J/A+A/552/A106 NGC 1316 BVI images (Cantiello+, 2013)
The distance to NGC 1316 (Fornax A): yet another curious case.
Cantiello M., Grado A., Blakeslee J.P., Raimondo G., Di Rico G.,
Limatola L., Brocato E., Della Valle M., Gilmozzi R.
<Astron. Astrophys. 552, A106 (2013)>
=2013A&A...552A.106C 2013A&A...552A.106C
ADC_Keywords: Galaxies, photometry
Keywords: galaxies: elliptical and lenticular, cD -
galaxies: distances and redshift -
galaxies: clusters: individual: NGC 1316 - galaxies: photometry -
galaxies: stellar content - galaxies: peculiar
Abstract:
The distance of NGC1316, the brightest galaxy in the Fornax cluster,
provides an interesting test for the cosmological distance scale.
First, because Fornax is the second largest cluster of galaxies within
≲25Mpc after Virgo and, in contrast to Virgo, has a small
line-of-sight depth; and second, because NGC1316 is the single galaxy
with the largest number of detected Type Ia supernovae (SNe Ia),
giving the opportunity to test the consistency of SNe Ia distances
both internally and against other distance indicators.
We measure surface brightness fluctuations (SBF) in NGC1316 from
ground- and space-based imaging data. The sample provides a
homogeneous set of measurements over a wide wavelength interval. The
SBF magnitudes, coupled with empirical and theoretical absolute SBF
calibrations, are used to estimate the distance to the galaxy. We also
present the first B-band SBF measurements of NGC1316 and use them
together with the optical and near-IR SBF data to analyze the
properties of field stars in the galaxy.
We obtain m-M=31.59±0.05(stat)±0.14(sys.)mag, or
d=20.8±0.5(stat)±1.5(sys.)Mpc. When placed in a consistent Cepheid
distance scale, our result agrees with the distances from other
indicators. On the other hand, our distance is ∼17% larger than the
most recent estimate based on SNe Ia. Possible explanations for this
disagreement are the uncertain level of internal extinction, and/or
calibration issues. Concerning the stellar population analysis, we
confirm the results from other spectro-photometric indicators: the
field stars in NGC1316 are dominated by a component with roughly solar
metallicity and intermediate age. A non-negligible mismatch exists
between B-band SBF models and data. We confirm that such behavior can
be accounted for by an enhanced percentage of hot horizontal branch
stars.
Our study of the SBF distance to NGC1316, and the comparison with
distances from other indicators, raises some concern about the
homogeneity between the calibrations of different indicators. If not
properly placed in the same reference scale, significant differences
can occur, with dramatic impact on the cosmological distance ladder.
Our results on the stellar populations properties show that SBF data
over a broad wavelength interval are an efficient means of studying
the properties of unresolved systems in peculiar cases like NGC1316.
Description:
This work is based on data of NGC1316 from the Very Large Telescope
(VLT). We used B, V and I-band observations obtained with the FORS1
Imager at ESO's VLT in Paranal (Program 64.H-0624(A), P.I. M. Della
Valle).
The data reduction was carried out with the VST-Tube imaging pipeline.
VST-Tube is a very versatile software for astronomical data analysis,
tested against imaging data taken with different telescopes/detectors,
adaptable to existing or future multi-CCD cameras
Objects:
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RA (2000) DE Designation(s)
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03 22 41.52 -37 12 33.5 NGC 1316 = NAME FORNAX A
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 54 3 List of FITS images
fits/* . 3 FITS images
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 22 F3.1 arcsec/pix Scale [0.2] Scale of the image
24- 27 I4 pix Nx [2085] Number of pixels along X-axis
28 A1 --- --- [x]
29- 32 I4 pix Ny [2108] Number of pixels along Y-axis
34- 46 A13 --- FileName Name of FITS file in subdirectory fits
48- 54 A7 --- Title Title of the file
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Acknowledgements:
Michele Cantiello, cantiell(at)oa-teramo.inaf.it
(End) Patricia Vannier [CDS] 27-Feb-2013