Flat-spectrum symmetric objects with ~1 kpc sizes I. The candidates

In order to understand the origin and evolution of radio galaxies, searches for the youngest such sources have been conducted. Compact-medium symmetric objects (CSO-MSOs) are thought to be the earliest stages of radio sources, with possible ages of <10^3 yrs for CSOs (<1 kpc in size) and 10^4-10^5 yrs for MSOs (1-15 kpc). From a literature selection in heterogeneous surveys, we have established a sample of 37 confirmed CSOs. In addition, we only found three confirmed flat-spectrum MSOs in the literature. The typical CSO resides on a z<0.5 galaxy, has a flat radio spectrum (a_thin<0.5; S_v proportional to v^-a), is <0.3 kpc in size, has an arm length ratio <2, and well-aligned (theta<20 deg) opposite lobes with a flux density ratio <10. In order to populate the 0.3-1 kpc size range (large CSOs) and also in order to find more flat-spectrum MSOs, we have built a sample of 157 radio sources with a_{1.40}^{4.85}<0.5 that were resolved with the VLA-A 8.4 GHz. As first results, we have 'rediscovered' nine of the known CSO/MSOs while identifying two new ~14 kpc MSOs and two candidate CSO/MSOs (which only lack redshifts for final classification). We were able to reject 61 of the remaining 144 objects from literature information alone. In the series of papers that starts with this one we plan to classify the remaining 83 CSO/MSO candidates (thanks to radio and optical observations) as well as characterize the physical properties of the (likely) many 0.3-15 kpc flat-spectrum CSO/MSOs to be found.Comment: 19 pages, 14 figures, 6 tables (note that Table 2, in landscape format, has a separate file); accepted by MNRA

Ultraluminous Infrared Galaxies

Ever since their discovery in the 1970's, UltraLuminous InfraRed Galaxies (ULIRGs; classically Lir>10^12Lsun) have fascinated astronomers with their immense luminosities, and frustrated them due to their singularly opaque nature, almost in equal measure. Over the last decade, however, comprehensive observations from the X-ray through to the radio have produced a consensus picture of local ULIRGs, showing that they are mergers between gas rich galaxies, where the interaction triggers some combination of dust-enshrouded starburst and AGN activity, with the starburst usually dominating. Very recent results have thrown ULIRGs even further to the fore. Originally they were thought of as little more than a local oddity, but the latest IR surveys have shown that ULIRGs are vastly more numerous at high redshift, and tantalizing suggestions of physical differences between high and low redshift ULIRGs hint at differences in their formation modes and local environment. In this review we look at recent progress on understanding the physics and evolution of local ULIRGs, the contribution of high redshift ULIRGs to the cosmic infrared background and the global history of star formation, and the role of ULIRGs as diagnostics of the formation of massive galaxies and large-scale structures.Comment: Review article, published in "Astrophysics Update 2 - topical and timely reviews on astronomy and astrophysics". Ed. John W. Mason. Springer/Praxis books. ISBN: 3-540-30312-X. 53 pages, 5 figures. Higher quality figures available on reques

International demands for austerity: examining the impact of the IMF on the public sector

What effects do International Monetary Fund (IMF) loans have on borrow-ing countries? Even after decades of research, no consensus exists. We offer a straight-forward explanation for the seemingly mixed effects of IMF loans. We argue thatdifferent loans have different effects because of the varied conditions attached to IMFfinancing. To demonstrate this point, we investigate IMF loans with and withoutconditions that require public sector reforms in exchange for financing. We find thatthe addition of a public sector reform condition to a country’s IMF program signifi-cantly reduces government spending on the public sector wage bill. This evidencesuggest that conditions are a key mechanism linking IMF lending to policy outcomes.Although IMF loans with public sector conditions prompt cuts to the wage bill in theshort-term, these cuts do not persist in the longer-term. Borrowers backslide oninternationally mandated spending cuts in response to domestic political pressures

Herschel photometric observations of the low metallicity dwarf galaxy NGC 1705

We present Herschel SPIRE and PACS photometeric observations of the low metallicity (Z ~ 0.35ΖΘ ) nearby dwarf galaxy, NGC 1705, in six wavelength bands as part of the Dwarf Galaxy Survey guaranteed time Herschel key program. We confirm the presence of two dominant circumnuclear IR-bright regions surrounding the central super star cluster that had been previously noted at mid-IR wavelengths and in the sub-mm by LABOCA. On constructing a global spectral energy distribution using the SPIRE and PACS photometry, in conjunction with archival IR measurements, we note the presence of an excess at sub-mm wavelengths. This excess suggests the presence of a signiPcant cold dust component within NGC 1705 and was modeled as an additional cold component in the SED. Although alternative explanations for the sub-mm excess beyond 350 μm, such as changes to the dust emissivity cannot be ruled out, the most likely explanation for the observed submillimetre excess is that of an additional cold dust component.Peer reviewe