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Operations funding for AMI ­ Scientific Justification
The Arcminute Microkelvin Imager (AMI) is specifically designed for high sensitivity measurements of low-surface-brightness cm-wave features, giving it unique capabilities, and it observes in a region of scientifically exciting parameter space inaccessible to observatories such as the JVLA, eMERLIN and ALMA. AMI already has a track record of addressing the STFC priority areas of large scale structure formation, extreme astrophysics and Galactic structure. Its programmes support satellite missions such as Planck, Swift, Spitzer and Herschel, allowing the UK to fully exploit its investment in these missions. AMI is an extremely powerful instrument that many would like to use, so we propose that 80% of the observing time become open access. In addition, two recent developments open new scientific possibilities: an automatic target-ofopportunity facility for transient sources has been implemented, and the ERC have awarded full funding for a software correlator upgrade for AMI. This correlator upgrade work will not only explore one of the key technologies being investigated for the SKA, but will also substantially enhance AMI's capabilities by dealing with satellite interference and allowing access to equatorial regions of the sky which are currently inaccessible. This will enable new science programmes from key extragalactic deep fields (COSMOS, Subaru/XMM-Newton Deep Survey UKIDSS-UltraDeep Survey, VIDEO) and AMI will be able to image sky visible to both ALMA and VISTA.

Science with AMI
AMI has been very productive for studying the Universe both locally and out to high redshift. We summarise AMI's achievements and future prospects; more detail is available at http://arxiv.org/abs/1208.1966

Sunyaev-Zel'dovich (SZ) Effect from galaxy clusters
Operating at 14­18 GHz with very deep brightness sensitivity, robust point-source subtraction and interferometric suppression of systematics, AMI is uniquely powerful for SZ observation out to 10 arcmin, allowing mapping of the gas out to the virial radius in galaxy clusters at z=0.15­2. Two key areas are: to constrain cosmology and large scale structure formation through blind surveying for galaxy clusters; and to explore the physics of clusters and tie down their scaling relations and evolution through pointed observations towards known or candidate clusters. Unlike the Atacama Cosmology Telescope (ACT) and South Pole Telescope (SPT), the AMI blind survey is sensitive enough to measure the high-redshift mass function of typical clusters rather than that of just the rare, most massive ones. AMI has imaged the SZ effect in over 100 clusters selected from the LoCuSS, MACS, CCCP and eBCS samples. A current AMI programme (which Cambridge propose to continue as part of its 10% guaranteed time ­ see below) is dedicated to a collaboration with the Planck project, validating the accessible Planck cluster candidates with the higher sensitivity and higher angular resolution of AMI. In the first example of this work we confirmed at 13 the Planck detection of the previously unknown cluster G139.59+24.19 as well as providing a refined position estimate; observations are now proceeding on the full Planck cluster catalogue. In addition, a detailed comparison between SZ measurements obtained by both Planck and AMI has been performed for a pilot sample of previously known clusters. Since the two telescopes are sensitive to different angular scales, their combination is already revealing new cluster physics, challenging the Universal Pressure Profile. There are thus huge opportunities for new science from pointed AMI SZ observations as new cluster samples become available, such as those from WISE and eROSITA, in addition to the equatorial deep fields. Furthermore, AMI is providing the SZ super-cluster observations for the Super-CLASS programme (which will be analysed in conjunction with eMERLIN and JVLA high resolution radio data) as well as follow-up observations to clusters observed as part of the LOFAR and MeerKAT surveys.

Transients, variables and Galactic astrophysics with AMI
AMI has been extremely successful in providing key monitoring and follow-up data on a number of high-energy astrophysical sources e.g. X-ray binaries (XRBs) and gamma-ray bursts. These systems are the sites of some of the most extreme astrophysics in the Universe, and black hole (BH) accretion has been shown to be mass-scalable such that we can learn about AGN accretion


and feedback from studying BH XRBs (and vice versa). This has already led to a large number of publications and citations (>3000). A collaboration between Southampton and Cambridge, funded in part by Fender's ERC grant, has allowed the development of a 'robotic' response mode for AMI in which the telescope responds to Swift GRB alerts within seconds, with no human intervention, already providing the most rapid radio follow-up of GRBs ever performed. This is the first time such a mode has been implemented on a radio array, and is a test-bed for such modes for LOFAR. Furthermore, other programmes continue to produce key results, such as the recent discovery and monitoring of a compact jet from a BH in M31 (Nature, submitted). The cm-wave band is a highly under-utilised spectral window for Galactic research. However, given AMI's sensitivity and its extensive spatial dynamic range, this band offers a unique window on numerous vital physical processes including, but not limited to, the formation of stars in both the high and low mass regimes, as well as the earliest stages of planet formation from circumstellar disks. Consequently the AMI Galactic programme has already provided a slew of successful science, including playing a leading role in the identification and characterization of the anomalous microwave emission attributed to spinning dust, which explores a new manifestation of the very small dust grain population. This work has only been possible due to the high sensitivity to low surface brightness on large angular scales offered by AMI, which probes a region of parameter space inaccessible to other radio telescopes such as the JVLA. The full utility of the cm-wave band in Galactic science is only now beginning to be realised and forms the basis for key science programmes with next generation telescopes, such as the MeerKAT array in South Africa. Galactic studies with AMI are SKA precursor science, allowing the design of SKA projects that will leverage AMI users into a stronger position to gain time on SKA later

Economic and societal impact
AMI's science programmes will lead to a deeper understanding of structure and star formation in the Universe, which is of great interest to the public. New findings in these fields fire the imagination of school-age students and so enthuse them to become the next generation of scientists and engineers. We plan to collaborate with the Science Learning Centre, East of England (building on links with the University of Hertfordshire) to use the AMI site as a satellite venue for their work in Continuing Professional Development for school teachers. Once access to AMI is opened up we will hold short visiting-student programmes on experimental radio astronomy.

Future operational model for AMI
We propose that an STFC-appointed Board will set the broad scientific agenda for the telescope and will appoint a TAC. There will be two calls for proposals per year. We propose that 80% of the observing time will be open; Cambridge and Southampton Universities will each be directly allocated 10% of the telescope time to reflect their contributions (see Other Support). At the discretion of the Board, additional contributions to the project will be accepted to guarantee observing time at the rate of ё69 per hour, offsetting costs to STFC. After a 12 month proprietary period, reduced data will be archived and made available through a web interface.

Estimated costs to STFC
The per annum operation costs to STFC for the 80% open telescope time we estimate as totalling ё268k. We request 3 years of support. The operation costs are: Staff: 0.8 PDRA (telescope manager); 0.15 PI; 2 technicians: ё174k per annum Consumables, repairs, maintenance: ё59k per annum Electricity: ё35k per annum

Other support
We request only part of the incremental costs of operating the telescope. Cambridge University will pay for: electricity for the Small Array; maintenance of the Lord's Bridge site; management overhead; additional technician effort. This contribution is estimated to be ё278k per annum. ERC grants held at Southampton University include: 398k to provide a software correlator upgrade for AMI (Scaife); funding of the development of AMI rapid response modes (Fender).