# Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities

## Abstract

Published B and V fluxes from nearby Type Ia supernova are fitted to light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a post-maximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B{sub max} and B{sub BV}. Their difference varies systematically with decline rate {Delta}m{sub 15} in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of B{sub max} itself. A Hubble fit to the average of B{sub max} and B{sub BV} requires a systematic correction for observed B-V color that can be described by a linear coefficient R = 2.59 {+-} 0.24, well below the coefficient R{sub B} {approx} 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, B{sub max} and B{sub BV} exhibit mutual rms intrinsic variation equal to 0.074 {+-} 0.019 mag, of which at least anmore »

- Authors:

- Publication Date:

- Research Org.:
- Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)

- Sponsoring Org.:
- USDOE Director. Office of Science. Office of High EnergyPhysics

- OSTI Identifier:
- 891354

- Report Number(s):
- LBNL-59261

R&D Project: PSUOPS; BnR: KA1301020; TRN: US0605371

- DOE Contract Number:
- DE-AC02-05CH11231

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: The Astrophysical Journal; Journal Volume: 641; Journal Issue: 1pt1; Related Information: Journal Publication Date: 04/10/2006

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COLOR; DISTRIBUTION; MILKY WAY; VELOCITY; Supernovae: general Cosmology: observations distancescale

### Citation Formats

```
Wang, Lifan, Strovink, Mark, Conley, Alexander, Goldhaber,Gerson, Kowalski, Marek, Perlmutter, Saul, and Siegrist, James.
```*Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities*. United States: N. p., 2005.
Web.

```
Wang, Lifan, Strovink, Mark, Conley, Alexander, Goldhaber,Gerson, Kowalski, Marek, Perlmutter, Saul, & Siegrist, James.
```*Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities*. United States.

```
Wang, Lifan, Strovink, Mark, Conley, Alexander, Goldhaber,Gerson, Kowalski, Marek, Perlmutter, Saul, and Siegrist, James. Wed .
"Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities". United States.
doi:. https://www.osti.gov/servlets/purl/891354.
```

```
@article{osti_891354,
```

title = {Nonlinear decline-rate dependence and intrinsic variation of typeIa supernova luminosities},

author = {Wang, Lifan and Strovink, Mark and Conley, Alexander and Goldhaber,Gerson and Kowalski, Marek and Perlmutter, Saul and Siegrist, James},

abstractNote = {Published B and V fluxes from nearby Type Ia supernova are fitted to light-curve templates with 4-6 adjustable parameters. Separately, B magnitudes from the same sample are fitted to a linear dependence on B-V color within a post-maximum time window prescribed by the CMAGIC method. These fits yield two independent SN magnitude estimates B{sub max} and B{sub BV}. Their difference varies systematically with decline rate {Delta}m{sub 15} in a form that is compatible with a bilinear but not a linear dependence; a nonlinear form likely describes the decline-rate dependence of B{sub max} itself. A Hubble fit to the average of B{sub max} and B{sub BV} requires a systematic correction for observed B-V color that can be described by a linear coefficient R = 2.59 {+-} 0.24, well below the coefficient R{sub B} {approx} 4.1 commonly used to characterize the effects of Milky Way dust. At 99.9% confidence the data reject a simple model in which no color correction is required for SNe that are clustered at the blue end of their observed color distribution. After systematic corrections are performed, B{sub max} and B{sub BV} exhibit mutual rms intrinsic variation equal to 0.074 {+-} 0.019 mag, of which at least an equal share likely belongs to B{sub BV}. SN magnitudes measured using maximum-luminosity or cmagic methods show comparable rms deviations of order {approx}0.14 mag from the Hubble line. The same fit also establishes a 95% confidence upper limit of 486 km s{sup -1} on the rms peculiar velocity of nearby SNe relative to the Hubble flow.},

doi = {},

journal = {The Astrophysical Journal},

number = 1pt1,

volume = 641,

place = {United States},

year = {Wed Dec 14 00:00:00 EST 2005},

month = {Wed Dec 14 00:00:00 EST 2005}

}