Archive for gravitational microlensing

Euclid Stares at the Galactic Bulge

Posted in Euclid, The Universe and Stuff with tags , , , , , , on June 24, 2026 by telescoper

Time for another update from ESA’S Euclid Space Mission: today is Q2 Day!

The largest and most detailed photo ever made of the Galactic Centre in visible light was taken by the Euclid mission. For just one day (23rd March 2025), Euclid turned its gaze towards the extremely bright inner region of our Milky Way galaxy, known as the galactic bulge.  The extraordinary picture that resulted is not part of Euclid’s main cosmological survey, which is designed to look at objects far outside our own Galaxy, but was made in response to a special request from astronomers who were after what Euclid does best: capturing large areas of the sky in crisp detail. Packed with more than 60 million stars, this image opens the door for scientists to confirm the existence of any exoplanet found in this region and measure its mass using tiny changes in starlight over time.  The observational data obtained in this project were released today as Euclid’s Q2 data release; for details of Q1 please see here.

Designed to observe billions of faraway galaxies, the space telescope’s visible light camera is sensitive enough to tell apart individual stars in our super-crowded galactic bulge, without being blinded. This ability is crucial for what scientists want to use this image for: studying planets around other stars using a special technique called gravitational microlensing.

For comparison, Euclid’s sharpness and sensitivity in visible light is similar to the NASA/ESA Hubble Space Telescope’s wide field camera. But each pointing that Euclid captures in a few hours spans an area 270 times larger than Hubble’s field of view. To observe the same Euclid mosaic, the Keck Observatory would need around 2000 hours. Euclid is faster, and able to capture details from fainter stars that would be otherwise missed when observing from the ground. This single mosaic also encompasses the entire region that the upcoming Roman space telescope will monitor for planet hunting. 

You can learn more about this by visiting the official account of this on the ESA website and/or watching this video:

Weekly Update from the Open Journal of Astrophysics – 15/11/2025

Posted in OJAp Papers, Open Access, The Universe and Stuff with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on November 15, 2025 by telescoper

It’s Saturday again, so it’s time for the usual update of the week’s new papers at the Open Journal of Astrophysics. It has been quite a busy week. Since the last update we have published another seven papers, which brings the number in Volume 8 (2025) up to 175, and the total so far published by OJAp up to 410.

First on the menu for this week is “Dynamical friction and measurements of the splashback radius in galaxy clusters” by Talia M. O’Shea (U. Wisconsin-Madison, USA), Josh Borrow & Stephanie O’Neil (U. Pennsylvania, USA) and Mark Vogelsberger (MIT, USA). Published on Tuesday 11th November in the folder Cosmology and NonGalactic Astrophysics, this one presents a study suggesting that dynamical friction does not play a major role in reducing the radius of the splashback feature in real data compared to numerical simulations.

The overlay is here:

You can find the officially accepted version on arXiv here.

The Fediverse announcement is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Dynamical friction and measurements of the splashback radius in galaxy clusters" by Talia M. O'Shea (U. Wisconsin-Madison, USA), Josh Borrow & Stephanie O'Neil (U. Pennsylvania, USA) and Mark Vogelsberger (MIT, USA)

doi.org/10.33232/001c.147125

November 11, 2025, 8:36 am 3 boosts 1 favorites

 

The second paper of the week is “Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction” by Nikki Arendse (Stockholm University, Sweden) and and international cast of 11 others based in Sweden, UK and France. This one was published on 11th November 2025 in the folder Astrophysics of Galaxies. It is about combining observations of two supernovae, iPTF16geu and SN Zwicky, with microlensing magnification maps to probe the properties of the lens galaxy.

The overlay is here:

 

You can find the official version of this one on arXiv here. The federated announcement on Mastodon is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction" by Nikki Arendse (Stockholm University, Sweden) and 11 others based in Sweden, UK and France

doi.org/10.33232/001c.147126

November 11, 2025, 8:53 am 1 boosts 1 favorites

 

Next one up is “Neutrino Constraints on Black Hole Formation in M31” by Yudai Sawa (U. Tokyo, Japan) and 11 others all based in Japan. This was published on Tuesday 11th November in the folder High-Energy Astrophysical Phenomena. It presents a calculation of the neutrino emission expected from the collapse of massive stars and its use in constraining black hole formation using neutrino detectors.

 

The overlay is here:

You can find the official accepted version on arXiv here. The fediverse announcement is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Neutrino Constraints on Black Hole Formation in M31" by Yudai Sawa (U. Tokyo, Japan) and 11 others all based in Japan

doi.org/10.33232/001c.147127

November 11, 2025, 9:04 am 0 boosts 1 favorites

The fourth paper this week is “Redshift Drift in Relativistic N-Body Simulations” by Alexander Oestreicher (U. Southern Denmark, DK), Chris Clarkson (QMUL, UK), Julian Adamek (U. Zürich, CH) and Sofie Marie Koksbang (U. Southern Denmark, DK). This one was published on Wednesday 12th November in the folder marked Cosmology and NonGalactic Astrophysics. It presents numerical calculations of the cosmological redshift drift effect for comparison with future surveys.

The overlay is here:

 

 

You can find the official published version on arXiv here. The Fediverse announcement follows:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Redshift Drift in Relativistic N-Body Simulations" by Alexander Oestreicher (U. Southern Denmark, DK), Chris Clarkson (QMUL, UK), Julian Adamek (U. Zürich, CH) and Sofie Marie Koksbang (U. Southern Denmark, DK)

doi.org/10.33232/001c.147178

November 12, 2025, 8:35 am 1 boosts 0 favorites

 

The fifth paper for this week is “Attributing the point symmetric structure of core-collapse supernova remnant N132D to the jittering jets explosion mechanism” by Noam Soker (Technion, Haifa, Israel). This one, published on Wednesday November 12th in the folder High-Energy Astrophysical Phenomena, presents a discussion of the morphology of a supernova remnant and possible explanation for it in terms of the explosion mechanism.

The overlay is here:

 

The officially accepted version can be found on arXiv here. The Fediverse announcement is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Attributing the point symmetric structure of core-collapse supernova remnant N132D to the jittering jets explosion mechanism" by Noam Soker (Technion, Haifa, Israel)

doi.org/10.33232/001c.147183

November 12, 2025, 8:46 am 1 boosts 0 favorites

The sixth paper to report this week is “Witnessing downsizing in the making: quiescent and breathing galaxies at the dawn of the Universe” by Emiliano Merlin (Osservatorio Astronomico di Roma, Italy) and an international cast of 20 others based in Italy, Germany, UK, USA, Switzerland, Spain and China. This one was published on Friday November 14th in the folder Astrophysics of Galaxies.

You can find the officially-accepted version on arXiv here. The fediverse announcement is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Witnessing downsizing in the making: quiescent and breathing galaxies at the dawn of the Universe" by Emiliano Merlin (Osservatorio Astronomico di Roma, Italy) and 20 others based in Italy, Germany, UK, USA, Switzerland, Spain and China

doi.org/10.33232/001c.147267

November 14, 2025, 8:38 am 1 boosts 1 favorites

And finally (for this week) we have “Beyond No No Tension: JWST z > 10 Galaxies Push Simulations to the Limit” by Joe McCaffrey (NUI Maynooth, Ireland), Samantha Hardin & John Wise (Georgia Institute of Technology, USA) and John Regan (Maynooth). This one was also published on Friday 14th November, in the folder marked Astrophysics of Galaxies. It asks the question whether newly-discovered high redshift galaxies are consistent with simulations of galaxy formation. The overlay is here:

You can find the officially acceopted version on arXiv here. The fediverse announcement is here:

Open Journal of Astrophysics

New Publication at the Open Journal of Astrophysics: "Beyond No No Tension: JWST z > 10 Galaxies Push Simulations to the Limit" by Joe McCaffrey (NUI Maynooth, Ireland), Samantha Hardin & John Wise (Georgia Institute of Technology, USA) and John Regan (Maynooth)

doi.org/10.33232/001c.147278

November 14, 2025, 9:02 am 2 boosts 0 favorites

And that concludes the update for this week. There will be another next Saturday.