For refcode 1995ApJ...452...16T: Retrieve 86 NED objects in this reference. Please click here for ADS abstract
NED Abstract
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1995ApJ...452...16T
THE HUBBLE DIAGRAM FOR SUPERNOVAE OF TYPE Ia. II. THE EFFECT ON THE
HUBBLE CONSTANT OF A CORRELATION BETWEEN ABSOLUTE MAGNITUDE
AND LIGHT DECAY RATE
G. A. TAMMANN
Astronomisches Institut der Universitat Basel, Venusstrasse 7, CKAI02
Binningen, Switzerland
AND
ALLAN SANDAGE
The Observatories of the Carnegie Institution of Washington, 813 Santa
Barbara Street, Pasadena, CA 91101
Received 1994 October 12; accepted 1995 April 21
ABSTRACT
New Hubble diagrams in B and V are derived for supernovae of type I
based on light curves from the archive literature plus 13 new light
curves with superior modern photometry observed in the Cerro
Tololo/University of Chile program (Hamuy et al, 1995). The sample is
restricted to SNe Ia whose light curves are defined by photometry
beginning 5 days or less after maximum light and with (B  V)max < 0.5
mag. Supernovae of known type Ib or Ic are also excluded.
The resulting Hubble diagrams, extending to redshifts of 30,00 km s^
1^, have dispersions in absolute magnitude of 0.34 mag in B and 0.33 mag
in V, confirming that spectroscopically "normal" (Branch et al. 1993) SNe
Ia are among the best standard candles known.
A solution for the slope of the Hubble diagram gives n(B) = 0.977 +/
0.025 and n(V) = 1.020 +/ 0.024 for the exponent in {nu}~D^n^, proving
linearity of the expansion field to a high level.
The residuals in magnitude from the ridge line of the Hubble diagram
are compared with the light decay rate during the first 15 days to test
the correlation between the two suggested by Pskovskii and by Phillips.
The strongest possible correlation using the extant data has a slope 3
times smaller than that derived by Phillips, and 2 times smaller than
suggested by Hamuy et al., leading to a decrease of less than 10% in the
distance scale based on the present (1995) SNe Ia calibration by means of
three supernovae whose distances are known from Cepheids in their parent
galaxies.
Applying the maximum possible correction to M(max) for a Psko'vskii
Phillips effect would give Hubble constants of
H_0_(B)<= 54 +/ 4 km s^1^ Mpc^1^,
and
H_0_(V) <= 59 +/ 4 km s^1^ Mpc^1^,
where the errors are internal. It is argued that the absence of
measurable bias effects in the Hubble diagrams shows that the three local
(nearest) SNe Ia presently calibrated via Cepheid distances cannot all be
overluminous relative to the average of more distant SNe. If they are
underluminous, which must be the case by the statistics of the Malmquist
effect if the large dispersion in M(max) for SNe Ia claimed by Hamuy et
al. applies to the calibrators, then the value of H_0_ = 52 km s^1^
Mpc^1^ given by Saha et al. is an upper limit to the Hubble constant.
Subject headings: cosmology: observations distance scale  supernovae:
general
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