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 galaxies. By surveying vast numbers of nearby galaxies of all types with $\mu$Jy sensitivity and sub-arcsecond angular resolutions at radio wavelengths, the SKA will provide the cornerstone of our understanding of star-formation and accretion activity in the local Universe. In this chapter we outline the key continuum and molecular line science areas where the SKA, both during phase-1 and when it becomes the full SKA, will have a significant scientific impact.
We present the first publicly available service which allows astronomers to obtain customised radio interferometry images remotely, using the AstroGrid Virtual Observatory interface.This uses ParselTongue, a python-based scripting language developed by RadioNet, to extract customised images from calibrated MERLIN visibility data stored at Jodrell Bank Observatory.Similar services are being developed by other archives.We discuss this in the context of older, more limited, data access methods, and future developments.We thank all members of the AstroGrid (http:/
The e-MERLIN Galaxy Evolution Survey (eMERGE) is an ambitious, multi-tiered extragalactic radio continuum survey being carried out with e-MERLIN and the VLA at 1.4GHz and 6 GHz. Exploiting the unique combination of high sensitivity and high angular resolution provided by radio interferometry, these observations will provide a powerful, obscuration-independent tool for tracing intense star-formation and AGN activity in galaxies out to z∼5. In our first data release (DR1) we present eMERGE Tier 1, a 15-arcmin pointing centred on the GOODS-N field, imaged at 1.4GHz with the VLA and e-MERLIN at ∼0.28" resolution down to an rms sensitivy of ∼1.2μJy/beam. This unique radio survey – unrivalled at 1.4 GHz in its combination of depth, areal coverage and angular resolution in the pre-SKA era – allows us to localise and separate extended star-forming regions, nuclear starbursts and compact AGN core/jet systems in galaxies over the past two-thirds of cosmic history, a crucial step in tracing the apparently simultaneous growths of the stellar populations and central black holes in massive galaxies. In these proceedings we highlight some early science results from eMERGE DR1, including some examples of the sub-arcsecond morphologies and cold dust properties of 1.4GHz-selected galaxies. eMERGE Tier 1 will eventually reach sub-μJy/beam sensitivity at 0.28" resolution over a 30-arcmin field, providing crucial benchmarks for deep extragalactic surveys which will be undertaken with SKA in the next decade.
The star formation rate (SFR) in starburst galaxies can be measured by many methods, one of which is through the supernova rate. Due to the heavy dust obscuration in these galaxies, searches for new supernovae in the optical or infra-red can easily miss events occurring in the central starburst regions. As part of a long term program to estimate the SFR in a sample of nearby starbursts we are using MERLIN and the VLA to regularly observe the galaxies for new radio supernovae. As part of this project, regular MERLIN observations have been made of two recent optically bright supernovae: 2004dj and 2004et. Both supernovae are of Type II and have been monitored frequently over periods of a few months, resulting in well sampled radio light curves for both objects.
We present observations made with the Australia Telescope Compact Array (ATCA), the Jansky Very Large Array (JVLA) and the Giant Metre-Wave Telescope of the radio source within the galaxy WISE~J071634.59-190039.2, claimed to be host of FRB~150418 by Keane et al. (2016). We have established a common flux density scale between the ATCA and JVLA observations, the main result of which is to increase the flux densities obtained by Keane et al. At a frequency of 5.5 GHz, the source has a mean flux density of 140uJy and is variable on short timescales with a modulation index of 0.36. Statistical analysis of the flux densities shows that the variations seen are consistent with refractive interstellar scintillation of the weak active galactic nucleus at the centre of the galaxy. It may therefore be the case that the FRB and the galaxy are not associated. However, taking into account the rarity of highly variable sources in the radio sky, and our lack of knowledge of the progenitors of FRBs as a class, the association between WISE~J071634.59-190039.2 and FRB~150418 remains a possibility.
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