摘要
Observations show that Type Ia supernovae （SNe Ia） are dimmer than ex- pected from a matter dominated Universe. It has been suggested that this observed phenomenon can also be explained using light absorption instead of dark energy. However, there is a serious degeneracy between the cosmic absorption parameter and the present matter density parameter Ωm when one tries to place constraints on the cosmic opacity using SNe Ia data. We combine the latest baryon acoustic oscillation （BAO） and Union2 SNe Ia data in order to break this degeneracy. Assuming a fiat ACDM model, we find that, although an opaque Universe is favored by SNe Ia＋BAO since the best fit value of the cosmic absorption parameter is larger than zero, fire = 1 is ruled out at the 99.7% confidence level. Thus, cosmic opacity is not sufficient to account for the present observations and dark energy or modified gravity is still re- quired.
Observations show that Type Ia supernovae （SNe Ia） are dimmer than ex- pected from a matter dominated Universe. It has been suggested that this observed phenomenon can also be explained using light absorption instead of dark energy. However, there is a serious degeneracy between the cosmic absorption parameter and the present matter density parameter Ωm when one tries to place constraints on the cosmic opacity using SNe Ia data. We combine the latest baryon acoustic oscillation （BAO） and Union2 SNe Ia data in order to break this degeneracy. Assuming a fiat ACDM model, we find that, although an opaque Universe is favored by SNe Ia＋BAO since the best fit value of the cosmic absorption parameter is larger than zero, fire = 1 is ruled out at the 99.7% confidence level. Thus, cosmic opacity is not sufficient to account for the present observations and dark energy or modified gravity is still re- quired.
基金
supported by the National Natural Science Foundation of China(Grant Nos. 10935013, 11175093, 11222545 and 11075083)
Zhejiang Provincial Natural Science Foundation of China (Grant Nos. Z6100077 and R6110518)
the Foundation for the Author of National Excellent Doctoral Dissertation of PR China (FANEDD, Grant No. 200922)
the National Basic Research Program of China (973 program, Grant No. 2010CB832803)
the Program for New Century Excellent Talents in University (NCET, Grant No. 09-0144)
the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT, Grant No. IRT0964)
Hunan Provincial Natural Science Foundation of China (Grant No. 11JJ7001)
the Specialized Research Fund for the Doctoral Program of Higher Education (SRFDP, Grant No. 20124306110001)
the Program for the Key Discipline in Hunan Province
