Galaxy Zoo and sparcfire: constraints on spiral arm formation mechanisms from spiral arm number and pitch angles

dc.contributor.authorHart, Ross E.
dc.contributor.authorBamford, Steven P.
dc.contributor.authorHayes, Wayne B.
dc.contributor.authorCardamone, Carolin N.
dc.contributor.authorKeel, William C.
dc.contributor.authorKruk, Sandor J.
dc.contributor.authorLintott, Chris J.
dc.contributor.authorMasters, Karen L.
dc.contributor.authorSimmons, Brooke D.
dc.contributor.authorSmethurst, Rebecca J.
dc.contributor.otherUniversity of Nottingham
dc.contributor.otherUniversity of California System
dc.contributor.otherUniversity of California Irvine
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.contributor.otherUniversity of Oxford
dc.contributor.otherUniversity of Portsmouth
dc.contributor.otherUniversity of California San Diego
dc.date.accessioned2018-09-24T19:17:33Z
dc.date.available2018-09-24T19:17:33Z
dc.date.issued2017-08-22
dc.description.abstractIn this paper, we study the morphological properties of spiral galaxies, including measurements of spiral arm number and pitch angle. Using Galaxy Zoo 2, a stellar mass-complete sample of 6222 SDSS spiral galaxies is selected. We use the machine vision algorithm SPARCFIRE to identify spiral arm features and measure their associated geometries. A support vector machine classifier is employed to identify reliable spiral features, with which we are able to estimate pitch angles for half of our sample. We use these machine measurements to calibrate visual estimates of arm tightness, and hence estimate pitch angles for our entire sample. The properties of spiral arms are compared with respect to various galaxy properties. The star formation properties of galaxies vary significantly with arm number, but not pitch angle. We find that galaxies hosting strong bars have spiral arms substantially (4 degrees-6 degrees) looser than unbarred galaxies. Accounting for this, spiral arms associated with many-armed structures are looser (by 2 degrees) than those in two-armed galaxies. In contrast to this average trend, galaxies with greater bulge-to-total stellar mass ratios display both fewer and looser spiral arms. This effect is primarily driven by the galaxy disc, such that galaxies with more massive discs contain more spiral arms with tighter pitch angles. This implies that galaxy central mass concentration is not the dominant cause of pitch angle and arm number variations between galaxies, which in turn suggests that not all spiral arms are governed by classical density waves or modal theories.en_US
dc.format.mimetypeapplication/pdf
dc.identifier.citationHart, R., et al. (2017): Galaxy Zoo and SPARCFIRE: Constraints on Spiral Arm Formation Mechanisms from Spiral Arm Number and Pitch Angles. Monthly Notices of the Royal Astronomical Society, 472(2). DOI: https://doi.org/10.1093/mnras/stx2137
dc.identifier.doi10.1093/mnras/stx2137
dc.identifier.orcidhttps://orcid.org/0000-0003-0846-9578
dc.identifier.orcidhttps://orcid.org/0000-0001-8010-8879
dc.identifier.orcidhttps://orcid.org/0000-0001-6417-7196
dc.identifier.orcidhttps://orcid.org/0000-0001-7821-7195
dc.identifier.orcidhttps://orcid.org/0000-0002-4893-1264
dc.identifier.orcidhttps://orcid.org/0000-0002-3310-6042
dc.identifier.orcidhttps://orcid.org/0000-0001-5882-3323
dc.identifier.urihttp://ir.ua.edu/handle/123456789/3945
dc.languageEnglish
dc.language.isoen_US
dc.publisherOxford University Press
dc.rights.licenseAttribution-NonCommercial 4.0 International (CC BY-NC 4.0)
dc.rights.urihttps://creativecommons.org/licenses/by-nc/4.0/
dc.subjectmethods: data analysis
dc.subjectgalaxies: general
dc.subjectgalaxies: spiral
dc.subjectgalaxies: structure
dc.subjectDIGITAL SKY SURVEY
dc.subjectNEAR-INFRARED PROPERTIES
dc.subjectSTAR-FORMATION RATES
dc.subjectMORPHOLOGICAL CLASSIFICATIONS
dc.subjectBARRED GALAXIES
dc.subjectPHYSICAL-PROPERTIES
dc.subjectMOLECULAR CLOUDS
dc.subjectNEUTRAL HYDROGEN
dc.subjectRINGED GALAXIES
dc.subjectDATA RELEASE
dc.subjectAstronomy & Astrophysics
dc.titleGalaxy Zoo and sparcfire: constraints on spiral arm formation mechanisms from spiral arm number and pitch anglesen_US
dc.typetext
dc.typeArticle
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