Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Publication
- Publication Type
Articles 1 - 6 of 6
Full-Text Articles in Physical Sciences and Mathematics
Quantified H I Morphology – I. Multi-Wavelength Analysis Of The Things Galaxies., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden, E. C. Elson
Quantified H I Morphology – I. Multi-Wavelength Analysis Of The Things Galaxies., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden, E. C. Elson
Faculty Scholarship
Galaxy evolution is driven to a large extent by interactions and mergers with other galaxies and the gas in galaxies is extremely sensitive to the interactions. One method to measure such interactions uses the quantified morphology of galaxy images. Well-established parameters are Concentration, Asymmetry, Smoothness, Gini and M20 of a galaxy image. Thus far, the application of this technique has mostly been restricted to rest-frame ultraviolet and optical images. However, with the new radio observatories being commissioned [South African Karoo Array Telescope (MeerKAT), Australian SKA Pathfinder (ASKAP), Extended Very Large Array (EVLA), Westerbork Synthesis Radio Telescope/APERture Tile In Focus instrument …
Quantified H I Morphology – Ii. Lopsidedness And Interaction In Whisp Column Density Maps., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden, E. C. Elson
Quantified H I Morphology – Ii. Lopsidedness And Interaction In Whisp Column Density Maps., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden, E. C. Elson
Faculty Scholarship
Lopsidedness of the gaseous disc of spiral galaxies is a common phenomenon in disc morphology, profile and kinematics. Simultaneously, the asymmetry of a galaxy’s stellar disc, in combination with other morphological parameters, has seen extensive use as an indication of recent merger or interaction in galaxy samples. Quantified morphology of stellar spiral discs is one avenue to determine the merger rate over much of the age of the Universe. In this paper, we measure the quantitative morphology parameters for the H I column density maps from the Westerbork observations of neutral Hydrogen in Irregular and SPiral galaxies (WHISP). These are …
Quantified H I Morphology – V. H I Discs In The Virgo Cluster., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, W. Van Driel
Quantified H I Morphology – V. H I Discs In The Virgo Cluster., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, W. Van Driel
Faculty Scholarship
We explore the quantified morphology of atomic hydrogen (H i) discs in the Virgo cluster. These galaxies display a wealth of phenomena in their H i morphology, e.g., tails, truncation and warps. These morphological disturbances are related to the ram pressure stripping and tidal interaction that galaxies undergo in this dense cluster environment. To quantify the morphological transformation of the H i discs, we compute the morphological parameters of Concentration, Asymmetry, Smoothness, Gini and M20 and our own GM for 51 galaxies in 48 H i column density maps from the VLA Imaging of Virgo spirals in Atomic gas (VIVA) …
Quantified H I Morphology – Iv. The Merger Fraction And Rate In Whisp., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden
Quantified H I Morphology – Iv. The Merger Fraction And Rate In Whisp., Benne W. Holwerda, N. Pirzkal, W. J. G. De Blok, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden
Faculty Scholarship
The morphology of the atomic hydrogen (H I) disc of a spiral galaxy is the first component to be disturbed by a gravitational interaction such as a merger between two galaxies. We use a simple parametrization of the morphology of H I column density maps of the Westerbork observations of neutral Hydrogen in Irregular and SPiral galaxies (WHISP) project to select those galaxies that are likely undergoing a significant interaction. Merging galaxies occupy a particular part of parameter space defined by Asymmetry (A), the relative contribution of the 20 per cent brightest pixels to the second-order moment of the column …
Quantified H I Morphology – Iii. Merger Visibility Times From H I In Galaxy Simulations., Benne W. Holwerda, N. Pirzkal, T. J. Cox, W. J. G. De Blok, J. Weniger, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden
Quantified H I Morphology – Iii. Merger Visibility Times From H I In Galaxy Simulations., Benne W. Holwerda, N. Pirzkal, T. J. Cox, W. J. G. De Blok, J. Weniger, A. Bouchard, S. -L. Blyth, K. J. Van Der Heyden
Faculty Scholarship
Major mergers of disc galaxies are thought to be a substantial driver in galaxy evolution. To trace the fraction and rate of galaxy mergers over cosmic times, several observational techniques have been developed over the last decade, including parametrized morphological selection. We apply this morphological selection of mergers to 21 cm radio emission line (H I) column density images of spiral galaxies in nearby surveys. In this paper, we investigate how long a 1:1 merger is visible in H I from N-body simulations. We evaluate the merger visibility times for selection criteria based on four parameters: Concentration, Asymmetry, M20 and …
Rest-Frame Uv--Optically Selected Galaxies At 2.3, Yicheng Guo, Mauro Giavalisco, Paolo Cassata, Henry C. Ferguson, Christina C. Williams, Mark Dickinson, Anton Koekemoer, Norman A. Grogin, Ranga-Ram Chary, Hugo Messias, Elena Tundo, Lihwai Lin, Seong-Kook Lee, Adriano Fontana, Andrea Grazian, Dale Kocevski, Kyoung-Soo Lee, Edward Villanueva, Arjen Van Der Wel
Rest-Frame Uv--Optically Selected Galaxies At 2.3, Yicheng Guo, Mauro Giavalisco, Paolo Cassata, Henry C. Ferguson, Christina C. Williams, Mark Dickinson, Anton Koekemoer, Norman A. Grogin, Ranga-Ram Chary, Hugo Messias, Elena Tundo, Lihwai Lin, Seong-Kook Lee, Adriano Fontana, Andrea Grazian, Dale Kocevski, Kyoung-Soo Lee, Edward Villanueva, Arjen Van Der Wel
Mauro Giavalisco
A new set of color selection criteria (VJL) analogous with the BzK method is designed to select both star-forming galaxies (SFGs) and passively-evolving galaxies (PEGs) at 2.310^{10}M_{Sun}) galaxies at 2.30.4) SFGs, which however, only account for ~20% of the number density of massive SFGs. We also use the mid-infrared fluxes to clean our PEG sample, and find that galaxy size can be used as a secondary criterion to effectively eliminate the contamination of dusty SFGs. The redshift distribution of the cleaned PEG sample peaks at z~2.5. We find 6 PEG candidates at z>3 and discuss possible methods to distinguish …