SIGNATURES OF LONG-LIVED SPIRAL PATTERNS

Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a sur...

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Published inThe Astrophysical journal Vol. 765; no. 2; pp. 1 - 15
Main Authors Martinez-Garcia, Eric E, GONZALEZ-LOPEZLIRA, ROSA A
Format Journal Article
LanguageEnglish
Published United States 10.03.2013
Subjects
Astronomical models
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COLOR
COMPARATIVE EVALUATIONS
Density
GALAXIES
Imaging
MASS
MONTE CARLO METHOD
Monte Carlo methods
NEAR INFRARED RADIATION
PHOTOMETRY
Searching
Signatures
Spirals
STAR MODELS
STARS
VISIBLE RADIATION
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Summary:Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a surface density stellar mass map. Mass maps were obtained from optical and near-infrared imaging, by comparison with a Monte Carlo library of stellar population synthesis models that allowed us to obtain the mass-to-light ratio in the J band, (M/L) sub(J), as a function of (g - i) versus (i - J) color. The selected spirals were analyzed with Fourier methods in search of other signatures of long-lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two-armed spiral in different wavebands, as expected from theory. The results show additional signatures of long-lived spirals in at least 50% of the objects.
Bibliography:ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/765/2/105