Apertif - EOI abstracts and contact information

This page contains a list of the received Expressions of Interest for Apertif surveys. The call for expressions of interest can be found here.


PI: Dr. Juergen Kerp
Contact: jkerp"at"astro.uni-bonn.de
Title: Deep Blind HI Survey of the Large-Scale Structure of the Local Universe
Abstract: We propose to perform a blind HI survey along the orientation of the CFA-Stick Man. The survey area covers about 900 sq. deg. With about 110 x 12 h coverages, we reach a mass sensitivity of 1x10^6 solar masses out to 10 Mpc. From optical surveys we know that we probe about 7000 galaxies, 300 galaxy groups and about 80 galaxy clusters with this sensitivity. This provides statistically highly significant insights into the structure formation and HI evolution in different gravitationally environments.



PI: Hans-Rainer Kloeckner
Contact: hrk"at"astro.ox.ac.uk
Title: WASHY
Abstract: Measuring the Hydrogen Mass Function (HIMF) with high accuracy is essential for understanding the distribution and the quantity of baryons in the universe. Once established, the characteristics of the HIMF provide crucial information on galaxy formation models including the environmental effects on galaxy evolution.

This proposal intends to make robust measurement of the hydrogen (HI) properties of the 1000 brightest HI sources in the northern hemisphere, and will provide a benchmark of the HI mass function with unprecedented accuracy. This will make the best determination of the baryon content, traced by HI, of galaxies in the local Universe.

In addition, this survey will provide the only solid foundation for future investigations of the evolution of the HIMF. To ensure accurate calibration, the individual measurements will involve an
additional calibration step connecting the extragalactic HI signal to standard Galactic HI calibrators. The resulting database will act as an HI calibration ladder (also for current HI observations); linking fundamental Galactic HI calibration sources with external galaxies.



PI: Neeraj Gupta
Contact: gupta"at"astron.nl
Title: Blind search for 21-cm absorbers using Apertif
Abstract: We propose a blind search of 21-cm absorbers using APERTIF to trace the evolution of cold neutral gas in normal and active galaxies at z<0.4. Main goals are: (i) measure the number density of 21-cm absorbers and constrain the evolution of cold gas in normal galaxies, and (ii) trace the evolution of cold gas in active galaxies and its relationship with radio source luminosity and morphology. To achieve this, we propose two possible approaches: a shallow (12 hrs per pointing) all-sky survey with first priority to cover the areas of the SDSS-I and SDSS-II at declinations>30 degrees and a deeper (10x12 hrs per pointing) survey of about 1000 degrees^2 to explore the incidence of low optical depth absorbers and the presence of gas in low luminosity AGN. Both surveys will greatly expand the number of both intervening and associated absorbers known so far. Our team will also obtain the additional multi-wavelength data required to achieve these goals.



PI: Dr. Gyula Jozsa
Contact: jozsa"at"astron.nl
Title: WNSHS: Westerbork Northern Sky HI Survey
Abstract: We propose WNSHS, the 'Westerbork Northern Sky HI Survey', a blind Apertif HI survey of the Northern sky (Dec > +27 deg). Our aim is to study the HI content, evolution, and the small- and large-scale structure of the nearby Universe out to a redshift of z = 0.26, equivalent to a look-back time of ~2.4 Gyr, and the HI dynamics and star formation of extended galaxies. WNSHS complements the ASKAP HI survey known as WALLABY (Dec < +30deg). Together, WNSHS and WALLABY will deliver a true all-sky HI survey, going well beyond what each survey alone can accomplish.
We discuss two strategies, one aiming at matching WALLABY (4h integrations on ~1300 pointings in mosaicing mode), the other better suited for simpler calibration, possibly better commensurability with other surveys, and allowing for an extended science case (full 12h-integrations on each pointing).



PI: Mr Martin Bell
Contact: meb1w07"at"soton.ac.uk
Title: Serendipitous Westerbork APERTIF Transient Study (SWATS)
Abstract: We propose the Serendipitous Westerbork APERTIF Transient Study (SWATS) as a key science project operating in a 100% commensal mode with the proposed APERTIF surveys. We plan to explore the sub-mJy GHz radio sky for 'slow' transient and variable sources which will be dominated by synchrotron emission and constitute a tracer of relativistic particle acceleration across a range of astrophysical environments. The scope and depth of transient radio science is vast, encompassing relativistic accretion and consequent jet launch around black holes, neutron stars and white dwarfs in binary systems to distant gamma ray burst afterglows, supernovae and active galactic nuclei. Via these observations we can tackle some of the current outstanding problems in astrophysics, such as how does kinetic feedback affect galaxy growth and how did massive star formation proceed in the early Universe? Characterising sub-mJy variability is also key for planning programs for the SKA. Potentially most excitingly, we will open up new discovery space not accessible to other transient search projects in the North.



PI: Dr Alan Penny
Contact: alan.penny"at"st-andrews.ac.uk
Title: APERSETI - A SETI survey of nearby galaxies with Apertif (with a deep HI survey)
Abstract: Are there `extra-strong' ETI (Extra-Terrestrial Intelligence) radio sources in nearby galaxies?

The imaging Apertif of these extended galaxies will be much more powerful than past single beam surveys. This survey would consist of 500 hours of integration time spread over 10 nearby large galaxies. The survey, around the 'natural marker' HI line, with 16,384 channels of 100 Hz width each, would look for narrow-band emission lines, too narrow to be natural.

The Apertif FOV area will cover much of the galaxy for the nearest targets and most of the galaxy for the more distant ones. The time allocated to each galaxy will be split into three: an integration centre on the frequency of the HI line in that galaxy: one at -1.6 MHz from that; one at +1.6 MHz from that.

The survey will also enable a detailed study of the velocity distribution of the natural HI galaxy emission enable studies of the distribution of the HI.



PI: Dr John McKean
Contact: mckean"at"astron.nl
Title: Apertif Survey for Hydroxyl from Extragalactic Sources (ASHES)
Abstract: The sensitivity and wide-field of view of Apertif will allow the first blind surveys for extragalactic OH to be carried out. OH megamaser galaxies trace regions of hot and dense gas in merger systems and can be used to i) study the fueling mechanisms of AGN, ii) trace the evolution of the most extreme starbursts, iii) study magnetic fields and iv) look for variations in the fine structure constant. With this expression of interest we outline an ambitious survey for extragalactic OH with Apertif.



PI: Dr Naomi McClure-Griffiths
Contact: Naomi.McClure-Griffiths"at"csiro.au
Title: GAMES: Galactic and Magellanic Evolution Survey
Abstract: The Galactic and Magellanic Evolution Survey (GAMES) will use the outstanding speed of APERTIF on the Westerbork Synthesis Radio Telescope to conduct a high spectral resolution study of the HI and OH lines in a 3400 square deg region covering the Galactic plane, Galactic warp and Northern Magellanic Stream. By studying the HI and OH lines we will be able to probe gas evolution from warm diffuse phases to cold molecular and on to star-formation and evolved stars through OH masers. GAMES, together with the Australian SKA Pathfinder counterpart, GASKAP, will provide a complete census of HI and OH in the Galactic plane and Magellanic system with more than one order of magnitude greater surface brightness sensitivity and resolution than previous surveys. GAMES will provide an extraordinarily detailed view of galaxy evolution in our own backyard.



PI: Shri Kulkarni
Contact: srk"at"astro.caltech.edu
Title: The Dynamic Sky: A Joint Radio & Optical Assault
Abstract: Variable stars and transients have played a surprisingly significant role in astronomy. We propose a program to systematically investigate radio transients in the 20-cm band. It is our view that in general the investigations of radio transients will benefit (and in most cases require) identification of optical transients. Our proposed program takes advantage of the depth and density (cadence) of the Palomar Transient Factory. The primary strength of our proposal is the optical history for putative radio variables as well as optical light curves for variables (Galactic and extragalactic) identified in joint WSRT-Palomar fields


PI: Dr Anna Scaife
Contact: ascaife"at"cp.dias.ie
Title: BEOWULF: B-field Estimation and Observational Wide-field Understanding of Large-scale Faraday-structure
Abstract: We propose a deep polarization survey with Apertif of 64 square degrees within the Perseus-Pisces super-cluster of galaxies, in order to construct a finely spaced rotation measure (RM) grid tuned for cosmological and large-scale structure studies of magnetism within both clusters and the filamentary inter-cluster medium. This survey will complement other wide area polarization surveys: by measuring RMs to 5,000 background sources it will give an RM-grid sampling of 3.5 arcmin. This survey will provide vital insights into whether magnetic fields were primordial in clusters of galaxies, or whether the galaxies themselves later injected the field. Such a survey is ideally suited to the specifications of Apertif where the wide FOV becomes highly advantageous when observing large scale structures. In addition, the comparatively high RMs expected from such a region are well matched to the frequency coverage of Apertif. In this proposal we consider and outline both an optimal RM survey, which will require an integration time of 7573 hrs, as well as a reduced survey of 4451 hrs, both excluding overheads.



PI: Dr. Rainer Beck
Contact: rbeck"at"mpifr-bonn.mpg.de
Title: FRIGG: Faraday Rotation Investigation of Galaxies and Groups
Abstract: With its high sensitivity and large field of view APERTIF is the ideal telescope to measure grids of Faraday rotation measures (RM) of background sources and faint diffuse emission, in order to unravel the extent and dynamical importance of cosmic magnetic fields in galaxies and in intergalactic space in galaxy groups. We propose to observe large areas around 4 large northern nearby spiral galaxies, the bridge between M 31 and M 33, and 5 galaxy groups. We request two separate bandpasses (1050-1350 and 1350-1650 MHz) to improve the precision in Faraday depth space obtained by RM Synthesis.



PI: Dr. Benne Willem Holwerda
Contact: benne.holwerda"at"gmail.com
Title: WSRT/Apertif Survey of Galaxies Observed at Extreme Distances (WASGOED)
Abstract: A single deep observation targeting the 21cm line emission of galaxies out to redshift z=0.43 in the Extended Groth Strip. The field offers excellent multi-wavelength data, a large existing spectroscopic campaign and good visibility of the WSRT observatory. We plan to address the HIMF evolution, the Tully-Fisher relation, the HI content of galaxy types and cosmic volumes using both direct line detections and stacked HI line limits.

This data-set would guide future observational efforts by the SKA pathfinders MeerKAT and ASKAP as well as the future science with SKA. The overlap with the AEGIS multi-wavelength and DEEP2 spectroscopic campaigns will ensure a data-set with lasting value.



PI: Dr Matt Jarvis
Contact: M.J.Jarvis"at"herts.ac.uk
Title: APERTIF Survey of the Herschel-ATLAS (ASH-ATLAS)
Abstract: We propose to carry out a deep spectral line and continuum survey over the 150 square degree northern field of the largest open time key survey with Herschel, Herschel-ATLAS. This will allow us to address a number of fundamental questions in the formation and evolution of galaxies, how environment influences such processes and determine the link to AGN activity. Our HI observations will allow us to detect galaxies at the break of the HI mass function out to z~0.3, and gas-rich galaxies out to the limit of redshift limit of APERTIF. This redshift range is in almost perfect overlap with the redshift range of the bulk of the optically identified H-ATLAS sources, as such we can measure the gas and star-formation rate in these galaxies, elucidating the link between the initial gas supply and the final processing of this gas. The deep continuum survey will enable us to probe the far-infrared--radio correlation out to z~1, determine how star-formation and AGN activity are related and trace this over the largest scales.



PI: Dr Jarle Brinchmann
Contact: jarle"at"strw.leidenuniv.nl
Title: Deep Apertif HI Survey - DASH
Abstract: We propose here a very deep survey of the HI sky to address some of the most urgent questions in galaxy formation, namely how galaxies accrete, process and return gas to the intergalactic medium. We will take advantage of the potential of Apertif to survey 40 square degrees of the Northern sky with extensive ancillary data. By exposing these 5 fields for 1200 hrs each, we will provide a unique data-set that allows us, for the first time, to study in detail the connection between normal galaxies and the cosmic web as traced by the Ly-alpha forest at modest redshift by linking Apertif to HST/COS; the data will also help us understand the fueling of cold gas in very gas-rich galaxies and to carry out a comprehensive characterisation of the HI content of galaxies, and its link to galaxy properties, out to z=0.3.



PI: Dr. Ashish Asgekar
Contact: asgekar"at"astron.nl
Title: Westerbork and ApertiF Recombination-Line Survey (WAFRS)
Abstract: We propose to carry out WAFRS, the Westerbork and Apertif Recombination-line Survey. We aim to image four most interesting areas of the Galaxy's plane (|b|<20^{\circ}) for Hydrogen and Helium radio recombination lines (RRLs) with a channel rms of 0.1 mJy per beam. Phased-Array Feed (PAF) system has wide bandwidth, so we can observe many different lines simultaneously (\sim15) and stack them together for needed sensitivity. WAFRS is designed to observe regions of most stellar activity, and will be complimentary to similar future surveys carried out by LOFAR at the lowest and EMBRACE at intermediate frequencies. Previous recombination-line surveys were carried out with single-dish telescopes, resulting in only limited spatial resolution and sensitivities. With an enhancement of 30, both in resolution and sensitivity, WAFRS will contribute significantly to studies of the interstellar matter.



PI: Marc Verheijen
Contact: verheyen"at"astro.rug.nl
Title: A medium-deep blind survey of HI in the local Universe
Abstract: We propose a blind, medium-deep survey of neutral hydrogen out to z=0.25 over an area of 500 square degree with an integration time of 12x12 hours per pointing, focusing our survey area on the nearby CVn-I, M101, CVn-II and UMa groups, while also including 100 distant Abell clusters. The proposed area is covered by both the SDSS and the UKIDSS-LAS surveys to ensure available optical and NIR photometry for all detected sources. The main scientific drivers are 1) to explore the HI mass function down to a minimum HI mass of 2x10^5 Msun, 2) to map and measure in detail the extended morphologies and kinematics of the neutral hydrogen in and around galaxies in different environments, and 3) to determine the cosmic evolution of the gas content of galaxies over the past 3 Gyr. A survey of this kind can only be surpassed by the Square Kilometre Array.



PI: Huub Rottgering
Contact: rottgering"at"strw.leidenuniv.nl
Title: WODAN: Westerbork Observations of the Deep APERTIF Northern-Sky
Abstract: Here we propose to carry out WODAN: Westerbork Observations of the Deep APERTIF Northern-Sky. The aim is to chart the entire northern sky (delta>30) down to an rms of 10 microJy/beam and 1000 sqr deg down to an rms of 5 microJy/beam. The scientific impact of WODAN will be maximised making optimal use of large complementary radio surveys that LOFAR will carry out at lower frequencies and that ASKAP will conduct at delta < 30 in the context of the EMU (Evolutionary Map of the Universe) project. During the next decade many large area surveys encompassing virtually the entire
EM spectrum will be carried out . With WODAN containing 30 million radio sources including 100,000 clusters, 10 million starbursting galaxies at z>1 and virtually all radio loud AGN in the Universe, the combined multiwavelength data base will address many important question related to virtually every aspect of (radio) astronomy.



PI: Dr Joeri van Leeuwen
Contact: leeuwen"at"astron.nl
Title: ALERT -- The APERTIF legacy exploration of the fast radio transient sky
Abstract: The transient radio sky reflects some of the most exotic and energetic phenomena in the known Universe. Fast transients and radio pulsars illuminate dynamic processes fundamental to our understanding of physics, ranging from the extremes of gravity to the strong and weak forces and the dense matter equation of state.
Here we propose ALERT, by far the deepest all-sky survey for fast transients ever undertaken. With 12 -hr integrations, one order of magnitude longer than in previous surveys, coupled with the enormous field of view (FoV) of APERTIF, even dim and extremely rare events can be detected through their short radio bursts and/or periodic pulsations. By covering 10,000 sq. deg. of sky, ALERT will certainly find new radio pulsars and rotating radio transients. Unlike previous pulsar surveys however, ALERT is also highly sensitive to classes of transient radio emitters that have only been hypothesized and, until now, beyond the reach of such surveys.
To find these, we will exploit the unique regular layout of the WSRT to record high-time-resolution data at full sensitivity over the entire FoV. While technically challenging, the proposed method enables a survey that cannot be matched for a decade or more, until the SKA is fully operational. The WSRT/APERTIF system is uniquely capable of exploring a virtually uncharted area of transient parameter space this efficiently; it will increase by a factor of 10 the exploration volume for fast transients, throughout the Universe.



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