EMU: Evolutionary Map of the Universe

AbstractEMU is a wide-field radio continuum survey planned for the new Australian Square Kilometre Array Pathfinder (ASKAP) telescope. The primary goal of EMU is to make a deep (rms ∼ 10 μJy/beam) radio continuum survey of the entire Southern sky at 1.3 GHz, extending as far North as +30° declination, with a resolution of 10 arcsec. EMU is expected to detect and catalogue about 70 million galaxies, including typical star-forming galaxies up to z ∼ 1, powerful starbursts to even greater redshifts, and active galactic nuclei to the edge of the visible Universe. It will undoubtedly discover new classes of object. This paper defines the science goals and parameters of the survey, and describes the development of techniques necessary to maximise the science return from EMU.

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Evolutionary Map of the Universe

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312009684 ◽

2011 ◽

Vol 7 (S284) ◽

pp. 489-493

Author(s):

Ray P. Norris

Keyword(s):

Radio Continuum ◽

Wide Field ◽

Square Kilometre Array ◽

Star Forming ◽

Far North ◽

The Universe

AbstractEMU is a wide-field radio continuum survey planned for the new Australian Square Kilometre Array Pathfinder (ASKAP) telescope, due to be completed in 2012. The primary goal of EMU is to make a deep (~10μJy/bm rms) radio continuum survey of the entire Southern Sky at 1.4 GHz, extending as far North as +30° declination, with a 10 arcsec resolution. EMU is expected to detect and catalog about 70 million galaxies, including typical star-forming galaxies up to z = 1, powerful starbursts to even greater redshifts, and AGNs to the edge of the Universe. EMU will undoubtedly discover new classes of object. Here I present the science goals and survey parameters.

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The role of AGN jets in the reionization epoch

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833952 ◽

2018 ◽

Vol 617 ◽

pp. L3 ◽

Cited By ~ 5

Author(s):

V. Bosch-Ramon

Keyword(s):

Black Hole ◽

Ionizing Radiation ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Black Hole Mass ◽

Star Forming ◽

Inverse Compton Scattering ◽

Inverse Compton ◽

Mass Functions ◽

The Universe

The reionization of the Universe ends the dark ages that started after the recombination era. In the case of H, reionization finishes around z ~ 6. Faint star-forming galaxies are the best candidate sources of the H-ionizing radiation, although active galactic nuclei may have also contributed. We have explored whether the termination regions of the jets from active galactic nuclei may have contributed significantly to the ionization of H in the late reionization epoch, around z ~ 6−7. We assumed that, as it has been proposed, active galactic nuclei at z ~ 6 may have presented a high jet fraction, accretion rate, and duty cycle, and that non-thermal electrons contribute significantly to the pressure of jet termination regions. Empirical black-hole mass functions were adopted to characterize the population of active galactic nuclei. From all this, estimates were derived for the isotropic H-ionizing radiation produced in the jet termination regions, at z ~ 6, through inverse Compton scattering off CMB photons. We find that the termination regions of the jets of active galactic nuclei may have radiated most of their energy in the form of H-ionizing radiation at z ~ 6. For typical black-hole mass functions at that redshift, under the considered conditions (long-lasting, common, and very active galactic nuclei with jets), the contribution of these jets to maintain (and possibly enhance) the ionization of H may have been non-negligible. We conclude that the termination regions of jets from active galactic nuclei could have had a significant role in the reionization of the Universe at z ≳ 6.

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Constraining photoionization models with a reprojected optical diagnostic diagram

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3259 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5749-5764 ◽

Cited By ~ 1

Author(s):

Xihan Ji ◽

Renbin Yan

Keyword(s):

Star Formation ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Theoretical Models ◽

Line Ratio ◽

Star Forming ◽

Optical Diagnostic ◽

Diagnostic Diagram ◽

Upper Limits ◽

Nitrogen Abundance

ABSTRACT Optical diagnostic diagrams are powerful tools to separate different ionizing sources in galaxies. However, the model-constraining power of the most widely used diagrams is very limited and challenging to visualize. In addition, there have always been classification inconsistencies between diagrams based on different line ratios, and ambiguities between regions purely ionized by active galactic nuclei (AGNs) and composite regions. We present a simple reprojection of the 3D line ratio space composed of [N ii]λ6583/H α, [S ii]λλ6716, 6731/H α, and [O iii]λ5007/H β, which reveals its model-constraining power and removes the ambiguity for the true composite objects. It highlights the discrepancy between many theoretical models and the data loci. With this reprojection, we can put strong constraints on the photoionization models and the secondary nitrogen abundance prescription. We find that a single nitrogen prescription cannot fit both the star-forming locus and AGN locus simultaneously, with the latter requiring higher N/O ratios. The true composite regions stand separately from both models. We can compute the fractional AGN contributions for the composite regions, and define demarcations with specific upper limits on contamination from AGN or star formation. When the discrepancy about nitrogen prescriptions gets resolved in the future, it would also be possible to make robust metallicity measurements for composite regions and AGNs.

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Multiwavelength analysis of OH Megamaser galaxies: The case of IRAS11506-3851

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320004317 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 347-349

Author(s):

Carpes P. Hekatelyne ◽

Thaisa Storchi-Bergmann

Keyword(s):

Active Galactic Nuclei ◽

Hubble Space Telescope ◽

Galactic Nuclei ◽

Large Array ◽

Very Large Array ◽

Star Forming ◽

Star Forming Regions ◽

Field Unit ◽

Mixed Transition ◽

Integral Field

AbstractWe present Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU), Hubble Space Telescope (HST) and Very Large Array (VLA) observations of the inner kpc of the OH Megamaser galaxy IRAS 11506-3851. In this work we discuss the kinematics and excitation of the gas as well as its radio emission. The HST images reveal an isolated spiral galaxy and the combination with the GMOS-IFU flux distributions allowed us to identify a partial ring of star-forming regions surrounding the nucleus with a radius of ≍500 pc. The emission-line ratios and excitation map reveal that the region inside the ring present mixed/transition excitation between those of Starbursts and Active Galactic Nuclei (AGN), while regions along the ring are excited by Starbursts. We suggest that we are probing a buried or fading AGN that could be both exciting the gas and originating an outflow.

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Herschelfar-infrared photometry of the Swift Burst Alert Telescope active galactic nuclei sample of the local universe – III. Global star-forming properties and the lack of a connection to nuclear activity

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stw3268 ◽

2016 ◽

Vol 466 (3) ◽

pp. 3161-3183 ◽

Cited By ~ 27

Author(s):

T. Taro Shimizu ◽

Richard F. Mushotzky ◽

Marcio Meléndez ◽

Michael J. Koss ◽

Amy J. Barger ◽

...

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Infrared Photometry ◽

Local Universe ◽

Nuclear Activity ◽

Star Forming ◽

Burst Alert Telescope

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Constraints on the production and escape of ionizing radiation from the emission-lines of metal-poor star-forming galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319009347 ◽

2019 ◽

Vol 15 (S352) ◽

pp. 121-122

Author(s):

A. Plat ◽

S. Charlot ◽

G. Bruzual ◽

A. Feltre ◽

A. Vidal-Garca ◽

...

Keyword(s):

Ionizing Radiation ◽

Emission Line ◽

Active Galactic Nuclei ◽

High Redshift ◽

Galactic Nuclei ◽

Emission Lines ◽

High Redshift Galaxies ◽

Star Forming ◽

Radiative Shocks ◽

Metal Poor Star

AbstractTo understand how the nature of the ionizing sources and the leakage of ionizing photons in high-redshift galaxies can be constrained from their emission-line spectra, we compare emission-line models of star-forming galaxies including leakage of ionizing radiation, active galactic nuclei (AGN) and radiative shocks, with observations of galaxies at various redshifts with properties expected to approach those of primeval galaxies.

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Symmetry and the Arrow of Time in Theoretical Black Hole Astrophysics

Journal of Gravity ◽

10.1155/2015/530850 ◽

2015 ◽

Vol 2015 ◽

pp. 1-5

Author(s):

David Garofalo

Keyword(s):

Black Holes ◽

Black Hole ◽

Active Galactic Nuclei ◽

Accretion Disks ◽

Time Reversal ◽

Large Scale ◽

Galactic Nuclei ◽

Arrow Of Time ◽

Time Symmetry ◽

The Universe

While the basic laws of physics seem time-reversal invariant, our understanding of the apparent irreversibility of the macroscopic world is well grounded in the notion of entropy. Because astrophysics deals with the largest structures in the Universe, one expects evidence there for the most pronounced entropic arrow of time. However, in recent theoretical astrophysics work it appears possible to identify constructs with time-reversal symmetry, which is puzzling in the large-scale realm especially because it involves the engines of powerful outflows in active galactic nuclei which deal with macroscopic constituents such as accretion disks, magnetic fields, and black holes. Nonetheless, the underlying theoretical structure from which this accreting black hole framework emerges displays a time-symmetric harmonic behavior, a feature reminiscent of basic and simple laws of physics. While we may expect such behavior for classical black holes due to their simplicity, manifestations of such symmetry on the scale of galaxies, instead, surprise. In fact, we identify a parallel between the astrophysical tug-of-war between accretion disks and jets in this model and the time symmetry-breaking of a simple overdamped harmonic oscillator. The validity of these theoretical ideas in combination with this unexpected parallel suggests that black holes are more influential in astrophysics than currently recognized and that black hole astrophysics is a more fundamental discipline.

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The photometric system of the Nanshan One-meter Wide field Telescope

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313006935 ◽

2013 ◽

Vol 9 (S298) ◽

pp. 427-427

Author(s):

Jinzhong Liu ◽

Yu Zhang ◽

Guojie Feng ◽

Chunhai Bai

Keyword(s):

Active Galactic Nuclei ◽

Gamma Ray ◽

Galactic Nuclei ◽

Variable Stars ◽

Optical Quality ◽

Gamma Ray Bursts ◽

Wide Field ◽

Photometric System ◽

Tracking Accuracy ◽

Pointing Accuracy

AbstractA one-meter wide field astronomical telescope with Alt-Az mount, putting in work at prime focus with field corrector, is located at the Nanshan site of Xinjiang Astronomical Observatory. The Nanshan One meter Wide-field Telescope (hereafter NOWT) provides excellent optical quality, pointing accuracy and tracking accuracy. The main scientific goals of NOWT are supernovae, gamma-ray bursts, novae, variable stars, and active galactic nuclei. It is worthwhile to point out that the sky background at the Nanshan is a classic optical site.

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