Wide-field VLBA Observations of the Chandra Deep Field South

Abstract

Wide-field surveys are a commonly-used method for studying thousands of objects simultaneously, to investigate, e.g., the joint evolution of star-forming galaxies and active galactic nuclei. VLBI observations can yield valuable input to such studies because they are able to identify AGN. However, VLBI observations of large swaths of the sky are impractical using standard methods, because the fields of view of VLBI observations are of the order of 10" or less. We have embarked on a project to carry out Very Long Baseline Array (VLBA) observations of all 96 known radio sources in one of the best-studied areas in the sky, the Chandra Deep Field South (CDFS). The challenge was to develop methods which could significantly reduce the amount of observing (and post-processing) time. We have developed an extension to the DiFX software correlator which allows one to correlate hundreds of positions within the primary beams. This extension enabled us to target many sources, at full resolution and high sensitivity, using only a small amount of observing time. The combination of wide fields-of-view and high sensitivity across the field in this survey is unprecedented. We have observed with the VLBA a single pointing containing the Chandra Deep Field South, in which 96 radio sources were known from previous observations with the ATCA. From our input sample, 20 were detected with the VLBA. The majority of objects have flux densities in agreement with arcsec-scale observations, implying that their radio emission comes from very small regions. One VLBI-detected object had earlier been classified as a star-forming galaxy. Comparing the VLBI detections to sources found in sensitive, co-located X-ray observations we find that X-ray detections are not a good indicator for VLBI detections. Wide-field VLBI survey science is now coming of age.

20 pages, 7 figures, accepted for publication in A&A

References in corpus (8)

• DiFX: A software correlator for very long baseline interferometry using multi-processor computing environments
• Deep ATLAS radio observations of the CDFS-SWIRE field
• The VLA Survey of the Chandra Deep Field South: I. Overview of the Radio Data
• The VLA Survey of the Chandra Deep Field South. II. Identification and host galaxy properties of submillijansky sources
• The radio properties of infrared-faint radio sources
• A deep, high resolution survey of the low frequency radio sky
• The first VLBI image of an Infrared-Faint Radio Source
• Beam squint and Stokes V with off-axis feeds

Cited by in corpus (41)

• CANDELS Multi-wavelength Catalogs: Source Detection and Photometry in the GOODS-South Field
• Evidence for Wide-Spread AGN Driven Outflows in the Most Massive z~1-2 Star Forming Galaxies
• The KMOS^3D Survey: Demographics and Properties of Galactic Outflows at z = 0.6 - 2.7
• The faint radio sky: radio astronomy becomes mainstream
• The sub-mJy radio sky in the Extended Chandra Deep Field South: source population
• Cosmological evolution of atomic gas and implications for 21 cm HI absorption
• The VLA Survey of the Chandra Deep Field South. V. Evolution and Luminosity Functions of sub-mJy radio sources and the issue of radio emission in radio-quiet AGN
• GOODS-Herschel: Ultra-deep XMM-Newton observations reveal AGN/star-formation connection
• Radio Continuum Surveys with Square Kilometre Array Pathfinders
• mJIVE-20: a survey for compact mJy radio objects with the Very Long Baseline Array
• The faint radio sky: VLBA observations of the COSMOS field
• On the nature of bright compact radio sources at z>4.5
• Mosaiced wide-field VLBI observations of the Lockman Hole/XMM
• The first low-mass black hole X-ray binary identified in quiescence outside of a globular cluster
• Interplanetary Scintillation studies with the Murchison Wide-field Array II: Properties of sub-arcsecond compact sources at low radio frequencies
• Compact radio cores in radio-quiet AGNs
• Nowhere to Hide: Radio-faint AGN in the GOODS-N field. I. Initial catalogue and radio properties
• The XMM deep survey in the CDF-S. IX. An X-ray outflow in a luminous obscured quasar at z~1.6
• VLBI observations of the radio quasar J2228+0110 at z=5.95 and other field sources in multiple-phase-centre mode
• VLBI imaging throughout the primary beam using accurate UV shifting
• What are the megahertz peaked-spectrum sources?
• Four dual AGN candidates observed with the VLBA
• Visible and near-infrared reflectance of hyperfine and hyperporous particulate surfaces
• Radio-loud Quasars above Redshift 4: VLBI Imaging of an Extended Sample
• Nowhere to Hide: Radio-faint AGN in the GOODS-N field. II. Multi-wavelength AGN selection techniques and host galaxy properties
• The preferentially magnified active nucleus in IRAS F10214+4724 - III. VLBI observations of the radio core
• Widefield VLBI observations of M31: A Unique Probe of the Ionized ISM of a nearby galaxy
• A single radio-emitting nucleus in the dual AGN candidate NGC 5515
• An X-ray underluminous cluster of galaxies in the 4Ms CDFS observations
• Unveiling the weak radio quasar population at z $\ge$ 4
• A census of compact sources at 162MHz: first data release from the MWA Phase II IPS Survey
• Active galactic nuclei cores in infrared-faint radio sources: Very long baseline interferometry observations using the Very Long Baseline Array
• An Evolutionary Sequence of Young Radio Galaxies
• Revealing faint compact radio jets at redshifts above 5 with very long baseline interferometry
• Are the hosts of VLBI selected radio-AGN different to those of radio-loud AGN?
• VLBA astrometry of PSRs B0329+54 and B1133+16: Improved pulsar distances and comparison of global ionospheric models
• Searching for obscured AGN in z $\sim$ 2 submillimetre galaxies
• A wider audience: Turning VLBI into a survey instrument
• Radio Jet Properties of the Flaring Gamma-Ray Blazar PKS 0346-27
• Radio Properties of Narrow-Line and Broad-Line Seyfert 1 Galaxies
• Milliarcsecond-resolution Radio-imaging Survey of Blazar Candidates at 4 < z < 5.4