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Institute of Astronomy

 

Wed 16 Jul 13:15: Chasing the First Stars With Outliers

Next Wednesday Seminars - Mon, 14/07/2025 - 07:25
Chasing the First Stars With Outliers

he OUTLIERS project aims to find and study the most ancient stars in our Galaxy — stars that formed shortly after the Big Bang. These stars carry unique chemical fingerprints that tell us about the very first generations of stars, the first supernovae, and the early stages of galaxy formation. Although extremely rare and faint, they can still be found today thanks to the combined power of Gaia — which maps the positions and motions of over a billion stars — and new large spectroscopic surveys like DESI , WEAVE, and 4MOST. OUTLIERS uses this data to select and follow up the most promising candidates. By studying these stellar fossils in detail, we hope to answer long-standing questions about how the first stars formed, what elements they created, and how the Universe evolved in its earliest phases.

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Categories: Talks

Hubble Snaps Galaxy Cluster’s Portrait

Astronomy News - Sat, 12/07/2025 - 10:38
Explore Hubble

2 min read

Hubble Snaps Galaxy Cluster’s Portrait This NASA/ESA Hubble Space Telescope image features the galaxy cluster Abell 209. ESA/Hubble & NASA, M. Postman, P. Kelly

A massive, spacetime-warping cluster of galaxies is the setting of today’s NASA/ESA Hubble Space Telescope image. The galaxy cluster in question is Abell 209, located 2.8 billion light-years away in the constellation Cetus (the Whale).

This Hubble image of Abell 209 shows more than a hundred galaxies, but there’s more to this cluster than even Hubble’s discerning eye can see. Abell 209’s galaxies are separated by millions of light-years, and the seemingly empty space between the galaxies is filled with hot, diffuse gas that is visible only at X-ray wavelengths. An even more elusive occupant of this galaxy cluster is dark matter: a form of matter that does not interact with light. Dark matter does not absorb, reflect, or emit light, effectively making it invisible to us. Astronomers detect dark matter by its gravitational influence on normal matter. Astronomers surmise that the universe is comprised of 5% normal matter, 25% dark matter, and 70% dark energy.

Hubble observations, like the ones used to create this image, can help astronomers answer fundamental questions about our universe, including mysteries surrounding dark matter and dark energy. These investigations leverage the immense mass of a galaxy cluster, which can bend the fabric of spacetime itself and create warped and magnified images of background galaxies and stars in a process called gravitational lensing.

While this image lacks the dramatic rings that gravitational lensing can sometimes create, Abell 209 still shows subtle signs of lensing at work, in the form of streaky, slightly curved galaxies within the cluster’s golden glow. By measuring the distortion of these galaxies, astronomers can map the distribution of mass within the cluster, illuminating the underlying cloud of dark matter. This information, which Hubble’s fine resolution and sensitive instruments help to provide, is critical for testing theories of how our universe evolved.

Text Credit: ESA/Hubble

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Media Contact:

Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight CenterGreenbelt, MD

Share Details Last Updated Jul 11, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms Keep Exploring Discover More Topics From Hubble Hubble Space Telescope

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Astronomy News - Sat, 12/07/2025 - 10:35

Nature, Published online: 11 July 2025; doi:10.1038/d41586-025-02108-6

NASA’s New Horizons probe, which hurtled past Pluto in 2015, demonstrates that it can sail through interstellar space using its onboard camera.

We may have finally solved an ultra-high-energy cosmic ray puzzle

Astronomy News - Sat, 12/07/2025 - 10:33

The IceCube neutrino detector has allowed researchers to resolve a debate about what types of particles make up ultra-high-energy cosmic rays – but much remains unknown about these rare events

Cyril Hazard (18 March 1928 – 14 June 2025)

Latest News - Sat, 12/07/2025 - 09:31

We are saddened to report the passing of Cyril Hazard (18 March 1928 – 14 June 2025). Cyril was a pioneering radio astronomer whose work on quasars helped transform our understanding of the Universe. Cyril began his career at Jodrell Bank and went on to work across three continents -- including positions at Cambridge (from...

Mystery interstellar object could be oldest known comet

Astronomy News - Fri, 11/07/2025 - 11:00

Scientists have been racing to discover the origins of 3I/Atlas since it was spotted last week.

CLASS_SZ II: Notes and Examples of Fast and Accurate Calculations of Halo Model, Large Scale Structure and Cosmic Microwave Background Observables

Cosmology and Fundamental physics - Fri, 11/07/2025 - 10:54
arXiv:2507.07346v1 Announce Type: new Abstract: These notes are very much work-in-progress and simply intended to showcase, in various degrees of details (and rigour), some of the cosmology calculations that class_sz can do. We describe the class_sz code in C, Python and Jax. Based on the Boltzmann code class, it can compute a wide range of observables relevant to current and forthcoming CMB and Large Scale Structure surveys. This includes galaxy shear and clustering, CMB lensing, thermal and kinetic Sunyaev and Zeldovich observables, Cosmic Infrared Background, cross-correlations and three-point statistics. Calculations can be done either within the halo model or the linear bias model. For standard $\Lambda$CDM cosmology and extensions, class_sz uses high-accuracy cosmopower emulators of the CMB and matter power spectrum to accelerate calculations. With this, along with efficient numerical integration routines, most class_sz output can be obtained in less than 500 ms (CMB $C_\ell$'s or matter $P(k)$ take $\mathcal{O}(1\mathrm{ms})$), allowing for fast or ultra-fast parameter inference analyses. Parts of the calculations are "jaxified", so the software can be integrated into differentiable pipelines.

CLASS_SZ II: Notes and Examples of Fast and Accurate Calculations of Halo Model, Large Scale Structure and Cosmic Microwave Background Observables

Recent IoA Publications - Fri, 11/07/2025 - 10:54
arXiv:2507.07346v1 Announce Type: new Abstract: These notes are very much work-in-progress and simply intended to showcase, in various degrees of details (and rigour), some of the cosmology calculations that class_sz can do. We describe the class_sz code in C, Python and Jax. Based on the Boltzmann code class, it can compute a wide range of observables relevant to current and forthcoming CMB and Large Scale Structure surveys. This includes galaxy shear and clustering, CMB lensing, thermal and kinetic Sunyaev and Zeldovich observables, Cosmic Infrared Background, cross-correlations and three-point statistics. Calculations can be done either within the halo model or the linear bias model. For standard $\Lambda$CDM cosmology and extensions, class_sz uses high-accuracy cosmopower emulators of the CMB and matter power spectrum to accelerate calculations. With this, along with efficient numerical integration routines, most class_sz output can be obtained in less than 500 ms (CMB $C_\ell$'s or matter $P(k)$ take $\mathcal{O}(1\mathrm{ms})$), allowing for fast or ultra-fast parameter inference analyses. Parts of the calculations are "jaxified", so the software can be integrated into differentiable pipelines.

Cool Gas in the Circumgalactic Medium of Massive Post Starburst Galaxies

Recent IoA Publications - Fri, 11/07/2025 - 10:19
arXiv:2506.22287v2 Announce Type: replace Abstract: Observing the interplay between galaxies and their gaseous surroundings is crucial for understanding how galaxies form and evolve, including the roles of long-lived cool gas reservoirs, starburst and AGN driven outflows. We use stacked Mg II absorption lines in the spectra of background quasars to study the cool gas out to 9Mpc from massive quiescent, star-forming and post-starburst galaxies with stellar masses $\log_{10}(M_{\mathrm{gal}}/M_\odot) \gtrsim 11.4$ and $0.4 \lesssim z \lesssim 0.8$ selected from the Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxies. Consistent with previous studies, we observe a decline in absorption strength indicating a decrease in cool gas content with increasing distance from the galaxies, as well as decreasing star formation rate of the galaxies. Beyond 1Mpc, this decline levels off to the same absorption strength in all galaxy types, suggesting a transition from the circumgalactic medium (CGM) to the intergalactic medium (IGM) at approximately the virial radius of the host dark matter haloes. We find that post-starburst galaxies, that have experienced a recent burst of star formation that has rapidly quenched, exhibit significantly stronger Mg II absorption within 1Mpc than star-forming or quiescent galaxies of the same stellar mass. Because post-starburst galaxies are a potentially significant pathway for the formation of quiescent elliptical galaxies, our results have wide reaching implications for understanding the mechanisms involved in quenching star formation in galaxies. We speculate that the excess cool gas absorption out to 1Mpc around post-starburst galaxies is related to their observed high velocity ($\sim$1000\,km/s) cool gas outflows. Thus, strong, short-lived bursts of star formation impact the CGM around galaxies on Mpc distances and Gyr timescales.

Cool Gas in the Circumgalactic Medium of Massive Post Starburst Galaxies

Galaxy Evolution and AGN - Fri, 11/07/2025 - 10:19
arXiv:2506.22287v2 Announce Type: replace Abstract: Observing the interplay between galaxies and their gaseous surroundings is crucial for understanding how galaxies form and evolve, including the roles of long-lived cool gas reservoirs, starburst and AGN driven outflows. We use stacked Mg II absorption lines in the spectra of background quasars to study the cool gas out to 9Mpc from massive quiescent, star-forming and post-starburst galaxies with stellar masses $\log_{10}(M_{\mathrm{gal}}/M_\odot) \gtrsim 11.4$ and $0.4 \lesssim z \lesssim 0.8$ selected from the Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxies. Consistent with previous studies, we observe a decline in absorption strength indicating a decrease in cool gas content with increasing distance from the galaxies, as well as decreasing star formation rate of the galaxies. Beyond 1Mpc, this decline levels off to the same absorption strength in all galaxy types, suggesting a transition from the circumgalactic medium (CGM) to the intergalactic medium (IGM) at approximately the virial radius of the host dark matter haloes. We find that post-starburst galaxies, that have experienced a recent burst of star formation that has rapidly quenched, exhibit significantly stronger Mg II absorption within 1Mpc than star-forming or quiescent galaxies of the same stellar mass. Because post-starburst galaxies are a potentially significant pathway for the formation of quiescent elliptical galaxies, our results have wide reaching implications for understanding the mechanisms involved in quenching star formation in galaxies. We speculate that the excess cool gas absorption out to 1Mpc around post-starburst galaxies is related to their observed high velocity ($\sim$1000\,km/s) cool gas outflows. Thus, strong, short-lived bursts of star formation impact the CGM around galaxies on Mpc distances and Gyr timescales.

Open Source Planning & Control System with Language Agents for Autonomous Scientific Discovery

Instrumentation and Surveys - Fri, 11/07/2025 - 10:05
arXiv:2507.07257v1 Announce Type: cross Abstract: We present a multi-agent system for automation of scientific research tasks, cmbagent. The system is formed by about 30 Large Language Model (LLM) agents and implements a Planning & Control strategy to orchestrate the agentic workflow, with no human-in-the-loop at any point. Each agent specializes in a different task (performing retrieval on scientific papers and codebases, writing code, interpreting results, critiquing the output of other agents) and the system is able to execute code locally. We successfully apply cmbagent to carry out a PhD level cosmology task (the measurement of cosmological parameters using supernova data) and evaluate its performance on two benchmark sets, finding superior performance over state-of-the-art LLMs. The source code is available on GitHub, demonstration videos are also available, and the system is deployed on HuggingFace and will be available on the cloud.

Open Source Planning & Control System with Language Agents for Autonomous Scientific Discovery

Recent IoA Publications - Fri, 11/07/2025 - 10:05
arXiv:2507.07257v1 Announce Type: cross Abstract: We present a multi-agent system for automation of scientific research tasks, cmbagent. The system is formed by about 30 Large Language Model (LLM) agents and implements a Planning & Control strategy to orchestrate the agentic workflow, with no human-in-the-loop at any point. Each agent specializes in a different task (performing retrieval on scientific papers and codebases, writing code, interpreting results, critiquing the output of other agents) and the system is able to execute code locally. We successfully apply cmbagent to carry out a PhD level cosmology task (the measurement of cosmological parameters using supernova data) and evaluate its performance on two benchmark sets, finding superior performance over state-of-the-art LLMs. The source code is available on GitHub, demonstration videos are also available, and the system is deployed on HuggingFace and will be available on the cloud.

NASA’s James Webb Space Telescope Inspects Cat’s Paw

Astronomy News - Fri, 11/07/2025 - 09:42
To celebrate its third year of revealing stunning scenes of the cosmos in infrared light, NASA’s James Webb Space Telescope has “clawed” back the thick, dusty layers of a section within the Cat’s Paw Nebula (NGC 6334). NASA, ESA, CSA, STScI

NASA’s James Webb Space Telescope team released this image of the Cat’s Paw Nebula on July 10, 2025, in honor of the telescope’s third anniversary. Webb’s NIRCam (Near-Infrared Camera)  revealed never-before-seen structural details and features: Massive young stars carve away at nearby gas and dust, while their bright starlight produces a bright nebulous glow represented in blue. As a consequence of these massive stars’ lively behavior, the local star formation process will eventually come to a stop.

Take a tour through this section of the Cat’s Paw Nebula.

Image credit: NASA, ESA, CSA, STScI

The cosmos is vast, so how do we measure it?

Astronomy News - Fri, 11/07/2025 - 09:41

The awe-inspiring distances of the cosmos are hard to visualise, so how can we be certain we are measuring them correctly? Chanda Prescod-Weinstein explains

Interstellar visitor 3I/ATLAS might be the oldest comet ever seen

Astronomy News - Fri, 11/07/2025 - 09:41

Astronomers tracking an interstellar object flying through the solar system think it comes from a star at least 8 billion years old, almost twice the age of our sun

Astronomers found a completely new type of plasma wave near Jupiter

Astronomy News - Fri, 11/07/2025 - 09:41

Observations from NASA’s Juno spacecraft reveal that Jupiter’s strong magnetic field and the unique properties of its plasma can produce a truly novel kind of extraterrestrial wave near its poles

High-Resolution Optical IFU Spectroscopy of the Complex Galaxy Merger II Zw 096

Recent IoA Publications - Thu, 10/07/2025 - 11:21
arXiv:2507.06339v1 Announce Type: new Abstract: Luminous and Ultra-luminous IR galaxies ((U)LIRGs) are critical for investigating feedback mechanisms due to a combination of intense star formation (SF) episodes and active galactic nuclei (AGN), particularly in the context of complex galaxy interactions. We conduct a detailed analysis of the II ZW 096 merging system using the Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT), combining high-resolution Narrow Field Mode (NFM) and large-area Wide Field Mode (WFM) observations. We mapped the morphology, kinematics, and ionizing radiation of the system's gas by fitting atomic emission lines and the optical continuum. We identify three or more distinct galaxies within II ZW 096, revealing rotational patterns and complex interactions consistent with a collapsing small galaxy group. The kinematics and ionization structures suggest high star formation rates and shock-driven processes, which align with this proposed scenario. Focusing on the D1 compact region, which contributes 40-70% of the system's IR emission, and combining information from archival multi-wavelength observations, we find strong evidence of a heavily obscured AGN powering it. Our analysis of the internal structure, interactions, and merger state of II ZW 096 offers novel insights into the galaxy evolution processes in this dynamic and highly chaotic system

High-Resolution Optical IFU Spectroscopy of the Complex Galaxy Merger II Zw 096

Galaxy Evolution and AGN - Thu, 10/07/2025 - 11:21
arXiv:2507.06339v1 Announce Type: new Abstract: Luminous and Ultra-luminous IR galaxies ((U)LIRGs) are critical for investigating feedback mechanisms due to a combination of intense star formation (SF) episodes and active galactic nuclei (AGN), particularly in the context of complex galaxy interactions. We conduct a detailed analysis of the II ZW 096 merging system using the Multi-Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT), combining high-resolution Narrow Field Mode (NFM) and large-area Wide Field Mode (WFM) observations. We mapped the morphology, kinematics, and ionizing radiation of the system's gas by fitting atomic emission lines and the optical continuum. We identify three or more distinct galaxies within II ZW 096, revealing rotational patterns and complex interactions consistent with a collapsing small galaxy group. The kinematics and ionization structures suggest high star formation rates and shock-driven processes, which align with this proposed scenario. Focusing on the D1 compact region, which contributes 40-70% of the system's IR emission, and combining information from archival multi-wavelength observations, we find strong evidence of a heavily obscured AGN powering it. Our analysis of the internal structure, interactions, and merger state of II ZW 096 offers novel insights into the galaxy evolution processes in this dynamic and highly chaotic system