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Full-Text Articles in Astrophysics and Astronomy
The Onset Of Warps In Spitzer Observations Of Edge-On Spiral Galaxies., Kanak Saha, Roelof De Jong, Benne W. Holwerda
The Onset Of Warps In Spitzer Observations Of Edge-On Spiral Galaxies., Kanak Saha, Roelof De Jong, Benne W. Holwerda
Benne Holwerda
We analyse warps in the nearby edge-on spiral galaxies observed in the Spitzer/Infrared Array Camera (IRAC )4.5-μm band. In our sample of 24 galaxies, we find evidence of warp in 14 galaxies. We estimate the observed onset radii for the warps in a subsample of 10 galaxies. The dark matter distribution in each of these galaxies are calculated using the mass distribution derived from the observed light distribution and the observed rotation curves. The theoretical predictions of the onset radii for the warps are then derived by applying a self-consistent linear response theory to the obtained mass models for six …
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
Benne Holwerda
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
Benne Holwerda
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 – 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
Benne Holwerda
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 – 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
Benne Holwerda
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 – 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
Benne Holwerda
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 …
On The Origin Of Lopsidedness In Galaxies As Determined From The Spitzer Survey Of Stellar Structure In Galaxies (S4g)., Dennis Zaritsky, Heikki Salo, Eija Laurikainen, Debra M. Elmegreen, E. Athanassoula, Albert Bosma, Sebastien Comeron, Santiago Erroz-Ferrer, Bruce G. Elmegreen, Dimitri A. Gadotti, Armando Gil De Paz, Joannah L. Hinz, Luis C. Ho, Benne W. Holwerda, Taehyun Kim, Johan H. Knapen, Jarkko Laine, Seppo Laine, Barry F. Madore, Sharon Meidt, Karin Menendez-Delmestre, Trisha Mizusawa, Juan Carlos Munoz-Mateos, Michael W. Regan, Mark Seibert, Kartik Sheth
On The Origin Of Lopsidedness In Galaxies As Determined From The Spitzer Survey Of Stellar Structure In Galaxies (S4g)., Dennis Zaritsky, Heikki Salo, Eija Laurikainen, Debra M. Elmegreen, E. Athanassoula, Albert Bosma, Sebastien Comeron, Santiago Erroz-Ferrer, Bruce G. Elmegreen, Dimitri A. Gadotti, Armando Gil De Paz, Joannah L. Hinz, Luis C. Ho, Benne W. Holwerda, Taehyun Kim, Johan H. Knapen, Jarkko Laine, Seppo Laine, Barry F. Madore, Sharon Meidt, Karin Menendez-Delmestre, Trisha Mizusawa, Juan Carlos Munoz-Mateos, Michael W. Regan, Mark Seibert, Kartik Sheth
Benne Holwerda
We study the m = 1 distortions (lopsidedness) in the stellar components of 167 nearby galaxies that span a wide range of morphologies and luminosities. We confirm the previous findings of (1) a high incidence of lopsidedness in the stellar distributions, (2) increasing lopsidedness as a function of radius out to at least 3.5 exponential scale lengths, and (3) greater lopsidedness, over these radii, for galaxies of later type and lower surface brightness. Additionally, the magnitude of the lopsidedness (1) correlates with the character of the spiral arms (stronger arm patterns occur in galaxies with less lopsidedness), (2) is not …
Galaxy And Mass Assembly (Gama) : Galaxy Close Pairs, Mergers And The Future Fate Of Stellar Mass., A. S. G. Robotham, S. P. Driver, L. J. M. Davies, A. M. Hopkins, I. K. Baldry, N. K. Agius, A. E. Bauer, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. Cluver, R. De Propis, M. J. Drinkwater, Benne W. Holwerda, L. S. Kelvin, M. A. Lara-Lopez, J. Liske, Angel R. Lopez-Sanchez, J. Loveday, S. Mahajan, T. Mcnaught-Roberts, A. Moffett, P. Norberg, D. Obreschkow, M. S. Owers, S. J. Penny, K. A. Pimbblet, M. Prescott, E. N. Taylor, E. Van Kampen, S. M. Wilkins
Galaxy And Mass Assembly (Gama) : Galaxy Close Pairs, Mergers And The Future Fate Of Stellar Mass., A. S. G. Robotham, S. P. Driver, L. J. M. Davies, A. M. Hopkins, I. K. Baldry, N. K. Agius, A. E. Bauer, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. Cluver, R. De Propis, M. J. Drinkwater, Benne W. Holwerda, L. S. Kelvin, M. A. Lara-Lopez, J. Liske, Angel R. Lopez-Sanchez, J. Loveday, S. Mahajan, T. Mcnaught-Roberts, A. Moffett, P. Norberg, D. Obreschkow, M. S. Owers, S. J. Penny, K. A. Pimbblet, M. Prescott, E. N. Taylor, E. Van Kampen, S. M. Wilkins
Benne Holwerda
We use a highly complete subset of the Galaxy And Mass Assembly II (GAMA-II) redshift sample to fully describe the stellar mass dependence of close pairs and mergers between 108 and 1012 M⊙. Using the analytic form of this fit we investigate the total stellar mass accreting on to more massive galaxies across all mass ratios. Depending on how conservatively we select our robust merging systems, the fraction of mass merging on to more massive companions is 2.0–5.6 per cent. Using the GAMA-II data we see no significant evidence for a change in the close pair fraction between redshift z …
Herschel Observations Of Edge-On Spirals (Heroes) : Ii. Tilted-Ring Modelling Of The Atomic Gas Disks., F. Allaert, G. Gentile, M. Baes, G. De Geyter, T. M. Hughes, F. Lewis, S. Bianchi, I. De Looze, J. Fritz, Benne W. Holwerda, J. Verstappen, S. Viaene
Herschel Observations Of Edge-On Spirals (Heroes) : Ii. Tilted-Ring Modelling Of The Atomic Gas Disks., F. Allaert, G. Gentile, M. Baes, G. De Geyter, T. M. Hughes, F. Lewis, S. Bianchi, I. De Looze, J. Fritz, Benne W. Holwerda, J. Verstappen, S. Viaene
Benne Holwerda
Context. Edge-on galaxies can offer important insight into galaxy evolution because they are the only systems where the distribution of the different components can be studied both radially and vertically. The HEROES project was designed to investigate the interplay between the gas, dust, stars, and dark matter (DM) in a sample of 7 massive edge-on spiral galaxies. Aims. In this second HEROES paper, we present an analysis of the atomic gas content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently analysed according to the same strategy. The primary aim of this work is to …
The High-Ion Content And Kinematics Of Low-Redshift Lyman Limit Systems, Andrew J. Fox, Nicolas Lehner, Jason Tumlinson, J. Christopher Howk, Todd M. Tripp, J. Xavier Prochaska, John M. O'Meara, Jessica K. Werk, Rognmon Bordoloi, Neal S. Katz, Benjamin D. Oppenheimer, Romeel Dave
The High-Ion Content And Kinematics Of Low-Redshift Lyman Limit Systems, Andrew J. Fox, Nicolas Lehner, Jason Tumlinson, J. Christopher Howk, Todd M. Tripp, J. Xavier Prochaska, John M. O'Meara, Jessica K. Werk, Rognmon Bordoloi, Neal S. Katz, Benjamin D. Oppenheimer, Romeel Dave
Neal S. Katz
We study the high-ion content and kinematics of the circumgalactic medium around low-redshift galaxies using a sample of 23 Lyman limit systems (LLSs) at 0.08 < z < 0.93 observed with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. In Lehner et al., we recently showed that low-z LLSs have a bimodal metallicity distribution. Here we extend that analysis to search for differences between the high-ion and kinematic properties of the metal-poor and metal-rich branches. We find that metal-rich LLSs tend to show higher O VI columns and broader O VI profiles than metal-poor LLSs. The total H I line width (Δv 90 statistic) in LLSs is not correlated with metallicity, indicating that the H I kinematics alone cannot be used to distinguish inflow from outflow and gas recycling. Among the 17 LLSs with O VI detections, all but two show evidence of kinematic sub-structure, in the form of O VI-H I centroid offsets, multiple components, or both. Using various scenarios for how the metallicities in the high-ion and low-ion phases of each LLS compare, we constrain the ionized hydrogen column in the O VI phase to lie in the range log N(H II) ~ 17.6-20. The O VI phase of LLSs is a substantial baryon reservoir, with M(high-ion) ~ 108.5-10.9 (r/150 kpc)2 M ☉, similar to the mass in the low-ion phase. Accounting for the O VI phase approximately doubles the contribution of low-z LLSs to the cosmic baryon budget.
Co Distribution And Kinematics Along The Bar In The Strongly Barred Spiral Ngc 7479, S Laine, J D P Kenny, Min S. Yun, S T. Gottesman
Co Distribution And Kinematics Along The Bar In The Strongly Barred Spiral Ngc 7479, S Laine, J D P Kenny, Min S. Yun, S T. Gottesman
Min S. Yun
We report on the 2farcs5 (400 pc) resolution CO (J=1→0) observations covering the whole length of the bar in the strongly barred late-type spiral galaxy NGC 7479. CO emission is detected only along a dust lane that traverses the whole length of the bar, including the nucleus. The emission is strongest in the nucleus. The distribution of emission is clumpy along the bar outside the nucleus and consists of gas complexes that are unlikely to be gravitationally bound. The CO kinematics within the bar consist of two separate components. A kinematically distinct circumnuclear disk, <500 pc in diameter, is undergoing predominantly circular motion with a maximum rotational velocity of 245 km s-1 at a radius of 1'' (160 pc). The CO-emitting gas in the bar outside the circumnuclear disk has substantial noncircular motions that are consistent with a large radial velocity component, directed inward. The CO emission has a large velocity gradient across the bar dust lane, ranging from 0.5 to 1.9 km s-1 pc-1 after correcting for inclination, and the projected velocity change across the dust lane is as high as 200 km s-1. This sharp velocity gradient is consistent with a shock front at the location of the bar dust lane. A comparison of Hα and CO kinematics across the dust lane shows that, although the Hα emission is often observed both upstream and downstream from the dust lane, the CO emission is observed only where the velocity gradient is large. We also compare the observations with hydrodynamic models and discuss star formation along the bar.