Rubin-LSST

Abstract:

We present a study of the internal kinematics and stellar populations of early-type galaxies in the Fornax cluster. 10 galaxies in a luminosity range of 21.8MB17.4 were observed with the integral field units (IFU) of Gemini South GMOS and VLT-VIMOS. Velocity maps and age-metallicity diagrams are presented for NGC 1404 and NGC 1419. © 2008 Copyright International Astronomical Union 2008.

Abstract:

Circinus X-1 is a neutron star X-ray binary system with an interesting and at times puzzling behaviour over a broad range of frequencies, specifically in the X-ray and radio bands. The system seems to harbour the most relativistic outflow (likely oriented close to the line of sight) observed so far within the Milky Way. It lies within a radio synchrotron nebula and has variable radio flux densities at cm wavelengths. The radio flares associated to the orbital phase zero reached up to 1 Jy in the late '70s, then have been observed at the tens of mJy level until recently; in 2007 January, Circinus X-1 seemed to have entered a very active radio flaring state. Here we present a sample of the 4.8 and 8.6 GHz radio observations made with the Australia Telescope Compact Array, covering 10 years time period. The entire data set comprised 41 epochs, unequally spread in time between 1996 and 2006. We investigate the long-term changes in the brightness, morphology and spectrum of the radio structures. We have detected linear polarisation in a third of the epochs and a good case for Faraday rotation in one epoch. The analysis reveals structural changes in the radio emission at time scales as short as days. Clear evidence for a counter-jet was found in a few epochs.

Abstract:

We determine the ensemble properties of Lyman-break galaxies (LBGs) selected as V-band dropouts to in the Chandra Deep Field-South using their rest-frame UV-to-visible spectral energy distributions. By matching the selection and performing the same analysis that has been used for samples, we show clear differences in the ensemble properties of two samples of LBGs which are separated by 1 Gyr in look-back time. We find that LBGs are typically much younger (<100 Myr) and have lower stellar masses than their counterparts (which are typically ∼ few × and ∼320 Myr old). The difference in mass is significant even when considering the presence of an older, underlying population in both samples. Such young and moderately massive systems dominate the luminous LBG population (≳70 per cent), whereas they comprise ≲30 per cent of LBG samples at. This result, which we demonstrate is robust under all reasonable modelling assumptions, shows a clear change in the properties of the luminous LBGs between and. These young and moderately massive LBGs appear to be experiencing their first (few) generations of large-scale star formation and are accumulating their first significant stellar mass. Their dominance in luminous LBG samples suggests that witnesses a period of wide-spread, recent galaxy formation. As such, LBGs are the likely progenitors of the spheroidal components of present-day massive galaxies. This is supported by their high stellar mass surface densities, and is consistent with their core phase-space densities, as well as the ages of stars in the bulge of our Galaxy and other massive systems. With implied formation redshifts of, these luminous LBGs could have only contributed to the UV photon budget at the end of reionization. However, their high star formation rates per unit area suggest these systems host outflows or winds that enrich the intragalactic and intergalactic media with metals, as has been established for LBGs. Their estimated young ages are consistent with inefficient metal-mixing on galaxy-wide scales. Therefore these galaxies may contain a significant fraction of Population III stars as proposed for LBGs by Jiminez & Haimann. © 2007 The Authors. Journal compilation © 2007 RAS.