Rubin-LSST

Abstract:

In order to understand the formation and subsequent evolution of galaxies one must first distinguish between the two main morphological classes of massive systems: spirals and early-type systems. This paper introduces a project, Galaxy Zoo, which provides visual morphological classifications for nearly one million galaxies, extracted from the Sloan Digital Sky Survey (SDSS). This achievement was made possible by inviting the general public to visually inspect and classify these galaxies via the internet. The project has obtained more than 4 × 107 individual classifications made by ∼10 5 participants. We discuss the motivation and strategy for this project, and detail how the classifications were performed and processed. We find that Galaxy Zoo results are consistent with those for subsets of SDSS galaxies classified by professional astronomers, thus demonstrating that our data provide a robust morphological catalogue. Obtaining morphologies by direct visual inspection avoids introducing biases associated with proxies for morphology such as colour, concentration or structural parameters. In addition, this catalogue can be used to directly compare SDSS morphologies with older data sets. The colour-magnitude diagrams for each morphological class are shown, and we illustrate how these distributions differ from those inferred using colour alone as a proxy for morphology. © 2008 RAS.

Abstract:

High energy astrophysics has made good use of combined high energy (X-ray, g-ray) and radio observations to uncover connections between outbursts, accretion, particle acceleration and kinetic feedback to the local ambient medium. In the field of microquasars the connections have been particularly important. However, radio astronomy has been relying on essentially the same facilities for the past ∼ 25 years, whereas high-energy astrophysics, in particular space-based research, has had a series of newer and more powerful missions. In the next fifteen years this imbalance is set to be redressed, with a whole familiy of new radio facilities under development en route to the Square Kilometre Array (SKA) in the 2020s. In this brief review I will summarize these future prospects for radio astronomy, and focus on possibly the most exciting of the new facilities to be built in the next decade, the Low Frequency Array LOFAR, and its uses in high energy astrophysics. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike Licence.

Abstract:

High energy astrophysics has made good use of combined high energy (X-ray, g-ray) and radio observations to uncover connections between outbursts, accretion, particle acceleration and kinetic feedback to the local ambient medium. In the field of microquasars the connections have been particularly important. However, radio astronomy has been relying on essentially the same facilities for the past ∼ 25 years, whereas high-energy astrophysics, in particular space-based research, has had a series of newer and more powerful missions. In the next fifteen years this imbalance is set to be redressed, with a whole familiy of new radio facilities under development en route to the Square Kilometre Array (SKA) in the 2020s. In this brief review I will summarize these future prospects for radio astronomy, and focus on possibly the most exciting of the new facilities to be built in the next decade, the Low Frequency Array LOFAR, and its uses in high energy astrophysics. © Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial- ShareAlike Licence.

Abstract:

This paper discusses infrared and millimetre-wavelength observations of a Lyman α blob (LAB) discovered by Smith & Jarvis, a candidate for ionization by the cold accretion scenario discussed in Fardal et al. and Dijkstra et al. We have observed the counterpart galaxy at infrared wavelengths in deep observations with the Spitzer Space Telescope using the IRAC 3.6, 4.5, 5.8 and 8.0 μm and MIPS 24 μm bands, as well as using the Max-Planck Millimeter Bolometer (MAMBO-2) at a wavelength of 1.2 mm with the IRAM 30 m telescope. These observations probe the ≳95 kpc Lyman α halo for the presence of obscured active galactic nucleus (AGN) components or the presence of a violent period of star formation invoked by other models of ionization for these mysterious objects. 24 μm observations suggest that an obscured AGN would be insufficiently luminous to ionize the halo, and that the star formation rate within the halo may be as low as <140 M⊙ yr -1 depending on the model spectral energy distribution (SED) used. This is reinforced by our observations at 1.2 mm using MAMBO-2, which yield an upper limit of star formation rate <550 M⊙ yr-1 from our non-detection to a 3σ flux limit of 0.86 mJy beam-1. Finding no evidence for either AGN or extensive star formation, we conclude that this halo is ionized by a cold accretion process. We derive model SEDs for the host galaxy, and use the Bruzual & Charlot and Maraston libraries to show that the galaxy is well described by composite stellar populations of total mass 3.42 ± 0.13 × 1011 or 4.35 ± 0.16 × 1011 M⊙ depending on the model SEDs used. © 2008 RAS.