How Large Are the Bars in Barred Galaxies?

I present a study of the sizes (semimajor axes) of bars in disc galaxies, combining a detailed study of 65 S0-Sb galaxies with measurements of 70 Sb-Sd galaxies from Martin (1995). As has been noted before with smaller samples, bars in early-type (S0-Sb) galaxies are clearly larger than bars in late-type (Sc-Sd) galaxies; this is true both for relative sizes (bar length as fraction of isophotal radius R_25 or exponential disc scale length h) and absolute sizes (kpc). S0-Sab bars extend to ~1-10 kpc (mean ~3.3 kpc), ~0.2-0.8 R_25 (mean \~0.38 R_25) and ~0.5-2.5 h (mean ~1.4 h). Late-type bars extend to only \~0.5-3.5 kpc, 0.05-0.35 R_25 and 0.2-1.5 h; mean sizes are ~1.5 kpc, 0.14 R_25 and 0.6 h. Sb galaxies resemble earlier-type galaxies in terms of bar size relative to h; their smaller R_25-relative sizes may be a side effect of higher star formation, which increases R_25 but not h. For S0-Sbc galaxies, bar size correlates well with disc size (both R_25 and h); these correlations are stronger than the known correlation with M_B. All correlations appear to be weaker or absent for late-type galaxies; in particular, there seems to be no correlation between bar size and either h or M_B for Sc-Sd galaxies. I show that the bars detected in HST near-IR images at z ~ 1 by Sheth et al. (2003) have absolute sizes consistent with those in bright, nearby S0-Sb galaxies. I also compare the sizes of real bars with those produced in simulations, and discuss some possible implications for scenarios of secular evolution along the Hubble sequence. Simulations often produce bars as large as -- or larger than -- those seen in S0-Sb galaxies, but rarely any as small as those in Sc-Sd galaxies. (Abridged.)Comment: LaTeX, 22 pages, 15 EPS figures. To appear in Monthly Notices of the Royal Astronomical Societ

Bimodality in the transverse fluctuations of a grafted semiflexible polymer and the diffusion-convection analogue: An effective-medium approach

Recent Monte Carlo simulations of a grafted semiflexible polymer in 1+1 dimensions have revealed a pronounced bimodal structure in the probability distribution of the transverse (bending) fluctuations of the free end, when the total contour length is of the order of the persistence length G. Lattanzi , Phys. Rev E 69, 021801 (2004)]. In this paper, we show that the emergence of bimodality is related to a similar behavior observed when a random walker is driven in the transverse direction by a certain type of shear flow. We adapt an effective-medium argument, which was first introduced in the context of the sheared random-walk problem E. Ben-Naim , Phys. Rev. A 45, 7207 (1992)], in order to obtain a simple analytic approximation of the probability distribution of the free-end fluctuations. We show that this approximation captures the bimodality and most of the qualitative features of the free-end fluctuations. We also predict that relaxing the local inextensibility constraint of the wormlike chain could lead to the disappearence of bimodality

Double barred galaxies at intermediate redshifts: A feasibility study

Despite the increasing number of studies of barred galaxies at intermediate and high redshifts, double-barred (S2B) systems have only been identified in the nearby (z<0.04) universe thus far. In this feasibility study we demonstrate that the detection and analysis of S2Bs is possible at intermediate redshifts (0.1 < z < 0.5) with the exquisite resolution of the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS). We identify barred galaxies in the HST/ACS data of the Great Observatories Origins Deep Survey (GOODS) using a novel method. The radial profile of the Gini coefficient -- a model-independent structure parameter -- is able to detect bars in early-type galaxies that are large enough that they might host an inner bar of sufficient angular size. Using this method and subsequent examination with unsharp masks and ellipse fits we identified the two most distant S2Bs currently known (at redshifts z=0.103 and z=0.148). We investigate the underlying stellar populations of these two galaxies through a detailed colour analysis, in order to demonstrate the analysis that could be performed on a future sample of intermediate-redshift S2Bs. We also identify two S2Bs and five S2B candidates in the HST/ACS data of the Cosmic Evolution Survey (COSMOS). Our detections of distant S2Bs show that deep surveys like GOODS and COSMOS have the potential to push the limit for S2B detection and analysis out by a factor of ten in redshift and lookback time (z=0.5, t=5Gyr) compared to the previously known S2Bs. This in turn would provide new insight into the formation of these objects.Comment: 9 pages + 10 figures. Accepted for publication in MNRAS. Main change from version 1 is an extension of the introduction/motivation and discussion section. A full resolution version including colour figures is available at http://www.astro.unibas.ch/~tlisker/papers/lisker2006_s2b.pd

Three-dimensional electronic instabilities in polymerized solid A1C60

The low-temperature structure of A1C60 (A=K, Rb) is an ordered array of polymerized C60 chains, with magnetic properties that suggest a non-metallic ground state. We study the paramagnetic state of this phase using first-principles electronic-structure methods, and examine the magnetic fluctuations around this state using a model Hamiltonian. The electronic and magnetic properties of even this polymerized phase remain strongly three dimensional, and the magnetic fluctuations favor an unusual three-dimensional antiferromagnetically ordered structure with a semi-metallic electronic spectrum.Comment: REVTeX 3.0, 10 pages, 4 figures available on request from [email protected]

Gauge Theories on Deformed Spaces

The aim of this review is to present an overview over available models and approaches to non-commutative gauge theory. Our main focus thereby is on gauge models formulated on flat Groenewold-Moyal spaces and renormalizability, but we will also review other deformations and try to point out common features. This review will by no means be complete and cover all approaches, it rather reflects a highly biased selection.Comment: v2 references added; v3 published versio

Penggunaan Bahasa Mbojo di Lingkungan Masyarakat Bima di Bima: sebuah Kajian Variasi Bahasa

Penelitian ini merupakan kajian variasi bahasa dengan menggunakan pendekan sosiolinguistik yang bertujuan untuk mendeskripsikan dan menjelaskan penggunaan bahasa Mbojo di lingkungan masyarakat Bima berdasarkan usia, jenis kelamin, dan kedudukan. Penelitian ini menggunakan rancangan deskriptif kualitatif. Subjek penelitian adalah masyarakat Bima penutur asli Bahasa Mbojo (dou Donggo). Data penelitian berupa percakapan yang dikumpulkan dengan metode perekaman, dan observasi, serta wawancara. Analisis data menggunakan model interaktif dengan tahap, sebagai berikut: (1) analisis data, (2) reduksi data, (3) penyajian data, dan (4) kesimpulan/verifikasi. Hasil penelitian ini menunjukkan bahwa berdasarkan usia, Pn-Mt sebaya, dan Pn tua-Mt muda menggunakan variasi lumrah dan kadang-kadang kasar; Pn muda-Mt tua, menggunaan variasi lumrah dan halus. Berdasarkan jenis kelamin, Pn–Mt L/P sebaya menggunaan variasi lumrah; Pn L-Mt P/Pn P-Mt L sebaya menggunakan variasi lumrah dan halus; Pn L tua/atasan-Mt L muda/bawahan menggunakan variasi lumrah dan kasar, sedangkan Pn-Mt P menggunakan variasi lumrah. Berdasarkan kedudukan, Pn atasan-Mt bawahan menggunakan variasi lumrah dan halus, kadang-kadang kasar; Pn-Mt yang kedudukan sama, menggunakan variasi lumrah, dan kadang-kadang halus; Pn bawahan-Mt atasan menggunakan variasi halus dan kadang-kadang lumrah. Dengan demikian, dapat disimpulkan bahwa penggunaan bahasa Mbojo di lingkungan masyarakat Bima bervariasi sesuai dengan usia, jenis kelamin, dan kedudukan/jabatan Pn-Mt- nya. Kata Kunci : penggunaan, variasi bahasa, masyarakat, bima The purposes of this study are described and explain of language user of Bima language (Bahasa Mbojo) in Bima area based on aged, gender (male and female), and status. In this research, the researcher used describes method. The subject of this study is Bima nees that use Bima language (Bahasa Mbojo). The data collections in this study are record, observation and interview. Analysis data in this study, the researcher used interactive model, like data analysis, data reduction, data display and verifying. In this study shown that Bima nees used language variety. Based on age, Bima ness used language variety, suck like Pn-Mt same age, and Pn old-Mt young they used language standard and sometime bad language; Pn young-Mt old, they used language standard and soft language. Based on gender (female and male) they used language variety suck like, Pn-Mt fame and female of the same age, they used language standard. Pn men-Mt women/Pn men-Mt women of the same age they used language standard and soft language; Pn old men-Mt young men they used language standard and bad language, while Pn-Mt women they used language standard. Whereas, based on status; Pn superior-Mt junior, they used language soft language and sometime they used language standard. In this research can conclusion that user language of Bima language (Bahasa Mbojo) in Bima area is variety based on the age, gender (male and famale) and their status