The Velocity Field from Type Ia Supernovae Matches the Gravity Field from Galaxy Surveys

Abstract

We compare the peculiar velocities of nearby SNe Ia with those predicted by the gravity fields of full sky galaxy catalogs. The method provides a powerful test of the gravitational instability paradigm and strong constraints on the density parameter β ≡ Ω 0.6 /b. For 24 SNe Ia within 10,000 km s −1 , we find the observed SNe Ia peculiar velocities are well modeled by the predictions derived from the 1.2 Jy IRAS survey and the Optical Redshift Survey (ORS). Our best β is 0.4 from IRAS, and 0.3 from the ORS, with β > 0.7 and β < 0.15 ruled out at 95% confidence levels from the IRAS comparison. Bootstrap resampling tests show these results to be robust in the mean and in its error. The precision of this technique will improve as additional nearby SNe Ia are discovered and monitored.subject headings: supernovae:general ; cosmology:observations, large-scale structure of universe-Local Group

[ITAL]BVRI[/ITAL] Light Curves for 22 Type I[CLC]a[/CLC] Supernovae

“…As test particles in the nearby Hubble Ñow, they have been used to measure the current expansion rate of the universe (Sandage et al 1992(Sandage et al , 1994(Sandage et al , 1996Sandage & Tammann 1993 ;Schaefer 1994Schaefer , 1995aSchaefer , 1995bSchaefer , 1996Branch & Tammann 1992 ;Tammann & Leibundgut 1990 ;Arnett, Branch, & Wheeler 1985 ;Cadonau, Sandage, & Tammann 1995 ;Hamuy et al 1995Hamuy et al , 1996aHamuy et al , 1996bRiess et al 1995aRiess et al , 1996aRiess et al , 1998bTripp 1998 ;Branch 1998 and references therein). Combined with their positions on the sky, SNe Ia have been used to reveal the peculiar velocities of distant galaxies, as well as the bulk Ñow of our own local neighborhood (Tammann & Leibundgut 1990 ;Jerjen & Tammann 1993 ;Riess et al 1995b ;Watkins & Feldman 1995 ;Riess et al 1997a ;Zehavi et al 1998 ;Tammann 1998). SN Ia evolution is the only wellunderstood time-variable process that can be used to mark the passage of time at high redshift.…”

Untitled

“…Recently, Zaroubi et al (2002) have applied the UMVestimator to SEcat, a combination of the SFI and the ENEAR catalogs, and found consistent estimates from both -and v-v comparison methods. Interestingly, low estimates of ( ¼ 0:2-0.4) have been reported by Riess et al (1997) and Blakeslee et al (1999), who have compared the Optical Redshift Survey (ORS; Santiago et al 1995) As shown in Figure 8, the value of in the quasi-linear regime is more accurate than that in the linear-regime. This implies that if we rely on the linear regime where the density and velocity PSs are simply related by the linear gravitational instability theory as in equation (5), we need peculiar velocity data with a large survey volume for accurate determination of the -parameter.…”

“…These are the Mark III catalog ( Willick et al 1997a), which contains about 3300 spiral and elliptical galaxies, the SFI catalog (Giovanelli et al 1994), with about 1300 late-type spiral galaxies with I-band TF distance estimates, and the ENEAR catalog ), containing about 1400 early-type galaxies with D n -distances. Recently, new distance indicators such as Type Ia supernovae (SNe Ia; Riess et al 1997;Radburn-Smith et al 2004) and the surface brightness fluctuation of early-type galaxies have been used in the peculiar velocity study.…”

Dark energy rest frame and the CMB dipole

“…1, this theoretical framework is not conclusively confirmed by observations. Indeed, in recent years several peculiar velocity surveys [2] have tried to determine the volume size at which the streaming motion of matter with respect to the CMB vanishes. In the figure the results of different observations are compared with the rms expected bulk velocity V b for standard ΛCDM model in a sphere of radius R. The results seem to agree with the theoretical expectations only at scales R < ∼ 60h −1 Mpc.…”