Archive for Euclid Deep Field North

Weekly Update from the Open Journal of Astrophysics – 26/07/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , on July 26, 2025 by telescoper

It’s Saturday morning again, so it’s time again for an update of papers published at the Open Journal of Astrophysics. Since the last update we have published seven new papers, which brings the number in Volume 8 (2025) up to 105, and the total so far published by OJAp up to 340. I expect we’ll pass the century for this year sometime next week. I had expected a bit of a slowdown in July, but that doesn’t seem to have happened. Anyway, with the century for the year having been achieved, the next target is 120 (the total number we published last year). At the current rate I expect us to reach that sometime in August.

The papers published this week, with their overlays, are as follows. You can click on the images of the overlays to make them larger should you wish to do so.

The first paper to report is “Non-equilibrium ionization in the multiphase circumgalactic medium – impact on quasar absorption-line analyses” by Suyash Kumar and Hsiao-Wen Chen (University of Chicago, USA). This was published on Tuesday 22nd July 2025 in the folder Astrophysics of Galaxies. It discusses time-dependent photoionization (TDP) models that self-consistently solve for the ionization state of rapidly cooling gas irradiated by the extragalactic ultraviolet background (UVB) and the application thereof to observed systems.

The overlay is here:

The officially-accepted version can be found on arXiv here.

The second paper of the week, also published on Tuesday 22nd July but in the folder Cosmology and Nongalactic Astrophysics, is “Do We Know How to Model Reionization?” by Nick Gnedin (University of Chicago, USA). This paper discusses the similarities and differences between the radiation fields produced by different numerical simulations of cosmic reionization. The overlay is here:

You can find the officially accepted version of the paper on arXiv here.

The third paper of the week is “The effects of projection on measuring the splashback feature” by Xiaoqing Sun (MIT), Stephanie O’Neil (U. Penn.), Xuejian Shen (MIT) and Mark Vogelsberger (MIT), all based in the USA. This paper describes an investigation whether projection effects could lead to any systematic bias in determining the position of the boundary between infalling and accreting matter around haloes. It was published on Wednesday 23rd July in the folder Astrophysics of Galaxies. The overlay is here:

The officially-accepted version can be found on arXiv here.

The fourth paper of the week, also published on Wednesday 22nd July in the folder Astrophysics of Galaxies, is “Host galaxy identification of LOFAR sources in the Euclid Deep Field North” by Laura Bisigello, Marika Giulietti, Isabella Prandoni, Marco Bondi, & Matteo Bonato (INAF, Bologna, Italy), Manuela Magliocchetti (INAF-IAPS Roma, Italy), Huub Rottgering (Leiden Observatory, Netherlands), Leah, K. Morabito (Durham University, UK) and Glenn, J. White (Open Universirty, UK). This presents a catalogue of optical and near-infrared counterparts to radio sources detected in the Euclid Deep Field North using observations from the LOw-Frequency ARray (LOFAR). The overlay is here:

The final, accepted version of the paper is on arXiv here.

Fifth one up is “Constraining the dispersion measure redshift relation with simulation-based inference” by Koustav Konar (Ruhr University Bochum), Robert Reischke (Universität Bonn), Steffen Hagstotz (Ludwig-Maximilians Universität München), Andrina Nicola (Bonn) and Hendrik Hildebrandt (Bochum); all authors based in Germany. This was published on Thursday 24th July in the folder Cosmology and NonGalactic Astrophysics. It discusses using simulations to develop the use of Dispersion Measures of Fast Radio Bursts as cosmological probes. The overlay is here:

You can find the officially accepted version on arXiv here.

The penultimate (sixth) article published this week is “Generating Dark Matter Subhalo Populations Using Normalizing Flows” by Jack Lonergan (University of Southern California), Andrew Benson (Carnegie Observatories) and Daniel Gilman (University of Chicago), all based in the USA. This paper describes a generative AI approach to subhalo populations, trained using the semi-analytical model Galacticus. This paper was published yesterday (i.e. on Friday 25th July) in the folder Astrophysics of Galaxies.

You can find the final version on arXiv here.

The last article published this week is “21 Balmer Jump Street: The Nebular Continuum at High Redshift and Implications for the Bright Galaxy Problem, UV Continuum Slopes, and Early Stellar Populations” by Harley Katz of the University of Chicago, and 13 others based in the USA, UK, Germany, Denmark and Austria. This discusses the implications of extreme nebular emission for the spectroscopic properties of galaxies, especially at high redshift. It was published on Friday 25th July in the folder Astrophysics of Galaxies.

The overlay is here:

You can find the officially-accepted version on arXiv here.

And that’s all the papers for this week. I’ll do another update next Saturday, when we’ll be into August.

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The Euclid Survey(s)

Posted in Euclid, The Universe and Stuff with tags , , , , , , , , , on February 27, 2024 by telescoper

Since it’s been a couple of weeks since Euclid commenced its routine survey operations, I thought I would share this little video from the European Space Agency that shows how the surveying will proceed over the next six years with explanatory text adapted from here:

This animation shows the location of the fields on the sky that will be covered by Euclid’s wide (blue) and deep (yellow) surveys. The sky is shown in the Galactic coordinate system, with the bright horizontal band corresponding to the plane of our Milky Way.

The wide survey will cover more than one third of the sky as shown in blue. Other regions are avoided because they are dominated by Milky Way stars and interstellar matter, or by diffuse dust in the Solar System – the so-called zodiacal light. The wide survey is complemented by a deep survey, taking about 10% of the total observing time and repeatedly observing just three patches of the sky called the Euclid Deep Fields, highlighted in yellow.

The Euclid Deep Field North – towards the top left – has an area of 20 square degrees and is located very close to the Northern Ecliptic Pole. The proximity to the ecliptic pole ensures maximum coverage throughout the year; the exact position was chosen to obtain maximum overlap with one of the deep fields surveyed by NASA’s Spitzer Space Telescope.

The Euclid Deep Field Fornax – in the lower right of the image – spans 10 square degrees and is located in the southern constellation Fornax, the furnace. It encompasses the much smaller Chandra Deep Field South, a 0.11 square degree region of the sky that has been extensively surveyed in the past couple of decades with the Chandra and XMM-Newton X-ray observatories, as well as the Hubble Space Telescope and major ground-based telescopes.

The third and largest of the fields is the Euclid Deep Field South – between the Large Magellanic Cloud and the Euclid Deep Field Fornax. It covers 20 square degrees in the southern constellation of Horologium, the pendulum clock. This field has not been covered to date by any deep sky survey and so has a huge potential for new, exciting discoveries. It has been planned to be observed from the ground by the Vera C. Rubin Observatory.

P.S. According to my latest calculations, I shall have retired by the time the Wide survey is completed.

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