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Star Formation History of M100: Swift/UVOT. Alison Newell, Ignacio Ferreras & Mark Cropper Mullard Space Science Laboratory, University College London. Scope of talk. Describe current UV Imaging Surveys M100 (NGC 4321) Describe the data Models of Unresolved Stellar Populations

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Star formation history of m100 swift uvot

Star Formation History of M100: Swift/UVOT

Alison Newell, Ignacio Ferreras & Mark Cropper

Mullard Space Science Laboratory, University College London


Scope of talk
Scope of talk

  • Describe current UV Imaging Surveys

  • M100 (NGC 4321)

  • Describe the data

  • Models of Unresolved Stellar Populations

  • Further Work


Uv imaging surveys
UV Imaging Surveys

  • Galex

    • 5 arcsec , FUV, NUV

  • XMM-OM & Swift UVOT

    • 2 arcsec, 3 UV + 3 Optical


Gain in spatial resolution m81
Gain in spatial resolution – M81

Galex (2 UV colours)

Swift-UVOT (3 UV colours)


Swift/UVOT

30 cm modified RC telescope

17x17 arcmin FoV

Photon counting detectors

1700 – 6000 Å


Om uvot galex filter bandpasses uvot uvw2 uvm2 uvw1 u galex fuv nuv
OM/UVOT & GALEX filter bandpassesUVOT: UVW2,UVM2,UVW1,UGALEX: FUV,NUV


M100 basic properties
M100 Basic Properties

  • Grand design barred Sc Spiral

  • Nearby, well studied

    • Central region

    • Spiral arms

  • Nearly face-on, ~16 Mpcs

    • Optical, Hα, CO maps

    • Spitzer-SINGS

    • HST – central

    • GALEX – NUV only

    • Herschel

  • UVOT 6 colour M100


    Uvot images m100
    UVOT Images M100

    • Observed 2005 November 5

    • UVOT Software – combine and register

    • Max count rate 1.47 c/s/pixel (B)


    Source detection
    Source Detection

    Process

    Background

    • SExtractor – 3σ

    • UVW2 image used for detections – 1928 Å

    • Background subtraction complex – stellar emission spiral arms

    • SF regions: extended, crowded


    Photometry
    Photometry

    Kron elliptical apertures

    Kron - magnitude

    Small circular aperture for colours

    SE Double image mode

    Large errors on optical images

    Use SDSS images


    Sdss images m100 dr 7
    SDSS images M100 DR 7

    • Observed 2003 January 28, 2004 January 28

    • Exposure time 53.9s

    • 4 separate images

    • SWARP – combine and register


    Sdss photometry
    SDSS Photometry

    2 runs, 2 frames

    3 arcsec apertures

    4 catalogues - amalgamated

    Removed:

    Foreground stars

    Background galaxies


    Catalogue
    Catalogue

    • 428 sources with 3 UV colours

    • ~ 91% have SDSS u,g,r colours, ~ 50% i,z

    • ~ 2.5 sources per kpc2


    Radial distribution
    Radial Distribution

    UVW2

    Similar for UVM2, UVW1

    HII Cepa & Beckman (1996)

    Sharp edge at 50’’

    Sharp fall off at 150 “

    Disk edge


    Models
    Models

    • Unresolved

    • 1 px ~ 0.5arcsec ~ 50pc

    • Age, metallicity, dust

    • Bruzual & Charlot 2003 models

    • Simple Stellar Population




    Cc plots dust
    CC plots - dust

    Degeneracy

    Model – low dust, young population

    Cover the UV extent with UVW2 – UVW1

    Break degeneracy for older populations


    Future work
    Future work

    • Comparison with other models

    • Composite models – more complex analysis

    • Star formation rate

    • Radial trends

    • Comparison with Spitzer SINGS

      Complementary approach to GALEX


    Summary
    Summary

    • Swift/UVOT photometry

    • Described M100 data, some properties

    • Compared data with Bruzual & Charlot 2003 models

    • Determined young dust free regions with solar Z

    • Identified future work


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