Tuesday, January 7, 2025

astronomers ngc 5018 globular cluster system

NGC 5018 Galaxy Group: Astronomers Unveil Intra-Group Globular Cluster System

Introduction to the Study of NGC 5018 and Its Globular Clusters

Astronomers using VLT Survey Telescope to study globular clusters in the NGC 5018 galaxy group, revealing important stellar evolution insights.

Astronomers from Italy and Germany utilized the VLT Survey Telescope (VST) to investigate the galaxy group NGC 5018. Findings from this research, shared on arXiv on December 23, reveal valuable details about the group's globular cluster system.

What Are Globular Clusters Why Are They Important?

Globular clusters (GCs), composed of densely packed stars orbiting galaxies, serve as natural laboratories for studying stellar and galactic evolution. These clusters, closely associated with episodes of intense star formation, hold key insights into the formation and development of early-type galaxies. Additionally, GCs provide valuable data on interaction events within their host galaxies and the larger galaxy group.

The NGC 5018 Galaxy Group: Key Members and Composition

NGC 5018: The Luminous Elliptical Galaxy

The NGC 5018 galaxy group derives its name from its most luminous member, NGC 5018, a massive elliptical galaxy located approximately 132.5 million light-years away in the Virgo constellation.

Other Prominent Member of NGC 5018

Other prominent members of this group include the edge-on spiral NGC 5022, the face-on spiral NGC 5006, and two lenticular galaxies, MCG-03-34-013 and PGC140148.

Earlier Research on Globular Clusters in NGC 5018

Earlier research has identified two distinct sub-populations of globular clusters (GCs) in the galaxy NGC 5018: a smaller group of younger GCs aged several hundred million to six billion years, and a larger group of older GCs.

In-Depth Investigation into NGC 5018's GC System

Research Team and Methodology

A research team, headed by Pratik Lonare from the Abruzzo Astronomical Observatory in Teramo, Italy, has undertaken a deeper investigation into both the globular cluster system of NGC 5018 and the entire galaxy group.

Deep Imaging with VST and VEGAS

According to the researchers, "This work employs deep, multi-band, wide-field imaging of the NGC 5018 galaxy group gathered with the VLT Survey Telescope (VST) during the VST Elliptical Galaxy Survey (VEGAS), and we conduct a thorough investigation of its GC system."

Discovering the Intra-Group Globular Cluster System

Thanks to VEGAS imaging data, Lonare's team was able to pinpoint globular cluster candidates throughout the NGC 5018 galaxy group, unveiling the existence of an intra-group GC system. The 2D distribution map highlights a concentration of GC candidates in NGC 5018, while no notable GC concentrations are detected in the other group members.

Radial and Color Profile Analysis of Globular Clusters

Radial Density Profile

Overall, the radial density profile of globular cluster candidates in NGC 5018 mirrors the surface brightness profile of the galaxy. The color profile of these candidates exhibits a dominant component, peaking around 0.75 mag.

Spatial Distribution and Color profile

The observations revealed that the intra-group globular cluster population is distributed along the five bright galaxies and encircles the NGC 5018 group. This spatial arrangement corresponds with the intra-group light (IGL) detected in the group, but extends to greater from the group's center.

Blue and Red Globular Cluster Components in the Intra-Group System

The analysis of the color profile of intra-group globular cluster candidates indicates the existence of both blue and red GC components, with peaks at approximately 0.45 and 0.80 mag, respectively. The blue GC component is observed to be more spatially extended than the red GC component relative to NGC 5018.

Conclusion: Dispersal of Blue Globular Clusters

"The combination of these findings with previous studies on the intra-group light (IGL) leads to the hypothesis that part of the blue GC population in the intra-grou p region may have once been part of NGC 5018, subsequently dispersed by tidal forces from neighbouring galaxies," the authors conclude.

Number of Globular Cluster Candidates in NGC 5018

The astronomers note that the total numbers of globular cluster candidates across the entire NGC 5018 group is approximately 4,000, with NGC 5018 itself hosting estimated 485 candidates.

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Saturday, December 28, 2024

DA362 multiwavelength study insights

Exploring DA 362: Study Unveils More About Compact Symmetric Objects

Introduction to DA 362 and Compact Symmetric Objects (CSOs)

Diagram illustrating DA 362, a compact symmetric object emitting gamma rays, with observed jet activity and parsec-scale radio emissions.

Indian researchers conducted a comprehensive multiwavelength investigation of DA 362, a gamma-ray-emitting compact symmetric object. Findings, detailed in a December 17 arXiv preprint, offer valuable insights into this mysterious phenomenon.

What Are Compact Symmetric Objects (CSOs)?

Compact symmetric objects (CSOs) are young jetted active galactic nuclei (AGN) with projected sizes under 3,300 light-years. While their characteristics remain insufficiently explored, observations reveal symmetric radio morphologies, suggesting these objects are in their early evolutionary stages, with kinematic ages of only a few thousand years. Notably, gamma-ray emissions have been detected from just four CSOs so far.

Introduction to DA 362: A Newly Identified Gamma-Ray Emitting CSO

The most recently identified gamma-ray-emitting compact symmetric object (CSO) is DA 362, also referred to as B2 1413+34. Initially, it was categorized as a blazar condidate of uncertain classification, linked to the gamma-ray source 4FGLJ1416.0+3443.

Multiwavelength Study of DA 362

Astronomers, led by Subhashree Swain from the Inter-University Center for Astronomy and Astrophysics in Pune, India, recently conducted a long-term multiwavelength analysis of DA 362 using data from NASA's Fermi Large Area Telescope (LAT) and Swift satellite. This investigation provided new insights into the nature of this compact symmetric object (CSO).

Key Findings from the Multiwavelength Analysis

"In our investigation, we analyzed the multiwavelength properties of DA 362, a CSO newly recognized as a gamma-ray source by Fermi-LAT, marking it as only the fourth gamma-ray-detected AGN of this type," the authors stated.

Verification of the Gamma-Ray Source Link

The analysis of LAT data verified the link between the gamma-ray source 4FGLJ1416.0+3443 and DA 362. The refined gamma-ray position aligned with the radio source with the 95% confidence interval for gamma-ray uncertainty.

Gamma-Ray Light Curve and Activity

Analysis of the gamma-ray light curve of DA 362 indicates that the source remained predominantly inactive during the first 12 years of LAT observations (2008-2020). However, episodes of flaring activity suggest that the gamma-ray emission likely originates from its core or jet, rather than the radio lobes.

Radio Emissions and Jet Characteristics

In addition, the research identified small, parsec-scale bipolar radio emissions from DA 362 and determined its jet separation velocity to be subluminal. These results establish DA 362 as a bonafide compact symmetric object.

Spectral Properties and Comparison with Other Gamma-Ray Emitting CSOs

By analyzing the gamma-ray spectral properties relative to the three other identified gamma-ray-emitting CSOs, astronomers concluded that DA 362 stands out as the brightest and exhibits a steeper spectrum.

Optical Spectrum and Dust Obscuration

Nevertheless, it was found that DA 362 is exceptionally faint in the optical spectrum, implying potential dust obscuration.

Future Observations and Researcher Directions

The paper's authors suggest that more in-depth observations using advanced facilities are necessary to investigate the broadband physical properties of this CSO and gain further insight into the source of its gamma-ray emission.

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  1. Space and Science Updates: Discover more groundbreaking research and multiwavelength studies at FSNews365.
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Tuesday, December 10, 2024

webb telescope cosmic expansion theories

Webb Telescope's Largest Study Challenges Conventional Cosmic Expansion Theories

Detailed view of the James Webb Space Telescope observing cosmic galaxies to study the Hubble constant and cosmic expansion.

New Observations from Webb Telescope Challenge Long-Standing Expansion Theories

Recent observations from the James Webb Space Telescope indicate that a previously unknown universal phenomenon, rather than measurement errors, may explain the decade-long mystery of the accelerated expansion of the universe compared to its early growth.

Cross-Verification of Hubble Space Telescope Measurements

Validating Observations

The latest data validates Hubble Space Telescope measurements of distances between nearby stars and galaxies, providing a critical cross-verification to tackle the unresolved Hubble tensionan enduring challenge for cosmology.

Insights from Adam Riess

Nobel laureate Adam Riess, lead author and Bloomberg Distinguished Professor at Johns Hopkins University, emphasized, "The mismatch between the universe's observed expansion rate and standard model predictions indicates gaps in our understanding. With two NASA flagship telescopes corroborating each other's results, the Hubble tension presents a serious challenge and a remarkable opportunity to deepen our knowledge of the cosmos."

Extending Nobel Prize-Winning Discoveries

The Role of Dark Energy

Published in The Astrophysical Journal, the study extends Adam Riess' Nobel Prize—winning discovery that the universe's expansion is accelerating, driven by an enigmatic 'dark energy' filling the interstellar void.

Webb's Contribution

Riess' team utilized the most extensive dataset from Webb's first two years in operation to validate the Hubble Space Telescope's measurements of the universe's expansion rate, termed the Hubble constant.

Methodology: Analyzing Cosmic Distances

Precision Measurements

The team employed three distinct methods to determine distances to galaxies containing supernovae, prioritizing those previously measured by the Hubble telescope, which provided the most accurate 'local' estimates of this value.

Comparison of Observations

Observations from both telescopes closely matched, confirming the accuracy of Hubble's measurements and eliminating the possibility of significant errors causing the observed tension.

Understanding the Hubble Constant and Its Implications

The Discrepancy Explained

The Hubble constant remains enigmatic, as present-day telescope observations yield higher values than those predicted by the 'standard model of cosmology,' which is based on cosmic microwave background data from the Big Bang.

Measurement Variations

The standard model predicts a Hubble constant around 6768 kilometers per second per megaparsec, whereas telescope-based measurements consistently show higher values, typically ranging from 70 to 76, with an average of 73 km/s/Mpc.

Significance of the Discrepancy

Cosmologists have been puzzled by this discrepancy for more than a decade, as a 56 km/s/Mpc variation is too significant to be attributed solely to measurement errors or observational issues. (A megaparsec is an enormous distance, equal to 3.26 million light-years, and a light-year represents the distance light travels in one year—about 9.4 trillion kilometers or 5.8 trillion miles.)

Riess' team reports that, since Webb's latest data eliminates significant biases in Hubble's measurements, the Hubble tension might be due to unidentified factors or unex plored gaps in cosmologists' understanding of physics.

Verify the distances derived from HST and JWST using the complete HST dataset of four anchors and 42 Type Ia supernovae.

Webb's Data: Eliminating Biases

High-Definition Observations

Siyang Li, a graduate student at Johns Hopkins University involved in the study, said, "The Webb data is akin to observing the universe in high definition for the first time, significantly enhancing the signal-to-noise ratio of our measurements."

Data Precision and Reliability

The recent study analyzed about one-third of Hubble's complete galaxy sample, using the known distance of NGC 4258 as a reference. Despite the reduced dataset, the team achieved remarkable precision, with differences between measurements under 2%—significantly smaller than the approximately 8—9% discrepancy observed in the Hubble tension.

Cross-Checking Methodologies

Additional Verification Methods

Along with their analysis of Cepheid variables, the team's gold-standard method for measuring cosmic distances, they also verified their findings by cross-checking measurements using carbon-rich stars and the brightest red giants in the same galaxies.

Results and Findings

Webb's observations of galaxies and their supernovae yielded a Hubble constant of 72.6 km/s/Mpc, a value nearly identical to the 72.8 km/s/Mpc determined by Hubble for these very galaxies.

Broader Implications of the Study

Contributions and Collaborations

This study utilized Webb data from two separate groups that independently work on refining the Hubble constant: Riess' SH0ES team (Supernova, H0, for the Equation of State of Dark Energy) and the Carnegie-Chicago Hubble Program, as well as contributions from additional research teams.

The combined measurements represent the most accurate determination to date of the distances measured using Cepheid stars observed by the Hubble Telescope, which are crucial for calculating the Hubble constant.

Understanding the Universe's Expansion

While the Hubble constant has no direct impact on the solar system, Earth, or our daily activities, it provides insights into the universe's evolution on an immense scale, with vast regions of space expanding and pushing galaxies apart, akin to raisins in a rising loaf of dough.

Significance for Cosmology

This value is essential for scientist to map the structure of the universe, enhance their understanding of its condition 13-14 billion year post-Big Bang, and compute other fundamental cosmic properties.

Addressing the Hubble Tension: Future Directions

Theoretical Implications

Addressing the Hubble tension could uncover fresh insights into other inconsistencies with the standard cosmological model that have emerged in recent years, according to Marc Kamionkowski, a cosmologist at Johns Hopkins who contributed to calculating the Hubble constant and recently worked on a potential new explanation for the tension.

Gaps in Current Understanding

The standard model provides a framework for understanding the evolution of galaxies, the cosmic microwave background originating from the Big Bang, the distribution of chemical elements in the universe, and numerous other fundamental observations, all rooted in established laws of physics. However, it falls short of explaining the true nature of dark matter and dark energyenigmatic elements believed to comprise 96% of the universe's composition and drive its accelerated expansion.

Potential Explanations

Kamionkowski, who was not part of the recent study, suggested that one potential explanation for the Hubble tension could involve a gap in our comprehension of the early universe, such as an unknown form of matter—early dark energy—that may have provided the universe with an unforeseen boost post-Big Bang.

Other Theoretical Possibilities

"Other possibilities include unusual properties of dark matter, exotic particles, variation in electron mass, or even primordial magnetic fields as potential explanations. Theoretical physicists are encouraged to explore a wide range of creative ideas."

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Tuesday, December 3, 2024

toi-396-three-planet-system-discovery

New Observations Reveal Insights into the TOI-396 Three-Planet System

An artistic rendering showing the TOI-396 system and its three exoplanets orbiting the bright star HR 858 A.

An international team has studied a planetary system containing three exoplanets orbiting the star TOI-396. This groundbreaking research, published on November 22 on the pre-print server arXiv, offers the first mass measurements for these planets, enriching the understanding of the system's properties.

Overview of the TOI-396 Star System

Star Properties and Location

TOI-396 (HR 858 A), located about 103 light-years from Earth, is a bright star of spectral type F6 V. It has a size 26% larger and a mass 20% greater than the sun, an effective temperature of 6,354 K, and an estimated ago of two billion years. It is part of a binary system with a faint M dwarf companion, HR 858 B.

Exoplanet Discovery via NASA's TESS

In 2019, NASA's Transiting Exoplanet Survey Satellite (TESS) identified three exoplanets orbiting TOI-396, designated TOI-396 b, c, and d. Each of these planets, approximately twice Earth's size, was found within 0.1 AU of their host star, with orbital periods of 3.6, 6.0, and 11.2 days, respectively.

Observational Methods and Analysis

HARPS Radial Velocity Observations

Andrea Bonfanti of the Austrian Academy of Sciences in Graz, led a group of astronomers who used the HARPS spectrograph fro radial velocity studies of TOI-396 and analyzed NASA's TESS photometric data, revealing further details about the system.

Mass and Radius Measurement

"To determine the masses of the three planets, improve their radius estimates, and explore the possibility of Mean Motion Resonance (MMR) between planets b and c, we conducted HARPS radial velocity measurements of TOI-396 and analyzed archival high-precision photometric data from four TESS sectors," the researchers stated.

Findings from the Observations

Mass and Density of TOI-396 Planets

The observations revealed that TOI-396 and TOI-396 d have masses of approximately 3.55 and 7.1 Earth masses, respectively, corresponding to mean densities of 2.44 g/cm³ and 4.9 g/cm³. For TOI-396 c, only an upper mass limit of 3.8 Earth masses was determined, yielding a maximum density of 2.9 g/cm³.

Uniqueness of the TOI-396 System

The research underscores the uniqueness of the TOI-396 system, characterized by its mid-planet being the least dense and its outermost planet the most dense. Equilibrium temperatures for TOI-396 b, c, and d were estimated at 1,552 K, 1,309 K, and 1,061 K, respectively.

Dynamical Analysis of the System

Transit Timing Variations (TTV)

Additionally, the researchers conducted a Transit Timing Variation (TTV) dynamical analysis of the TOI-396 system. The analysis suggests that TOI-396 b and TOI-396 c may display TTVs with a super-period of approximately five years and semi-amplitudes of roughly two and five hours, respectively.

Conclusions and Future Implications

Atmospheric Characterization of TOI-396 Planets

In their concluding remarks, the researchers highlighted that all three planets orbiting TOI-396 exhibit favorable atmospheric characterization metrics, both in transmission and emission, among sub-Neptune exoplanets. This positions the TOI-396 system as an ideal setting for studying planetary formation and evolution.

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Thursday, November 28, 2024

cosmic filaments and baryon density contrast

New Insights into the Intergalactic Medium and Cosmic Filaments Unveiled

eROSITA count rate map of the analysis footprint.

The Intergalactic Medium: A Vast and Mysterious Expanse

The majority of the universe's mass is not contained within stars or galaxies but resides in the vast expanse between them, known as the intergalactic medium. This medium is warm to hot, often referred to as the "warm-hot intergalactic medium" (WHIM), and accounts for nearly half of the universe's baryonic matter (excluding dark matter), though its hydrogen ion density is remarkably lowfewer than 100 ions per cubic meter.

Cosmic Filaments: The Building Blocks of the Cosmic Web

At temperatures ranging from 100,000 to 10 million Kelvin, the intergalactic medium forms a network of "cosmic filaments," massive regions of hot, diffuse gas connecting galaxies. These structures, also known as "galactic filaments," are the largest known in the universe, typically stretching 150 to 250 megaparsecs (500 to 800 million light-years), a span approximately 8,000 times the width of the Milky Way.

Together, these structures create the cosmic web, defining the boundaries of vast cosmic voidsimmense regions of space nearly devoid of galaxies.

The WHIM's Role in Astrophysical Research

"The warm-hot intergalactic medium within cosmic filaments remains one of the least characterized components modern astrophysics," notes a team of European scientists, primarily based in Germany.

New Research on Cosmic Filaments

By leveraging an instrument aboard a satellite that began its survey of the univerrse in late 2019, the researchers analyzed X-ray emissions from nearly 8,000 cosmic filaments. They applied a model to estimate the temperature and baryon density contrast of the WHIM, publishing their findings in Astronomy & Astrophysics.

Understanding the Vast Voids Between Filaments

Cosmic filaments stretch across nearly the entire universe, with vast voids in between where atom densities are approximately one per cubic meter. For perspective, interstellar space within our galaxy has densities of one million to one trillion atoms per cubic meter, while Earth's most advanced vacuums contain about 10¹⁶ atoms per cubic meter.

The Local Void and Its Significance

The "Local Void" is the nearest cosmic void to Earth. Cosmic filaments, which link galaxies into a sprawling web, are primarily filled with gas, dust, stars, and a significant amount of dark matter. Although incredibly hot and in a plasma state, their temperature and density are much lower than the Sun's. They are composed of ionized hydrogen atoms and can be observed by the way they absorb light emitted by quasars.

Data Collection and Analysis Methodology

Researchers utilized data from eROSITA, an X-ray telescope onboard the Russion-German Spectrum Roentgen Gamma observatory. Although designed to survey the entire sky over seven years following its launch in July 2019, eROSITA ceased functioning in February 2022 due to the breakdown of institutional relations after Russia's invasion of Ukraine.

filaments in the redshift and physical length space.

The researchers collected "stacked" scansrepeated imaging of the same area to enhance weak signal intensitiesbetween December 12 and 19, 2021, at X-ray energies of approximately 1 kilo-electronvolt (wavelengths near 1 nm), with four stacks in total. They utilized a 2011 filament catalog derived from the Sloan Digital Sky Survey, which lists over 63,000 optical filaments.

The Filament Lengths and Cosmological Analysis

Using standard cosmological parameters from the canonical ΛCDM modelsuch as the Hubble constant, matter density, baryon density, and dark matter energy densitythe researchers determined the physical lengths of the filaments.

Detailed Data Analysis for Temperature and Density

An extensive data analysis process ensued. Initially, the team calculated the surface brightness profile of all filaments at specific distances along their length, meticulously addressing factors such as  projection effects, filament overlap, and local background subtraction.

The team then estimated the contribution of unmasked galactic sourcessuch as X-ray point sources, galaxy clusters, and groupsto each signal. Ultimately, they employed detailed astrophysical models, corrected for instrument biases, and applied statistical methods to derive the most accurate temperature and density profiles of the gas in the WHIM.

Key Findings and Implications

The team determined a best-fit temperature of 10·⁸⁴ Kelvin, approximately 7 million K. They calculated a baryon density contrast of 10¹·⁸⁸, equivalent to 76, indicating that the WHIM's baryonic matter density is 76 times greater than the average background density in space.

The average density contrast aligns with predictions from numerical simulations, but the calculated temperature approached the upper limit for the X-ray-emitting WHIM. This result was anticipated, the authors note, as the simplified temperature estimation tends to reflect the higher end of a multi-temperature spectrum.

Future Research and Advancements in Understanding the WHIM

Advancements in the understanding of X-ray-emitting cosmic filaments and the WHIM are anticipated in the next decade. driven by enhanced filament detection tools and refined knowledge of X-ray properties in galaxy groups, active galactic nuclei, and fast radio bursts, enabling more precise subtration form the WHIM signal.

Upcoming X-ray Missions and Their Potential Impact

Future X-ray missions, including the Hot Universe Baryon Surveyor and Line Emission Mapper, are expected to expand the exploration of WHIM properties, shedding light on the enigmatic intergalactic medium.

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Thursday, November 21, 2024

desi cosmic gravity dark energy insights

DESI Data Unveils New Insights into Gravity's Cosmic Influence

DESI instrument capturing data from galaxies and quasars at the Nicholas U. Mayall Telescope, Kitt Peak National Observatory.

Overview of Gravity's Role in the Universe

The force of gravity, pivotal in shaping our universe, magnified minor early matter fluctuations into the expansive galaxy networks visible today. Recent research employing DESI data has charted 11 billion years of cosmic development, delivering the most precise large-scale test of gravity.

What is DESI?

The Dark Energy Spectroscopic Instrument (DESI) is a global collaboration involving over 900 scientists from more than 70 institutions worldwide, overseen by the U.S. Department of Energy's Lawrence Berkeley National Laboratory.

Key Findings from DESI Research

In their recent study, DESI researchers confirmed that gravity operates in line with Einstein's general relativity, supporting the prevailing cosmological model and constraining alternative theories of modified gravity, often invoked to explain phenomena like the universe's accelerating expansion typically linked to dark energy.

Gravity and Einstein's General Relativity

Testing Gravity on Cosmic Scales

"General relativity has been extensively validated on solar system scales, but testing its applicability on much larger cosmic scales is crucial," said Pauline Zarrouk, a cosmologist at CNRS and co-leader of the analysis at the Laboratory of Nuclear and High-Energy Physics (LPNHE).

Importance of Galaxy Formation Rates

"Analyzing galaxy formation rates provides a direct means to test our theories, which, thus far, remain consistent with general relativity at cosmological scales," Zorrouk added.

Neutrino Mass and Its Implications

The research additionally set new upper boundaries on neutrino mass, the only fundamental particles whose exact masses remain undetermined.

Findings on Neutrino Mass

Earlier neutrino experiments determined that the combined mass of the three neutrino types must be at least 0.059 eV/c², compared to the electron's mass of approximately 511,000 eV/c². DESI's findings suggest the sum is less than 0.071 eV/c², narrowing the range for neutrino masses.

DESI's Groundbreaking Data on the Universe's Evolution

The DESI collaboration has published their findings in multiple papers on the FSNews365 preprint server. Leveraging data from nearly 6 million galaxies and quasars, the analysis offers a glimpse into the universe's past stretching back 11 billion years.

Advancements in Structure Growth Measurement

Remarkably, DESI achieved the most precise measurement of structure growth within a single year, exceeding results that took decades to accomplish.

Exploring DESI's Inaugural Year and Major Discoveries

This study offers a deeper exploration of DESI's inaugural year of data, which, in April, unveiled the largest-ever 3D cosmic map and suggested that dark energy may evolve with time.

Insights from April's Findings

April's findings focused on baryon acoustic oscillations (BAO), a key aspect of galaxy clustering. The new "full-shape analysis" extends this work, examining the distribution of galaxies and matter across various spatial scales.

Ensuring Accuracy: The Blinding Technique

The research involved months of meticulous work and verification. Similar to the prior study, a blinding technique was employed to conceal results until completion, reducing potential unconscious bias.

Key Insights from Dragan Huterer

"Our BAO findings and the full-shape analysis are remarkable achievements," states Dragan Huterer, a University of Michigan professor and co-leader of DESI's cosmological data interpretation team.

Looking Ahead: The Future of DESI and Cosmological Research

For the first time, DESI has examined the growth of cosmic structures, demonstrating remarkable potential to investigate modified gravity and refine dark energy models. And this is just the beginning.

Dark Energy Spectroscopic Instrument imaging the night sky

DESI's Cutting-Edge Instrumentation

DESI, a cutting-edge instrument, simultaneously captures light from 5,000 galaxies. Mounted on the Nicholas U. Mayall 4-meter Telescope at NSF's Kitt Peak National Observatory, this experiment is in its fourth year of a five-year survey and aims to collect data from 40 million galaxies and quasars by its conclusion.

Anticipated Results by Spring 2025

Researchers are now analyzing data from DESI's first three years and anticipate releasing updated insights on dark energy and the universe's expansion history by spring 2025. Early findings, indicating a possible evolution of dark energy, heighten excitement for these forthcoming results.

Uncovering the Mysteries of Dark Matter and Dark Energy

Dark matter constitutes roughly 25% of the universe, while dark energy accounts for 70%. Yet, their true nature remains elusive.

Insights from Mark Maus

"It's astonishing to think that capturing images of the universe allows us to address these profound questions," noted Mark Maus, a Ph.D. candidate at Berkeley Lab and UC Berkeley, involved in theoretical and validation modeling for the analysis.

Cultural Significance of DESI's Research Location

The DESI collaboration is privileged to undertake scientific research on I'oligam Du'ag (Kitt Peak), a mountain of profound cultural importance to the Tohono O'odham Nation.

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Saturday, November 16, 2024

astronomers discover compound lens system

Astronomers Unlock the Mystery of Compound Gravitational Lensing by Two Galaxies

Illustration of two galaxies aligned to form a compound gravitational lens, distorting light from a distant quasar.

Introduction of Gravitational Lensing

Astronomers from an international team have discovered two galaxies aligned in a way that their gravitational forces create a compound lens. Their study has been published on arXiv.

Previous Research on Gravitational Lensing

Gravitational Lensing: Gravitational Lensing occurs when the gravitational field of a massive object, like a galaxy, bends light from a more distant object, such as a quasar.

Previous Research: Earlier investigations have identified galaxies or galaxy clusters bending light in alignment with predictions from Einstein's general relativity. Astronomers observe that such lenses imperfectly distort the light behind them in intriguing patterns.

Discovery of a Compound Lens

Elliptical Galaxies as Lenses

Elliptical galaxies have been observed by some researchers to function as lenses, amplifying the light form objects behind them.

What is a Compound Lens?

A compound lens consists of two lenses. In artificial lenses, the lenses are bonded to counteract each other's dispersion. In astronomy, this lens naturally forms when two galaxies align precisely in space, creating a more complex lensing effect.

Groundbreaking Study: Two Galaxies as Compound Lenses

In this groundbreaking study, the team identified, for the first time, two galaxies whose alignment enables their gravitational forces to act as a compound lens.

A compound lens, as implied by its name, consists of two lenses. Artificially created ones are bonded together to counteract each other's dispersion. In astronomy, such a lens forms naturally when two galaxies align precisely.

Case Study: J1721+8842

Initial Observations of J1721+8842

When J1721+8842 was first identified, researchers thought a solitary elliptical galaxy was distorting light from a background quasar.

Extended Study Reveals Light Fragment Variations

A two-year study, however, revealed image variations and seemingly duplicated light fragments.

Closer examination revealed that the additional light fragments matched the main quartet, confirming all six originated from the same source. Previous research suggested such imagery could result from a natural compound lens.

Verifying the Compound Lens

Role of the James Webb Space Telescope

Using additional data from the James Webb Space Telescope, researchers determined that a reddish ring, previously thought to be an Einstein ring, was a second lensing galaxy.

Confirmation via Computer Modeling

They verified this findings by constructing a computer model, confirming the compound lens.

Implications of the Discovery

Refining Calculations of the Hubble Constant

The research team anticipates that their findings will enable other scientists to refine calculations of the Hubble constantpotentially resolving the ongoing debate about its true value.

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