Signatures of Long-Lived Spiral Patterns

Martínez-García, Eric E.; González-Lópezlira, Rosa A.

doi:10.1088/0004-637x/765/2/105

Cited by 21 publications

(18 citation statements)

References 70 publications

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“…The analysis, via Fourier techniques, indicates a gradual increase of P with increasing λ. Although based on a small number of objects, these results add statistical weight to the previous findings of Grosbol & Patsis (1998), Martínez-García (2012), and Martínez-García & González-Lópezlira (2013). This notwithstanding, the relationships found between spiral arm pitch angle and supermassive black hole mass by Seigar et al (2008), and Berrier et al (2013) are likely to hold, given the larger errors of these studies.…”

Section: Discussionsupporting

confidence: 62%

The Behavior of the Pitch Angle of Spiral Arms Depending on Optical Wavelength

Martínez-García

Puerari

Rosales-Ortega

et al. 2014

ApJ

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Based on integral field spectroscopy data from the CALIFA survey, we investigate the possible dependence of spiral arm pitch angle with optical wavelength. For three of the five studied objects, the pitch angle gradually increases at longer wavelengths. This is not the case for two objects where the pitch angle remains constant. This result is confirmed by the analysis of SDSS data. We discuss the possible physical mechanisms to explain this phenomenon, as well as the implications of the results.

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Section: Discussionsupporting

confidence: 62%

The Behavior of the Pitch Angle of Spiral Arms Depending on Optical Wavelength

Martínez-García

Puerari

Rosales-Ortega

et al. 2014

ApJ

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“…Instead, recurrent shortlived transient spirals are often obtained (e.g., Sellwood 2011; Wada et al 2011;Fujii et al 2011;Grand et al 2012;Baba et al 2013;D'Onghia et al 2013;Roca-Fàbrega et al 2013). However, azimuthal age gradients studies suggest otherwise (e.g., Martínez-García et al 2009a;Martínez-García & González-Lópezlira 2013), and are in agreement with other observational studies of age patterns (or offsets) across spiral arms (e.g., Efremov 1985;Egusa et al 2009;Grosbøl & Dottori 2009;Sánchez-Gil et al 2011;Cedrés et al 2013). In a study of the age and the star formation rate of HII regions, Cedrés et al (2013), had found newly evidence of the triggering of star formation by den-sity waves (DWs).…”

Section: Introductionsupporting

confidence: 85%

The Shock-Induced Star Formation Sequence Resulting From a Constant Spiral Pattern Speed

Martínez-García

Puerari

2014

ApJ

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We utilize a suite of multiwavelength data of nine nearby spirals to analyze the shock-induced star formation sequence that may result from a constant spiral pattern speed. The sequence involves tracers as the H i, CO 24 μm, and FUV, where the spiral arms were analyzed with Fourier techniques in order to obtain their azimuthal phases as a function of radius. It was found that only two of the objects, NGC 628 and NGC 5194, present coherent phases resembling the theoretical expectations, as indicated by the phase shifts of CO-24 μm. The evidence is more clear for NGC 5194 and moderate for NGC 628. It was also found that the phase shifts are different for the two spiral arms. With the exception on NGC 3627, a two-dimensional Fourier analysis showed that the rest of the objects do not exhibit bi-symmetric spiral structures of stellar mass, i.e., grand-design spirals. A phase order inversion indicates a corotation radius of ∼89 for NGC 628 and ∼202 for NGC 5194. For these two objects, the CO-Hα phase shifts corroborate the CO-24 μm azimuthal offsets. Also for NGC 5194, the CO-70 μm, CO-140 μm, and CO-250 μm phase shifts indicate a corotation region.

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“…However, in a study by Scarano & Lépine (2013) on a sample of 27 galaxies, the authors concluded that the break found in the radial metallicity distribution near to corotation resonance (CR), implies that the spiral structure is a rather long lived feature. Other authors, employing different techniques, seem to find observational proofs of long-lasting spiral arms (Martínez-García & González-Lópezlira 2013;Donner & Thomasson 1994;Zhang 1998).…”

Section: Introductionmentioning

confidence: 99%

The galactic branches as a possible evidence for transient spiral arms

Pérez-Villegas¹,

Gómez²,

Pichardo³

2015

Monthly Notices of the Royal Astronomical Society

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With the use of a background Milky-Way-like potential model, we performed stellar orbital and magnetohydrodynamic (MHD) simulations. As a first experiment, we studied the gaseous response to a bisymmetric spiral arm potential: the widely employed cosine potential model and a self-gravitating tridimensional density distribution based model called PERLAS. Important differences are noticeable in these simulations, while the simplified cosine potential produces two spiral arms for all cases, the more realistic density based model produces a response of four spiral arms on the gaseous disk, except for weak arms -i.e. close to the linear regime-where a two-armed structure is formed. In order to compare the stellar and gas response to the spiral arms, we have also included a detailed periodic orbit study and explored different structural parameters within observational uncertainties. The four armed response has been explained as the result of ultra harmonic resonances, or as shocks with the massive bisymmetric spiral structure, among other. From the results of this work, and comparing the stellar and gaseous responses, we tracked down an alternative explanation to the formation of branches, based only on the orbital response to a self-gravitating spiral arms model. The presence of features such as branches, might be an indication of transiency of the arms.

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Signatures of Long-Lived Spiral Patterns

Cited by 21 publications

References 70 publications

The Behavior of the Pitch Angle of Spiral Arms Depending on Optical Wavelength

The Behavior of the Pitch Angle of Spiral Arms Depending on Optical Wavelength

The Shock-Induced Star Formation Sequence Resulting From a Constant Spiral Pattern Speed

The galactic branches as a possible evidence for transient spiral arms

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