An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 14 Search : lensing
CMB lensing
  لنزش ِ CMB   
lenzeš-e CMB

Fr.: effet de lentille du rayonnement du fond cosmique, ~ ~ du CMB   

The gravitational effect of the intervening large-scale potentials on the → cosmic microwave background radiation (CMBR). This effect smoothes out the temperature peaks and alters the statistics of the CMB.

CMB; → lensing.

gravitational lensing
  لنزش ِ گرانشی   
lenzeš-e gerâneši

Fr.: effet de lentille gravitationelle   

The act of producing or the state of a → gravitational lens.

gravitational; → lensing.

gravitational lensing time delay
  درنگ ِ زاییده‌ی ِ لنزش ِ گرانشی   
derang-e zâyide-ye lenzeš-e gerâneši

Fr.: retard dû à l'effet de lentille gravitationnelle   

The difference in light travel times along the various light paths from the source to the observer when the source image is divided into several images because of → gravitational lensing. According to the theory of → general relativity, light rays are deflected in the vicinity of massive objects. If the light source, and the deflector are sufficiently well aligned, we can observe several (generally distorted and magnified) images of the source. A property of → strong lensing is that the light travel time from the source to the observer is generally not identical for the different images. In other words, we not only see several images of one same object, but we also see this object, in each image, at different times. This means, in one image the lensed object will be observed before the other image. Given a physical model of the gravitational lens, the light travel time for each image can be computed. The expression giving the time delay has two components: a term is called → geometric delay, and the second term, known as the → Shapiro delay. The latter is due to time dilation by the gravitational field of the lens, a direct consequence of general relativity. See also → time delay distance.

gravitational; → lensing; → time; → delay.

lensing
  ۱) لنزش؛ ۲) لنزنده   
1) (n.) lenzeš; 2) (adj.) lenzandé

Fr.: 1) effet de lentille; 2) amplificateur   

1) The act or effect produced by a lens, in particular a → gravitational lens.
2) Pertaining to the object that produces the lensing effect. → lensing galaxy.

From → lens + → -ing.

1) Lenzeš, verbal noun of lenzidan, verb formed from E. lens + -idan infinitive suffix.
2) Lenzandé, verbal adj. from lenzidan, as above.

lensing effect
  ا ُسکر ِ لنزش   
oskar-e lenzeš

Fr.: effet de lentille   

Effect created by a → gravitational lens.

lensing; → effect.

lensing galaxy
  کهکشان ِ لنزنده   
kahkeâân-e lenzandé

Fr.: galaxie amplificatrice   

A galaxy that acts as a → gravitational lens. The effect can also be due to a cluster of galaxies.

lensing; → galaxy.

lensing object
  بر‌آخت ِ لنزنده   
barâxt-e lenzandé

Fr.: objet amplificateur   

An astronomical object that creates → gravitational lensing. See also → lensing galaxy.

lensing; → object.

lensing potential
  توند ِ لنزش   
tavand-e lenzeš

Fr.: potentiel de l'effet de lentille gravitationnelle   

An important quantity in the characterization of → gravitational lensing. The lensing potential is obtained by projecting the three-dimensional Newtonian potential on the lens plane and by properly re-scaling it. It is a two-dimensional analog to the → gravitational potential.

lensing; → potential.

microlensing
  ریز‌لنزش   
riz-lenzeš

Fr.: effet de microlentille   

A type of → gravitational lens, where the foreground → lensing object is of low mass. Microlensing is used in the search for → dark matter inthe → Milky Way galaxy and its nearest neighbours, as well as for → extrasolar planets.

micro-; → lensing.

microlensing degeneracy
  واگنی ِ ریز‌لنزش   
vâgeni-ye riz-lenzeš

Fr.: dégénérescence des paramètres de l'effet de microlentille   

Determining the three various parameters of a microlensing event (the lens-source relative parallax and proper motion, and the mass of the lens) from only one physical parameter (the event time scale). Currently the microlensing degeneracy affects the vast majority of events and makes any individual event impossible to interpret with certainty.

microlensing; → degeneracy.

strong gravitational lensing
  لنزش ِ گرانشی ِ سترگ   
lenzeš-e gerâneši-ye sotorg

Fr.: effet de lentille gravitationnelle forte   

A → gravitational lensing phenomenon in which the image distortion is strong enough to be readily recognized, such as in the case of the → Einstein cross or when giant luminous arcs show up in → galaxy clusters (e.g. Abell 2218). Opposite to → weak gravitational lensing.

strong; → gravitational; → lensing.

strong lensing
  لنزش ِ سترگ   
lenzeš-e sotorg

Fr.: effet de lentille fort   

A situation where the mass concentration in the central regions of → galaxy clusters exceeds the → critical density required for lensing, resulting in multiple images of background objects.

strong; → lensing.

weak gravitational lensing
  لنزش ِ گرانشی ِ نزار   
lenzeš-e gerâneši-ye nezâr

Fr.: effet de lentille gravitationnelle faible   

A gravitational bending of light by structures in the Universe that distorts the images of distant galaxies. The distortion allows the distribution of → dark matter and its evolution with time to be measured, thereby probing the influence of → dark energy on the growth of structures. Weak gravitational lensing is generally difficult to identify in individual images, in contrast to → strong gravitational lensing (see, e.g., Bartelmann & Peter Schneider, 2001, Phys. Rept. 340, 291).

weak; → gravitational; → lensing.

weak lensing
  لنزش ِ نزار   
lenzeš-e nazâr

Fr.: effet de lentille faible   

The → gravitational lensing in which the images are only weakly distorted, and do not form wide arcs or multiple image systems. This happens if the → gravitational lens mass in front of a source is not concentrated enough to form multiple images. The resulting small distortions cannot be seen on individual sources, as we do not know their unlensed, "intrinsic" shape. However, if an entire population of background sources is available, the distortions can be revealed, either statistically or by local averaging. See also → strong lensing.

weak; → lensing.