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93-535: The VST program is a cooperation between the Osservatorio Astronomico di Capodimonte (OAC), Naples , Italy, and the European Southern Observatory (ESO) that began in 1997. The OAC is one of the institute members of Istituto Nazionale di AstroFisica (INAF), which created a separate institute for the coordination of both technological and scientific aspects of the project, named Centro VST

186-413: A ). This can be understood intuitively: for an ordinary particle in a cube-shaped box, doubling the length of an edge of the box decreases the density (and hence energy density) by a factor of eight (2 ). For radiation, the decrease in energy density is greater, because an increase in spatial distance also causes a redshift. The final component is dark energy: it is an intrinsic property of space and has

279-530: A Napoli (VSTceN). VSTcen was founded and directed by Prof. Massimo Capaccioli of the VST project, and hosted at the OAC. ESO and VSTceN collaborated in the commission phase, while ESO was responsible for the civil engineering works and the dome on site. The telescope has now started observations and ESO is solely responsible for managing its operations and maintenance. The VST is an alt-azimuthal wide-field survey telescope with

372-593: A constant energy density, regardless of the dimensions of the volume under consideration ( ρ  ∝  a ). Thus, unlike ordinary matter, it is not diluted by the expansion of space. The evidence for dark energy is indirect but comes from three independent sources: In 1998, the High-Z Supernova Search Team published observations of Type Ia ("one-A") supernovae . In 1999, the Supernova Cosmology Project followed by suggesting that

465-565: A decree dated 29 January 1807 in the ancient monastery of San Gaudioso on the Caponapoli hill. The astronomer Giuseppe Cassella was the first director of the Neapolitan specola. When Joachim Murat was appointed king of Naples, he approved 8 March 1812 the foundation of a new Observatory on the Miradois hill, a site not far from the royal palace of Capodimonte . The astronomer Federigo Zuccari and

558-406: A deformable platform able to tilt the mirror during exposure. The active optics system also includes a Shack-Hartmann wavefront sensor , mounted under the primary mirror cell together with the local guide system, able to furnish the optical correction feedback. These systems give the VST the capability to be autonomous in terms of guiding, tracking and active optics control. At its Cassegrain focus,

651-529: A direct estimate of the Hubble parameter The reliance on a differential quantity, ⁠ Δ z / Δ t ⁠ , brings more information and is appealing for computation: It can minimize many common issues and systematic effects. Analyses of supernovae and baryon acoustic oscillations (BAO) are based on integrals of the Hubble parameter, whereas ⁠ Δ z / Δ t ⁠ measures it directly. For these reasons, this method has been widely used to examine

744-649: A large dewar window. This window not only protects the detectors from air and moisture, but also acts as an additional corrector lens. The primary function of the VST is to support the Very Large Telescope by providing surveys – both extensive, multi-colour imaging surveys and more specific searches for rare astronomical objects. Three started in October 2011 as part of the Public Surveys Project, and they are anticipated to take five years to carry out. These are

837-499: A non-standard form of kinetic energy such as a negative kinetic energy . They can have unusual properties: phantom energy , for example, can cause a Big Rip . A group of researchers argued in 2021 that observations of the Hubble tension may imply that only quintessence models with a nonzero coupling constant are viable. This class of theories attempts to come up with an all-encompassing theory of both dark matter and dark energy as

930-554: A primary mirror diameter of 2.65 meters that was constructed from 2007 to 2011 at the ESO Cerro Paranal Observatory , in Chile . With a field of view of one square degree (roughly two full moons), its main scientific role is as a wide-field imaging instrument for exploring the large-scale structure of the universe (as visible from the southern hemisphere), able to identify the most suitable candidates for detailed examination by

1023-508: A profound effect on the universe, making up 68% of universal density in spite of being so dilute, is that it is believed to uniformly fill otherwise empty space. The vacuum energy , that is, the particle-antiparticle pairs generated and mutually annihilated within a time frame in accord with Heisenberg's uncertainty principle in the energy-time formulation, has been often invoked as the main contribution to dark energy. The mass–energy equivalence postulated by general relativity implies that

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1116-430: A single phenomenon that modifies the laws of gravity at various scales. This could, for example, treat dark energy and dark matter as different facets of the same unknown substance, or postulate that cold dark matter decays into dark energy. Another class of theories that unifies dark matter and dark energy are suggested to be covariant theories of modified gravities. These theories alter the dynamics of spacetime such that

1209-435: A universe which contracts slightly will continue contracting. According to Einstein, "empty space" can possess its own energy. Because this energy is a property of space itself, it would not be diluted as space expands. As more space comes into existence, more of this energy-of-space would appear, thereby causing accelerated expansion. These sorts of disturbances are inevitable, due to the uneven distribution of matter throughout

1302-530: Is a proposed form of energy that affects the universe on the largest scales. Its primary effect is to drive the accelerating expansion of the universe . Assuming that the lambda-CDM model of cosmology is correct, dark energy dominates the universe, contributing 68% of the total energy in the present-day observable universe while dark matter and ordinary (baryonic) matter contribute 26% and 5%, respectively, and other components such as neutrinos and photons are nearly negligible. Dark energy's density

1395-401: Is called "cosmological coupling" because the black holes couple to a cosmological requirement. Other astrophysicists are skeptical, with a variety of papers claiming that the theory fails to explain other observations. The evidence for dark energy is heavily dependent on the theory of general relativity. Therefore, it is conceivable that a modification to general relativity also eliminates

1488-414: Is close to flat . For the shape of the universe to be flat, the mass–energy density of the universe must be equal to the critical density . The total amount of matter in the universe (including baryons and dark matter ), as measured from the cosmic microwave background spectrum, accounts for only about 30% of the critical density. This implies the existence of an additional form of energy to account for

1581-452: Is engaged in several relevant international projects and researches, such as Solar Orbiter and ExoMars missions, gravitational waves studies, and observational instruments development for E-ELT , the next generation huge telescope. The Astronomical Observatory is the oldest scientific institution in Naples, and plays also an important role to promote and disseminate the scientific culture and

1674-478: Is known. This allows the object's distance to be measured from its actual observed brightness, or apparent magnitude . Type Ia supernovae are the best-known standard candles across cosmological distances because of their extreme and consistent luminosity . Recent observations of supernovae are consistent with a universe made up 71.3% of dark energy and 27.4% of a combination of dark matter and baryonic matter . The theory of large-scale structure , which governs

1767-409: Is measured as a function of cosmological redshift . OHD directly tracks the expansion history of the universe by taking passively evolving early-type galaxies as "cosmic chronometers". From this point, this approach provides standard clocks in the universe. The core of this idea is the measurement of the differential age evolution as a function of redshift of these cosmic chronometers. Thus, it provides

1860-434: Is minimally coupled to gravity, and does not feature higher order operations in its Lagrangian. No evidence of quintessence is yet available, nor has it been ruled out. It generally predicts a slightly slower acceleration of the expansion of the universe than the cosmological constant. Some scientists think that the best evidence for quintessence would come from violations of Einstein's equivalence principle and variation of

1953-417: Is more hypothetical than that of dark matter, and many things about it remain in the realm of speculation. Dark energy is thought to be very homogeneous and not dense , and is not known to interact through any of the fundamental forces other than gravity . Since it is rarefied and un-massive—roughly 10  kg/m —it is unlikely to be detectable in laboratory experiments. The reason dark energy can have such

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2046-500: Is possible to investigate the effect of dark energy in the history of the universe, and constrain parameters of the equation of state of dark energy. To that end, several models have been proposed. One of the most popular models is the Chevallier–Polarski–Linder model (CPL). Some other common models are Barboza & Alcaniz (2008), Jassal et al. (2005), Wetterich. (2004), and Oztas et al. (2018). Researchers using

2139-400: Is sometimes labeled "gravitational repulsion". In standard cosmology, there are three components of the universe: matter, radiation, and dark energy. This matter is anything whose energy density scales with the inverse cube of the scale factor, i.e., ρ  ∝  a , while radiation is anything whose energy density scales to the inverse fourth power of the scale factor ( ρ  ∝ 

2232-458: Is that it is an intrinsic, fundamental energy of space. This is the cosmological constant, usually represented by the Greek letter Λ (Lambda, hence the name Lambda-CDM model ). Since energy and mass are related according to the equation E = mc , Einstein's theory of general relativity predicts that this energy will have a gravitational effect. It is sometimes called vacuum energy because it

2325-525: Is the stress–energy tensor , which contains both the energy (or matter) density of a substance and its pressure. In the Friedmann–Lemaître–Robertson–Walker metric , it can be shown that a strong constant negative pressure ( i.e., tension) in all the universe causes an acceleration in the expansion if the universe is already expanding, or a deceleration in contraction if the universe is already contracting. This accelerating expansion effect

2418-575: Is the Neapolitan department of Istituto Nazionale di Astrofisica (National Institute for Astrophysics, INAF), the most important Italian institution promoting, developing and conducting scientific research in the fields of astronomy, astrophysics, and space science. The Astronomical Observatory is located in Naples , Italy, on Capodimonte hill, where the splendid panorama of the city and bay of Naples from Vesuvius to Castel Sant'Elmo passing through Sorrento and Capri can be admired. The Observatory

2511-415: Is the energy density of empty space – of vacuum . A major outstanding problem is that the same quantum field theories predict a huge cosmological constant , about 120  orders of magnitude too large. This would need to be almost, but not exactly, cancelled by an equally large term of the opposite sign. Some supersymmetric theories require a cosmological constant that is exactly zero. Also, it

2604-536: Is the larger of the two, with a diameter of 265 cm and a thickness of 14 cm. The secondary mirror is less than half the size of M1 with a diameter of just 93.8 cm and a thickness of 13 cm. VST's original optical components were manufactured at the Lytkarino Glass Factory, Moscow . The mirrors were completed ahead of schedule, but on arrival in Chile in 2002, the primary was found to be broken and

2697-414: Is thought to have completely ended when the universe was just a fraction of a second old. It is unclear what relation, if any, exists between dark energy and inflation. Even after inflationary models became accepted, the cosmological constant was thought to be irrelevant to the current universe. Nearly all inflation models predict that the total (matter+energy) density of the universe should be very close to

2790-399: Is unknown whether there is a metastable vacuum state in string theory with a positive cosmological constant, and it has been conjectured by Ulf Danielsson et al. that no such state exists. This conjecture would not rule out other models of dark energy, such as quintessence, that could be compatible with string theory. In quintessence models of dark energy, the observed acceleration of

2883-489: Is very low: 7 × 10  g/cm ( 6 × 10  J/m in mass-energy ), much less than the density of ordinary matter or dark matter within galaxies. However, it dominates the universe's mass–energy content because it is uniform across space. The first observational evidence for dark energy's existence came from measurements of supernovae . Type Ia supernovae have constant luminosity, which means that they can be used as accurate distance measures. Comparing this distance to

VLT Survey Telescope - Misplaced Pages Continue

2976-566: The Australian Astronomical Observatory scanned the galaxies to determine their redshift. Then, by exploiting the fact that baryon acoustic oscillations have left voids regularly of ≈150 Mpc diameter, surrounded by the galaxies, the voids were used as standard rulers to estimate distances to galaxies as far as 2,000 Mpc (redshift 0.6), allowing for accurate estimate of the speeds of galaxies from their redshift and distance. The data confirmed cosmic acceleration up to half of

3069-633: The Dark Energy Spectroscopic Instrument (DESI) to make the largest 3-D map of the universe as of 2024, have obtained an expansion history that has greater than 1% precision. From this level of detail, DESI Director Michael Levi stated: We're also seeing some potentially interesting differences that could indicate that dark energy is evolving over time. Those may or may not go away with more data, so we're excited to start analyzing our three-year dataset soon. Some alternatives to dark energy, such as inhomogeneous cosmology , aim to explain

3162-523: The Friedmann-Robertson-Walker metric (which describes the isotropic and homogeneous universe that is the basic assumption of modern cosmology), then one finds that black holes gain mass as the universe expands. The rate is measured to be ∝ a , where a is the scale factor . This particular rate means that the energy density of black holes remains constant over time, mimicking dark energy (see Dark_energy#Technical_definition ). The theory

3255-629: The Lambda-CDM model . Some people argue that the only indications for the existence of dark energy are observations of distance measurements and their associated redshifts. Cosmic microwave background anisotropies and baryon acoustic oscillations serve only to demonstrate that distances to a given redshift are larger than would be expected from a "dusty" Friedmann–Lemaître universe and the local measured Hubble constant. Supernovae are useful for cosmology because they are excellent standard candles across cosmological distances. They allow researchers to measure

3348-683: The Planck spacecraft and the Supernova Legacy Survey. First results from the SNLS reveal that the average behavior (i.e., equation of state) of dark energy behaves like Einstein's cosmological constant to a precision of 10%. Recent results from the Hubble Space Telescope Higher-Z Team indicate that dark energy has been present for at least 9 billion years and during the period preceding cosmic acceleration. The nature of dark energy

3441-614: The VLT . Together with its camera OmegaCAM, the VST is able to obtain a high angular resolution (0.216 arcsec/pixel), and it is capable of performing stand-alone survey projects in the visible part of the spectrum. The telescope has two mirrors, the primary (M1) and a smaller secondary mirror (M2), which reflect light from the sky down to the OmegaCAM camera. Both mirrors are made from a crystalline ceramic material called Sitall , chosen for its low coefficient of thermal expansion . The VST primary mirror

3534-436: The critical density . During the 1980s, most cosmological research focused on models with critical density in matter only, usually 95% cold dark matter (CDM) and 5% ordinary matter (baryons). These models were found to be successful at forming realistic galaxies and clusters, but some problems appeared in the late 1980s: in particular, the model required a value for the Hubble constant lower than preferred by observations, and

3627-471: The equation of state had possibly crossed the cosmological constant boundary (w = −1) from above to below. A no-go theorem has been proved that this scenario requires models with at least two types of quintessence. This scenario is the so-called Quintom scenario . Some special cases of quintessence are phantom energy , in which the energy density of quintessence actually increases with time, and k-essence (short for kinetic quintessence) which has

3720-400: The expansion of the universe are required to understand how the expansion rate changes over time and space. In general relativity, the evolution of the expansion rate is estimated from the curvature of the universe and the cosmological equation of state (the relationship between temperature, pressure, and combined matter, energy, and vacuum energy density for any region of space). Measuring

3813-431: The redshift (which measures the speed at which the supernova is receding) shows that the universe's expansion is accelerating . Prior to this observation, scientists thought that the gravitational attraction of matter and energy in the universe would cause the universe's expansion to slow over time. Since the discovery of accelerating expansion, several independent lines of evidence have been discovered that support

VLT Survey Telescope - Misplaced Pages Continue

3906-893: The Kilo-Degree Survey (KiDS), VST ATLAS and the VST Photometric Hα Survey of the Southern Galactic Plane (VPHAS+). They focus on a wide range of astronomical issues from searching for highly energetic quasars to understanding the nature of dark energy. More information about the surveys can be found on the ESO - The VST Surveys website. The data volume produced by OmegaCAM is large. About 30 terabytes of raw data will be produced per year and will flow back into data centres in Europe for processing. A novel and sophisticated software system has been developed at Groningen and Naples to handle

3999-529: The Lambda-CDM model then became the leading model. Soon after, dark energy was supported by independent observations: in 2000, the BOOMERanG and Maxima cosmic microwave background experiments observed the first acoustic peak in the cosmic microwave background, showing that the total (matter+energy) density is close to 100% of critical density. Then in 2001, the 2dF Galaxy Redshift Survey gave strong evidence that

4092-468: The Universe began when it did. If acceleration began earlier in the universe, structures such as galaxies would never have had time to form, and life, at least as we know it, would never have had a chance to exist. Proponents of the anthropic principle view this as support for their arguments. However, many models of quintessence have a so-called "tracker" behavior, which solves this problem. In these models,

4185-548: The VST hosts an imaging wide-field camera ( OmegaCAM ), comprising a mosaic of 32 2Kx4K CCDs (268 megapixels total), and produced by an international consortium between the Netherlands, Germany, Italy, and the ESO. Design features of OmegaCAM include four auxiliary CCD cameras , two for auto-guiding and two for on-line image analysis. Up to 12 filters can be used, ranging from ultraviolet to near-infrared. The entire detector system operates in vacuum at about −140 degrees Celsius behind

4278-466: The VST were released on June 8, 2011. In planetary science, the survey telescope aims to discover and study remote Solar System bodies such as trans-Neptunian objects, as well as search for extrasolar planet transits. The Galactic plane will also be extensively studied with VST, which will look for signatures of tidal interactions in the Milky Way, and will provide astronomers with data crucial to understand

4371-464: The accelerated cosmic expansion and study properties of dark energy. Dark energy's status as a hypothetical force with unknown properties makes it an active target of research. The problem is attacked from a variety of angles, such as modifying the prevailing theory of gravity (general relativity), attempting to pin down the properties of dark energy, and finding alternative ways to explain the observational data. The simplest explanation for dark energy

4464-411: The age of the universe (7 billion years) and constrain its inhomogeneity to 1 part in 10. This provides a confirmation to cosmic acceleration independent of supernovae. The existence of dark energy, in whatever form, is needed to reconcile the measured geometry of space with the total amount of matter in the universe. Measurements of cosmic microwave background anisotropies indicate that the universe

4557-449: The architect Stefano Gasse conceived a monumental building in the neoclassical style, the first to be designed in the capital of the Kingdom of Naples . On 4 November 1812 the foundation stone of the new observatory was laid with a solemn ceremony presided over by Interior Minister Giuseppe Zurlo . Defined by the astronomer Franz Xaver von Zach " The Vesuvius of Astronomy erupting gold ",

4650-521: The astronomical knowledge in the society. For this purpose it houses some outreach facilities like a planetarium and a 40-cm telescope, and owns an important collection of ancient astronomical instruments exhibited in the MuSA-Museum of Astronomical Instruments, and a rare and valuable old books preserved in the Ancient library. The Astronomical Observatory of Naples was established by Joseph Bonaparte with

4743-695: The collection grew from 195 to 620 books. Zuccari acquired some of these books from the Berlin astronomer Johann Elert Bode , the secretary of Neapolitan embassy in Vienna Severo Gargani, and the Paris booksellers of the King of the Two Sicilies, Borel and Pichard. In the middle of 1815, Ferdinand I of Bourbon was back to being the king of Naples and he called in the capital the astronomer Giuseppe Piazzi to supervise

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4836-418: The competing theories successfully explain observations to the same level of precision as standard dark energy. Cosmologists estimate that the acceleration began roughly 5 billion years ago. Before that, it is thought that the expansion was decelerating, due to the attractive influence of matter. The density of dark matter in an expanding universe decreases more quickly than dark energy, and eventually

4929-493: The conclusion of building works with the help of Pietro Bianchi  [ it ] , the architect of Basilica of San francesco di Paola . The new observatory was completed in the autumn of 1819. The astronomer Carlo Brioschi made the first observation from the Observatory est dome in the night of 17 December 1819 observing the star α Cassiopeia . Dark energy In physical cosmology and astronomy , dark energy

5022-564: The cosmic distance scale and understand the expansion of the Universe. The VST will also look for cosmic structures at medium-high redshift, active galactic nuclei and quasars to further our understanding of galaxy formation and the Universe's early history. Through the VST ATLAS survey, the telescope will target one of the most fundamental questions in astrophysics today: the nature of dark energy . The survey aims to detect small-amplitude oscillations known as ´baryon wiggles’ that can be detected in

5115-508: The cosmic microwave background aligned with vast supervoids and superclusters. This so-called late-time Integrated Sachs–Wolfe effect (ISW) is a direct signal of dark energy in a flat universe. It was reported at high significance in 2008 by Ho et al. and Giannantonio et al. A new approach to test evidence of dark energy through observational Hubble constant data (OHD), also known as cosmic chronometers, has gained significant attention in recent years. The Hubble constant, H ( z ),

5208-437: The dark energy dominates. Specifically, when the volume of the universe doubles, the density of dark matter is halved, but the density of dark energy is nearly unchanged (it is exactly constant in the case of a cosmological constant). Projections into the future can differ radically for different models of dark energy. For a cosmological constant, or any other model that predicts that the acceleration will continue indefinitely,

5301-536: The entire image. The data were processed using the Astro-WISE software system developed by E.A. Valentijn and collaborators at Groningen and elsewhere. The second released VST image (top on the right) may be the best portrait of the globular star cluster Omega Centauri ever made. Omega Centauri, in the constellation of Centaurus (The Centaur), is the largest globular cluster in the sky, but the very wide field of view of VST and its powerful camera OmegaCAM can encompass even

5394-446: The equation of state for dark energy is one of the biggest efforts in observational cosmology today. Adding the cosmological constant to cosmology's standard FLRW metric leads to the Lambda-CDM model, which has been referred to as the " standard model of cosmology " because of its precise agreement with observations. As of 2013, the Lambda-CDM model is consistent with a series of increasingly rigorous cosmological observations, including

5487-575: The existence of dark energy. The exact nature of dark energy remains a mystery, and possible explanations abound. The main candidates are a cosmological constant (representing a constant energy density filling space homogeneously) and scalar fields (dynamic quantities having energy densities that vary in time and space) such as quintessence or moduli . A cosmological constant would remain constant across time and space, while scalar fields can vary. Yet other possibilities are interacting dark energy, an observational effect, and cosmological coupling (see

5580-444: The expansion history of the universe by looking at the relationship between the distance to an object and its redshift , which gives how fast it is receding from us. The relationship is roughly linear, according to Hubble's law . It is relatively easy to measure redshift, but finding the distance to an object is more difficult. Usually, astronomers use standard candles: objects for which the intrinsic brightness, or absolute magnitude ,

5673-533: The expansion of the universe is accelerating . The 2011 Nobel Prize in Physics was awarded to Saul Perlmutter , Brian P. Schmidt , and Adam G. Riess for their leadership in the discovery. Since then, these observations have been corroborated by several independent sources. Measurements of the cosmic microwave background , gravitational lensing , and the large-scale structure of the cosmos , as well as improved measurements of supernovae, have been consistent with

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5766-598: The faint outer regions of this object. The view seen on the left includes about 300 000 stars. The data were processed using the VST-Tube system developed by A. Grado and collaborators at the INAF-Capodimonte Observatory. The third released VST image (middle on the right) shows a triplet of bright galaxies in the constellation of Leo (The Lion), together with a multitude of fainter objects: distant background galaxies and much closer Milky Way stars. The image hints at

5859-472: The formation of structures in the universe ( stars , quasars , galaxies and galaxy groups and clusters ), also suggests that the density of matter in the universe is only 30% of the critical density. A 2011 survey, the WiggleZ galaxy survey of more than 200,000 galaxies, provided further evidence towards the existence of dark energy, although the exact physics behind it remains unknown. The WiggleZ survey from

5952-473: The fundamental constants in space or time. Scalar fields are predicted by the Standard Model of particle physics and string theory , but an analogous problem to the cosmological constant problem (or the problem of constructing models of cosmological inflation ) occurs: renormalization theory predicts that scalar fields should acquire large masses. The coincidence problem asks why the acceleration of

6045-413: The interstellar space'. The mechanism was an example of fine-tuning , and it was later realized that Einstein's static universe would not be stable: local inhomogeneities would ultimately lead to either the runaway expansion or contraction of the universe. The equilibrium is unstable: if the universe expands slightly, then the expansion releases vacuum energy, which causes yet more expansion. Likewise,

6138-471: The matter density is around 30% of critical. The large difference between these two supports a smooth component of dark energy making up the difference. Much more precise measurements from WMAP in 2003–2010 have continued to support the standard model and give more accurate measurements of the key parameters. The term "dark energy", echoing Fritz Zwicky 's "dark matter" from the 1930s, was coined by Michael S. Turner in 1998. High-precision measurements of

6231-680: The model under-predicted observations of large-scale galaxy clustering. These difficulties became stronger after the discovery of anisotropy in the cosmic microwave background by the COBE spacecraft in 1992, and several modified CDM models came under active study through the mid-1990s: these included the Lambda-CDM model and a mixed cold/hot dark matter model. The first direct evidence for dark energy came from supernova observations in 1998 of accelerated expansion in Riess et al. and in Perlmutter et al. , and

6324-428: The modified dynamics stems to what have been assigned to the presence of dark energy and dark matter. Dark energy could in principle interact not only with the rest of the dark sector, but also with ordinary matter. However, cosmology alone is not sufficient to effectively constrain the strength of the coupling between dark energy and baryons, so that other indirect techniques or laboratory searches have to be adopted. It

6417-475: The need for dark energy. There are many such theories, and research is ongoing. The measurement of the speed of gravity in the first gravitational wave measured by non-gravitational means ( GW170817 ) ruled out many modified gravity theories as explanations to dark energy. Astrophysicist Ethan Siegel states that, while such alternatives gain mainstream press coverage, almost all professional astrophysicists are confident that dark energy exists and that none of

6510-564: The new observatory was equipped with a most advanced collection of new telescopes, like the Fraunhofer equatorial telescope with an objective of 17.5 cm, the biggest one ever made until that time, and two repeating circle realised by the Reichenbach & Utzschneider Company in Munich . In 1812 Zuccari established also an astronomical library in the san Gaudioso observatory. In four years

6603-481: The observational data by a more refined use of established theories. In this scenario, dark energy does not actually exist, and is merely a measurement artifact. For example, if we are located in an emptier-than-average region of space, the observed cosmic expansion rate could be mistaken for a variation in time, or acceleration. A different approach uses a cosmological extension of the equivalence principle to show how space might appear to be expanding more rapidly in

6696-564: The original paper. Another study questioning the essential assumption that the luminosity of Type Ia supernovae does not vary with stellar population age was also swiftly rebutted by other cosmologists. This theory was formulated by researchers of the University of Hawaiʻi at Mānoa in February 2023. The idea is that if one requires the Kerr metric (which describes rotating black holes) to asymptote to

6789-537: The power of the VST and OmegaCAM for surveying the extragalactic Universe and for mapping the low brightness objects of the galactic halo. The image on the left is a composite created by combining exposures taken through three different filters. Light that passed through a near-infrared filter was coloured red, red light is coloured green, and green light is coloured magenta. Osservatorio Astronomico di Capodimonte The Astronomical Observatory of Capodimonte ( Italian : Osservatorio Astronomico di Capodimonte )

6882-437: The power-spectrum of galaxies and are the imprint of sound waves in the early Universe on the distribution of matter. The dark energy equation of state can be determined by measuring the features of these oscillations. Extrapolating from previous surveys, it is very likely that the VST will make some unexpected discoveries with major consequences for the current understanding of the Universe. The first released VST image (below on

6975-421: The primary mirror cell is another instrument able to modify the telescope's optical configuration by moving from a corrector composed by a double set of lenses, to an atmospheric dispersion corrector (ADC) composed of a counter-rotating set of prisms, able to correct the optical dispersion phenomena due to the variation of air mass induced by changing the altitude angle. The secondary mirror is actively controlled by

7068-456: The problem remains unresolved. Independently of its actual nature, dark energy would need to have a strong negative pressure to explain the observed acceleration of the expansion of the universe . According to general relativity, the pressure within a substance contributes to its gravitational attraction for other objects just as its mass density does. This happens because the physical quantity that causes matter to generate gravitational effects

7161-400: The quintessence field has a density which closely tracks (but is less than) the radiation density until matter–radiation equality , which triggers quintessence to start behaving as dark energy, eventually dominating the universe. This naturally sets the low energy scale of the dark energy. In 2004, when scientists fit the evolution of dark energy with the cosmological data, they found that

7254-557: The remaining 70%. The Wilkinson Microwave Anisotropy Probe (WMAP) spacecraft seven-year analysis estimated a universe made up of 72.8% dark energy, 22.7% dark matter, and 4.5% ordinary matter. Work done in 2013 based on the Planck spacecraft observations of the cosmic microwave background gave a more accurate estimate of 68.3% dark energy, 26.8% dark matter, and 4.9% ordinary matter. Accelerated cosmic expansion causes gravitational potential wells and hills to flatten as photons pass through them, producing cold spots and hot spots on

7347-528: The right) shows the star-forming region Messier 17, also known as the Omega Nebula or the Swan Nebula, as it has never been seen before. This vast region of gas, dust and hot young stars lies in the heart of the Milky Way in the constellation of Sagittarius (The Archer). The VST field of view is so large that the entire nebula, including its fainter outer parts, is captured — and retains its superb sharpness across

7440-417: The scale factor is caused by the potential energy of a dynamical field , referred to as quintessence field. Quintessence differs from the cosmological constant in that it can vary in space and time. In order for it not to clump and form structure like matter, the field must be very light so that it has a large Compton wavelength . In the simplest scenarios, the quintessence field has a canonical kinetic term,

7533-448: The secondary was damaged. The new primary and repaired secondary arrived in Chile in 2006. A computer-controlled active optics system controls the shape of M1 and the position of M2. This technology preserves the optical image quality by keeping the mirrors optimally positioned at all times. M1 is continuously reshaped by an actuator network of 84 axial motors distributed under the mirror surface and 24 radial dislocated laterally. Also in

7626-407: The section Dark energy § Theories of dark energy ). The " cosmological constant " is a constant term that can be added to Einstein field equations of general relativity . If considered as a "source term" in the field equation, it can be viewed as equivalent to the mass of empty space (which conceptually could be either positive or negative), or " vacuum energy ". The cosmological constant

7719-428: The statistical methods employed were flawed. A laboratory direct detection attempt failed to detect any force associated with dark energy. Observational skepticism explanations of dark energy have generally not gained much traction among cosmologists. For example, a paper that suggested the anisotropy of the local Universe has been misrepresented as dark energy was quickly countered by another paper claiming errors in

7812-402: The structure and evolution of our Galaxy. Further afield, the VST will explore nearby galaxies, extragalactic and intra-cluster planetary nebulae, and will perform surveys of faint object and micro-lensing events. The telescope will also peer into the distant Universe to help astronomers find answers to long-standing questions in cosmology. It will target medium-redshift supernovae to help pin down

7905-452: The ultimate result will be that galaxies outside the Local Group will have a line-of-sight velocity that continually increases with time, eventually far exceeding the speed of light. This is not a violation of special relativity because the notion of "velocity" used here is different from that of velocity in a local inertial frame of reference , which is still constrained to be less than

7998-438: The universe. Further, observations made by Edwin Hubble in 1929 showed that the universe appears to be expanding and is not static. Einstein reportedly referred to his failure to predict the idea of a dynamic universe, in contrast to a static universe, as his greatest blunder. Alan Guth and Alexei Starobinsky proposed in 1980 that a negative pressure field, similar in concept to dark energy, could drive cosmic inflation in

8091-438: The vacuum energy should exert a gravitational force. Hence, the vacuum energy is expected to contribute to the cosmological constant , which in turn impinges on the accelerated expansion of the universe . However, the cosmological constant problem asserts that there is a huge disagreement between the observed values of vacuum energy density and the theoretical large value of zero-point energy obtained by quantum field theory ;

8184-521: The very early universe. Inflation postulates that some repulsive force, qualitatively similar to dark energy, resulted in an enormous and exponential expansion of the universe slightly after the Big Bang . Such expansion is an essential feature of most current models of the Big Bang. However, inflation must have occurred at a much higher (negative) energy density than the dark energy we observe today, and inflation

8277-465: The very large data flow. The end products from the processing will be huge lists of the objects found, as well as images, and these will be made available to astronomers worldwide for scientific analysis. Funding for the data analysis was uncertain in 2011. The loss of the first mirror in 2002 while being transported from Europe to Chile caused delays in the construction of the telescope. The new primary and repaired secondary were completed in 2006. Testing

8370-409: The voids surrounding our local cluster. While weak, such effects considered cumulatively over billions of years could become significant, creating the illusion of cosmic acceleration, and making it appear as if we live in a Hubble bubble . Yet other possibilities are that the accelerated expansion of the universe is an illusion caused by the relative motion of us to the rest of the universe, or that

8463-523: Was briefly theorized in the early 2020s that excess observed in the XENON1T detector in Italy may have been caused by a chameleon model of dark energy, but further experiments disproved this possibility. The density of dark energy might have varied in time during the history of the universe. Modern observational data allows us to estimate the present density of dark energy. Using baryon acoustic oscillations , it

8556-555: Was finished in Italy and the telescope was dismounted, painted and packed, then shipped and mounted at Paranal. The first parts arrived in June 2007, and the first phase of integration at Paranal was completed in April, 2008. The mirrors were stored while their cells were constructed; further delays occurred when the primary mirror cell suffered water damage while in transit to Chile, requiring it to be returned to Europe for repair. The first images from

8649-419: Was first proposed by Einstein as a mechanism to obtain a solution to the gravitational field equation that would lead to a static universe, effectively using dark energy to balance gravity. Einstein gave the cosmological constant the symbol Λ (capital lambda). Einstein stated that the cosmological constant required that 'empty space takes the role of gravitating negative masses which are distributed all over

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