SUMSS: The Sydney University Molonglo Sky Survey, 19972005 - PowerPoint PPT Presentation

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SUMSS: The Sydney University Molonglo Sky Survey, 19972005

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Lawrence Cram. David Crawford. Ralph Davison. 17 Nov 2005. E.M. Sadler. 3. Dedication. Prototype: SKAMP (10,000 m2) ... Wide-field images of the radio sky ... – PowerPoint PPT presentation

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Title: SUMSS: The Sydney University Molonglo Sky Survey, 19972005


1
SUMSS The Sydney University Molonglo Sky Survey,
1997-2005
2
People involved
  • 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
  • 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

3
Dedication
The Sydney University Molonglo Sky Survey is
dedicated to our friend and colleague Dr Michael
Large, whose expertise and vision made the
project possible
Prototype SKAMP (10,000 m2) operating to 1 GHz
by 2007
4
Wide-field images of the radio sky
Radio Schmidt telescope 2.7o field of view,
excellent surface-brightness sensitivity
5
Images of the optical radio sky
Radio 843 MHz Mostly very distant radio galaxies
(median z1)
Optical Blue light Mostly nearby galaxies
(median z0.1)
6

SUMSS source populations
  • Predicted radio-source population at 843MHz
  • Dominant population is radio galaxies (median
    z1)
  • 10 QSOs above 100 mJy
  • Increasing contribution from local starburst
    galaxies below 10 mJy

Jackson Wall, 1999
7
Radio galaxies black holes
Radio synchrotron emission from collimated radio
jets powered by an accretion disk around a
supermassive black hole (Blandford Rees 1978).
8
A brief history of the universe
SUMSS
9
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.

10
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.
11
Automated recognition and removal of telescope
artefacts
Mauch, Murphy, Curran et al. (2003)
12
Uniformity of the SUMSS catalogue
13
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
14
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 z0, 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)

15
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
16
NVSS/SUMSS radio sources in the 6dF Galaxy Survey
A census of local radio sources
  • Main survey science
  • Accurate radio luminosity functions for AGN,
    starbursts
  • Clustering study via the 2-point Correlation
    function
  • Accurate z0 benchmarks for studies of cosmic
    evolution
  • Extra targets science
  • Compact objects and some galaxies with blue
    colours (QSOs, starburst galaxies)

17
All-sky radio continuum surveys
NVSS n 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
  • ltzgt 0.8
  • Only 1-2 of extragalactic radio sources in local
    universe (z lt 0.1)

18
The 6dF Galaxy Survey (6dFGS)
  • Primary Survey K-selected from 2MASS-XSC (2
    Micron All Sky Survey eXtended Source Catalog)
  • K lt 12.75
  • All southern sky except b lt 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

19
Radio Source Detection
  • Primary Sample (Klt12.75)
  • 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 Blt18 in the SuperCOSMOS database
  • 6997 NVSS (dec.gt-40o) and 2614 SUMSS (dec.lt-50o)
    additional targets
  • 1191 NVSS (17) and 6 SUMSS (0.2) observed
    serendipitously in first data release

20
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 (zlt0.1) sample of radio source
    redshifts ever obtained!

21
Local radio luminosity functions
1569 AGNs -Dominate radio source population above
P1.41023 W/Hz - AGN radio luminosity function
has power-law form for 4 decades of radio
power. - Unaffected by cosmic evolution
(ltV/Vmaxgt0.510.01)
(Mauch 2005)
2507 Star-forming galaxies - Dominate radio
source population below P1.41023 W/Hz - All lie
on radio-FIR correlation
22
Local star-formation density
  • 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.

Zero point of Madau diagram
(Mauch 2005)
Local SF density(0.0210.001) Msun yr-1 Mpc-3
23
Fractional radio luminosity function
  • 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.)

AGNs
  • 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)
24
Angular clustering of radio sources
(Blake et al. 2004)
25
Real-space 2 point correlation functionMauch
Rawlings
All
SF
AGN
ro7.90.6 Mpc 0 Mpcltslt40 Mpc
ro7.90.7 Mpc 0 Mpcltslt40 Mpc
ro12.60.9 Mpc 0 Mpcltslt40 Mpc
Magliocchetti et al.(2004) ro10.91.0 Mpc
(AGN), ro7.90.6 Mpc (ALL)
Norberg et al. (2002) (2dFGRS Galaxies) bright
early types ro13.851.7 Mpc faint late-type
ro5.21.1 Mpc bright late-type ro9.01.4 Mpc
Radio sources cluster in a similar fashion to the
optical host galaxy population.
26
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 z0, 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)

27
Searching for the earliest massive galaxies in
the universe
(Chambers et al. 1996 De Breuck et al. 2000)
(Mauch et al. 2003)
Radio spectral index, a
1) Radio filter (alt-1.3, NVSS-SUMSS) 2) IR
(K-band) imaging to estimate z 3) Optical/IR
spectra (8m telescopes)
28
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 z0, 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)

29
Effective u-v weighting of the MOST synthesized
beam
Excellent uv coverage allows detection and
imaging of extended, low-surface brightness radio
emission
30
A complete sample of Mpc-sized double radio
galaxies from SUMSS
SGRS J0331-7710 Largest-known SUMSS radio
galaxy, z0.146, projected linear size 2.67 Mpc
Giant radio galaxies (sizes gt 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
Saripalli et al. 2005, AJ 130, 896
31
Giant radio galaxies J0515-8100
  • 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

Subrahmanyan et al. 2005, ApJ in press
32
X-ray transient XTE 1550-564
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
Hannikainen et al. 2001
33
SUMSS data release policy
Imaging survey of the entire southern sky now
gt95 complete. FITS images and catalogue are
released on the web, and incorporated into
international databases (NASA Skyview, NED)
www.astrop.physics.usyd.edu.au/SUMSS
34
What next?
  • SUMSS now gt95 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.

35
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36

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.
37
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

38
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
39
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40
Galaxies in the Hubble Deep Field
Our deepest view of the Universe in optical
light Median redshift of z1 implies galaxies
typically appear as they were when the Universe
was a third of its current age.
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