sumss: the sydney university molonglo sky survey, 1997-2005

17 Nov 2005 E.M. Sadler 1

SUMSS: The Sydney University Molonglo Sky Survey, 1997-2005


People involved:

Richard Hunstead Carole Jackson Sebastian Juraszek Michael Large Tom Mauch Tara Murphy Bruce McAdam Vincent McIntyre Barbara Piestrzynska Gordon Robertson Elaine Sadler

Tony Turtle George Warr

Molonglo: Duncan Campbell-Wilson Jeff Webb Michael White John Barry Adrian Blake Sydney: Anne Green Douglas Bock Edward Boyce Ben Chan Lawrence Cram David Crawford Ralph Davison


Dedication

Prototype: SKAMP (10,000 m2) operating to 1 GHz by 2007

The Sydney University Molonglo Sky Survey is dedicated to our friend and colleague Dr Michael Large, whose expertise and vision made the project possible


Wide-field images of the radio sky

‘Radio Schmidt’ telescope: 2.7o field of view, excellent surface-brightness sensitivity


Images of the optical & radio sky

Optical Blue light: Mostly nearby galaxies (median z~0.1)

Radio 843 MHz: Mostly very distant radio galaxies (median z~1)


SUMSS source populations

Jackson & Wall, 1999

Predicted radio-source population at 843MHz:

• Dominant population is radio galaxies (median z~1)

• 10% QSOs above ~100 mJy

• Increasing contribution from local starburst galaxies below ~10 mJy


Radio galaxies & black holes

Radio synchrotron emission from collimated radio jets powered by an accretion disk around a supermassive black hole (Blandford & Rees 1978).


A brief history of the universe…

SUMSS


Why the whole sky?

Radio telescopes are highly efficient machines for probing the distant universe and measuring the cosmic evolution of galaxies and their central black holes.

Developing a proper physical understanding of galaxy formation and evolution requires data sets much larger than those available in the past.

“The astronomy of the 21st century will be dominated by computer-based manipulation of huge homogeneous surveys of various types of astronomical objects.’’

Van den Bergh (2000), PASP 112, 4.


Processing SUMSS data

Individual 2.7o diameter fields processed automatically in a data pipeline, then combined to produce final 4o x 4o mosaics with uniform sensitivity.

Mosaics are catalogued using ‘decision-tree’ artificial intelligence methods to remove telescope artefacts.


Automated recognition and removal of telescope artefacts

Mauch, Murphy, Curran et al. (2003)


Uniformity of the SUMSS catalogue


SUMSS and NVSS

NVSS (1400 MHz) and SUMSS (843 MHz) surveys have similar sensitivity and resolution. Overlap at declination -30o to -40o

NRAO Very Large Array (VLA), New Mexico, USA


SUMSS science goals

What does SUMSS do (particularly) well? Identify and study objects which are common:

Cross-match with optical redshift surveys to study global properties of AGN and star-forming galaxies at z~0, local benchmark for studies of cosmic evolution (Mauch, this meeting)

Identify and study objects which are rare: e.g. High-redshift radio galaxies (Klamer, this meeting)

Identify low surface-brightness radio sources: Complete samples of giant radio galaxies, relic sources, extended sources in the Galactic Plane

Identify and monitor transient sources: (Ball, this meeting)


SUMSS and optical redshift surveys

Overlap with 2dF/6dF gives spectra of 10,000+ radio AGN and starburst galaxies.

Local radio luminosity functions and timescales; local benchmark for high-z studies.

6dFGS spectra


NVSS/SUMSS radio sources in the 6dF Galaxy Survey

‘Main survey’ science:• Accurate radio luminosity functions for AGN, starbursts

• Clustering study via the 2-point Correlation function

• Accurate z=0 benchmarks for studies of cosmic evolution

‘Extra targets’ science: • Compact objects and some galaxies with blue colours (QSOs, starburst galaxies…)

A census of local radio sources:


All-sky radio continuum surveys

NVSS

= 1.4 GHz

dec +90o to -40o

SUMSS = 843 MHz dec -30o to -90o

Both surveys have 45” beam, 3-6 mJy det. limit, position accuracy 1-2”<z> = 0.8 Only 1-2% of extragalactic radio sources in local universe (z < 0.1)


The 6dF Galaxy Survey (6dFGS)

Primary Survey K-selected from 2MASS-XSC (2 Micron All Sky Survey eXtended Source Catalog)• K < 12.75• All southern sky except |b| < 10deg• 113,000 objects over 15,000deg2

Selection from CCD photometry• Accurate K-band magnitudes!• Measures old stellar population• Dust extinction less problematic in K-band than at shorter

wavelengths 1500 fields means 75 targets per field Spare fibres for “additional targets”


Radio Source Detection

Primary Sample (K<12.75):• Preliminary list of all NVSS/SUMSS radio sources within 30”

of 2MASS-XSC (~18%).• Confirmed identifications by eye• 4506 out of ~29000 observed objects in first data release

accepted as genuine (~16% detection rate) Additional Targets:

• NVSS/SUMSS Radio sources within 10” of ‘extended’ objects and 5” of ‘stellar’ objects with B<18 in the SuperCOSMOS database

• 6997 NVSS (dec.>-40o) and 2614 SUMSS (dec.<-50o) additional targets

• 1191 NVSS (17%) and 6 SUMSS (0.2%) observed serendipitously in first data release


Radio Sources in the Primary 2MASS-XSC Sample

4506 NVSS radio sources in 6dF-DR1• 16% Detection rate

109 SUMSS• 7.6% Detection rate

Spectral classification for NVSS:• 1268 Aa• 162 Ae• 187 Aae• 2644 SF• 8 Star• 235 Unclassifiable (Low S/N spectra)

40% AGN , 60% SF (2dFGRS: 60% AGN , 40% SF)Largest local (z<0.1) sample of radio source redshifts ever

obtained!


Local radio luminosity functions

1569 AGNs-Dominate radio source population above P1.4=1023 W/Hz- AGN radio luminosity function has power-law form for 4 decades of radio power.- Unaffected by cosmic

evolution (<V/Vmax>=0.51±0.01)

2507 Star-forming galaxies - Dominate radio source population below P1.4=1023 W/Hz- All lie on radio-FIR correlation

(Mauch 2005)


Local star-formation density

Zero point of Madau diagram

• P1.4 measures star-formation rate (Sullivan et al. 2001).• Star-formation rate derived from P1.4 is free from dust extinction.• Local SF density agrees with optical and IR values.

Local SF density=(0.021±0.001) Msun yr-1 Mpc-3

(Mauch 2005)


Fractional radio luminosity function

AGNs

• Many galaxies contribute to AGN luminosity function so can separate into MK bins to compute fractional LF.• Use preliminary 6dFGS K-band luminosity function (Jones et al. in prep.)

• Gives probability that a galaxy of a given near-infrared magnitude is a radio source above a given radio power.• Fraction of galaxies hosting AGN increases with MK

corresponding to an increase with black hole mass via MBH-Mbulge relation.

(Mauch 2005)


Angular clustering of radio sources

(Blake et al. 2004)


Real-space 2 point correlation function[Mauch & Rawlings]

All SF AGN

ro=7.9±0.6 Mpc0 Mpc<s<40 Mpc



Magliocchetti et al.(2004): ro=10.9±1.0 Mpc (AGN), ro=7.9±0.6 Mpc (ALL)

Norberg et al. (2002) (2dFGRS Galaxies): bright early types: ro=13.85±1.7 Mpcfaint late-type: ro=5.2±1.1 Mpcbright late-type: ro=9.0±1.4 Mpc

Radio sources cluster in a similar fashion to the optical host galaxy population.


SUMSS science goals







Searching for the earliest massive galaxies in the universe

1) Radio filter 1.3, NVSS-SUMSS)

2) IR (K-band) imaging to estimate z

3) Optical/IR spectra (8m telescopes)

(Chambers et al. 1996; De Breuck et al. 2000)(Mauch et al. 2003)

Radio spectral index,


SUMSS science goals







Effective u-v weighting of the MOST

synthesized beam

Excellent uv coverage allows detection and imaging of extended, low-surface brightness radio emission


A complete sample of Mpc-sized double radio galaxies from SUMSS

Saripalli et al. 2005, AJ 130, 896

SGRS J0331-7710: Largest-known SUMSS radio galaxy, z=0.146, projected linear size = 2.67 Mpc

Giant radio galaxies (sizes > 0.7 Mpc) are believed to represent the final stages of radio galaxy evolution.

SUMSS complete sample south of dec -50o, volume density is roughly one per (215 Mpc)3


Giant radio galaxies: J0515-8100

Subrahmanyan et al. 2005, ApJ in press

• Projected linear size = 1.0 Mpc

• Lowest-known surface brightness for a double radio galaxy

• Host galaxy interacting with fainter companion; perturbations in jet axis produce the ‘fat’ radio lobes


X-ray transient XTE 1550-564

Hannikainen et al. 2001

The fixed format of the Molonglo telescope makes it ideal for finding and monitoring transient and variable radio

sources.

Radio emission from a Galactic soft X-ray transient source


SUMSS data release policy

www.astrop.physics.usyd.edu.au/SUMSS

Imaging survey of the entire southern sky now >95% complete.

FITS images and catalogue are released on the web, and incorporated into international databases (NASA Skyview, NED)


What next?

• SUMSS now >95% complete, will be finished by early 2006.

• The data products (images and catalogue) are available online, have already been used in a wide range of analyses (Galactic plane, nearby galaxies, distant galaxies, large-scale structure), and will continue to be used in the future.

• From 2006 the Molonglo telescope will undergo a further upgrade as a technology prototype for the Square Kilometre Array (SKAMP), allowing it to survey polarized sources and measure the redshifted 21cm line of neutral hydrogen in distant galaxies.


Energy output from a black hole

Energy output is set by the accretion rate onto the black hole. The Eddington limit is the maximum rate at which gas can be accreted. Above this, the luminosity is so high that radiation pressure prevents further inflow. Eddington limit is higher for more massive black holes.


The AT 20GHz survey

• First all-sky radio survey at mm wavelengths

• Catalogue foreground discrete-source population for future CMB missions (variability, polarization particularly important).

• Set up new calibration network for ATCA, ALMA at 20-100 GHz


SUMSS and the AT20GHz survey

AT20G detects only a small subset of low-frequency (NVSS/ SUMSS) radio sources, but almost all AT20G sources are in the SUMSS and/or NVSS

catalogues -

Most optical IDs are stellar (QSO candidates), many are 6dFGS ‘additional targets’

SUMSS

AT20G


Galaxies in the Hubble Deep Field

Our deepest view of the Universe in optical light:

Median redshift of z~1 implies galaxies typically appear as they were when the Universe was a third of its current age.

sumss: the sydney university molonglo sky survey, 1997-2005

Documents

radio telescopes

cosmic evolution of

collimated radio jets

nearby galaxies median

local starburst galaxies

sumss catalogue

o mosaics

sadler sumss science