Query : 1998A&A...333..795Y

1998A&A...333..795Y - Astronomy and Astrophysics, volume 333, 795-802 (1998/5-3)

Distance indicators based on the luminosity-profile shapes of early-type galaxies-a reply.


Abstract (from CDS):

In a recent paper, Binggeli & Jerjen (1998A&A...333...17B) question the value of the extragalactic distance indicators presented by Young & Currie (1994MNRAS.268L..11Y & 1995MNRAS.273.1141Y) and state that they have refuted `the claim that the Virgo dEs [dwarf-elliptical galaxies]...are distributed in a prolate structure stretching from 8 to 20 Mpc distance (Young & Currie, 1995MNRAS.273.1141Y).' even though no such claim was ever made. In this paper, we examine Binggeli & Jerjen's claims that intrinsic scatter rather than spatial depth must be the main cause of the large scatters observed in the relevant scaling relationships for Virgo galaxies. We investigate the accuracy of Binggeli & Jerjen's photometric parameters and find that while their profile curvature and scalelength measurements are probably useful, their total magnitude and central surface-brightness measurements are not useful for the purpose of investigating scaling laws because they suffer from serious systematic and random errors. We also investigate Binggeli & Jerjen's criticisms of our (1995MNRAS.273.1141Y) analysis. We demonstrate that their test for strong mutual dependence between distance estimates based on the two different scaling laws is invalid because of its prior assumption of negligible cluster depth. We further demonstrate that the [relative] distance estimates on which their kinematical arguments are based cannot be meaningful, not only because of the seriousness of the photometric errors, but also because they are undermined by the prior assumption that depth effects can again be neglected. Interestingly, we also find that Binggeli & Jerjen's own dataset does itself contain evidence for large depth. Using the observed correlation between scale-length and profile-curvature, (the only correlation that can be investigated meaningfully using their dataset), we find that the frequency distribution of residuals with respect to the best fitting curve deviates significantly from that expected from a uni-modal Gaussian distribution. Clearly, if as Binggeli & Jerjen claim, the very large scatter observed in this scaling relationship for Virgo galaxies (which is not observed for Fornax or Local Group ones) were intrinsic, one would expect a uni-modal Gaussian distribution.

Abstract Copyright:

Journal keyword(s): cosmology: distance scale - galaxies: clusters: individual: Virgo - galaxies: elliptical and lenticular - galaxies: distances and redshifts - galaxies: fundamental parameters - galaxies: photometry

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 M 110 GiG 00 40 22.0572349992 +41 41 07.507220136   8.92 8.07     ~ 1266 1
2 M 84 Sy2 12 25 03.74333 +12 53 13.1393 12.67 12.09 10.49     ~ 1694 2
3 M 86 GiG 12 26 11.814 +12 56 45.49 10.32 9.83 8.90   7.50 ~ 1044 1
4 NAME Virgo Cluster ClG 12 26 32.1 +12 43 24           ~ 6249 0
5 M 49 Sy2 12 29 46.798 +08 00 01.48   13.21 12.17     ~ 2022 2
6 M 87 BiC 12 30 49.42338230 +12 23 28.0438581 10.16 9.59 8.63   7.49 ~ 6644 3

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