reported. The chamber design emphasizes dual goals of high accuracy position measurement and excellent two track resolution. These requirements are met by using a slow gas, dimethyl ether, in a jet chamber geometry with a double plane of field-shaping wires near the anodes. Resolution of nearby hits is facilitated by 100 MHz flash digitization of the signal pulses. The prototype tested consisted of a full-length (97 cm) model of one azimuthal sector of the innermost layer of the detector, with 8 anode wires. Position measurement accuracy of 30–80 μm for drift distances of 2–11 mm and pulse pair resolution of 0.7 mm (for 90% of all pulses) is achieved.

D0 vertex drift chamber construction and test results

A jet-cell based vertex chamber has been built for the D{O} experiment at Fermilab and operated in a test beam there. Low drift velocity and diffusion properties were achieved using CO{sub 2}(95%)-ethane(5%) at atmospheric pressure. The drift velocity is found to be consistent with (9.74+8.68( E -1.25)) {mu}m/nsec where E is the electric field strength in (kV/cm < E z 1.6 kV/cm.) An intrinsic spatial resolution of 60 {mu}m or better for drift distances greater than 2 mm is measured. The track pair efficiency is estimated to be better than 90% for separations greater than 630 {mu}m. 8 refs., 6 figs., 1 tab.

Review of multimuon production by muons

Production of 2, 3, 4, and 5‐muon final states by high‐energy muons at Fermilab and CERN SPS is reviewed. Sixty‐three 4μ, 5μ, and odd‐sign 3μ final states have been observed. Corresponding limits on muoproduction of Υ, bb, and M0 are summarized. Precise data on the Q2 and ν‐dependence of muoproduced elastic‐ψ, inelastic‐ψ, and open‐charm states are presented. Elastic and inelastic μ muoproduction results are extended to include distributions in production and decay angle, elasticity, and momentum transfer to hadrons. Calculations using the lowest‐order photon‐gluon‐fusion graph can be adjusted to reroduce the ν‐dependence of elastic ψ production, the ν and Q2 dependence of open charm production, and the combined (hidden+open) charm production cross section. Unfortunately, the model does not account for the angular distributions and Q2‐dependence observed for elastic ψ production. Unless inhibited by order‐of‐magnitude threshold effects, the ‘‘the intrinsic charm’’ model predicts more copious open charm ...