Galaxy Zoo: Clump Scout: Surveying the Local Universe for Giant Star-forming Clumps

Abstract

Massive, star-forming clumps are a common feature of high-redshift star-forming galaxies. How they formed, and why they are so rare at low redshift, remains unclear. In this paper we identify the largest yet sample of clumpy galaxies (7,052) at low redshift using data from the citizen science project \textit{Galaxy Zoo: Clump Scout}, in which volunteers classified over 58,000 Sloan Digital Sky Survey (SDSS) galaxies spanning redshift $0.02<z<0.15$. We apply a robust completeness correction by comparing with simulated clumps identified by the same method. Requiring that the ratio of clump-to-galaxy flux in the SDSS $u$ band be greater than 8\% (similar to clump definitions used by other works), we estimate the fraction of local galaxies hosting at least one clump ($f_{clumpy}$) to be $2.68_{-0.30}^{+0.33}\%$. We also compute the same fraction with a less stringent cut of 3\% ($11.33_{-1.16}^{+0.89}\%$), as the higher number count and lower statistical noise of this fraction permits sharper comparison with future low-redshift clumpy galaxy studies. Our results reveal a sharp decline in $f_{clumpy}$ over $0<z<0.5$. The minor merger rate remains roughly constant over the same span, so we suggest that minor mergers are unlikely to be the primary driver of clump formation. Instead, the rate of galaxy turbulence is a better tracer for $f_{clumpy}$ over $0<z<1.5$ for galaxies of all masses, which supports the idea that clump formation is primarily driven by violent disk instability for all galaxy populations during this period.

arXiv comment23 pages, 13 figures, 4 tables, submitted to ApJ

References in corpus (47)

• The Sloan Digital Sky Survey: Technical Summary
• The Dust Content and Opacity of Actively Star-Forming Galaxies
• The physical properties of star forming galaxies in the low redshift universe
• The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission
• Stellar Masses and Star Formation Histories for 10^5 Galaxies from the Sloan Digital Sky Survey
• High Redshift Galaxies in the Hubble Deep Field. Color Selection and Star Formation History to z=4
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• The propagation of uncertainties in stellar population synthesis modeling III: model calibration, comparison, and evaluation
• The CANADA-FRANCE REDSHIFT SURVEY XIII: The luminosity density and star-formation history of the Universe to z ~ 1
• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• The SINS survey of z~2 galaxy kinematics: properties of the giant star forming clumps
• Galaxy Zoo 2: detailed morphological classifications for 304,122 galaxies from the Sloan Digital Sky Survey
• From rings to bulges: evidence for rapid secular galaxy evolution at z~2 from integral field spectroscopy in the SINS survey
• On the Estimation of Confidence Intervals for Binomial Population Proportions in Astronomy: The Simplicity and Superiority of the Bayesian Approach
• The Major and Minor Galaxy Merger Rates at z < 1.5
• Preparing Red-Green-Blue (RGB) Images from CCD Data
• The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA Derived Quantities, Data Visualization Tools and Stellar Library
• Resolved Galaxies in the Hubble Ultra Deep Field: Star Formation in Disks at High Redshift
• Signatures of Cool Gas Fueling a Star-Forming Galaxy at Redshift 2.3
• The Epoch of Disk Settling: z~1 to Now
• Clumpy Galaxies in CANDELS. I. The Definition of UV Clumps and the Fraction of Clumpy Galaxies at 0.5<z<3
• Faintest Galaxy Morphologies from $HST$ WFPC2 Imaging of the Hawaii Survey Fields
• The long lives of giant clumps and the birth of outflows in gas-rich galaxies at high redshift
• Clumpy Galaxies in GOODS and GEMS: Massive Analogs of Local Dwarf Irregulars
• Multi-Wavelength View of Kiloparsec-Scale Clumps in Star-Forming Galaxies at z~2
• The Population of Giant Clumps in Simulated High-z Galaxies: In-situ and Ex-situ, Migration and Survival
• Discovery of Face-On Counterparts of Chain Galaxies in the Tadpole ACS Field
• Giant Clumps in Simulated High-z Galaxies: Properties, Evolution and Dependence on Feedback
• Morphologies of ~190,000 Galaxies at z=0-10 Revealed with HST Legacy Data II. Evolution of Clumpy Galaxies
• Hubble Space Telescope H-alpha imaging of star-forming galaxies at z = 1-1.5: evolution in the size and luminosity of giant HII regions
• Local Lyman Break Galaxy Analogs: The Impact of Massive Star-forming Clumps on the Interstellar Medium and the Global Structure of Young, Forming Galaxies
• The nature of giant clumps in distant galaxies probed by the anatomy of the Cosmic Snake
• Clumpy Galaxies in CANDELS. II. Physical Properties of UV-bright Clumps at $0.5\le z<3$
• DYNAMO-HST Survey: Clumps in Nearby Massive Turbulent Disks and the Effects of Clump Clustering on Kiloparsec Scale Measurements of Clumps
• Chain Galaxies in the Tadpole ACS Field
• A contribution of star-forming clumps and accreting satellites to the mass assembly of z ~ 2 galaxies
• Clumpy galaxies at z~0.6: kinematics, stability, and comparison with analogs at other redshifts
• On the stellar masses of giant clumps in distant star-forming galaxies
• A Magnified View of the Kinematics and Morphology of RCSGA 032727-132609: Zooming in on a Merger at z=1.7
• Evolution of the Fraction of Clumpy Galaxies at 0.2<z<1.0 in the COSMOS field
• Stellar Masses of Giant Clumps in CANDELS and Simulated Galaxies Using Machine Learning
• Nature of H-alpha selected galaxies at z>2. II. Clumpy galaxies and compact star-forming galaxies
• Extreme gas fractions in clumpy, turbulent disk galaxies at z~0.1
• First constraints on the stellar mass function of star-forming clumps at the peak of cosmic star formation
• Star-forming clumps in the Lyman Alpha Reference Sample of galaxies -- I. Photometric analysis and clumpiness
• HeII emission in Lyman-alpha nebulae: AGN or cooling radiation?
• Matched photometric catalogs of GALEX UV sources with Gaia DR2 and SDSS DR14 databases (GUVmatch)

Cited by in corpus (2)

• A spatially resolved analysis of star-formation burstiness by comparing UV and H$\alpha$ in galaxies at z$\sim$1 with UVCANDELS
• Deep Large Binocular Camera r-band Observations of the GOODS-N Field