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Photometric Properties of Ly  Emitters at z = 3.1

Photometric Properties of Ly  Emitters at z = 3.1. Robin Ciardullo (PSU) Collaborators: Caryl Gronwall (PSU), Eric Gawiser (Rutgers), John Feldmeier (YSU) + the MUSYC collaboration. Photometry.

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Photometric Properties of Ly  Emitters at z = 3.1

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  1. Photometric Properties of Ly Emitters at z = 3.1 Robin Ciardullo (PSU) Collaborators: Caryl Gronwall (PSU), Eric Gawiser (Rutgers), John Feldmeier (YSU) + the MUSYC collaboration Heidelberg

  2. Photometry • Narrow-band survey of the E-CDFS generated a sample of 160 LAEs with 3.08 < z < 3.12, EW0 > 19.4 Å and L(Lya) > 1.3  1042 ergs-s-1 • Deep broadband photometry from MUSYC allows for detailed exploration of the continuum properties of this sample • 5 mAB limits: U=26.0, B=26.9, V=26.4, R=26.4 • Knowledge of LAE positions allows for fainter photometry beyond completeness limits Heidelberg

  3. Rest Frame Equivalent Widths • Less than 10% of LAEs have EW0 > 240 Å • EW distribution is exponential with scale length of 76  10 Å • Extrapolation implies ~20% of LAEs fall below the EW cutoff • EW distribution agrees with Le Delliou models Heidelberg

  4. Rest Frame Equivalent Widths UV-bright galaxies have (relatively) low Ly equivalent widths No correlation between LyEW and slope of UV continuum Heidelberg

  5. LAE Broadband Colors • LAEs are blue, B-R ~ 0.5 • LAEs are inhomogeneous, B-R > 0.3 (intrinsic) • LAEs usually lie below the limits of LBG identifications Heidelberg

  6. LAE Broadband Colors • LAEs are blue, B-R ~ 0.5 • LAEs are inhomogeneous, B-R > 0.3 (intrinsic) • LAEs usually lie below the limits of LBG identifications • LAEs fall in the same region of color-color space as LBGs (all with 1 of locus) Heidelberg

  7. Implied Star-Formation Rates If we translate the UV continuum to a SFR (via Kennicutt 1998) and the Ly flux to a SFR (via Case B), then UV SFRs are ~ 3 times greater than Ly rates. SFR(Ly): ~ 3 M yr-1 When normalized to mass (talk by Guaita) SFR(Ly)/Mass ~ 4 10-9 Myr-1 M-1 Heidelberg

  8. Extinction (Assuming Calzetti Law) Note: it doesn’t take much dust to make the UV and Ly SFRs agree E(B-V)s < 0.05 Heidelberg

  9. LAE and the Universal SFR Density • Ignore dust for now… • Take LAE Luminosity Function Heidelberg

  10. LAE and the Universal SFR Density • Ignore dust for now… • Take LAE Luminosity Function • Take Schechter parameter likelihoods = 1.49  0.4 L* = 42.6  0.2 T = 1.46  0.14  10-3 Mpc-3 Heidelberg

  11. LAE and the Universal SFR Density • Ignore dust for now… • Take LAE Luminosity Function • Take Schechter parameter likelihoods • Compute likelihoods for SFR density • Most-likely SFR density 6.5  10-3 M yr-1 Mpc-3 • For E(B-V) ~ 0.05, SFRD ~ 0.012 M yr-1 Mpc-3 LBG SFRD is between 0.01 and 0.05 M yr-1 Mpc-3 Heidelberg

  12. Conclusions • LAEs at z ~ 3.1 are young, low-mass, low dust systems -- galaxies in the act of formation, but not Pop III • No extremely high EW LAEs seen • Low amount of inferred dust (also from SED fitting); • Typical SFRs between 1 and 10 M yr-1 • Very high specific star formation rates (from SED fitting) • Two large, new samples in hand: z ~ 2.1 and 3.1 Heidelberg

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