eMerlin lenses and starbursts from the widest-area Herschel and SCUBA-2 surveys Stephen Serjeant, July 17th 2007

5  150mJy at 850  m over 4000 deg 2 (2 years) then the whole JCMT-accessible sky (5 years) Find galaxies in the top 2-3 most luminous in the Hubble volume; the complete range of submm galaxy properties Determine the bright submm number counts Determine the gravitational lensing fraction of submm galaxies Mapping the peaks in the star formation density field (SCUBA-2 follow-up of SASSy sources) Provide high-resolution foregrounds for Planck Identify new populations of local cold ultraluminous galaxies Provide new submm pointing and flux calibrators The SCUBA-2 All-Sky Survey

Approximately 1200 hours open time key project proposal - a SLOAN for Herschel 1000 deg 2 SPIRE and PACS survey (  m): 300 deg 2 in SDSS / UKIDSS-LAS NGP (LOFAR, eMerlin, Hawaii, La Palma) 300 deg 2 in KIDS-N (SKA pathfinders for HI and radio continuum; shallower LOFAR; visible from Atacama, ESO, La Palma) 400 deg 2 in KIDS-S (SKA pathfinders for HI and radio continuum; SPT/SZ surveys; ALMA; GAMA; DES over part) * = obligatory contrived acronyms under discussion The Herschel Kilo-Degree open time survey*

Local galaxies to M  of dust ~150,000 galaxies at z<0.3; half a million galaxies in total Around 1000 strong gravitational lenses; other rare objects Fluctuations in the far-IR background High-resolution imaging of Planck HFI galaxies, radiogalaxies, and S-Z clusters Large-scale structure of the submm sky * = obligatory contrived acronyms under discussion

Strong lensing predictions  UNLENSED proto-spheroids (black solid line; Granato et al. 2004)  IRAS galaxies (starbursts & spirals galaxies Silva et al. 2004, 2005)  radio sources (blazars; De Zotti et al. 2005)  STRONGLY LENSED proto-spheroids (black dashed line; Negrello et al. 2007) Mattia Negrello, priv. comm.

Strong lensing predictions Counts of unlensed proto-spheroids –shape of bright (S>100mJy) source counts unknown however for the magnifications considered (  ~10) the sources being magnified are in the constrained region of the counts –extrapolation of 850  m counts to shorter wavelengths uncertainties mainly at  m, but Granato model reproduces 160  m counts Modelling of strong lensing –dark matter halo profile SIS and NFW have similar integrated magnification distributions  less than x2 uncertainty in magnification bias –presence of satellites and structures not considered would enhance the lensing probability

Mattia Negrello, priv. comm. Strong lensing predictions 5  sensitivities (mJy) 250  m350  m500  m T 1000 (hours) PMode A = 1000 deg  m350  m500  m Time (hours) PMode2984 (1%) 1570 (4%) 741 (35%) 1168

Simon Dye, priv. comm. Relative probability that z s =3 galaxy is lensed Observed lens n(z L ) is a convolution of intrinsic n(z) and the probability that a galaxy at z will act as a lens Differences due to cosmology are much bigger than differences due to lens model uncertainty Plot shows normalized p(z L ) but in principle the absolutes give even stronger constraints on cosmology Cosmological constraints

Simon Dye, priv. comm. Cosmological constraints Method: 1.Create 1000 realisations of n(z L ) for a given cosmology (  m =0.3,   =0.7 in this case) 2.Fit n(z L ) for a range of cosmologies 3.Vary the redshifts and repeat 1. Current limitations: 1.Fitting ignores absolute probabilities (e.g. larger   makes lensing more likely)  can do better 2.Only fixed source redshifts 3.Selection effects ignored  uncertainties will really be higher

Simon Dye, priv. comm. Cosmological constraints 560 lenses, z s =3560 lenses, z s =6   Degeneracy different to CMB;  m better constrained than   mm mm

eMerlin imaging Confirmation of lensing: the most efficient lensing survey Multiple image statistics; lens matter distribution of 0.3<z<1.5 galaxies Starburst morphologies Identifications of ≤ 250  m drop-outs Confusing sources for eMerlin 1.4GHz snapshots: ~2 sources at ~10mJy per eMerlin primary beam