LOFAR and APERTIF Surveys of the Radio Sky: Probing Shocks and Magnetic Fields in Galaxy Clusters (original) (raw)

The Spitzer High-redshift Radio Galaxy Survey

The Astrophysical …, 2010

We present results from a comprehensive imaging survey of 70 radio galaxies at redshifts 1 < z < 5.2 using all three cameras onboard the Spitzer Space Telescope. The resulting spectral energy distributions unambiguously show a stellar population in 46 sources and hot dust emission associated with the active nucleus in 59. Using a new restframe S 3 µm /S 1.6 µm versus S 5 µm /S 3 µm criterion, we identify 42 sources where the restframe 1.6 µm emission from the stellar population can be measured. For these radio galaxies, the median stellar mass is high, 2 × 10 11 M ⊙ , and remarkably constant within the range 1 < z < 3. At z > 3, there is tentative evidence for a factor of two decrease in stellar mass. This suggests that radio galaxies have assembled the bulk of their stellar mass by z ∼ 3, but confirmation by more detailed decomposition of stellar and AGN emission is needed.

ATLASGAL: the APEX Telescope Large Area Survey of the Galaxy

Eas Publications Series, 2011

Context. Thanks to its excellent 5100 m high site in Chajnantor, the Atacama Pathfinder Experiment (APEX) systematically explores the southern sky at submillimeter wavelengths, in both continuum and spectral line emission. Studying continuum emission from interstellar dust is essential to locating the highest density regions in the interstellar medium, and deriving their masses, column densities, density structures, and large-scale morphologies. In particular, the early stages of (massive) star formation remain poorly understood, mainly because only small samples of high-mass proto-stellar or young stellar objects have been studied in detail so far. Aims. Our goal is to produce a large-scale, systematic database of massive pre-and proto-stellar clumps in the Galaxy, to understand how and under what conditions star formation takes place. Only a systematic survey of the Galactic Plane can provide the statistical basis for unbiased studies. A well characterized sample of Galactic star-forming sites will deliver an evolutionary sequence and a mass function of high-mass, star-forming clumps. This systematic survey at submillimeter wavelengths also represents a preparatory work for Herschel and ALMA. Methods. The APEX telescope is ideally located to observe the inner Milky Way. The Large APEX Bolometer Camera (LABOCA) is a 295-element bolometer array observing at 870 µm, with a beam size of 19. ′′ 2. Taking advantage of its large field of view (11. ′ 4) and excellent sensitivity, we started an unbiased survey of the entire Galactic Plane accessible to APEX, with a typical noise level of 50-70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). Results. As a first step, we covered ∼95 deg 2 of the Galactic Plane. These data reveal ∼6000 compact sources brighter than 0.25 Jy, or 63 sources per square degree, as well as extended structures, many of them filamentary. About two thirds of the compact sources have no bright infrared counterpart, and some of them are likely to correspond to the precursors of (high-mass) proto-stars or proto-clusters. Other compact sources harbor hot cores, compact Hii regions, or young embedded clusters, thus tracing more evolved stages after massive stars have formed. Assuming a typical distance of 5 kpc, most sources are clumps smaller than 1 pc with masses from a few 10 to a few 100 M ⊙. In this first introductory paper, we show preliminary results from these ongoing observations, and discuss the mid-and long-term perspectives of the survey.

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 mathsfmu\mathsf{\mu}mathsfmum

Astronomy & Astrophysics, 2009

Context. Thanks to its excellent 5100 m high site in Chajnantor, the Atacama Pathfinder Experiment (APEX) systematically explores the southern sky at submillimeter wavelengths, in both continuum and spectral line emission. Studying continuum emission from interstellar dust is essential to locating the highest density regions in the interstellar medium, and deriving their masses, column densities, density structures, and large-scale morphologies. In particular, the early stages of (massive) star formation remain poorly understood, mainly because only small samples of high-mass proto-stellar or young stellar objects have been studied in detail so far. Aims. Our goal is to produce a large-scale, systematic database of massive pre-and proto-stellar clumps in the Galaxy, to understand how and under what conditions star formation takes place. Only a systematic survey of the Galactic Plane can provide the statistical basis for unbiased studies. A well characterized sample of Galactic star-forming sites will deliver an evolutionary sequence and a mass function of high-mass, star-forming clumps. This systematic survey at submillimeter wavelengths also represents a preparatory work for Herschel and ALMA. Methods. The APEX telescope is ideally located to observe the inner Milky Way. The Large APEX Bolometer Camera (LABOCA) is a 295-element bolometer array observing at 870 μm, with a beam size of 19. 2. Taking advantage of its large field of view (11. 4) and excellent sensitivity, we started an unbiased survey of the entire Galactic Plane accessible to APEX, with a typical noise level of 50−70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). Results. As a first step, we covered ∼95 deg 2 of the Galactic Plane. These data reveal ∼6000 compact sources brighter than 0.25 Jy, or 63 sources per square degree, as well as extended structures, many of them filamentary. About two thirds of the compact sources have no bright infrared counterpart, and some of them are likely to correspond to the precursors of (high-mass) proto-stars or protoclusters. Other compact sources harbor hot cores, compact H ii regions, or young embedded clusters, thus tracing more evolved stages after massive stars have formed. Assuming a typical distance of 5 kpc, most sources are clumps smaller than 1 pc with masses from a few 10 to a few 100 M. In this first introductory paper, we show preliminary results from these ongoing observations, and discuss the mid-and long-term perspectives of the survey.

Focus Meeting #3: Radio Galaxies – Resolving the AGN Phenomenon

Proceedings of the International Astronomical Union, 2018

Radio galaxies provide excellent laboratories for investigating the physical aspects, unification and cosmic evolution of active galactic nuclei (AGN). Thanks to recent multiwavelength observations, we are now able to separate many different physical components of radio galaxies through imaging and spectroscopy. Observations from radio through X-ray wavelengths can probe the ejection of matter into jets and monitor decades of jet evolution. Gamma-ray observations have shown that radio galaxies are detectable up to the very-high-energy range despite unfavorable jet alignment. We observe radio galaxies out to redshifts greater than z = 5, which makes them important cosmological probes. Planck maps have provided us with new insights into the populations of radio galaxies and their distributions in space in the 30 − 900 GHz range. NuSTAR provides high-quality spectra in the hard X-ray range. The Event Horizon Telescope (EHT) has begun mapping close to the event horizon of the Milky Way's central black hole, and the Square Kilometre Array (SKA), the next generation of extremely large telescopes (ELTs) and other future telescopes will open up a new and vast discovery space. Focus Meeting #3 brought together multiwavelength observers and theorists to synthesize progress made over the last three years and to define future directions. In order to channel the presentations and discussions, the meeting was organized into five sessions: • During the first session, starting on August 22nd, we discussed the radio-galaxy structures that are produced on kiloparsec scales and beyond, with an emphasis on plasma composition, and sought to address their underlying causes. Daniel Schwartz (Harvard-Smithsonian Center for Astrophysics, USA) talked about high-resolution studies of 100 kpc jets based on data from the Chandra X-ray Observatory. For example, a new Chandra survey for jets in radio quasars at z > 3 has revealed X-ray jets and lobes extending beyond the region of detected radio emission (Schwartz 2018). • The second session focused on the central engine and production of the jet(s). Alexander Tchekhovskoy (University of California, Berkeley, USA) introduced the topic with a presentation about how numerical simulations incorporating general relativity and magnetism allow us to use black hole accretion phenomena to quantitatively probe strong-field gravity and constrain black hole physics in various astrophysical contexts. • On the second day of the meeting we first discussed populations and statistics of radio galaxies, motivated by a review from Elaine Sadler (University of Sydney, Australia) focusing on results from multi-wavelength radio surveys. • This was followed by a session about future prospects. Lindy Blackburn (Harvard-Smithsonian Center for Astrophysics, USA) started the discussion with a presentation on the goals and status of the EHT, which has already revealed structure on the scale of † This article was originally published with its supplementary material missing. This has since been updated in the online PDF and HTML versions and a correction notice has been published.

ATLASGAL – The APEX telescope large area survey of the galaxy at 870 μm

Astronomy and Astrophysics, 2009

Context. Thanks to its excellent 5100 m high site in Chajnantor, the Atacama Pathfinder Experiment (APEX) systematically explores the southern sky at submillimeter wavelengths, in both continuum and spectral line emission. Studying continuum emission from interstellar dust is essential to locating the highest density regions in the interstellar medium, and deriving their masses, column densities, density structures, and large-scale morphologies. In particular, the early stages of (massive) star formation remain poorly understood, mainly because only small samples of high-mass proto-stellar or young stellar objects have been studied in detail so far. Aims. Our goal is to produce a large-scale, systematic database of massive pre-and proto-stellar clumps in the Galaxy, to understand how and under what conditions star formation takes place. Only a systematic survey of the Galactic Plane can provide the statistical basis for unbiased studies. A well characterized sample of Galactic star-forming sites will deliver an evolutionary sequence and a mass function of high-mass, star-forming clumps. This systematic survey at submillimeter wavelengths also represents a preparatory work for Herschel and ALMA. Methods. The APEX telescope is ideally located to observe the inner Milky Way. The Large APEX Bolometer Camera (LABOCA) is a 295-element bolometer array observing at 870 µm, with a beam size of 19. ′′ 2. Taking advantage of its large field of view (11. ′ 4) and excellent sensitivity, we started an unbiased survey of the entire Galactic Plane accessible to APEX, with a typical noise level of 50-70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). Results. As a first step, we covered ∼95 deg 2 of the Galactic Plane. These data reveal ∼6000 compact sources brighter than 0.25 Jy, or 63 sources per square degree, as well as extended structures, many of them filamentary. About two thirds of the compact sources have no bright infrared counterpart, and some of them are likely to correspond to the precursors of (high-mass) proto-stars or proto-clusters. Other compact sources harbor hot cores, compact Hii regions, or young embedded clusters, thus tracing more evolved stages after massive stars have formed. Assuming a typical distance of 5 kpc, most sources are clumps smaller than 1 pc with masses from a few 10 to a few 100 M ⊙ . In this first introductory paper, we show preliminary results from these ongoing observations, and discuss the mid-and long-term perspectives of the survey.

STAGES: the Space Telescope A901/2 Galaxy Evolution Survey

Monthly Notices of the Royal Astronomical Society, 2009

We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey (STAGES). STAGES is a multiwavelength project designed to probe physical drivers of galaxy evolution across a wide range of environments and luminosity. A complex multi-cluster system at z ∼ 0.165 has been the subject of an 80-orbit F606W HST/ACS mosaic covering the full 0.5 • × 0.5 • (∼5×5 Mpc 2) span of the supercluster. Extensive multiwavelength observations with XMM-Newton, GALEX, Spitzer, 2dF, GMRT, and the 17-band COMBO-17 photometric redshift survey complement the HST imaging. Our survey goals include simultaneously linking galaxy morphology with other observables such as age, star-formation rate, nuclear activity, and stellar mass. In addition, with the multiwavelength dataset and new high resolution mass maps from gravitational lensing, we are able to disentangle the large-scale structure of the system. By examining all aspects of environment we will be able to evaluate the relative importance of the dark matter halos, the local galaxy density, and the hot X-ray gas in driving galaxy transformation. This paper describes the HST imaging, data reduction, and creation of a master catalogue. We perform Sérsic fitting on the HST images and conduct associated simulations to quantify completeness. In addition, we present the COMBO-17 photometric redshift catalogue and estimates of stellar masses and star-formation rates for this field. We define galaxy and cluster sample selection criteria which will be the basis for forthcoming science analyses, and present a compilation of notable objects in the field. Finally, we describe the further multiwavelength observations and announce public access to the data and catalogues.

ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870 microns

2009

(Abridged) Studying continuum emission from interstellar dust is essential to locating and characterizing the highest density regions in the interstellar medium. In particular, the early stages of massive star formation remain poorly understood. Our goal is to produce a large-scale, systematic database of massive pre- and proto-stellar clumps in the Galaxy, to understand how and under what conditions star formation takes place. A well characterized sample of star-forming sites will deliver an evolutionary sequence and a mass function of high-mass, star-forming clumps. This systematic survey at submm wavelengths also represents a preparatory work for Herschel and ALMA. The APEX telescope is ideally located to observe the inner Milky Way. The Large APEX Bolometer Camera (LABOCA) is a 295-element bolometer array observing at 870 microns, with a beam size of 19". Taking advantage of its large field of view (11.4') and excellent sensitivity, we started an unbiased survey of the Galactic Plane, with a noise level of 50-70 mJy/beam: the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). As a first step, we covered 95 sq. deg. These data reveal 6000 compact sources brighter than 0.25 Jy, as well as extended structures, many of them filamentary. About two thirds of the compact sources have no bright infrared counterpart, and some of them are likely to correspond to the precursors of (high-mass) proto-stars or proto-clusters. Other compact sources harbor hot cores, compact HII regions or young embedded clusters. Assuming a typical distance of 5 kpc, most sources are clumps smaller than 1 pc with masses from a few 10 to a few 100 M_sun. In this introductory paper, we show preliminary results from these ongoing observations, and discuss the perspectives of the survey.