Microlensing results from APO monitoring of the double quasar Q 0957 + 561 A , B between 1995 and 1998
نویسنده
چکیده
If the halo of the lensing galaxy 0957+561 is made of massive compact objects (MACHOs), they must affect the lightcurves of the quasar images Q0957+561 A and B differently. We search for this microlensing effect in the double quasar by comparing monitoring data for the two images A and B – obtained with the 3.5m Apache Point Observatory from 1995 to 1998 – with intensive numerical simulations. This way we test whether the halo of the lensing galaxy can be made of MACHOs of various masses. We can exclude a halo entirely made out of MACHOs with masses between 10−6 M and 10−2 M for quasar sizes of less than 3 × 1014 h−1/2 60 cm, hereby extending previous limits upwards by one order of magnitude.
منابع مشابه
Optical monitoring of the gravitationally lensed quasar Q 2237 + 0305 from APO between June 1995 and January 1998 ?
We present a data set of images of the gravitationally lensed quasar Q2237+0305, that was obtained at the Apache Point Observatory (APO) between June 1995 and January 1998. Although the images were taken under variable, often poor seeing conditions and with coarse pixel sampling, photometry is possible for the two brighter quasar images A and B with the help of exact quasar image positions from...
متن کاملA Rapid Microlensing Event in the Q0957+561 A,B Gravitational Lens System
We re-analyze brightness data sampled intensively over 5 nights at two epochs separated by the quasar lens time delay, to examine the nature of the observed microlensing. We find strong evidence for a microlensing event with an amplitude of 1% and a time scale of twelve hours. The existence of such rapid microlensing, albeit at low amplitude, imposes constraints on the nature of the quasar and ...
متن کاملConstraints on source and lens parameters from microlensing variability in QSO 0957 + 561 A , B
From regular monitoring of the Double Quasar QSO 0957+561 A,B there is now general agreement on a time delay of about 416 days. This has made it possible to determine the microlensing residual in the light-curve, see Pelt et al. (1998). We have used two significant microlensing features: 1) A " quiet " period with a variability less than 0.05 mag lasting about 8 years, and 2) A change in the re...
متن کاملConstraints on source and lens parameters from microlensing variability in QSO 0957
From regular monitoring of the Double Quasar QSO 0957+561 A,B there is now general agreement on a time delay of about 416 days. This has made it possible to determine the microlensing residual in the light-curve, see Pelt et al. (1998). We have used two significant microlensing features: 1) A " quiet " period with a variability less than 0.05 mag lasting about 8 years, and 2) A change in the re...
متن کاملLimits on MACHOs from microlensing in the double quasar Q0957+561
The light curves of the two images of the double quasar Q0957+561 as obtained by Kundić et al. (1997) are almost identical, except for an overall time delay and scaling factor. This allows us to put limits on the amount of microlensing that took place during the time interval corresponding to the monitoring observations. We perform numerical simulations in which we model the microlensing behavi...
متن کامل