2004A&A...420..881Z


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.03CET18:33:17

2004A&A...420..881Z - Astronomy and Astrophysics, volume 420, 881-888 (2004/6-4)

On the contribution of microlensing to X-ray variability of high-redshifted QSOs.

ZAKHAROV A.F., POPOVIC L.C. and JOVANOVIC P.

Abstract (from CDS):

We consider a contribution of microlensing to the X-ray variability of high-redshifted QSOs. Such an effect could be caused by stellar mass objects (SMO) located in a bulge or/and in a halo of this quasar as well as at cosmological distances between an observer and a quasar. Here, we not consider microlensing caused by deflectors in our Galaxy since it is well-known from recent MACHO, EROS and OGLE observations that the corresponding optical depth for the Galactic halo and the Galactic bulge is lower than 10–6. Cosmologically distributed gravitational microlenses could be localized in galaxies (or even in bulge or halo of gravitational macrolenses) or could be distributed in a uniform way. We have analyzed both cases of such distributions. As a result of our analysis, we obtained that the optical depth for microlensing caused by stellar mass objects is usually small for quasar bulge and quasar halo gravitational microlens distributions (τ∼10–4). On the other hand, the optical depth for gravitational microlensing caused by cosmologically distributed deflectors could be significant and could reach 10–2-0.1 at z∼2. This means that cosmologically distributed deflectors may contribute significantlly to the X-ray variability of high-redshifted QSOs (z>2). Considering that the upper limit of the optical depth (τ∼0.1) corresponds to the case where dark matter forms cosmologically distributed deflectors, observations of the X-ray variations of unlensed QSOs can be used for the estimation of the dark matter fraction of microlenses.

Abstract Copyright:

Journal keyword(s): accretion, accretion disks - gravitational lensing - galaxies: quasars: general

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 4C 05.19 QSO 04 14 37.7673624 +05 34 42.328449   24.100 23.800 21.270   ~ 333 2
2 QSO J0831+5245 QSO 08 31 41.7095363198 +52 45 17.620340544   19.2   14.5 13.9 ~ 493 1
3 8C 0958+561 QSO 10 01 20.6915852239 +55 53 55.595776916   17.16 16.95     ~ 701 3
4 QSO B0957+5608B QSO 10 01 20.8374436455 +55 53 49.543959298   17.16 16.95     ~ 266 1
5 QSO J1415+1129 QSO 14 15 46.25 +11 29 43.4   17.63 17.23     ~ 600 1
6 NGC 5548 Sy1 14 17 59.5401093128 +25 08 12.600227883   14.35 13.73     ~ 2425 0
7 QSO J2240+0321 QSO 22 40 30.234 +03 21 30.63           ~ 645 0
8 Z 378-15 G 22 40 30.23447 +03 21 30.6290           ~ 629 0

    Equat.    Gal    SGal    Ecl

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2020.12.03-18:33:17

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