G. Adam

Bio: G. Adam is an academic researcher from École Normale Supérieure. The author has contributed to research in topics: Integral field spectrograph & Supernova. The author has an hindex of 6, co-authored 19 publications receiving 482 citations.

Overview of the nearby supernova factory

Abstract: Overview of the Nearby Supernova Factory G. Aldering a , G. Adam b , P. Antilogus c , P. Astier d , R. Bacon b , S. Bongard c , C. Bonnaud b , Y. Copin c , D. Hardin d , F. Henault b , D. A. Howell a , J.-P. Lemonnier b , J.-M. Levy d , S. Loken a , P. Nugent a , R. Pain d , A. Pecontal b , E. Pecontal b , S. Perlmutter a , R. Quimby a , K. Schahmaneche d , G. Smadja c , and W.M. Wood-Vasey a , the Nearby Supernova Factory collaboration Berkeley National Laboratory, Berkeley CA, USA de Recherche Astronomique, Universite Lyon I and Ecole Normale Superieure, Lyon, France c Institut de Physique Nucleaire, Universite Lyon I, Lyon, France d Laboratoire de Physique Nucleaire et de Hautes Energies, Universites Paris VI and VII, Paris, France b Centre a Lawrence ABSTRACT The Nearby Supernova Factory (SNfactory) is an international experiment designed to lay the foundation for the next generation of cosmology experiments (such as CFHTLS, wP, SNAP and LSST) which will measure the expansion history of the Universe using Type Ia supernovae. The SNfactory will discover and obtain frequent lightcurve spectrophotome- try covering 3200-10000 A for roughly 300 Type Ia supernovae at the low-redshift end of the smooth Hubble flow. The quantity, quality, breadth of galactic environments, and homogeneous nature of the SNfactory dataset will make it the premier source of calibration for the Type Ia supernova width-brightness relation and the intrinsic supernova colors used for K-correction and correction for extinction by host-galaxy dust. This dataset will also allow an extensive investiga- tion of additional parameters which possibly influence the quality of Type Ia supernovae as cosmological probes. The SNfactory search capabilities and follow-up instrumentation include wide-field CCD imagers on two 1.2-m telescopes (via collaboration with the Near Earth Asteroid Tracking team at JPL and the QUEST team at Yale), and a two-channel integral-field-unit optical spectrograph/imager being fabricated for the University of Hawaii 2.2-m telescope. In addition to ground-based follow-up, UV spectra for a subsample of these supernovae will be obtained with HST. The pipeline to obtain, transfer via wireless and standard internet, and automatically process the search images is in operation. Software and hardware development is now underway to enable the execution of follow-up spectroscopy of supernova candidates at the Hawaii 2.2-m telescope via automated remote control of the telescope and the IFU spectrograph/imager. Keywords: supernova, survey, cosmology, integral-field-unit, spectrograph 1. PROBING DARK ENERGY WITH SUPERNOVAE A coherent view of the universe is emerging in which a mysterious form of “dark energy” accounts for about 2/3 of the total energy density in the Universe. Direct evidence for this radical conclusion comes from distance measurements of Type Ia supernovae (SNe Ia; see Fig. 1) which indicate the expansion of the Universe is not slowing down as would be expected in a Universe filled with only matter and radiation. 1, 2 Further support for this result has come from recent measurements of the CMB indicating a flat universe, 3 combined with determinations of Ω M ∼ 0.3 from structure formation. SNe Ia remain the most mature cosmological distance indicator, and therefore, offer the best current means of exper- imentally probing the properties of the dark energy. Their cosmological use was developed in the early 1990’s, paving the way for the discovery of dark energy. 1, 4–10 Now similar developmental efforts are needed so that the next order of magnitude improvement of the experimental constraints on the properties of dark energy can be made. Progress must be made on two fronts, at a level which cannot be pursued with existing programs alone. First a large number of nearby SNe must be observed in an appropriate fashion since they provide the fulcrum of the lever-arm needed to make cosmological inferences from high-redshift SNe observations. Furthermore, these SNe provide the critical Correspondence: e-mail galdering@lbl.gov; telephone 510-495-2203

The infrared and optical variability of OJ 287

Abstract: In this paper, the long-term historical optical (UBVRI) and near-infrared (JHK) data are presented with some new observations in the optical (February 1994-January 1995) and near-infrared (November 1995) bands included for BL Lac object OJ 287. The new optical data in V-band are in agreement with the results reported by other authors (Sillanpaa et al. 1996a; Arimoto et al. 1997), a close correlation between the color index of B - V and the magnitude V has been obtained from our new observations. The new infrared observations presented here indicate that the source was at a high level in the infrared band during the observation period. From the available literature, we have got that the largest variations for UBVRIJHK bands are respectively: Delta U = 4.(m)72; Delta B = 5.(m)93; Delta V = 5.(m)18; Delta R = 4.(m)45; Delta I = 4.(m)07; Delta J = 3.(m)87; Delta H = 3.(m)78; Delta K = 3.(m)54. A strong correlation is found between the optical and near-infrared bands when the DCF method is used, which suggests that these two bands have the same emission mechanism.

Correlation between the gamma-ray and the radio emissions

Abstract: In this paper, the correlation between the gamma-ray and the radio bands is investigated. The results show that there is a closer correlation between the gamma-ray emission and the high frequency (1.3 mm, 230 GHz) radio emission for maximum data than between the gamma-ray and the lower frequency (5GHz) radio emissions, which means that the gamma-ray is associated with the radio emission from the jet.

The Hubble Space Telescope Cluster Supernova Survey. V. Improving the Dark-energy Constraints above z > 1 and Building an Early-type-hosted Supernova Sample

Abstract: We present Advanced Camera for Surveys, NICMOS, and Keck adaptive-optics-assisted photometry of 20 Type Ia supernovae (SNe Ia) from the Hubble Space Telescope (HST) Cluster Supernova Survey. The SNe Ia were discovered over the redshift interval 0.623 1 SNe Ia. We describe how such a sample could be efficiently obtained by targeting cluster fields with WFC3 on board HST. The updated supernova Union2.1 compilation of 580 SNe is available at http://supernova.lbl.gov/Union.

Cosmological Results from High-z Supernovae* **

Abstract: The High-z Supernova Search Team has discovered and observed eight new supernovae in the redshift interval z = 0.3-1.2. These independent observations, analyzed by similar but distinct methods, confirm the results of Riess and Perlmutter and coworkers that supernova luminosity distances imply an accelerating universe. More importantly, they extend the redshift range of consistently observed Type Ia supernovae (SNe Ia) to z ≈ 1, where the signature of cosmological effects has the opposite sign of some plausible systematic effects. Consequently, these measurements not only provide another quantitative confirmation of the importance of dark energy, but also constitute a powerful qualitative test for the cosmological origin of cosmic acceleration. We find a rate for SN Ia of (1.4 ± 0.5) × 10-4 h3 Mpc-3 yr-1 at a mean redshift of 0.5. We present distances and host extinctions for 230 SN Ia. These place the following constraints on cosmological quantities: if the equation of state parameter of the dark energy is w = -1, then H0t0 = 0.96 ± 0.04, and ΩΛ - 1.4ΩM = 0.35 ± 0.14. Including the constraint of a flat universe, we find ΩM = 0.28 ± 0.05, independent of any large-scale structure measurements. Adopting a prior based on the Two Degree Field (2dF) Redshift Survey constraint on ΩM and assuming a flat universe, we find that the equation of state parameter of the dark energy lies in the range -1.48 -1, we obtain w < -0.73 at 95% confidence. These constraints are similar in precision and in value to recent results reported using the WMAP satellite, also in combination with the 2dF Redshift Survey.

First results from the catalina real-time transient survey

Abstract: We report on the results from the first six months of the Catalina Real-Time Transient Survey (CRTS). In order to search for optical transients (OTs) with timescales of minutes to years, the CRTS analyses data from the Catalina Sky Survey which repeatedly covers 26,000 of square degrees on the sky. The CRTS provides a public stream of transients that are bright enough to be followed up using small telescopes. Since the beginning of the survey, all CRTS transients have been made available to astronomers around the world in real time using HTML tables,RSS feeds, and VOEvents. As part of our public outreach program, the detections are now also available in Keyhole Markup Language through Google Sky. The initial discoveries include over 350 unique OTs rising more than 2 mag from past measurements. Sixty two of these are classified as supernovae (SNe), based on light curves, prior deep imaging and spectroscopic data. Seventy seven are due to cataclysmic variables (CVs; only 13 previously known), while an additional 100 transients were too infrequently sampled to distinguish between faint CVs and SNe. The remaining OTs include active galactic nucleus, blazars, high-proper-motions stars, highly variable stars (such as UV Ceti stars), and transients of an unknown nature. Our results suggest that there is a large population of SNe missed by many current SN surveys because of selection biases. These objects appear to be associated with faint host galaxies. We also discuss the unexpected discovery of white dwarf binary systems through dramatic eclipses.

Observational Constraints on the Nature of Dark Energy: First Cosmological Results from the ESSENCE Supernova Survey

Abstract: We present constraints on the dark energy equation-of-state parameter, w = P/(rho c(2)), using 60 SNe Ia fromthe ESSENCE supernova survey. We derive a set of constraints on the nature of the dark energy assuming a flat universe. By including constraints on (Omega(M), w) from baryon acoustic oscillations, we obtain a value for a static equation-of-state parameter w = -1:05(-0.12)(+0: 13) (stat 1 sigma) +/- 0: 13 (sys) and Omega(M) = 0:274(-0.020)(+0:033) (stat 1 sigma) with a bestfit chi(2)/dof of 0.96. These results are consistent with those reported by the Supernova Legacy Survey from the first year of a similar program measuring supernova distances and redshifts. We evaluate sources of systematic error that afflict supernova observations and present Monte Carlo simulations that explore these effects. Currently, the largest systematic with the potential to affect our measurements is the treatment of extinction due to dust in the supernova host galaxies. Combining our set of ESSENCE SNe Ia with the first-results Supernova Legacy Survey SNe Ia, we obtain a joint constraint of w = -1:07(-0: 09)(+0:09) (stat 1 sigma) +/- 0: 13 ( sys), Omega(M) 0:267(-0:028)(+0:028) (stat 1 sigma) with a best-fit chi(2)/dof of 0.91. The current global SN Ia data alone rule out empty (Omega(M) = 0), matter-only Omega(M) = 0: 3, and Omega(M) = 1 universes at > 4.5 sigma. The current SN Ia data are fully consistent with a cosmological constant.

Exploring the Optical Transient Sky with the Palomar Transient Factory

Abstract: The Palomar Transient Factory (PTF) is a wide-field experiment designed to investigate the optical transient and variable sky on time scales from minutes to years. PTF uses the CFH12k mosaic camera, with a field of view of 7.9 deg^2 and a plate scale of 1″ pixel^(-1), mounted on the Palomar Observatory 48 inch Samuel Oschin Telescope. The PTF operation strategy is devised to probe the existing gaps in the transient phase space and to search for theoretically predicted, but not yet detected, phenomena, such as fallback supernovae, macronovae, .Ia supernovae, and the orphan afterglows of gamma-ray bursts. PTF will also discover many new members of known source classes, from cataclysmic variables in their various avatars to supernovae and active galactic nuclei, and will provide important insights into understanding galactic dynamics (through RR Lyrae stars) and the solar system (asteroids and near-Earth objects). The lessons that can be learned from PTF will be essential for the preparation of future large synoptic sky surveys like the Large Synoptic Survey Telescope. In this article we present the scientific motivation for PTF and describe in detail the goals and expectations for this experiment.