scholarly journals Comparison of galaxy spiral arm pitch angle measurements using manual and automated techniques

2020 ◽  
Vol 493 (3) ◽  
pp. 3854-3865
Author(s):  
Ian B Hewitt ◽  
Patrick Treuthardt
Keyword(s):  
Pitch Angle ◽  
Spiral Galaxies ◽  
Small Sample ◽  
Automated Method ◽  
Angle Measurements ◽  
Barred Spiral Galaxy ◽  
Manual Input ◽  
Automated Methods ◽  
Disc Galaxies ◽  
Spiral Arm

ABSTRACT The pitch angle (PA) of arms in spiral galaxies has been found to correlate with a number of important parameters that are normally time intensive and difficult to measure. Accurate PA measurements are therefore important in understanding the underlying physics of disc galaxies. We introduce a semi-automated method that improves upon a parallelized two-dimensional fast Fourier transform algorithm (p2dfft) to estimate PA. Rather than directly inputting deprojected, star subtracted, and galaxy centred images into p2dfft, our method (p2dfft:traced) takes visually traced spiral arms from deprojected galaxy images as input. The tracings do not require extensive expertise to complete. This procedure ignores foreground stars, bulge and/or bar structures, and allows for better discrimination between arm and interarm regions, all of which reduce noise in the results. We compare p2dfft:traced to other manual and automated methods of measuring PA using both simple barred and non-barred spiral galaxy models and a small sample of observed spiral galaxies with different representative morphologies. We find that p2dfft:traced produces results that, in general, are more accurate and precise than the other tested methods and it strikes a balance between total automation and time-consuming manual input to give reliable PA measurements.

scholarly journals Determining the co-rotation radii of spiral galaxies using spiral arm pitch angle measurements at multiple wavelengths

2020 ◽  
Vol 496 (2) ◽  
pp. 1610-1619
Author(s):  
Shameer Abdeen ◽  
Daniel Kennefick ◽  
Julia Kennefick ◽  
Ryan Miller ◽  
Douglas W Shields ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Spiral Galaxies ◽  
Density Wave ◽  
Wave Theory ◽  
Time Lapse ◽  
Spiral Arms ◽  
Infrared Wavelength ◽  
Angle Measurements ◽  
Density Wave Theory ◽  
Spiral Arm

ABSTRACT The spiral arms spanning disc galaxies are believed to be created by density waves that propagate through galactic discs. We present a novel method of finding the co-rotation radius where the spiral arm pattern speed matches the velocities of the stars within the disc. Our method uses an image-overlay technique, which involves tracing the arms of spiral galaxies on images observed in different wavelengths. Density wave theory predicts that spiral arms observed from different wavelengths show a phase crossing at the co-rotation radius. For the purpose of this study, 20 nearby galaxies were analysed in four different wavelengths with pitch angle measurements performed by two independent methods. We used optical wavelength images (B band 440 nm), two infrared wavelength images provided by Spitzer (3.6 and 8 μm) and ultraviolet images from GALEX (1350, 1750 Å). The results were compared and verified with other records found in the literature. We then found rotation curve data for six of our galaxies and used our co-rotation radii estimates to measure the time that would elapse between star formation and moving to their observed positions in the B-band spirals. The average time lapse for this motion was found to be ∼50 Myr. The success of this new method of finding the co-rotation radius confirms density wave theory in a very direct way.

scholarly journals Galactic spiral structure

2009 ◽  
Vol 465 (2111) ◽  
pp. 3425-3446 ◽  
Author(s):  
Charles Francis ◽  
Erik Anderson
Keyword(s):  
Pitch Angle ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Stellar Orbits ◽  
Grand Design ◽  
Galactic Spiral Structure ◽  
Pattern Speed ◽  
Galactic Spiral ◽  
Almost All ◽  
Spiral Arm

We describe the structure and composition of six major stellar streams in a population of 20 574 local stars in the New Hipparcos Reduction with known radial velocities. We find that, once fast moving stars are excluded, almost all stars belong to one of these streams. The results of our investigation have led us to re-examine the hydrogen maps of the Milky Way, from which we identify the possibility of a symmetric two-armed spiral with half the conventionally accepted pitch angle. We describe a model of spiral arm motions that matches the observed velocities and compositions of the six major streams, as well as the observed velocities of the Hyades and Praesepe clusters at the extreme of the Hyades stream. We model stellar orbits as perturbed ellipses aligned at a focus in coordinates rotating at the rate of precession of apocentre. Stars join a spiral arm just before apocentre, follow the arm for more than half an orbit, and leave the arm soon after pericentre. Spiral pattern speed equals the mean rate of precession of apocentre. Spiral arms are shown to be stable configurations of stellar orbits, up to the formation of a bar and/or ring. Pitch angle is directly related to the distribution of orbital eccentricities in a given spiral galaxy. We show how spiral galaxies can evolve to form bars and rings. We show that orbits of gas clouds are stable only in bisymmetric spirals. We conclude that spiral galaxies evolve toward grand design two-armed spirals. We infer from the velocity distributions that the Milky Way evolved into this form about 9 billion years ago (Ga).

scholarly journals Spiral arm pitch angle and galactic shear rate inN-body simulations of disc galaxies

2013 ◽  
Vol 553 ◽  
pp. A77 ◽  
Author(s):  
R. J. J. Grand ◽  
D. Kawata ◽  
M. Cropper
Keyword(s):  
Shear Rate ◽  
Pitch Angle ◽  
Disc Galaxies ◽  
Spiral Arm

Feasibility and Evaluation of Automated Methods for Radiolabeling of Radiopharmaceutical Kits with Gallium-68

2019 ◽  
Vol 12 (3) ◽  
pp. 229-237 ◽  
Author(s):  
Alban Revy ◽  
François Hallouard ◽  
Sandrine Joyeux-Klamber ◽  
Andrea Skanjeti ◽  
Catherine Rioufol ◽  
...  
Keyword(s):  
The European Union ◽  
Preparation Time ◽  
Limit Of Quantification ◽  
Manual Method ◽  
Personnel Costs ◽  
Automated Method ◽  
Gallium 68 ◽  
The Right ◽  
First Time ◽  
Automated Methods

Objective: Recent gallium-68 labeled peptides are of increasing interest in PET imaging in nuclear medicine. Somakit TOC® is a radiopharmaceutical kit registered in the European Union for the preparation of [68Ga]Ga-DOTA-TOC used for the diagnosis of neuroendocrine tumors. Development of a labeling process using a synthesizer is particularly interesting for the quality and reproducibility of the final product although only manual processes are described in the Summary of Product (SmPC) of the registered product. The aim of the present study was therefore to evaluate the feasibility and value of using an automated synthesizer for the preparation of [68Ga]Ga-DOTA-TOC according to the SmPC of the Somakit TOC®. Methods: Three methods of preparation were compared; each followed the SmPC of the Somakit TOC®. Over time, overheads, and overexposure were evaluated for each method. Results: Mean±SD preparation time was 26.2±0.3 minutes for the manual method, 28±0.5 minutes for the semi-automated, and 40.3±0.2 minutes for the automated method. Overcost of the semi-automated method is 0.25€ per preparation for consumables and from 0.58€ to 0.92€ for personnel costs according to the operator (respectively, technician or pharmacist). For the automated method, overcost is 70€ for consumables and from 4.06€ to 6.44€ for personnel. For the manual method, extremity exposure was 0.425mSv for the right finger, and 0.350mSv for the left finger; for both the semi-automated and automated method extremity exposure were below the limit of quantification. Conclusion: The present study reports for the first time both the feasibility of using a [68Ga]- radiopharmaceutical kit with a synthesizer and the limits for the development of a fully automated process.

scholarly journals Theoretical investigation for the relation (supermassive black hole mass)–(spiral arm pitch angle): a correlation for galaxies with classical bulges

2019 ◽  
Vol 571 ◽  
pp. 012118
Author(s):  
Ismaeel A Al-Baidhany ◽  
Sami S Chiad ◽  
Wasmaa A Jabbar ◽  
Rasha A Hussein ◽  
Firas F K Hussain ◽  
...  
Keyword(s):  
Black Hole ◽  
Theoretical Investigation ◽  
Pitch Angle ◽  
Black Hole Mass ◽  
Supermassive Black Hole ◽  
Spiral Arm

scholarly journals The Dark Matter Halo Density Profile, Spiral Arm Morphology, and Supermassive Black Hole Mass of M33

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Marc S. Seigar
Keyword(s):  
Black Hole ◽  
Dark Matter ◽  
Density Profile ◽  
Pitch Angle ◽  
Rotation Curve ◽  
Dark Matter Halo ◽  
Black Hole Mass ◽  
Supermassive Black Hole ◽  
Virial Mass ◽  
Spiral Arm

We investigate the dark matter halo density profile of M33. We find that the HI rotation curve of M33 is best described by an NFW dark matter halo density profile model, with a halo concentration of and a virial mass of . We go on to use the NFW concentration of M33, along with the values derived for other galaxies (as found in the literature), to show that correlates with both spiral arm pitch angle and supermassive black hole mass.

Testing the Correlation between Spiral Arm Pitch Angle and Central Black Hole Mass

2010 ◽  
Author(s):  
Douglas W. Shields ◽  
J. Adam Hughes ◽  
Scott R. Barrows ◽  
Ben Davis ◽  
Daniel Kennefick ◽  
...  
Keyword(s):  
Black Hole ◽  
Pitch Angle ◽  
Black Hole Mass ◽  
Central Black Hole ◽  
Spiral Arm

scholarly journals A Kiloparsec-scale Molecular Wave in the Inner Galaxy: Feather of the Milky Way?

2021 ◽  
Vol 921 (2) ◽  
pp. L42
Author(s):  
V. S. Veena ◽  
P. Schilke ◽  
Á. Sánchez-Monge ◽  
M. C. Sormani ◽  
R. S. Klessen ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Aspect Ratio ◽  
Milky Way ◽  
Spiral Galaxies ◽  
Galactic Center ◽  
Velocity Data ◽  
Sinusoidal Wave ◽  
Angular Extent ◽  
The Vertical Distribution ◽  
Spiral Arm

Abstract We report the discovery of a velocity coherent, kiloparsec-scale molecular structure toward the Galactic center region with an angular extent of 30° and an aspect ratio of 60:1. The kinematic distance of the CO structure ranges between 4.4 and 6.5 kpc. Analysis of the velocity data and comparison with the existing spiral arm models support that a major portion of this structure is either a subbranch of the Norma arm or an interarm giant molecular filament, likely to be a kiloparsec-scale feather (or spur) of the Milky Way, similar to those observed in nearby spiral galaxies. The filamentary cloud is at least 2.0 kpc in extent, considering the uncertainties in the kinematic distances, and it could be as long as 4 kpc. The vertical distribution of this highly elongated structure reveals a pattern similar to that of a sinusoidal wave. The exact mechanisms responsible for the origin of such a kiloparsec-scale filament and its wavy morphology remains unclear. The distinct wave-like shape and its peculiar orientation makes this cloud, named as the Gangotri wave, one of the largest and most intriguing structures identified in the Milky Way.

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