1 / 19

Lulu Fan International School for Advanced Studies (SISSA)

Herschel Galaxy Counts and High Redshift Luminosity Functions: The Formation of Massive Early Type Galaxies. Lulu Fan International School for Advanced Studies (SISSA) Center for Astrophysics, Univ. of Science and Technology of China.

torgny
Télécharger la présentation

Lulu Fan International School for Advanced Studies (SISSA)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Herschel Galaxy Counts and High Redshift Luminosity Functions:The Formation of Massive Early Type Galaxies Lulu Fan International School for Advanced Studies (SISSA) Center for Astrophysics, Univ. of Science and Technology of China A. Lapi, J. Gonzalez-Nuevo, A. Bressan, G. De Zotti, L. Danese, M. Negrello April,28th,2011 Hangzhou

  2. Herschel: • launched on 14 May 2009! • 3.5 m Cassegrain telescope • photometry and spectroscopy in the 55-671 µm range • H-ATLAS: Herschel Astrophysical Terahertz Large Area Survey (Eales et al. 2010a) • ~600 hours • ~550 square degrees • both PACS and SPIRE cameras • H-ATLAS SDP data: • ~4*4 square degrees • 4851 galaxies with 250 µm fluxes >5σ(~35 mJy) and 350 µm fluxes >3σ

  3. Main purposes • FIR/sub-mm LFs and their evolutions at z>1 • Relation between SFR and halo mass • Constrain the timescale of dust-enshrouded SF in massive halos • Formation of massive ETGs at z>1

  4. Photometric Redshift : • SMM J2135-0102 (The Cosmic Eyelash) • All:three SPIRE bands(250,350,500 µm) • Part: two PACS bands(100 and 160 µm) • Similar redshift distribution • Peak at z~2 and a tail extending up to z~4 • |Δz|/(1+z) ~ 0.2

  5. LFs of high-z submm galaxies • LFs @ 100 and 250 µm (rest-frame) • 4 redshift intervals: 1~1.5;1.5~2;2~2.5;2.5~4 • 1/Vmax estimator • redshift estimates and K-corrections from SMM J2135-0102 SED • Systematic errors: Eddington bias(small,corrected using a Bayesian approach);the choice of SED(0.25 dex)

  6. LFs of high-z submm galaxies • Compared to Gruppioni et al(2010) (>70% spec-z) @ 100 µm • Compared to Eales et al(2010) (>31% spec-z) @ 250 µm • Good agreement between our LFs and theirs • LFs flatten at high luminosities! ------ the effect of strong gravitational lensing(Perrotta et al 2003;Negrello et al. 2007)

  7. LFs of high-z submm galaxies • Toy model: • Most of the star formation occurs soon after the fast collapse phase of the halo(Zhao et al. 2003) • At the redshifts (z > 1) and for the halo masses (>3*10^12M⊙) of interest here,the halo formation rate can be approximated by the positive term of the derivative with respect to the cosmic time of the cosmological mass function; • The SFR is proportional to the halo mass; • The duration Δtsfof the main star formation episode, before quenching by the AGN feedback, is roughly constant. • Full model: Granato et al. (2004) • No parameters are changed to fit the data!

  8. Timescales of UV bright,sub-mm and QSOs phase • sub-mm phase: • (consistent with the timescale inferred from the observed alpha-enhancement of massive local ETGs) • UV bright phase: (submm LFs vs. UV LFs with SFR>100 Msolar yr-1 and z~2) • QSOs phase: • assuming: the local ratio MBH/M*~0.002 already in place and Eddington rate; • compare the comoving density of massive submm galaxies with QSOs brighter than the corresponding luminosity.

  9. The Evolution of LFs • Exponential fall off • Evolve strongly up to z~2.5 • Slow down at higher z

  10. Sub-mm bright,strongly lensed galaxies • Negrello et al. 2010 Science • simple selection criteria:flux at 500um>100mJy • H-ATLAS SDP data • 5 SLGs are found • ~100% efficiency • Totally based on Granato et al.(2004) model prediction • Gonz´alez-Nuevo et al. 2011 in preparation • select based on the LFs • more complete • 25 candidates are found • >1000 SLGs are expected to be found in full H-ALTAS

  11. Submm counts • Main contributions: • Unlensed proto-spheroidal galaxies(Granato et al. 2004) • strongly lensed proto-spheroidal galaxies(Perrota et al.2003;Negrello et al. 2007) • normal and starburst galaxies(Negrello et al.2007)

  12. Conclusions • We have exploited the H-ATLAS SDP survey data to investigate the evolution of the 100 and 250 µm LFs of bright star-forming galaxies at z > 1. • The SED of SMM J2135-0102 was taken as our reference to compute the photometric redshift. • We find a significant luminosity evolution at 100µm up to z~2.5. • Our reference model(Granato et al.2004) reproduced well the 100 and 250 µm LFs and 250,350 and 500 µm counts. Evolutionary sequence in massive halos at z>1: (1) very short UV bright phase with dust-free star formation (~10^7 yr); (2) submm phase with dust-enshrouded star formation (~several 10^8 yr); (3) QSOs phase(~several 10^7 yr); (4) passive evolution towards a local ETG after QSO feedback;

  13. Thanks

  14. Photometric Redshift :Why the redshift estimates based on a single SED are sufficient for the LFs? • Three main contributions to the IR radiation: MCs,diffuse dust(cirrus) and AGN torus • (100,160 µm),250,350 and 500 µm • 1<z<3 • 50~300 µm • SFR > 100 solar mass per year • MCs components dominate

  15. Photometric Redshift :Why to take the SED of SMM J2135-0102 as the reference?

  16. Photometric Redshift :Effects on the determination of LFs with different SEDs

  17. Granato et al.(2004) model

More Related