Seibel, Daryl Lee (2016) Tully-Fisher distance measurements of spiral galaxies with well-observed type Ia supernovae. PhD thesis, James Cook University.

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Abstract

This thesis provides a comprehensive new set of distance measurements for nearby (cz < 6000 km s⁻¹) galaxies based on two of the best available distance indicators: the Tully-Fisher (TF) relation, and Type Ia Supernovae (SNe Ia). The Tully-Fisher relation relates absolute luminosity and rotation velocity, and is an excellent distance indicator for inclined spiral galaxies in the local Universe. SNe Ia are bright so-called 'standard candles' (albeit with a well-known dependences on colour and the decline rate of their light curves) that are used to measure distances to a range of host galaxies at large distances. Although generally more accurate than the former method, SNe Ia are relatively rare and distances can therefore only be measured to small samples of objects in the local Universe. This thesis provides new Tully-Fisher data for all southern hemisphere SN Ia host galaxies, thereby allowing a much better cross-comparison of the two methods than previously possible. Type Ia Supernova 2012fr is the latest SN Ia included in this thesis with a full light curve. Nevertheless, there are some SN Ia and host galaxy data that are incomplete. In many respects, this study is a pilot study for much larger samples that will be provided by the forthcoming SkyMapper supernova survey and the ASKAP WALLABY neutral hydrogen survey.

Measurements are presented for a total of 227 galaxies in the following three separate studies:

1. A sample of 130 galaxies for which homogenised optical and radio data is obtained from the literature, and are mainly in the northern hemisphere.

2. A sample of 46 galaxies with good existing photometry, but without prior radio data, were observed in 2005 with the ATNF Parkes 64 m Radio Telescope. This sample significantly adds to the available set of data for nearby southern galaxies.

3. New near-infrared imaging with the European Southern Observatory's New Technology Telescope (NTT), and the new 21 cm radio imaging with the Parkes 64 m telescope in 2004 is presented for a sample of 88 and 51 galaxies, respectively. This sample again significantly adds to the volume, and quality, of the available data.

For each of the above samples, SNe Ia distances are calculated using data published in the literature for optical photometry, namely peak brightness, colour and decay rate, where available. Tully-Fisher distances are calculated using neutral hydrogen line width measurements and optical luminosities in the optical (BT) and infrared (Hc and Ks) bands.

Although the total sample overlap between the SNe Ia and Tully-Fisher distances remains relatively small, no systematic significant differences are found. Nevertheless, the scatter is significant in our studies. Furthermore, compared with the SNe Ia distances, it is notable that there is significantly less dispersion in the distance moduli for the final Parkes / NTT sample, illustrating the value of the dedicated new observations presented here.

A comparison of our distance estimates with secondary calibration relations suggests higher values of the Hubble constant than previously measured: H₀ = 76 ± 4 km s⁻¹ Mpc⁻¹ and H₀ = 90 ± 5 km s⁻¹ Mpc⁻¹ for the Tully-Fisher and SNe Ia methods, respectively. The latter is significantly higher than the highly-accurate Planck result of H₀ = 67 ± 1 km s⁻¹ Mpc⁻¹ suggesting that our samples are subject to selection effects, and are not volume-limited. We are biased by the exclusion of faint SNe Ia and possibly by faint SN Ia host galaxies due to radio sensitivity limits.

Peculiar velocities were calculated from the measured distances and redshifts. Of the 227 total galaxies in our sample sets, 177 galaxies have complete data for our study. An analysis of the bulk flow using the peculiar velocities in a combined sample of 177 SNe Ia and Tully-Fisher measurements shows that the sample is substantially at rest with respect to the rest frame defined by the Cosmic Microwave Background. The residual bulk flow of 208 ± 160 km s⁻¹ is in agreement with the predictions of ΛCDM (Lambda-Cold Dark Matter) for a mean depth of 40 Mpc.

Finally, a comparison of our measured peculiar velocities with theoretical values reconstructed from models of the gravitational field deduced from redshift surveys has allowed us to investigate the relationship between gravity and the largescale galaxy distribution. A value for the growth parameter of β = 0.37 ± 0.08 is measured, corresponding to a value for the dark matter density parameter at the present epoch of Ωₘ = 0.16 ± 0.06, assuming a bias parameter b = 1; the latter not being measured in the thesis.

Future studies with SkyMapper and ASKAP will benefit greatly by having deeper, more numerous samples and will benefit from higher quality data. The existing data in the literature, particularly the photometry for historical SNe Ia, is of lower quality than newer data.

Item ID:	49763
Item Type:	Thesis (PhD)
Keywords:	extragalactic astronomy, galactic astronomy, galaxies, multibeam, Parkes sample, SNe Ia distance scale, spiral galaxies, supernovae, supernovae as distance indicators, Tully-Fisher relation theory
Date Deposited:	03 Aug 2017 23:00
FoR Codes:	02 PHYSICAL SCIENCES > 0201 Astronomical and Space Sciences > 020103 Cosmology and Extragalactic Astronomy @ 30% 02 PHYSICAL SCIENCES > 0201 Astronomical and Space Sciences > 020104 Galactic Astronomy @ 70%
SEO Codes:	97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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