PhD Thesis
HOPCAT, a complete Southern Sky Neutral
Hydrogen-Optical Galaxy Catalogue and the Star Formation Rate-Density
Relation.
Marianne. T. Doyle
Abstract: We investigate the star formation
rate (SFR)-density relation using a neutral hydrogen (HI) galaxy
sample. The SFR-density relation is the observation that the SFR
decreases with increasing local galaxy density. We determine which of
the two main alternatives explains
what causes the cessation of star formation in regions with high galaxy
density. Is it that fewer star forming HI galaxies are present in
galaxy dense regions or are galaxies capable of star formation present
but some physical process is suppressing their star formation? We
use the HI Parkes All Sky survey catalogue (HICAT) and find the optical
counterparts for the HI detections. We produce the HICAT Optical
Catalogue, HOPCAT which contains 4315 HI detections. Of these we
find optical counterparts for 3618 (84 per cent) galaxies.
For 481 (11 per cent), multiple galaxies are present but no single
optical
counterpart can be chosen and 216 (5 per cent) have no obvious optical
galaxy present. We conduct a search for possible isolated dark
galaxies
in HOPCAT and find no isolated optically dark galaxies within the
limits
of the HI Parkes All Sky survey. A compact disk copy of HOPCAT is
provided
with this thesis.
The SFR-density relation is investigated using the optically matched
HOPCAT galaxies. We use these galaxies along with 2 background
catalogues,
one optical and one k-band, to calculate the local surface density,
Sigma10. To calculate the SFRs we use
infrared (IR) and radio flux. We have 4
data sets: two with densities calculated using the optical background
catalogue each with IR and radio SFRs, and two with densities
calculated using the K-band background catalogue with IR and radio
SFRs.
Using the largest HI detected data set of the whole southern sky we
investigate the relationship between HI mass and the SFR and find that,
for nearby
(velocity<10000 km/s) HI galaxies, we find a strong correlation. We
find a larger population of HI galaxies compared to optical galaxies
for
Sigma10<2 galaxies Mpc-2. We also find the
number
of HI galaxies decreases by 50 per cent over a Sigma10 range
between
0 and 11 galaxies Mpc-2. For the same density range
the optical
galaxy population only decrease by 2.9 per cent. We do not find a
change
in the HI content of our galaxy sample with increasing local galaxy
density.
For HI galaxies (1000<velocity<6000 km s-1) there is
no significant change in the star formation rate or the efficiency of
star formation with respect to local surface density. We find that the
SFR-density relation as reported in previous studies can be explained
by their optical data sample. Their samples contain galaxies
detected by their stellar population
and not their star formation potential. The SFR is less in
regions of high
local galaxy density because the galaxies present in these regions are
predominately elliptical galaxies that display little or no star
formation. This density/morphology
mix is confirmed by the morphology-density relation.
For the first time we can explain the reasons behind the SFR-density
relation and we find that the decrease in the SFR with increasing local
galaxy density is explained by a decrease in the population of HI star
forming galaxies and not due to the suppression of star formation in
the
HI galaxies.
First Author Papers
The
effect of local galaxy surface density on star formation for HI
selected galaxies (MNRAS 2006, 372, 977-991pp)
M. T. Doyle & M. J. Drinkwater
Abstract: We present the result of
investigations into two theories to explain the star formation rate
(SFR)-density relationship. For regions of high galaxy density, either
there are fewer star-forming galaxies or galaxies capable of forming
stars are present but some physical process is suppressing their star
formation. We use HI Parkes All-Sky Survey's (HIPASS) HI detected
galaxies and infrared and radio fluxes to investigate SFRs and
efficiencies with respect to local surface density. For nearby (vel
< 10000 km s-1) HI galaxies, we find a strong correlation
between HI mass and SFR. The number of HI galaxies decreases with
increasing local surface density. For HI galaxies (1000 < vel <
6000 km s-1), there is no significant change in the SFR or
the efficiency of star formation with respect to local surface density.
We conclude that the SFR-density relation is due to a decrease in the
number of HI star-forming galaxies in regions of high galaxy density
and not to the suppression of star
formation.
The
HIPASS Catalogue: III - Optical Counterparts and Isolated Dark Galaxies
(MNRAS 2005, 361, 34-44pp)
M. T. Doyle, M. J. Drinkwater, D. J. Rohde, K. A. Pimbblet,
M. Read, M. J. Meyer, M. A. Zwaan, E. Ryan-Weber, J.
Stevens, B. S. Koribalski, R. L. Webster, L.
Staveley-Smith, D. G. Barnes, M. Howlett, V. A. Kilborn, M.
Waugh, M. J. Pierce, R. Bhathal, W. J. G. de Blok, M. J. Disney, R. D.
Ekers, K. C. Freeman, D. A. Garcia, B. K. Gibson, J.
Harnett, P. A. Henning, H. Jerjen, M. J. Kesteven, P. M. Knezek, S.
Mader, M. Marquarding, R. F. Minchin, J. O'Brien, T.
Oosterloo, R. M. Price, M. E. Putman, S. D. Ryder, E. M. Sadler, I. M.
Stewart, F. Stootman and A. E. Wright
Abstract: We present the largest catalogue to
date of optical counterparts for HI radio-selected galaxies, HOPCAT. Of
the 4315 HI radio-detected sources from the
HI Parkes All Sky Survey (HIPASS) catalogue, we find optical
counterparts for 3618 (84 per cent) galaxies. Of these, 1798 (42 per
cent) have confirmed optical velocities and 848 (20 per cent) are
single matches without confirmed velocities. Some galaxy matches are
members of
galaxy groups. From these multiple galaxy matches, 714 (16 per cent)
have confirmed optical velocities and a further 258 (6 per cent)
galaxies are without confirmed velocities. For 481 (11 per cent),
multiple galaxies are present but no single optical counterpart can be
chosen and 216 (5 per cent) have no obvious optical galaxy present.
Most of these `blank fields' are in crowded fields along the Galactic
plane or have high extinctions.
Isolated `dark galaxy' candidates are investigated using an extinction
cut of ABj < 1mag and the blank-fields
category. Of the 3692 galaxies with an ABj
extinction <1mag, only 13 are also blank fields. Of these, 12 are
eliminated either with follow-up Parkes observations or are
in crowded fields. The remaining one has a low surface brightness
optical counterpart. Hence, no isolated optically dark galaxies have
been found within the limits of the HIPASS survey.
HIPASS
III Images
HIPASS Papers
HOPCAT
On-line Searchable Catalogue
Download Complete HOPCAT From MNRAS
The
Chemical Composition of α Cen A: Strong Lines and the ABO Theory of
Collisional Line Broadening (PASA 2005, 22, 1-7p)
Marianne T. Doyle, Bernard J O'Mara, John E.
Ross and Michael S. Bessell
Abstract: The mean abundances of Mg, Si, Ca,
Ti, Cr, and Fe based on both strong and weak lines of α Cen A are
determined by matching the observed line profiles with those
synthesised from stellar atmospheric models and comparing these results
with a similar analysis for the Sun. There is good agreement between
the abundances from strong and weak lines. Strong lines should
generally be an excellent indicator of abundance and far easier to
measure than the weak lines normally used. Until the development of the
Anstee, Barklem, and O'Mara (ABO) theory for collisional line
broadening, the uncertainty in the value of the damping constant
prevented strong lines being used for abundance determinations other
than in close differential analyses. We found that α Cen A has a mean
overabundance of 0.12 +/- 0.06 dex compared to solar mean abundances.
This result agrees remarkably well with previous studies that did not
use strong lines or the ABO theory for collisional line broadening. Our
result supports the conclusion that reliable abundances can be derived
from strong lines provided this new theory for line broadening is used
to calculate the van der Waals damping.
Co-author Papers
The large peculiar velocity of the cD galaxy in Abell 3653(MNRAS,
2006, 368, 651–658pp)
Kevin A. Pimbblet, Isaac G. Roseboom and Marianne T. Doyle
Abstract: We present a catalogue of galaxies in
Abell 3653 from observations made with the 2-degree field (2dF)
spectrograph at the Anglo-Australian Telescope. Of the 391 objects
observed, we find 111 are bona fide members of Abell 3653. We show that
the cluster has a velocity of cz = 32 214 ± 83 km s−1 (z
= 0.10 738 ± 0.00 027), with a velocity dispersion typical of rich,
massive
clusters of σ cz = 880+66 −54.We find that the cD galaxy has a peculiar
velocity of 683 ± 96 km s−1 in the cluster rest frame – some 7σ away
from
the mean cluster velocity, making it one of the largest and most
significant peculiar velocities found for a cD galaxy to date. We
investigate the
cluster for signs of substructure, but do not find any significant
groupings
on any length scale. We consider the implications of our findings on
cD formation theories.
Applying machine learning to catalogue matching in astrophysics
(MNRAS 2005, 360, 69)
D. J. Rohde, M. J. Drinkwater, M. R.
Gallagher, T. Downs and M. T. Doyle
Abstract: We present the results of applying
automated machine learning techniques to the problem of matching
different object catalogues in astrophysics. In this
study, we take two partially matched catalogues where one of the two
catalogues has a large positional uncertainty. The two catalogues we
used here were taken from the HI Parkes All Sky Survey (HIPASS) and
SuperCOSMOS optical survey. Previous work had matched 44 per cent (1887
objects) of HIPASS to the SuperCOSMOS catalogue.
A supervised learning algorithm was then applied to construct a model
of the matched portion of our catalogue. Validation of the model shows
that we achieved a good classification performance (99.12 per cent
correct).
Applying this model to the unmatched portion of the catalogue found
1209 new matches. This increases the catalogue size from 1887 matched
objects
to 3096. The combination of these procedures yields a catalogue that is
72
per cent matched.
Galaxy Groups: Proceedings from a Swinburne University
Workshop (PASA,
2005, 22, 326-334pp)
Virginia A. Kilborn, Kenji Bekki, Sarah Brough,
Marianne T. Doyle, Ekaterina A. Evstigneeva, Duncan A. Forbes, Bärbel
S.
Koribalski, Matthew S. Owers, Chris Power, Michael J. Drinkwater, David
J. Rohde, Christopher A. Blake, Warrick J. Couch, Michael B. Pracy and
Brad K. Gibson
Abstract: We present the proceedings from a
two-day workshop held at Swinburne University on 2005 May 24–25. The
workshop participants highlighted current Australian research on both
theoretical and observational aspects of galaxy groups. These
proceedings include short one-page summaries of a number of the talks
presented at the workshop. The talks presented ranged from reconciling N-body
simulations with observations, to the Hi content of galaxies in groups
and the existence of 'dark galaxies'. The formation and existence of
ultra-compact dwarfs in groups, and a new
supergroup in Eridanus were also discussed.
Machine Learning for Matching Astronomy Catalogues
(Lecture Notes in Computer Science Vol. 3177, 2004, 702pp)
(Intelligent Data Engineering and Automated Learning - IDEAL 2004:
5th International Conference, Exeter, UK. August 25-27, 2004.
Proceedings Editors: Zheng Rong Yang, Hujun Yin,
Richard Everson)
D. J. Rohde, M. J. Drinkwater, M. R.
Gallagher, T. Downs
and M. T. Doyle
Abstract: An emerging issue in the field
of astronomy is the integration, management and utilization of
databases from around the world to facilitate scientific discovery. In
this paper, we
investigate application of the machine learning techniques of support
vector
machines and neural networks to the problem of amalgamating catalogues
of
galaxies as objects from two disparate data sources: radio and optical.
Formulating
this as a classification problem presents several challenges, including
dealing
with a highly unbalanced data set. Unlike the conventional approach to
the
problem (which is based on a likelihood ratio) machine learning does
not
require density estimation and is shown here to provide a significant
improvement
in performance. We also report some experiments that explore the
importance
of the radio and optical data features for the matching problem.
Multiple Co-Author Papers
The
Northern HIPASS catalogue - data presentation, completeness and
reliability measures (MNRAS, 2006, 371, 1855-1864pp)
NGC922
– a new drop-through ring galaxy (MNRAS, 2006, 370, 1607–1611pp)
The
Survey for Ionization in Neutral Gas Galaxies. I. Description and
Initial Results (AJSS, 2006, 165, 307–337pp)
The
Survey for Ionization in Neutral Gas Galaxies. II The Star Formation
Rate Density of the Local Universe (ApJ, 2006, 649, 150-162pp)
Posters
Star Formation Efficiency VS
Environment (2003IAUS..216E.129D)
(Maps of the Cosmos, International Astronomical Union. Symposium
no. 216, held 14-17 July, 2003 in Sydney, Australia, meeting abstract)
Marianne T. Doyle, Michael J. Drinkwater, Bärbel
S. Koribalski and
The HIPASS Team
Abstract: Star formation in galaxies is very sensitive to local
environment almost ceasing in regions of high galaxy density. This
morphology-density relation has been recognized for decades but its
underlying physical cause is still unclear. The new HI Parkes All-Sky
21cm Survey (HIPASS) allows
us to investigate the morphology-density relation effect for the
first time with a very large galaxy sample selected purely by neutral
hydrogen content. The 5000 HIPASS galaxies span a range in local galaxy
density from 0.02 to 1.4 galaxies per cubic Mpc. We estimate star
formation rates using optical photometry (SuperCOSMOS) and spectroscopy
(6dF) as well as radio
continuum measurements (ATCA). We introduce a new parameter the
efficiency
of star formation which is the ratio of current star formation to
measured
HI mass. We present measurements of how this varies with local galaxy
density
in the HIPASS sample and compare the results to models of the
morphology-density relation.
Bright & Dark Galaxies
from the HIPASS Radio Survey
(Annual Scientific Meeting of the Astronomical Society of
Australia, Brisbane 5-8th July,2004)
Marianne T. Doyle, Michael J. Drinkwater, David J. Rohde, Mike Read,
Baerbel S Koribalski and The HIPASS Team
* We have searched for optical counterparts for the
4315 HI Parkes
All-Sky 21cm Survey (HIPASS4) detections.
* We used images from the SuperCOSMOS optical
southern sky survey
* We have identified 84% of the 4315 HI detected
sources
* We have identified 3 possible candidates for “Dark
Galaxies”
* Using the HIPASS catalogue we are investigating:
* Estimators of Star Formation
Rates (SFR)
* Star Formation Efficiency (SFE)
* Dependence of Star Formation on
local galaxy density
Talks
¶
Star Formation & the
Morphology-Density Relation in the Local Universe
Astrophysics Group, University of Southern Queensland,
Toowoomba, June, 2004
Marianne T. Doyle , University of Queensland
The HICAT Optical
Catalogue - HOPCAT
Astrophysics Group, University of Melbourne, August, 2004
Marianne T. Doyle , University of Queensland
¶
HOPCAT, 6dFGS & Star
Formation Rates
6dF Workshop, Australian Telescope National Facility,
Sydney, April 2005
Marianne T. Doyle , University of Queensland
HOPCAT, 6dFGS
& Star Formation Rates
Galaxy Group Workshop, Swinburne
University, Melbourne, May 2005
Marianne T. Doyle , University of Queensland
HOPCAT, Dark
Galaxies & Star
Formation
ASA 2005 Mapping the Universe Session - Wed 6th July
Marianne T. Doyle, PhD Student , University of Queensland
(Winner of a PASA-ASA Oral Presentation "Highly Commended" Student
Talk Award)
I present the largest catalogue to date of optical counterparts for HI
radio-selected galaxies, HOPCAT. Of the 4315 HI radio-detected sources
from the HI Parkes All Sky Survey HIPASS catalogue, we find optical
counterparts for a large majority of the radio HI detections. We
use multiple radio-optical match categories to identify not only
various kinds of matches but the reliability level of the resulting
magnitudes. We also investigate whether isolated ‘dark galaxies’
are present within the HIPASS survey.
Using HOPCAT, star formation rates, star formation efficiency and
galaxy density will be investigated to test two theories for the
Morphology-Density relation, that, either fewer “star forming galaxies”
actually form in regions of high galaxy density or there are physical
processes that directly suppresses star formation.
HI Galaxies and the
SFR-Density Relation
ASA 2007 - Mon 2nd July
Dr. Marianne T. Doyle , University of Queensland
We present the result of investigations into two theories to explain the star formation rate-density relationship. For regions of high galaxy density, either there are fewer star-forming galaxies or galaxies capable of forming stars are present but some physical process is suppressing their star formation. We use HI Parkes All Sky Survey's (HIPASS) HI detected galaxies, their optical counterparts and IR and radio fluxes to investigate SFRs and efficiencies with respect to local surface density.
General Publications
UQ
astrophysicists shed light on dark galaxies (Published:
19 September 2005, UQ News)
Marianne T. Doyle
Dark
Galaxies: Do they Exist? (Published: October 2006,
Australasian Science)
Marianne
T. Doyle
General Public Talks
HOPCAT
& Dark Galaxies
Brisbane Astronomical Society, March 2007
Created : July 11th 2005 |
Last Updated : June 26th 2007 | VERSION : 1.0