TY - JOUR
T1 - The Carnegie Supernova Project
T2 - first near infrared Hubble diagram to z ∼ 0.7
AU - Freedman, Wendy L.
AU - Burns, Christopher R.
AU - Phillips, M. M.
AU - Wyatt, Pamela
AU - Persson, S. E.
AU - Madore, Barry F.
AU - Contreras, Carlos
AU - Folatelli, Gaston
AU - Gonzalez, E. Sergio
AU - Hamuy, Mario
AU - Hsiao, Eric
AU - Kelson, Daniel D.
AU - Morrell, Nidia
AU - Murphy, D. C.
AU - Roth, Miguel
AU - Stritzinger, Maximilian D.
AU - Sturch, Laura
AU - Suntzeff, Nick B.
AU - Astier, P.
AU - Balland, C.
AU - Bassett, Bruce A.
AU - Boldt, Luis
AU - Carlberg, R. G.
AU - Conley, Alexander J.
AU - Frieman, Joshua A.
AU - Garnavich, Peter M.
AU - Guy, J.
AU - Hardin, D.
AU - Howell, D. Andrew
AU - Kessler, Richard
AU - Lampeitl, Hubert
AU - Marriner, John P.
AU - Pain, R.
AU - Perrett, Kathy
AU - Regnault, N.
AU - Riess, Adam G.
AU - Sako, Masao
AU - Schneider, Donald P.
AU - Sullivan, Mark
AU - Wood-Vasey, W. Michael
N1 - copyright 2009. The American Astronomical Society.
PY - 2009/10/20
Y1 - 2009/10/20
N2 - The Carnegie Supernova Project (CSP) is designed to measure the
luminosity distance for Type Ia supernovae (SNe Ia) as a function of
redshift, and to set observational constraints on the dark energy
contribution to the total energy content of the universe. The CSP
differs from other projects to date in its goal of providing an I-band rest-frame
Hubble diagram. Here, we present the first results from near-infrared
observations obtained using the Magellan Baade telescope for SNe Ia with
0.1 <z < 0.7. We combine these results with those from the low-redshift CSP at z
< 0.1. In this paper, we describe the overall goals of this
long-term program, the observing strategy, data reduction procedures,
and treatment of systematic uncertainties. We present light curves and
an I-band Hubble diagram for this first sample of 35 SNe Ia, and
we compare these data to 21 new SNe Ia at low redshift. These data
support the conclusion that the expansion of the universe is
accelerating. When combined with independent results from baryon
acoustic oscillations, these data yield Ω m = 0.27 ± 0.02(statistical) and ΩDE
= 0.76 ± 0.13(statistical) ± 0.09(systematic), for the matter and dark
energy densities, respectively. If we parameterize the data in terms of
an equation of state, w (with no time dependence), assume a flat geometry, and combine with baryon acoustic oscillations, we find that w = –1.05 ± 0.13(statistical) ± 0.09(systematic). The largest source of systematic uncertainty on w
arises from uncertainties in the photometric calibration, signaling the
importance of securing more accurate photometric calibrations for
future supernova cosmology programs. Finally, we conclude that either
the dust affecting the luminosities of SNe Ia has a different extinction
law (RV = 1.8) than that in the Milky Way (where RV
= 3.1), or that there is an additional intrinsic color term with
luminosity for SNe Ia, independent of the decline rate. Understanding
and disentangling these effects is critical for minimizing the
systematic uncertainties in future SN Ia cosmology studies.
AB - The Carnegie Supernova Project (CSP) is designed to measure the
luminosity distance for Type Ia supernovae (SNe Ia) as a function of
redshift, and to set observational constraints on the dark energy
contribution to the total energy content of the universe. The CSP
differs from other projects to date in its goal of providing an I-band rest-frame
Hubble diagram. Here, we present the first results from near-infrared
observations obtained using the Magellan Baade telescope for SNe Ia with
0.1 <z < 0.7. We combine these results with those from the low-redshift CSP at z
< 0.1. In this paper, we describe the overall goals of this
long-term program, the observing strategy, data reduction procedures,
and treatment of systematic uncertainties. We present light curves and
an I-band Hubble diagram for this first sample of 35 SNe Ia, and
we compare these data to 21 new SNe Ia at low redshift. These data
support the conclusion that the expansion of the universe is
accelerating. When combined with independent results from baryon
acoustic oscillations, these data yield Ω m = 0.27 ± 0.02(statistical) and ΩDE
= 0.76 ± 0.13(statistical) ± 0.09(systematic), for the matter and dark
energy densities, respectively. If we parameterize the data in terms of
an equation of state, w (with no time dependence), assume a flat geometry, and combine with baryon acoustic oscillations, we find that w = –1.05 ± 0.13(statistical) ± 0.09(systematic). The largest source of systematic uncertainty on w
arises from uncertainties in the photometric calibration, signaling the
importance of securing more accurate photometric calibrations for
future supernova cosmology programs. Finally, we conclude that either
the dust affecting the luminosities of SNe Ia has a different extinction
law (RV = 1.8) than that in the Milky Way (where RV
= 3.1), or that there is an additional intrinsic color term with
luminosity for SNe Ia, independent of the decline rate. Understanding
and disentangling these effects is critical for minimizing the
systematic uncertainties in future SN Ia cosmology studies.
U2 - 10.1088/0004-637X/704/2/1036
DO - 10.1088/0004-637X/704/2/1036
M3 - Article
SN - 0004-637X
VL - 704
SP - 1036
EP - 1058
JO - The Astrophysical Journal
JF - The Astrophysical Journal
IS - 2
ER -