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1.
《Experimental Astronomy》2009,23(1):39-66
We describe the scientific motivations, the mission concept and the instrumentation of SPACE, a class-M mission proposed for concept study at the first call of the ESA Cosmic-Vision 2015–2025 planning cycle. SPACE aims to produce the largest three-dimensional evolutionary map of the Universe over the past 10 billion years by taking near-IR
spectra and measuring redshifts for more than half a billion galaxies at 0 < z < 2 down to AB~23 over 3π sr of the sky. In addition, SPACE will also target a smaller sky field, performing a deep spectroscopic survey of millions of galaxies to AB~26 and at 2 < z < 10 +. These goals are unreachable with ground-based observations due to the ≈500 times higher sky background (see e.g.
Aldering, LBNL report number LBNL-51157, 2001). To achieve the main science objectives, SPACE will use a 1.5 m diameter Ritchey-Chretien telescope equipped with a set of arrays of Digital Micro-mirror Devices covering
a total field of view of 0.4 deg2, and will perform large-multiplexing multi-object spectroscopy (e.g. ≈6000 targets per pointing) at a spectral resolution
of R~400 as well as diffraction-limited imaging with continuous coverage from 0.8 to 1.8 μm. Owing to the depth, redshift
range, volume coverage and quality of its spectra, SPACE will reveal with unique sensitivity most of the fundamental cosmological signatures, including the power spectrum of density
fluctuations and its turnover. SPACE will also place high accuracy constraints on the dark energy equation of state parameter and its evolution by measuring the
baryonic acoustic oscillations imprinted when matter and radiation decoupled, the distance-luminosity relation of cosmological
supernovae, the evolution of the cosmic expansion rate, the growth rate of cosmic large-scale structure, and high-z galaxy clusters. The datasets from the SPACE mission will represent a long lasting legacy for the whole astronomical community whose data will be mined for many years
to come.
相似文献
A. CimattiEmail: |
2.
A. Refregier 《Experimental Astronomy》2009,23(1):17-37
The Dark UNiverse Explorer (DUNE) is a wide-field space imager whose primary goal is the study of dark energy and dark matter
with unprecedented precision. For this purpose, DUNE is optimised for the measurement of weak gravitational lensing but will
also provide complementary measurements of baryonic accoustic oscillations, cluster counts and the Integrated Sachs Wolfe
effect. Immediate auxiliary goals concern the evolution of galaxies, to be studied with unequalled statistical power, the
detailed structure of the Milky Way and nearby galaxies, and the demographics of Earth-mass planets. DUNE is an Medium-class
mission which makes use of readily available components, heritage from other missions, and synergy with ground based facilities
to minimise cost and risks. The payload consists of a 1.2 m telescope with a combined visible/NIR field-of-view of 1 deg2. DUNE will carry out an all-sky survey, ranging from 550 to 1600 nm, in one visible and three NIR bands which will form a
unique legacy for astronomy. DUNE will yield major advances in a broad range of fields in astrophysics including fundamental
cosmology, galaxy evolution, and extrasolar planet search. DUNE was recently selected by ESA as one of the mission concepts
to be studied in its Cosmic Vision programme.
相似文献
A. RefregierEmail: |
3.
A sample of 230 galaxies has been compiled based on their IRAS FSC fluxes to study their multiwavelength properties and carry
out comparative analyses with other similar samples. To understand the nature of these galaxies, a comparison with a sample
of bright ULIRGs having fluxes at 60 μm fν > 1 Jy and 14 optically faint IRAS FSC galaxies is presented. This comparison shows that galaxies found by IRAS are not always
strong infrared sources and that the objects from the sample of ULIRGs represent a sample of extreme galaxies, which are very
powerful infrared sources. We have confirmed the consistency between Star Formation Rates (SFRs) calibrated based on luminosities
of the PAH feature at 7.7 μm and radio 1.4 GHz flux densities. We have estimated the extinction for our 230 objects using
SFRs calibrated from the PAH feature compared to ultraviolet flux, which shows that only 1% of the ultraviolet continuum typically
escapes extinction by dust within a starburst. 相似文献
4.
《Experimental Astronomy》2009,23(1):435-461
As a response to ESA call for mission concepts for its Cosmic Vision 2015–2025 plan, we propose a mission called Darwin. Its primary goal is the study of terrestrial extrasolar planets and the search for life on them. In this paper, we describe
different characteristics of the instrument.
相似文献
Charles S. CockellEmail: |
5.
The Space Infrared telescope for Cosmology and Astrophysics (SPICA) is planned to be the next space astronomy mission observing
in the infrared. The mission is planned to be launched in 2017 and will feature a 3.5 m telescope cooled to <5 K through the
use of mechanical coolers. These coolers will also cool the focal plane instruments thus avoiding the use of consumables and
giving the mission a long lifetime. SPICA’s large, cold aperture will provide a two order of magnitude sensitivity advantage
over current far infrared facilities (>30 microns wavelength). We describe the scientific advances that will be made possible
by this large increase in sensitivity and give details of the mission, spacecraft and focal plane conceptual design.
相似文献
Bruce SwinyardEmail: |
6.
S. Schiller G. M. Tino P. Gill C. Salomon U. Sterr E. Peik A. Nevsky A. Görlitz D. Svehla G. Ferrari N. Poli L. Lusanna H. Klein H. Margolis P. Lemonde P. Laurent G. Santarelli A. Clairon W. Ertmer E. Rasel J. Müller L. Iorio C. Lämmerzahl H. Dittus E. Gill M. Rothacher F. Flechner U. Schreiber V. Flambaum Wei-Tou Ni Liang Liu Xuzong Chen Jingbiao Chen Kelin Gao L. Cacciapuoti R. Holzwarth M. P. Heß W. Schäfer 《Experimental Astronomy》2009,23(2):573-610
The Einstein Gravity Explorer mission (EGE) is devoted to a precise measurement of the properties of space-time using atomic
clocks. It tests one of the most fundamental predictions of Einstein’s Theory of General Relativity, the gravitational redshift,
and thereby searches for hints of quantum effects in gravity, exploring one of the most important and challenging frontiers
in fundamental physics. The primary mission goal is the measurement of the gravitational redshift with an accuracy up to a
factor 104 higher than the best current result. The mission is based on a satellite carrying cold atom-based clocks. The payload includes
a cesium microwave clock (PHARAO), an optical clock, a femtosecond frequency comb, as well as precise microwave time transfer
systems between space and ground. The tick rates of the clocks are continuously compared with each other, and nearly continuously
with clocks on earth, during the course of the 3-year mission. The highly elliptic orbit of the satellite is optimized for
the scientific goals, providing a large variation in the gravitational potential between perigee and apogee. Besides the fundamental
physics results, as secondary goals EGE will establish a global reference frame for the Earth’s gravitational potential and
will allow a new approach to mapping Earth’s gravity field with very high spatial resolution. The mission was proposed as
a class-M mission to ESA’s Cosmic Vision Program 2015–2025.
相似文献
S. SchillerEmail: |
7.
Michele Kaufman 《Astrophysics and Space Science》1976,40(2):369-384
Absorption by gas and dust in circumstellar Hii regions within primeval galaxies could seriously depress the far-ultraviolet continuum radiation emitted by primeval galaxies. This effect might account for the failure of Partridge (1974) and Davis and Wilkinson (1974) to detect the redshifted radiation from primeval galaxies at optical and near-infrared wavelengths. A primeval galaxy becomes very bright only during the final stages of contraction. Provided that dust can form by the time the primeval galaxy reaches peak luminosity, a significant fraction of the stellar far-ultraviolet radiation is converted into far-infrared. Thus an appropriate spectral region to search for the redshifted integrated background from primeval galaxies lies between 350 , where the 2.7 K microwave background radiation becomes important, and 150 , where other extragalactic discrete sources, such as nearby galactic nuclei, may contribute. The expected IR flux is calculated with Kaufman's (1975) model for the star formation rate in the contracting galaxy. Letz
p be the redshift andT
g the grain temperature when the primeval galaxy becomes very bright. Unlessz
p10 orT
g is fairly high, the intensity of the far-infrared radiation from primeval galaxies would be dominated by the high frequency tail of the 2.7 K microwave background. On the other hand, if dust is unimportant, we determine the spectral energy distribution of a primeval galaxy emitted in the range 912 Å to 2050 Å; we find that the luminosities are not very sensitive to the dependence of effective temperatures on metal abundance. 相似文献
8.
The main goal of this paper is to compare the relative importance of destruction by tides vs. destruction by mergers, in order to assess if tidal destruction of galaxies in clusters is a viable scenario for explaining
the origin of intracluster stars. We have designed a simple algorithm for simulating the evolution of isolated clusters. The
distribution of galaxies in the cluster is evolved using a direct gravitational N-body algorithm combined with a subgrid treatment of physical processes such as mergers, tidal disruption, and galaxy harassment.
Using this algorithm, we have performed a total of 148 simulations. Our main results are:
相似文献
– | destruction of dwarf galaxies by mergers dominates over destruction by tides, and |
– | the destruction of galaxies by tides is sufficient to explain the observed intracluster light in clusters. |
9.
Minnie Y. Mao Rob Sharp D. J. Saikia Ray P. Norris Melanie Johnston-Hollitt Enno Middelberg Jim E. J. Lovell 《Journal of Astrophysics and Astronomy》2011,32(4):585-588
Using the Australia Telescope Compact Array (ATCA), ATLAS (Australia Telescope Large Area Survey) is imaging two fields totalling
7 square degrees down to 10 μJy beam − 1 at 1.4 GHz. We have found 6 wide-angle tail galaxies (WATs), 4 of which have sufficient data to identify associated galaxy
overdensities. The largest WAT, at a red-shift of 0.22, appears to be associated with an overdensity of galaxies that is spread
over an unusually large extent of 12 Mpc, with a velocity range of 4500 km s − 1. Here we present the WATs in ATLAS and discuss the implications of these observations for future large-scale radio surveys
such as ASKAP-EMU. 相似文献
10.
H. M. Tovmassian 《Astrophysics and Space Science》1990,164(2):257-262
It is shown that the brightness of the spiral galactic nuclei at 10 depends on the Byurakan type of galaxies: the brightness is higher in the case of galaxies of types 5, 2s, 4, and 2 with optical signs of activity in comparison with galaxies of types 3 and 1 without optical signs of activity. The noted difference is larger when nonstellar emission at 10 is considered. The obtained results confirm conclusions made earlier on the activity of the nuclei of galaxies of types 5, 2s, 4, and 2. 相似文献
11.
Matthias Beilicke 《Astrophysics and Space Science》2007,309(1-4):139-145
The HESS experiment (High Energy Stereoscopic System), consisting of four imaging atmospheric Cherenkov telescopes (IACTs)
in Namibia, has observed many extragalactic objects in the search for very high energy (VHE) γ-ray emission. These objects include active galactic nuclei (AGN), notably Blazars, Seyferts, radio galaxies, starburst galaxies
and others. Beyond the established sources, γ-ray emission has been detected for the first time from several of these objects by HESS, and their energy spectra and variability
characteristics have been measured. Multi-wavelength campaigns, including X-ray satellites, radio telescopes, and optical
observations, have been carried out for AGNs, in particular for PKS 2155-304, H 2356-309 and 1ES 1101-232, for which the implications
concerning emission models are presented. Also results from the investigations of VHE flux variability from the giant radio
galaxy M 87 are shown.
For the HESS Collaboration. 相似文献
12.
M. Ollivier O. Absil F. Allard J.-P. Berger P. Bordé F. Cassaing B. Chazelas A. Chelli O. Chesneau V. Coudé du Foresto D. Defrère P. Duchon P. Gabor J. Gay E. Herwats S. Jacquinod P. Kern P. Kervella J.-M. Le Duigou A. Léger B. Lopez F. Malbet D. Mourard D. Pelat G. Perrin Y. Rabbia D. Rouan J.-M. Reiss G. Rousset F. Selsis P. Stee J. Surdej 《Experimental Astronomy》2009,23(1):403-434
PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars
(particularly those in the DARWIN catalogue) and the observation of low mass companions around nearby stars. It is a space
interferometer project composed of three free flying spacecraft, respectively featuring two 40 cm siderostats and a beam combiner
working in the visible and near infrared. It has been proposed to ESA as an answer to the first “Cosmic Vision” call for proposals,
as an M mission. The concept also enables full-scale demonstration of space nulling interferometry operation for DARWIN.
相似文献
M. OllivierEmail: |
13.
《Experimental Astronomy》2009,23(1):91-120
The primary scientific goal of the GRIPS mission is to revolutionize our understanding of the early universe using γ-ray bursts. We propose a new generation gamma-ray observatory capable of unprecedented spectroscopy over a wide range of
γ-ray energies (200 keV–50 MeV) and of polarimetry (200–1000 keV). The γ-ray sensitivity to nuclear absorption features enables the measurement of column densities as high as 1028cm − 2. Secondary goals achievable by this mission include direct measurements of all types of supernova interiors through γ-rays from radioactive decays, nuclear astrophysics with massive stars and novae, and studies of particle acceleration near
compact stars, interstellar shocks, and clusters of galaxies.
See for the authors’ affiliations. 相似文献
14.
Until recently far infrared (FIR) observations of galaxies were limited to about a dozen bright and/or active galaxies. New photometric data has become available from Infrared Astronomical Satellite (IRAS) on 33 galaxies (most of them faint) from IRAS Circular Nos. 1, 2, and 3 The FIR spectra of these galaxies are similar. The far infrared fluxF
FIR in the wavelength interval 9–118 m of the brighter galaxies is seen to be correlated with the integrated optical magnitudeB
T
0
. The 12 and 25 m fluxes of these galaxies exhibit the same dependence onB
T
0
as the 10 and 21 m fluxes from Seyferts and other emission-line galaxies. This suggests that the galaxies detected by IRAS are some type of active galaxies in accord with the high percentage of these galaxies predicted by Lock and Rowan-Robinson (1983). 相似文献
15.
Using an apparent-magnitude limited Main galaxy sample of the Sloan Digital Sky Survey Data Release 7(SDSS DR7), we investigate
the correlation between morphologies and luminosity for the Main galaxy sample. Our Main galaxy sample is divided into two
classes: Main galaxies only with TARGET_GALAXY flag (bestPrimtarget = 64), and ones also with other flags. It is found that
for the second class Main galaxies, the early-type proportion monotonously increases with increasing luminosity nearly in
the whole luminosity region. But for the first class Main galaxies, the early-type proportion increases with increasing luminosity
only within a certain luminosity region (−22.2 < M
r
< −19.8). In the high luminosity region (M
r
< −22.2), the early-type proportion of the first class Main galaxies even decreases dramatically with increasing luminosity.
We also analyze the correlation between morphologies and luminosity of galaxies around the peak of the redshift distribution
( 0.07 ≤ z ≤ 0.08 ). In such a narrow redshift region, we still observe strong correlation between morphologies and luminosity,
which shows that this correlation is fundamental. 相似文献
16.
Dominic J. Benford Michael J. Amato John C. Mather S. Harvey Moseley Jr David T. Leisawitz 《Astrophysics and Space Science》2004,294(3-4):177-212
The Single Aperture Far-InfraRed (SAFIR) Observatory’s science goals are driven by the fact that the earliest stages of almost
all phenomena in the universe are shrouded in absorption by and emission from cool dust and gas that emits strongly in the
far-infrared (40μ–200μ) and submillimeter (200μ–1 mm). In the very early universe, the warm gas of newly collapsing, unenriched
galaxies will be revealed by molecular hydrogen emission lines at these long wavelengths. High redshift quasars are found
to have substantial reservoirs of cool gas and dust, indicative of substantial metal enrichment early in the history of the
universe. As a result, even early stages of galaxy formation will show powerful far-infrared emission. The combination of
strong dust emission and large redshift (1 < z < 7) of these galaxies means that they can only be studied in the far-infrared and submillimeter. For nearby galaxies, many
of the most active galaxies in the universe appear to be those whose gaseous disks are interacting in violent collisions.
The details of these galaxies, including the effect of the central black holes that probably exist in most of them, are obscured
to shorter wavelength optical and ultraviolet observatories by the large amounts of dust in their interstellar media. Within
our own galaxy, the earliest stages of star formation, when gas and dust clouds are collapsing and the beginnings of a central
star are taking shape, can only be observed in the far-infrared and submillimeter. The cold dust that ultimately forms the
planetary systems, as well as the cool “debris” dust clouds that indicate the likelihood of planetary sized bodies around
more developed stars, can only be observed at wavelengths longward of 20μ.
Over the past several years, there has been an increasing recognition of the critical importance of the far-infrared to submillimeter
spectral region to addressing fundamental astrophysical problems, ranging from cosmological questions to understanding how
our own Solar System came into being. The development of large, far-infrared telescopes in space has become more feasible
with the combination of developments for the James Webb Space Telescope (JWST) of enabling breakthroughs in detector technology.
We have developed a preliminary but comprehensive mission concept for SAFIR, as a 10 m-class far-infrared and submillimeter
observatory that would begin development later in this decade to meet the needs outlined above. Its operating temperature
(≤4 K) and instrument complement would be optimized to reach the natural sky confusion limit in the far-infrared with diffraction-limited
performance down to at least the atmospheric cutoff, λ {>rsim} 40 {μ}. This would provide a point source sensitivity improvement of several orders of magnitude over that of the Spitzer
Space Telescope (previously SIRTF) or the Herschel Space Observatory. Additionally, it would have an angular resolution 12
times finer than that of Spitzer and three times finer than Herschel. This sensitivity and angular resolution are necessary
to perform imaging and spectroscopic studies of individual galaxies in the early universe. We have considered many aspects
of the SAFIR mission, including the telescope technology (optical design, materials, and packaging), detector needs and technologies,
cooling method and required technology developments, attitude and pointing, power systems, launch vehicle, and mission operations.
The most challenging requirements for this mission are operating temperature and aperture size of the telescope, and the development
of detector arrays. SAFIR can take advantage of much of the technology under development for JWST, but with much less stringent
requirements on optical accuracy. 相似文献
17.
Renzo Sancisi Filippo Fraternali Tom Oosterloo Thijs van der Hulst 《Astronomy and Astrophysics Review》2008,15(3):189-223
Evidence for the accretion of cold gas in galaxies has been rapidly accumulating in the past years. HI observations of galaxies and their environment have brought to light new facts and phenomena which are evidence of ongoing
or recent accretion: (1) A large number of galaxies are accompanied by gas-rich dwarfs or are surrounded by HI cloud complexes, tails and filaments. This suggests ongoing minor mergers and recent arrival of external gas. It may be regarded,
therefore, as direct evidence of cold gas accretion in the local universe. It is probably the same kind of phenomenon of material
infall as the stellar streams observed in the halos of our galaxy and M 31. (2) Considerable amounts of extra-planar HI have been found in nearby spiral galaxies. While a large fraction of this gas is undoubtedly produced by galactic fountains,
it is likely that a part of it is of extragalactic origin. Also the Milky Way has extra-planar gas complexes: the Intermediate-
and High-Velocity Clouds (IVCs and HVCs). (3) Spirals are known to have extended and warped outer layers of HI. It is not clear how these have formed, and how and for how long the warps can be sustained. Gas infall has been proposed
as the origin. (4) The majority of galactic disks are lopsided in their morphology as well as in their kinematics. Also here
recent accretion has been advocated as a possible cause. In our view, accretion takes place both through the arrival and merging
of gas-rich satellites and through gas infall from the intergalactic medium (IGM). The new gas could be added to the halo
or be deposited in the outer parts of galaxies and form reservoirs for replenishing the inner parts and feeding star formation.
The infall may have observable effects on the disk such as bursts of star formation and lopsidedness. We infer a mean “visible”
accretion rate of cold gas in galaxies of at least . In order to reach the accretion rates needed to sustain the observed star formation (), additional infall of large amounts of gas from the IGM seems to be required. 相似文献
18.
Hα luminosities of a sample of galaxies in nearby compactgroups are presented. Our purpose is to study the influence of thegroup
environment on the star formation rates (SFRs) of the galaxies in thegroups, provided that the Hα luminosity is a good tracer of theSFR of disc galaxies. Measuring the global L
/L
B of the groups – including early-type galaxies – we find that the average value of the Hα emission is not significantly different from thatmeasured for field galaxies, and that most of the groups that show thehighest
level of L
/L
B, with respect to a set of synthetic groups built out of field galaxies, show tidal features in at least one of their members.
Finally, we have exploredthe relationship between the ratio L
/L
B and severalrelevant dynamical parameters of the groups (velocity dispersion, crossingtime, radius and mass-to-luminosity
ratio) and have found no clearcorrelation. This suggests that the exact dynamical state of a groupdoes not appear to control
the SFR of the group as a whole.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Ultra-high resolution hydrodynamic simulations using 10243 grid points are performed of early supernova burst in a forming galaxy, with properties similar to those inferred for Lyman
α emitters (LAEs) and Lyman Break Galaxies (LBGs). We show that, at the earliest stages of less than 300 Myr, continual supernova
explosions produce multitudinous hot bubbles and cooled H(I) shells in-between. The H(I) shells radiate intense Lyman α (Lyα) emission like LAEs. We found that the bubbly structures produced are quite similar to the observed features in the Lyα surface brightness distribution of the extended LAEs. After 1 Gyr, the galaxies are dominated by stellar continuum radiation
and then resemble the LBGs. At this point, the abundance of heavy elements appears to be solar. After 13 Gyr, these galaxies
resemble present-day ellipticals. 相似文献
20.
Comparisons of solar magnetic-field measurements made in different spectral lines are very important, especially in those
lines in which observations have a long history or (and) specific diagnostic significance. The spectral lines Fe i 523.3 nm and Fe i 525.0 nm belong to this class. Therefore, this study is devoted to a comprehensive analysis using new high-precision Stokes-meter
full-disk observations. The disk-averaged magnetic-field strength ratio R=B(523.3)/B(525.0) equals 1.97±0.02. The center-to-limb variation (CLV) is R=1.74−2.43μ+3.43μ
2, where μ is the cosine of the center-to-limb angle. For the disk center, we find R=2.74, and for near-limb areas with μ=0.3, R equals 1.32. There is only a small dependence of R on the spatial resolution. Our results are rather close to those published three decades ago, but differ significantly from
recent magnetographic observations. An application of our results to the important SOHO/MDI magnetic data calibration issue
is discussed. We conclude that the revision of the SOHO/MDI data, based only on the comparison of magnetic-field measurements
in the line pair Fe i 523.3 nm and Fe i 525.0 nm (increasing by a factor of 1.7 or 1.6 on average according to recent publications) is not obvious and new investigations
are urgently needed. 相似文献