Measurement of Galactic Logarithmic Spiral Arm Pitch Angle Using Two-Dimensional Fast Fourier Transform Decomposition

Davis, Benjamin L.; Berrier, Joel C.; Shields, Douglas W.; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S.; Lacy, Claud H.; Puerari, I.

doi:10.1088/0067-0049/199/2/33

Cited by 102 publications

(181 citation statements)

References 55 publications

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“…A large fraction of local spirals can be modeled by superpositions of logarithmic spiral functions. Based on this, automatic spiral arm finding and logarithmic function fitting tools have been developed and applied in local galaxy surveys (e.g., Davis et al 2012;Davis & Hayes 2014;Shields et al 2015;Hart et al 2017). Our on-going effort of testing and adapting these tools at high-redshift will help to quantify spiral arms and to separate spiral from irregular structures objectively.…”

Section: Spiral Arms Vs Clumpy Disks and Irregularsmentioning

confidence: 99%

The Most Ancient Spiral Galaxy: A 2.6-Gyr-old Disk with a Tranquil Velocity Field

Yuan

Richard

Gupta

et al. 2017

ApJ

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We report an integral-field spectroscopic (IFS) observation of a gravitationally lensed spiral galaxy A1689B11 at redshift z = 2.54. It is the most ancient spiral galaxy discovered to date and the second kinematically confirmed spiral at z 2. Thanks to gravitational lensing, this is also by far the deepest IFS observation with the highest spatial resolution (∼ 400 pc) on a spiral galaxy at a cosmic time when the Hubble sequence is about to emerge. After correcting for a lensing magnification of 7.2 ± 0.8, this primitive spiral disk has an intrinsic star formation rate of 22 ± 2 M ⊙ yr −1 , a stellar mass of 10 9.8±0.3 M ⊙ and a half-light radius of r 1/2 = 2.6 ± 0.7 kpc, typical of a main-sequence star-forming (SF) galaxy at z ∼ 2. However, the Hα kinematics show a surprisingly tranquil velocity field with an ordered rotation (V c = 200 ± 12 km s −1 ) and uniformly small velocity dispersions (V σ,mean = 23 ± 4 km s −1 and V σ,outer−disk = 15 ± 2 km s −1 ). The low gas velocity dispersion is similar to local spiral galaxies and is consistent with the classic density wave theory where spiral arms form in dynamically cold and thin disks. We speculate that A1689B11 belongs to a population of rare spiral galaxies at z 2 that mark the formation epoch of thin disks. Future observations with JWST will greatly increase the sample of these rare galaxies and unveil the earliest onset of spiral arms.

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Section: Spiral Arms Vs Clumpy Disks and Irregularsmentioning

confidence: 99%

The Most Ancient Spiral Galaxy: A 2.6-Gyr-old Disk with a Tranquil Velocity Field

Yuan

Richard

Gupta

et al. 2017

ApJ

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“…The method described in Saraiva Schroeder et al (1994) measures both the strength and the PA of the various modes between a given inner radius and a given outer radius on a deprojected image. The extension to this method in Davis et al (2012) eliminates the user defined inner radius and allows the user to quantitatively investigate how logarithmic the spiral arms are. This provides a systematic way of excluding barred nuclei from the pitch angle measurement annulus.…”

Section: Spiral Arms Analysismentioning

confidence: 99%

“…A stable mean PA is determined for the m = 2 harmonic mode from a minimum inner radius of 30 pixels (12 ) to a maximum inner radius of 200 pixels (80 ), with an outer radius of 440 pixels (176 ). Equation (7) in (Davis et al 2012) describes the final error in PA measurement:…”

Section: Spiral Arms Analysismentioning

confidence: 99%

“…Graham & Driver (2007), Savorgnan et al (2013), and Savorgnan et al (2016) revisited the previously reported (Graham et al 2001(Graham et al , 2003 correlation between the mass of a galaxy's central BH and its bulge concentration and constructed a relation between M BH and the galactic Sérsic index (which is a measure of bulge concentration). Furthermore, Seigar et al (2008) discovered a correlation between the morphology of the spiral arms and the mass of the central BH in disk galaxies (see also Davis et al 2012). This, was formulated as a relation between M BH and the spiral pitch angle (a measure of the tightness of spiral arms).…”

Section: Introductionmentioning

confidence: 96%

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Searching for intermediate-mass black holes in galaxies with low-luminosity AGN: a multiple-method approach

Koliopanos

Ciambur

Graham

et al. 2017

A&A

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Aims. This work is the first stage of a campaign to search for intermediate-mass black holes (IMBHs) in low-luminosity active galactic nuclei (LLAGN) and dwarf galaxies. An additional and equally important aim of this pilot study is to investigate the consistency between the predictions of several popular black hole scaling relations and the fundamental plane (FP) of black-hole activity (FP-BH). Methods. We used well established X-ray and radio luminosity relations in accreting black holes, along with the latest scaling relations between the mass of the central black hole (M BH ) and the properties of its host spheroid, to predict M BH in seven LLAGN, that were previously reported to be in the IMBH regime. Namely, we used the recently re-evaluated M BH − M sph (M sph : spheroid absolute magnitude at 3.6 µm) scaling relation for spiral galaxies, the M BH − n sph (n sph : major axis Sérsic index of the spheroid component) relation, the M BH − PA (PA: spiral pitch angle) relation, and a recently re-calibrated version of the FP-BH for weakly accreting BHs, to independently estimate M BH in all seven galaxies. Results. We find that all LLAGN in our list have low-mass central black holes with log M BH /M ≈ 6.5 on average, but that they are, most likely, not IMBHs. All four methods used predicted consistent BH masses in the 1σ range. Furthermore, we report that, in contrast to previous classification, galaxy NGC 4470 is bulge-less, and we also cast doubts on the AGN classification of NGC 3507. Conclusions. We find that our latest, state-of-the-art techniques for bulge magnitude & Sérsic index computations and the most recent updates of the M BH − L sph , M BH − n sph , and M BH − PA relations and the FP-BH produce consistent results in the low-mass regime. We thus establish a multiple-method approach for predicting BH masses in the regime where their spheres of gravitational influence cannot be spatially resolved. Our approach mitigates against outliers from any one relation and provides a more robust average prediction. We will use our new method to revisit more IMBH candidates in LLAGN.

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“…The best example of this is the pitch angle, which ranges from about 8-50 (Kennicutt 1981;Ma et al 2000;Davis et al 2012) for late type galaxies, for instance.…”

Section: Introductionmentioning

confidence: 99%

Stellar Orbital Studies in Normal Spiral Galaxies. Ii. Restrictions on Structural and Dynamical Parameters on Spiral Arms

Pérez-Villegas

Pichardo

Moreno

2015

ApJ

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Making use of a set of detailed potential models for normal spiral galaxies, we analyze disk stellar-orbital dynamics as the structural and dynamical parameters of spiral arms (mass, pattern speed, and pitch angle) are gradually modified. With this comprehensive study of ordered and chaotic behavior, we constructed an assemblage of orbitally supported galactic models and plausible parameters for orbitally self-consistent spiral arm models. We find that to maintain orbital support for the spiral arms, the spiral arm mass, M sp , must decrease with the increase of the pitch angle, i. If i is smaller than 10 , M sp can be as large as 7% , 6% , or 5% of the disk mass, for Sa, Sb, and Sc galaxies, respectively. If i increases up to 25 , the maximum M sp is 1% of the disk mass, independent of morphological type, in this case. For values larger than these limits, spiral arms would likely act as transient features. Regarding the limits posed by extreme chaotic behavior, we find a strong restriction on the maximum plausible values of spiral arm parameters on disk galaxies beyond which chaotic behavior becomes pervasive. We find that for i smaller than 20 , 25 , or 30 , for Sa, Sb, and Sc galaxies, respectively, M sp can go up to 10% , of the mass of the disk. If the corresponding i is around 40 , 45 , 50 , M sp is 1% , 2% , 3% of the mass of the disk. Beyond these values, chaos dominates phase space, destroying the main periodic orbits and the neighboring quasiperiodic orbits.

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Measurement of Galactic Logarithmic Spiral Arm Pitch Angle Using Two-Dimensional Fast Fourier Transform Decomposition

Cited by 102 publications

References 55 publications

The Most Ancient Spiral Galaxy: A 2.6-Gyr-old Disk with a Tranquil Velocity Field

The Most Ancient Spiral Galaxy: A 2.6-Gyr-old Disk with a Tranquil Velocity Field

Searching for intermediate-mass black holes in galaxies with low-luminosity AGN: a multiple-method approach

Stellar Orbital Studies in Normal Spiral Galaxies. Ii. Restrictions on Structural and Dynamical Parameters on Spiral Arms

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