Megan Argo

Megan Argo
University of Central Lancashire | UCLAN · Jeremiah Horrocks Institute (JHI)

PhD

About

108
Publications
4,989
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,042
Citations
Introduction
Research astronomer, VLBI expert, observer of trainwreck galaxies, writer and maintainer of the e-MERLIN pipeline, experienced science communicator and public event organiser.
Additional affiliations
August 2011 - August 2013
Netherlands Institute for Radio Astronomy
Position
  • Researcher
March 2011 - August 2011
The University of Manchester
Position
  • eMERLIN commissioning
May 2008 - March 2011
Curtin University
Position
  • Research Associate
Education
September 2003 - September 2006
The University of Manchester
Field of study
  • Radio Astronomy
September 1999 - June 2003
The University of Manchester
Field of study
  • Physics

Publications

Publications (108)
Article
Full-text available
The core of the nearby galaxy NGC 660 has recently undergone a spectacular radio outburst; using a combination of archival radio and Chandra X-ray data, together with new observations, the nature of this event is investigated. Radio observations made using e-MERLIN in mid-2013 show a new compact and extremely bright continuum source at the centre o...
Article
Full-text available
We present the highest resolution, wide-field radio survey of a nearby face-on star-forming galaxy to date. The multiphase centre technique is used to survey the entire disc of M51 (77 arcmin2) at a maximum resolution of 5 mas on a single 8 h pointing with the European Very Long Baseline Interferometry (VLBI) Network at 18 cm. In total, 7 billion p...
Article
Full-text available
We present results from three nearly simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and Chandra monitoring observations between 2012 September 2 and 2012 November 16 of the local star-forming galaxy NGC 253. The 3-40 keV intensity of the inner ~20 arcsec (~400 pc) nuclear region, as measured by NuSTAR, varied by a factor of ~2 across t...
Article
Full-text available
The VLBA was used at 1.6 GHz to observe a target field 50 arcminutes in diameter including the core of M31. Novel VLBI correlation techniques were used to observe 200 sources simultaneously, of which 16 were detected. We classify all 16 as background AGN based on their X-ray properties and arcsecond- and mas-scale morphology. The detected sources w...
Article
Full-text available
We present first results from electronic Multi-Element Remotely Linked Interferometer Network (e-MERLIN) and electronic European VLBI Network (e-EVN) observations of a small sample of ultra-steep spectrum radio sources, defined as those sources with a spectral index alpha < -1.4 between 74 MHz and 325 MHz, which are unresolved on arcsecond scales....
Preprint
Full-text available
All 280 of the statistically-complete Palomar sample of nearby (<120 Mpc) galaxies dec > 20 degrees have been observed at 1.5 GHz as part of the LeMMINGs e-MERLIN legacy survey. Here, we present Chandra X-ray observations of the nuclei of 213 of these galaxies, including a statistically-complete sub-set of 113 galaxies in the declination range 40 d...
Article
What determines the nuclear radio emission in local galaxies? To address this question, we combine optical [O iii] line emission, robust black hole (BH) mass estimates, and high-resolution e-MERLIN 1.5-GHz data, from the LeMMINGs survey, of a statistically complete sample of 280 nearby optically active (LINER and Seyfert) and inactive [H ii and abs...
Preprint
Full-text available
What determines the nuclear radio emission in local galaxies? We combine optical [O III] line emission, robust black hole (BH) mass estimates, and high-resolution e-MERLIN 1.5-GHz data, from the LeMMINGs survey, of a statistically-complete sample of 280 nearby, optically active (LINER and Seyfert) and inactive HII and Absorption line galaxies [ALG]...
Article
We present the second data release of high-resolution (≤0.2 arcsec) 1.5-GHz radio images of 177 nearby galaxies from the Palomar sample, observed with the e-MERLIN array, as part of the LeMMINGs (Legacy e-MERLIN Multi-band Imaging of Nearby Galaxy Sample) survey. Together with the 103 targets of the first LeMMINGs data release, this represents a co...
Preprint
We present the second data release of high-resolution ($\leq0.2$ arcsec) 1.5-GHz radio images of 177 nearby galaxies from the Palomar sample, observed with the e-MERLIN array, as part of the LeMMINGs (Legacy e-MERLIN Multi-band Imaging of Nearby Galaxy Sample) survey. Together with the 103 targets of the first LeMMINGs data release, this represents...
Article
A key characteristic of many active galactic nuclei (AGNs) is their variability, but its origin is poorly understood, especially in the radio domain. Williams et al. (2017) reported a ∼50 per cent increase in peak flux density of the AGN in the Seyfert galaxy NGC 4151 at 1.5 GHz with the e-MERLIN array. We present new high-resolution e-MERLIN obser...
Article
A key characteristic of many active galactic nuclei (AGNs) is their variability, but its origin is poorly understood, especially in the radio domain. Williams et al. (2017) reported a ∼50 per cent increase in peak flux density of the AGN in the Seyfert galaxy NGC 4151 at 1.5 GHz with the e-MERLIN array. We present new high-resolution e-MERLIN obser...
Article
Full-text available
We present an overview and description of the e-MERGE Survey (e-MERLIN Galaxy Evolution Survey) Data Release 1 (DR1), a large program of high-resolution 1.5-GHz radio observations of the GOODS-N field comprising ∼140 h of observations with enhanced-Multi-Element Remotely Linked Interferometer Network (e-MERLIN) and ∼40 h with the Very Large Array (...
Preprint
We present an overview and description of the eMERLIN Galaxy Evolution survey (eMERGE) Data Release 1 (DR1), a large program of high-resolution 1.5 GHz radio observations of the GOODS-N field comprising $\sim140$ hours of observations with eMERLIN and $\sim40$ hours with the Very Large Array (VLA). We combine the long baselines of eMERLIN (providin...
Article
Aims. Submillimetre-selected galaxies (SMGs) at high redshift ( z ∼ 2) are potential host galaxies of active galactic nuclei (AGN). If the local Universe is a good guide, ∼50% of the obscured AGN amongst the SMG population could be missed even in the deepest X-ray surveys. Radio observations are insensitive to obscuration; therefore, very long base...
Preprint
A key characteristic of many active galactic nuclei (AGN) is their variability, but its origin is poorly understood, especially in the radio domain. Williams et al. (2017) reported a ~50 per cent increase in peak flux density of the AGN in the Seyfert galaxy NGC 4151 at 1.5 GHz with the e-MERLIN array. We present new high resolution e-MERLIN observ...
Preprint
Submillimetre-selected galaxies (SMGs) at high redshift ($z$ $\sim$ 2) are potential host galaxies of active galactic nuclei (AGN). If the local Universe is a good guide, $\sim$ 50$\%$ of the obscured AGN amongst the SMG population could be missed even in the deepest X-ray surveys. Radio observations are insensitive to obscuration; therefore, very...
Article
Full-text available
We present high-sensitivity 1.51 GHz e-MERLIN (e-Multi-Element Radio-Linked Interferometer Network) radio images of the nearby galaxy NGC 6217. We resolve the compact radio source at the centre of NGC 6217 for the first time, finding a twin-lobed structure with a total linear size of ∼4 arcsec (∼400 pc). The radio source does not have a compact cen...
Article
Full-text available
p>We present high-sensitivity 1.51 GHz e-MERLIN (e-Multi-Element Radio-Linked Interferometer Network) radio images of the nearby galaxy NGC6217. We resolve the compact radio source at the centre of NGC6217 for the first time, finding a twin-lobed structure with a total linear size of ~4 arcsec (~400 pc). The radio source does not have a compact cen...
Article
We studied the nearby, interacting galaxy NGC 5195 (M51b) in the radio, optical and X-ray bands. We mapped the extended, low-surface-brightness features of its radio-continuum emission; determined the energy content of its complex structure of shock-ionized gas; constrained the current activity level of its supermassive nuclear black hole. In parti...
Article
Full-text available
We present the first data release of high-resolution ($\leq0.2$ arcsec) 1.5-GHz radio images of 103 nearby galaxies from the Palomar sample, observed with the eMERLIN array, as part of the LeMMINGs survey. This sample includes galaxies which are active (LINER and Seyfert) and quiescent (HII galaxies and Absorption line galaxies, ALG), which are rec...
Article
We have analysed a new high-resolution e-MERLIN 1.5 GHz radio continuum map together with $HST$ and SDSS imaging of NGC 5322, an elliptical galaxy hosting radio jets, aiming to understand the galaxy's central structure and its connection to the nuclear activity. We decomposed the composite $HST$ + SDSS surface brightness profile of the galaxy into...
Article
Full-text available
We present high-sensitivity eMERLIN radio images of the Seyfert galaxy NGC 4151 at 1.5 GHz. We compare the new eMERLIN images to those from archival MERLIN observations in 1993 to determine the change in jet morphology in the 22 years between observations. We report an increase by almost a factor of 2 in the peak flux density of the central core co...
Article
Full-text available
We present new observations of the GOODS-N field obtained at 5.5 GHz with the Karl G. Jansky Very Large Array (VLA). The central region of the field was imaged to a median r.m.s. of 3 microJy/beam with a resolution of 0.5 arcsec. From a 14-arcmin diameter region we extracted a sample of 94 radio sources with signal-to-noise ratio greater than 5. Ne...
Article
V959 Mon (Nova Mon 2012) was first detected by the Fermi Large Area Telescope in June 2012, as a transient gamma-ray source. Subsequent optical observations showed that this gamma-ray emission was due to a classical nova explosion. Multi-frequency observations of V959 Mon with the VLA between June and September 2012 revealed dramatic brightening, a...
Article
IC883 is a luminous infrared galaxy (LIRG) classified as a starburst-active galactic nucleus (AGN) composite. In a previous study we detected a low-luminosity AGN (LLAGN) radio candidate. Here we report on our radio follow-up at three frequencies which provides direct and unequivocal evidence of the AGN activity in IC883. Our analysis of archival X...
Article
We present high-resolution e-MERLIN radio continuum maps of the Dwarf Irregular galaxy IC10 at 1.5GHz and 5GHz. We detect 11 compact sources at 1.5GHz, 5 of which have complementary detections at 5GHz. We classify 3 extended sources as compact H{\sc ii} regions within IC10, 5 sources as contaminating background galaxies and identify 3 sources which...
Article
Full-text available
We present a radio light curve of supernova (SN) 2014C taken with the Arcminute Microkelvin Imager (AMI) Large Array at 15.7 GHz. Optical observations presented by Milisavljevic et al. demonstrated that SN 2014C metamorphosed from a stripped-envelope Type Ib SN into a strongly interacting Type IIn SN within 1 year. The AMI light curve clearly shows...
Article
Megan Argo and colleagues discuss what can be determined from galactic observations and surveys using e-MERLIN.
Article
Full-text available
We present results from sensitive, multi-epoch NuSTAR observations of the late-type star-forming galaxy M83 (d=4.6 Mpc), which is the first investigation to spatially resolve the hard (E>10 keV) X-ray emission of this galaxy. The nuclear region and ~ 20 off-nuclear point sources, including a previously discovered ultraluminous X-ray (ULX) source, a...
Article
Full-text available
We present multi-epoch millarcsecond resolution images of the most compact supernova remnants in the nearby starburst galaxy M82, spanning 25 years of evolution. In particular, we will briefly discuss the new transient source first detected in 2009 as well as the unusual object 41.95+57.5 and its potential as a GRB afterglow.
Article
Full-text available
Written in Python and utilising ParselTongue to interface with the Astronomical Image Processing System (AIPS), the e-MERLIN data reduction pipeline is intended to automate the procedures required in processing and calibrating radio astronomy data from the e-MERLIN correlator. Driven by a plain text file of input parameters, the pipeline is modular...
Article
Full-text available
Adding VLBI capability to the SKA arrays will greatly broaden the science of the SKA, and is feasible within the current specifications. SKA-VLBI can be initially implemented by providing phased-array outputs for SKA1-MID and SKA1-SUR and using these extremely sensitive stations with other radio telescopes, and in SKA2 by realising a distributed co...
Article
Full-text available
The SKA will be a transformational instrument in the study of our local Universe. In particular, by virtue of its high sensitivity (both to point sources and diffuse low surface brightness emission), angular resolution and the frequency ranges covered, the SKA will undertake a very wide range of astrophysical research in the field of nearby galaxie...
Article
Full-text available
We report on simultaneous observations of the local starburst system Arp 299 with NuSTAR and Chandra, which provides the first resolved images of this galaxy up to energies of ~ 45 keV. Fitting the 3-40 keV spectrum reveals a column density of $N_{\rm H}$ ~ 4 x10^{24} cm^{-2}, characteristic of a Compton-thick AGN, and a 10-30 keV luminosity of 1.2...
Article
Full-text available
Prior to the launch of NuSTAR, it was not feasible to spatially resolve the hard (E > 10 keV) emission from galaxies beyond the Local Group. The combined NuSTAR dataset, comprised of three ~165 ks observations, allows spatial characterization of the hard X-ray emission in the galaxy NGC 253 for the first time. As a follow up to our initial study of...
Article
Full-text available
We report deep EVN and eMERLIN observations of the Type Ia SN 2014J in the nearby galaxy M82. Our observations represent, together with those on SN 2011fe, the most sensitive radio study of a Type Ia SN ever. By combining data and a proper modelling of the radio emission, we constrain the mass-loss rate from the progenitor system of SN 2014J to dM/...
Article
The coeval growth of supermassive black holes (SMBH) and their stellar halo hosts provides evidence that star formation and AGN activity must be closely associated, but it is not clear to what extent they must always be coordinated. A prime test of this coordination is the search for AGN activity in starburst galaxies, which by definition have high...
Article
We report MERLIN radio observations of the Type Ia supernova 2013dy, which was discovered on 10.45 July 2013, shortly after its explosion, in the nearby (D=13.5 Mpc) galaxy NGC 7250 (cf. CBET #3588). Our observations were carried out during 4 - 6 August 2013, one week after the SN reached its B-band maximum (Zheng et al. 2013). The radio telescopes...
Article
Launched in mid-2012, NuSTAR is the first focusing hard X-ray (E10 keV) astronomical observatory. Hard X-ray emission from star-forming galaxies arises from a population of neutron stars and stellar-mass black holes, however few starburst galaxies have been detected above 10 keV. Here we present an overview of a program to survey six normal/starbur...
Article
Full-text available
Despite first being detected in the 1970s, surprisingly little is known about the OH main line maser population in the nearby starburst galaxy M82. Sometimes referred to as 'kilomasers', they have isotropic luminosities intermediate between Galactic masers and those found in more distant megamasers. Several observations have been carried by this gr...
Article
Full-text available
The partial shutdown of the Federal government had far-reaching effects on US science, and STEM research in general: research programs were put on hold, clinical trials have been postponed or cancelled, and scientists across many disciplines were on enforced, unpaid leave. Whilst this is devastating for many research programs in the US, there are m...
Article
Full-text available
This paper presents the results of the 2009–2010 monitoring sessions of the starburst galaxy M82, obtained with the Multi-Element Radio-Linked Interferometer Network (MERLIN) at 5 GHz and e-MERLIN at 6 GHz. Combining several 5 GHz MERLIN epochs to form a map with 33.0 μJy bm−1 noise level, 52 discrete sources, mostly supernova remnants and H ii reg...
Article
Full-text available
Article
Full-text available
The high star formation rates of luminous infrared galaxies (LIRGs) make them ideal places for core-collapse supernova (CCSN) searches. At radio frequencies, free from dust extinction, it is possible to detect compact components within the innermost LIRG nuclear regions, such as SNe and SN remnants, as well as AGN buried deep in the LIRG nuclei. We...
Article
Full-text available
The Square Kilometre Array is a global mega-science project to build the world's largest radio telescope. One of two short-listed locations for the telescope is Western Australia's Mid West region, a geologically stable area with a very low population density making it an ideal location for sensitive radio telescopes. It is vital that the local pop...
Article
Full-text available
We report on the VLBI detection of supernova SN2011dh at 22GHz using a subset of the EVN array. The observations took place 14 days after the discovery of the supernova, thus resulting in a VLBI image of the youngest radio-loud supernova ever. We provide revised coordinates for the supernova with milli-arcsecond precision, linked to the ICRF. The r...
Article
Full-text available
One of our closest neighbours, the Andromeda Galaxy (M31) has been the subject of numerous large area studies across the entire spectrum, but so far full-disk radio surveys have been conducted only at low resolution. The new wide-field capabilities of the DiFX software correlator present the possibility of imaging the entire primary beam of a VLBI...
Article
From a combination of Multi-Element Radio-Linked Interferometer Network (MERLIN) and global Very Long Baseline Interferometry (VLBI) observations of the starburst galaxy M82, images of 36 discrete sources at resolutions ranging from ∼3 to ∼80 mas at 1.7 GHz are presented. Of these 36 sources, 32 are identified as supernova remnants, two are H ii re...
Article
A faint new radio source has been detected in the nuclear region of the starburst galaxy M82 using Multi-Element Radio-Linked Interferometer Network radio observations designed to monitor the flux density evolution of the recent bright supernova SN2008iz. This new source was initially identified in observations made between 2009 May 1 and 5 but had...
Article
We propose to carry out NAPA observations of bright, nearby core-collapse supernovae (SNe) to: (1) Determine the physics of SNe through the study of the mass-loss rate, absorption mechanisms, and density distribution of the circumstellar medium (CSM) laid down by the pre-SN stellar wind; (2) Improve our understanding of the various subgroupings (Ty...
Article
CBET 2242 available at Central Bureau for Astronomical Telegrams.