Re-Evaluating the Chronology of Caracalla's Reign: When Was Caracalla in Nikomedia?

It has become increasingly common to assert that Caracalla wintered in Nicomedia in 213/214 rather than 214/215. This is important because it has led scholars to argue that Caracalla’s activities and campaigns in the Balkans are largely invented by ancient historiographers. The present article examines and rejects the evidentiary basis of the new dating and, through an analysis of Caracalla’s itinerary and relevant coinage, provides strong support for the theory that Caracalla wintered in Nicomedia in 214/215. This reconstruction significantly influences the wider chronology of Caracalla’s reign and restores his activities in the Balkans to the history books

Two novel methods of measuring cosmic distances in the Universe

We present two novel methods of distance measurement using photometric techniques. We compare the methods to each other and independently created methods to measure photometric redshifts.The first method we present in this thesis is based on SFR of galaxies which are typically either star forming, quenched, or in transition between the two. This causes the SFR measurements to group up into two distinct and well defined groups in SFR-M? space. We measure how these groups evolve with redshift and see a distinct non degenerate evolutionary path which makes it possible to use it for distance measurements. Since this method requires measurements of several different galaxies we apply this method to several galaxy clusters to test it and see how well it works.The second method uses BL Lac objects to measure distance. While using these objects is not by itself a novel concept, we do extract the host galaxy magnitudes needed to measure the distance in a way that has not before been done on this large an amount of data. We also present several thousand new BL Lac candidates in the SDSS BOSS catalogue which has not previously undergone a systematic and dedicated search for BL Lacs. By doing this we also find many more radio quiet BL Lac like objects which have previously not been detected in a high enough number to properly analyse through the use of statistics.Finally we compare the two methods to each other as well with an independent photometric redshift method as well as measure the Hubble constant to be able to compare the methods to the distance ladder as a whole. Here the SFR method does not match up well to the independent methods giving worse results, but the BL Lac method give results with similar precision to the independent methods

A new method to measure the mass of galaxy clusters

The mass measurement of galaxy clusters is an important tool for the determination of cosmological parameters describing the matter and energy content of the Universe. However, the standard methods rely on various assumptions about the shape or the level of equilibrium of the cluster. We present a novel method of measuring cluster masses. It is complementary to most of the other methods, since it only uses kinematical information from outside the virialized cluster. Our method identifies objects, as galaxy sheets or filaments, in the cluster outer region, and infers the cluster mass by modeling how the massive cluster perturbs the motion of the structures from the Hubble flow. At the same time, this technique allows to constrain the three-dimensional orientation of the detected structures with a good accuracy. We use a cosmological numerical simulation to test the method. We then apply the method to the Coma cluster, where we find two galaxy sheets, and measure the mass of Coma to be Mvir=(9.2\pm2.4)10^{14} Msol, in good agreement with previous measurements obtained with the standard methods.Comment: 10 pages, 12 figures, submitted to MNRA

Cassius Dio, competition and the decline of the Roman Republic

This thesis argues that Dio’s narrative of the Late Republic constitutes a sophisticated and consistent interpretation of the fall of the Republican governmental form, centred on competition. In Dio’s narrative, institutionally generated political competition is the central destructive factor of the Late Republic, which causes its deterioration and eventual collapse. This competition was inherent to the Republic according to Dio but underwent a destructive transformation in the Late Republic and Dio hereby presents an institutional explanation for the decline of the Republic. The discussion is divided into an introduction, two thematic chapters and two chapters containing case studies, all of which include a number of subchapters each. Chapter 1 (“Introduction”) presents the argument and the scholarly tradition on Dio’s Late Republic, and hereafter examines Dio’s fundamental ideas about and perspectives on competition. Chapter 2 (“Dio and the sources for the Late Republic”) compares Dio with the parallel sources for the events surrounding Lucullus and his command, the lex Gabinia and the Catilinarian Conspiracy. Through this, I will argue that Dio manipulated and selected his material carefully in order to present and strengthen an original interpretation in which competition is central. Chapter 3 (“Dio and the annalistic method”) examines Dio’s use of the annalistic tradition and, via a main focus on elections, omens and legislation, demonstrates that Dio was highly selective in his use of annalistic material as he only incorporated it when it furthered his interpretative aims. Chapter 4 (“A diachronic analysis of Book 36”) argues that Dio incorporated his main exploration of external competition in Book 36, and through skilful manipulation and structuring of the narrative, created a cumulative interrelation between individual parts of the book. This interrelation furthered the communication and strengthening of Dio’s overarching interpretative framework centred on institutional competition. Chapter 5 (“Book 39 and competition in practice”) asserts that Book 39 is Dio’s central investigation of internal competition and its intimate connection to the fall of the Republic. To support and communicate this, Dio again creates a sophisticated interrelation within the book, which presents violence, bribery and political manipulation as central tools used by dynasts to further their ambition. Thus Dio here further strengthens his explanation of the fall of the Republic, where institutionally generated competition is the central focal point

Redshift measurement through star formation

© ESO 2019. In this work we use the property that, on average, star formation rate increases with redshift for objects with the same mass - the so called galaxy main sequence - to measure the redshift of galaxy clusters. We use the fact that the general galaxy population forms both a quenched and a star-forming sequence, and we locate these ridges in the SFR-M⋆ plane with galaxies taken from the Sloan Digital Sky Survey in discrete redshift bins. We fitted the evolution of the galaxy main sequence with redshift using a new method and then subsequently apply our method to a suite of X-ray selected galaxy clusters in an attempt to create a new distance measurement to clusters based on their galaxy main sequence. We demonstrate that although it is possible in several galaxy clusters to measure the main sequences, the derived distance and redshift from our galaxy main sequence fitting technique has an accuracy of σz  =  ±0.017 ⋅  (z  +  1) and is only accurate up to z  ≈  0.2

Cassius Dio’s Ideal Government and the Imperial Senate

This chapter argues that Dio envisioned a surprisingly minimalist role for the Senate in his ideal government: magistrates and advisors were drawn from the senators, but the emperor should hold absolute power and the Senate should not constitute an important forum of genuine deliberation or advice. Instead, in Dio’s ideal government, the consilium was the key forum of debate informing imperial policy. Dio’s ideal government, and the place of the Senate therein, is distinctive as it broke with a long tradition of senatorial writing which idealised a system of government where the Senate played a central role. This nuances the widespread view of Dio as a ‘senatorial historian’