Near-infrared observations of type Ia supernovae: The best known standard candle for cosmology
We present an analysis of the Hubble diagram for 12 Type Ia supernovae (SNe Ia) observed in the near-infrared J and H bands. We select SNe exclusively from the redshift range 0.03 < z < 0.09 to reduce uncertainties coming from peculiar velocities while remaining in a cosmologically well-understood region. All of the SNe in our sample exhibit no spectral or B-band light-curve peculiarities and lie in the B-band stretch range of 0.8-1.15. Our results suggest that SNe Ia observed in the near-infrared (NIR) are the best known standard candles. We fit previously determined NIR light-curve templates to new high-precision data to derive peak magnitudes and to determine the scatter about the Hubble line. Photometry of the 12 SNe is presented in the natural system. Using a standard cosmology of (H_0, Omega_m, Lambda) = (70,0.27,0.73) we find a median J-band absolute magnitude of M_J = -18.39 with a scatter of 0.116 and a median H-band absolute magnitude of M_H = -18.36 with a scatter of 0.085. The scatter in the H band is the smallest yet measured. We search for correlations between residuals in the J- and H-band Hubble diagrams and SN properties, such as SN colour, B-band stretch and the projected distance from host-galaxy centre. The only significant correlation is between the J-band Hubble residual and the J-H pseudo-colour. We also examine how the scatter changes when fewer points in the near-infrared are used to constrain the light curve. With a single point in the H band taken anywhere from 10 days before to 15 days after B-band maximum light and a prior on the date of H-band maximum set from the date of B-band maximum, we find that we can measure distances to an accuracy of 6%. The precision of SNe Ia in the NIR provides new opportunities for precision measurements of both the expansion history of the universe and peculiar velocities of nearby galaxies.
Additional Information© 2012 The Authors. Accepted 2012 May 29. Received 2012 May 28; in original form 2012 April 5. This work is based on data collected at the ESO VLT (programme number 083.A-0480) and observations obtained at the Gemini Observatory (programme numbers GN2010A-Q-16, GN2010B-Q17, GN2011A-Q-11 and GN-2011B-Q-21), which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministrio da Cincia, Tecnologia e Inovao (Brazil) and Ministerio de Ciencia, Tecnologa e Innovacin Productiva (Argentina). CL is the recipient of an Australian Research Council Future Fellowship (project number FT0992259). This research was conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics (project number CE110001020). MS acknowledges support from the Royal Society. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. This publication has been made possible by the participation of more than 10 000 volunteers in the Galaxy Zoo Supernovae project, http://supernova.galaxyzoo.org/authors. AG-Y acknowledges support by ISF, BSF, GIF and Minerva grants, an ARCHES award and the Lord Sieff of Brimpton Fund. SBC acknowledges generous financial assistance from Gary & Cynthia Bengier, the Richard & Rhoda Goldman Fund, NASA/Swift grants NNX10AI21G and GO-7100028, the TABASGO Foundation and NSF grant AST-0908886. MMK acknowledges generous support from the Hubble Fellowship and Carnegie-Princeton Fellowship.
Published - 425-2-1007.pdf