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Populations Studies in the Fermi Era

Populations Studies in the Fermi Era. D. Gasparrini on behalf of M. Ajello and Fermi Lat collaboration. 2LAC Clean Sample. 310 FSRQ 395 BLLAC 157 Blazar of unknown type (no clear optical classification. |bII| >10º , single association, no analysis flags.

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Populations Studies in the Fermi Era

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  1. Populations Studies in the Fermi Era D. Gasparrini on behalf of M. Ajello and Fermi Lat collaboration

  2. 2LAC Clean Sample • 310 FSRQ • 395 BLLAC • 157 Blazar of unknown type (no clear optical classification |bII| >10º , single association, no analysis flags Completeness at 5x 10-12 erg cm-2s-1

  3. Counts Distribution in 2LAC Not corrected non-uniform sensitivity and detection/association efficiency FSRQ BL LAC Unknown Blazar Roughly compatible with 1LAC results and the FSRQ flattening at faint end shows that increasing the exposure will yield only a modest addition to the number of such sources.

  4. Counts Distribution in 2LAC Not corrected non-uniform sensitivity and detection/association efficiency FSRQ Unass. 2FGL Total Adding High Latitude unassociated sources with gamma >2.2 (FSRQ like), we observe a steepening of the distribution showing that the unassociated are not only FSRQ

  5. LF FRSQ Sample • The sample of 186 FSRQs is based on the 11month catalog : • Extremely clean, ~5% incompleteness • F100 ≥ 10−8 ph cm−2 s−1 • TS >50 (>7 sigma) , |b|>15deg • 0.1< z < 3.0

  6. LF estimate methodology The luminosity Function is modeled as: Where Is the intrinsic distribution of the photon index modeled as Gaussian The LF is determined fitting an analytical parameterization to the z, L,Γ space using Maximum Likelihood algorithm

  7. Pure Luminosity evolution (PLE) L-γ1 L-γ2 L. Evol. Evolution in luminosity as a power-law with index k with a cutoff after the Maximum of the Evolution Double Power law

  8. PLE results • PLE provides a reasonably good fit to the data • It implies: • Strong evolution in luminosity of FSRQ (k=5.7) • A cut-off in the evolution after z = ~1.6 • 2 findings: • PLE does not reproduce the source counts very well • There are hints that the redshift cut-off changes with luminosity

  9. Luminosity-dependent density evolution (LDDE) L-γ1 p1 p2 L-γ2 D. Evol. L. Evol. Evolution of the redshift peak with luminosity

  10. LDDE result LDDE represents the Fermi data well • It implies: • Strong evolution of FSRQ: factor 100 more FSRQs at z=1.5 • A cut-off in the evolution that changes with luminosity

  11. The representation of the GLF

  12. Redshift peak evolution

  13. Comparison with previous results Local GLF (Z=0) Z=1 g1 (low luminosity end) = 1.68 +/- 0.17 Increase of a factor 150 for a source with L = 1048 erg s-1 g2 (high luminosity end) = 3.15 +/- 0.63

  14. Contribution of FSRQs to EGB Total (e.g. resolved + unresolved) emission from FSRQs No EBL/cascade considered yet, but unimportant for soft spectra

  15. The Status of the γ-ray background FSRQ Star-forming Gal. BL Lac Radio Galaxies BL Lac contribution comes from LogN-LogS: a better estimate can be obtained with a study on LF

  16. BLLAC Luminosity function Main Problem: 55% of the BL Lacs in the 2LAC lack a redshift measurement However, several constraints can be put on BL Lacs redshifts: • Spectroscopic lower limits: metal absorption lines due to intervening systems along the line of sight • Spectroscopic upper limits: due to lack of Lyman forest in the spectra • Imaging of the host galaxy • ULs due to the detection at TeV Limits available thanks to the work M. Shaw and R. Romani

  17. Photometric redshift which yields a z<1.3 UL for 90% of the objects and estimate for the rest 10% (from Rue et al. A& A, 538, 26) Rue et al. A& A, 538, 26

  18. Redshift constrains For the |b|>15deg, TS>50, 1st yr sample: • ~75% of the (204) BLLs have a redshift constraint Constraints can be combined to obtain a pseudo redshift measurement We aim at having >90% redshift completeness

  19. How to derive BL Lac LF Monte-Carlo simulation to produce N samples of BL Lacs drawning the random redshift from the PDF of each source The PDF is convoluted by: • the constrains available for the source • the intrinsic PDF of the Fermi detected BL Lacs This distribution is unknown but there are some starting points: • Use the 2LAC detected BL Lac distribution • Use the sample distribution • Use a flat distribution • Etc..

  20. Motivations • First LF of BLLs at gamma-rays • most complete redshift coverage • Important for the IGRB • if LF is compatible with an ‘unbroken’ power law -> BLLs might be very numerous and might contribute most of the >10GeV IGRB • Cascade emission • quantify reprocessed component and contribution to the IGRB • Important for CTA/cosmology • easy to quantify/predict number of sources detectable by CTA • TeV blazar in the Universe might provide heating to the IGM • Important for the blazar sequence or FSRQ-BLL link • easy to check sequence prediction and a good framework to understand if a genetic link between the FSRQ-BLL class exists

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