The erschel ATLAS

Steve Eales

and the H-ATLAS and HerMES teams

The Herschel ATLAS

• The widest area survey with Herschel (~ 550 sq deg)

• Consortium of 150+ astronomers worldwide led by Cardiff and Nottingham (Eales, Dunne)

• Covering 5 bands with PACs and SPIRE (110 – 500 microns) in fast parallel mode

• 5 sigma sensitivities of 132, 126, 33, 36 and 45 mJy / beam from 110-500 m

• Detect ~105 sources to z~3

• Primary Aim: to provide the kind of leap 2Df/SDSS made in the optical for the FIR/sub-mm

Astrophysical Terahertz Large Area Survey

NGP and Equatorial SGP

Fields chosen to allow maximum overlap with existing and planned surveys

GALEX, 2dF, SDSS, GAMA, UKIDSS, KIDS, VIKING, PanSTARRS, DES, SPT, SASSy

and to be accessible to new facilities which will be valuable for follow-up

ALMA, SKA and prototypes, SCUBA2, LOFAR, e-MERLIN

SDP field

Key Science Themes in

ATLAS

1. Local Universe Survey

2. Synergies with Planck

3. The Herschel Lens Survey

4. AGN and rare objects

5. Large scale structure and High-z galaxies

6. Galactic star and planet formation

Herschel ATLAS

Science

Demonstration Field

Observations carried

out in November 2009;

public data release in

November 2010 (h-

atlas.org)

4 x 4 degrees

3% of final area

6600 sources detected

at >5σ

Surface brightness

sensitivity for extended

sources is very similar

to Planck at 350 and

500 microns‘The Blob’

What Planck Should Have

Seen at 500 microns

The ‘Blob’

Intriguing Galactic

Object

Either very low mass

prestellar core/protostar

(0.01 solar masses)

.. Or normal mass

but very far out of

the plane

Being followed up by SMA to

see whether this is a prestellar

core or a protostar.

Census of dust and obscured SF in ~70,000

galaxies at z<0.3

UNBIASED luminosity and dust mass functions

by Hubble type, environment and redshift

Unbiased probe of dust in ellipticals & dwarfs.

Overlap with UV / optical / NIR surveys allows energy balance modelling and

assessment of impact of dust on optical surveys

Survey contains 60 Abell clusters including Coma – evolution of ISM and SFR

in a range of environments and potential to study intra-cluster dust

H-ATLAS: Local Universe

We are collaborating with the GAMA consortium who

are carrying out a redshift survey in the equatorial

fields

Local SD science

• 5 sigma 250 m catalogue of 6600 sources

• XID to optical (r<22.4) using SDSS DR7 and a likelihood ratio method (Smith et al. astroph 1007.5260)

• 2240 reliable counterparts (>80% reliability) N(z) of identified sources

Evolution of the 250 m Luminosity Function

Dye et al, A&A special issue

LIRGS

What is causing the evolution?

Galaxies a

few billion

years ago

contained

more gas –

Dunne et

al. MN,

submitted

Cosmic Accountancy

The Far-IR/submm

background contains

50% of all the

energy ever emitted

by galaxies

The deepest Herschel surveys at 250μm (HERMES)

resolve about 15-20% of the background. H-ATLAS

resolves much less than this.

The HerMES Results

• Luminosity function shows

strong evolution out to z=1,

but there is no evidence for

strong evolution at z > 1

• More metals and star are

formed at 0.5<z<1.5 than at

1.5<z<2.5

• 12 out of 26 galaxies at

0.8<z<1.2 show clear spiral

morphology

Eales et al. 2010, A&A special

issue

A lot of the star

formation in the

Universe has

occurred in spirals

LIRG ULIRG

CIB fluctuations with Herschel-SPIRE

SPIRE 250, 350 and 500 micron three color

image of the Lockman-Hole, 16 deg2.

Amblard, A., Cooray, A., Serra, P. et al. Sub-millimetre Galaxies reside in Dark Matter Halos with mass greater than 3x1011 Msun, Nature in press (2011).

See the poster 255.11 (Cooray et al)

2-halo

1-halo

Fluctuations require significant star formation be high beyond z ~3

• Unresolved CIB fluctuations capture the

spatial clustering of all submm galaxies

• Minimum halo mass is about 3x1011

solar masses

• Star formation rate constant at z>1

The H-ATLAS lensing survey

• Models predict that the brighest 500-micron

sources should be a mixture of nearby

galaxies, blazars and lensed galaxies

(Negrello et al. 2007)

• In principle, it should be easy to filter out the

blazars and nearby galaxies

Brightest galaxies in SDP field

ID1

ID5

ID6

ID7

zspec = 0.0534

zspec = 0.0189

zspec = 0.0277

zspec = 0.0401

11 sources with

S500μm > 100 mJy in

SDP field – the blob,

one blazar and four

nearby galaxies

The other sources

ID81

ID11

ID130

ID9

ID17

zspec = 0.299

zspec = 0.7932

zspec = 0.220

zphot = 0.68±0.06

zphot = 0.77±0.13 . . .what about the

sub-mm SED?

ID9 : S500μm = 175 ± 28 mJy

ID11 : S500μm = 238 ± 37 mJy

ID17 : S500μm = 220 ± 34 mJy

ID81 : S500μm = 166 ± 27 mJy

ID130 : S500μm = 108 ± 18 mJy

Gravitational

Lenses

GRAVITATIONAL LENS CANDIDATES

ID81 - ID130:UV/optical/near-IR SED

inconsistent with sub-mm SED !

z > 2.5best lens candidates for DDT follow-ups

ID81

GRAVITATIONAL LENS CANDIDATES ID81

CSO/Z-spec blind redshift determination for ID81 (March 09 2010)from observations of the CO ladder

ID81

Credit: The Zspec team

ID81

Gravitational Lens candidates ID81

ID81

Redshift confirmed by follow-ups with PdB Interferometer(March 23 2010) and GBT/Zpectrometer (March 25 2010)

Credit: R. Neri, P. Cox, A. Beelen, H. Dannerbauer, F. Bertoldi

The First Five CandidatesSource Optical redshift CO redshift

9 0.679 1.577

11 0.72 1.786

17 0.77 (photo-z) 0.942+2.308

81 0.334 3.037

130 0.239 2.625

100% success rate for finding

lenses!Negrello et al. 2010, Science, 330, 800

How many Herschel sources

are lensed?• A calculation based on an

evolving population of dark-

matter halos implies that the

probability of a source at

z=3 being magnified by a

factor of >2 is 0.0027

(Pearson et al. in prep).

• The steep Herschel source

counts imply the fraction of

sources in any sample that

are lensed is ≈ 5%

1.2x104 lensed sources in surveyClements et al. 2010

What use is lensing?

• Study star-forming galaxies at z>3

with better resolution and sensitivity

• Investigate the structures of the

lenses (both in baryons and dark

matter)

• Test the paradigm of structure

evolution from

N(M,z) for the lenses – is the evolution

of dark halos really like the theorists

say?

• Measure cosmological parameters

from N(M,z) for the lenses

• Use JWST to find additional sources

for each lens, giving another route to

finding cosmological parameters

Simulation of reconstruction of unlensed

structure from an SMA map (Simon Dye)

Possible Herschel-Planck

Projects• High-resolution observations of Planck point sources,

including testing completeness and accuracy of

recovered parameters for Planck point-source

catalogue

• Investigations of Galactic dust on all scales (talk by

Lagache)

• Removing the effects of dusty high-z galaxies (lensed

and unlensed) for Planck SZ sample

• Integrated Sachs-Wolfe effect, using Herschel to

trace the distribution of matter at 1<z<3

• Investigation of CMB lensing, using the Herschel

sources to trace the distribution of matter at 3>z>1

(a) find 2.5 to 3 million dusty galaxies, with 1.5 million at z~2, 10,000 at z>4,

~1000 at z >5. Follow-up targets for ALMA, SPICA etc.

(b) 2000 strongly lensed bright sources: a goldmine for cosmology!

(c) 400 proto-clusters regions at z~2 to 5, trace structure formation

(d) ISW at z=2 with SMGs: A strong probe of modified gravity theories for

acceleration

(e) large-scale clustering constrain primordial non-Gaussianity with a higher z

probe than Euclid/LSST

sky HSLS

Planck

see the HSLS White Paper on the arxiv 1007.3519

The Herschel-SPIRE Legacy Survey –Map 4000 sq. degrees on the sky with SPIRE instrument in fast scan mode.

780 hours to complete, single scans in SPIRE fast-mode (60”/sec)

Next Steps for Herschel

ATLAS• 150 square degrees of GAMA fields

observed and all the SPIRE data reduced

• Virtually all of the Northen Galactic Pole

(150 square degrees) observed over

Christmas

• South Galactic Pole (250 square degrees)

scheduled for observations in Summer

2011

GAMA 9-hours – 25,000

sources

Summary• The Herschel ATLAS is a key legacy survey of 550 sq degrees.

• Strengths are unbiased selection, wide areal coverage and huge

statistical power

• 300 square degrees now completed

• 22 papers published, in press or submitted

• First set of data (SDP field) was released to the community at the

beginning of November (h-atlas.org)

• Lots of possible Herschel-Planck projects

• Anyone interested in the Herschel-SPIRE Legacy Survey should

contact Asantha Cooray (acoorary@uci.edu) or Steve Eales

(stephen.eales@astro.cf.ac.uk)