25 years after the discovery: some current topics on lensed qsos

25 YEARS AFTER THE DISCOVERY: SOME CURRENT TOPICS ON LENSED QSOs

Santander (Spain), 15th-17th December 2004

Short-time scale variability in gravitationally lensed quasars

Kharkov university, Ukraine

A.P. Zheleznyak, A.V.Sergeyev, V.V. Konichek , I.E.Sinelnikov

http://wise-obs.tau.ac.il/images/wise_tel2.jpg

http://linmax.sao.arizona.edu/help/FLWO/48/1.2m.jpg

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The goal of the workThe goal of the work : : reanalyze available data to check forreanalyze available data to check for

the presence of intranight brightness fluctuation in two the presence of intranight brightness fluctuation in two

gravitationally lensed quasars – Q0957+561 (“First Lens”) andgravitationally lensed quasars – Q0957+561 (“First Lens”) and

Q2237+0305 (“Einstein Cross”).Q2237+0305 (“Einstein Cross”).

An existence of brightness variation for both targets at large timeAn existence of brightness variation for both targets at large time

scales now is well established by many researchers. The situationscales now is well established by many researchers. The situation

is not so evident for the shorter time scales. Particularly, theis not so evident for the shorter time scales. Particularly, the

presence of fast brightness fluctuation for Q0957+561 A, B waspresence of fast brightness fluctuation for Q0957+561 A, B was

discovered by discovered by ColleyW.N & Schild R.E. ,2000, ApJ 540, p. 104ColleyW.N & Schild R.E. ,2000, ApJ 540, p. 104



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Maidanak observatory ( Central Asia, Maidanak observatory ( Central Asia, Uzbekistan altitude ~2500 m)Uzbekistan altitude ~2500 m)

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Q0957+561: Q0957+561: observational dataobservational data The data were obtained at Maidanak observatory during theThe data were obtained at Maidanak observatory during the

second run of QuOC monitoring programme. second run of QuOC monitoring programme.

The main QuOC result – the time delay determination of The main QuOC result – the time delay determination of

Q0957+561 A,B images with uncertainty of ~ 2h - is presented inQ0957+561 A,B images with uncertainty of ~ 2h - is presented in

Colley W.N., Schild R.E. &Colley W.N., Schild R.E. & 3838 coauthors coauthors, , ApJ ApJ 2003,2003, 587, 587, 11, , PP.. 71. 71.

The work similar to our with the QuOC data obtained with NOT,The work similar to our with the QuOC data obtained with NOT,

was fulfilled and published by Ovaldsen J.E., Teuber J. et al ., 2003,was fulfilled and published by Ovaldsen J.E., Teuber J. et al ., 2003,

MNRAS, 345, MNRAS, 345, 33 , P. 795. Reprocessing the NOT data had shown , P. 795. Reprocessing the NOT data had shown

no significant brightness variation of Q0957+561 A,B components.no significant brightness variation of Q0957+561 A,B components.



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The Maidanak observatory The Maidanak observatory

QuOC dataset includes ~ 380QuOC dataset includes ~ 380

images for 7 nights ofimages for 7 nights of

continuous observation withcontinuous observation with

frame rate ~10 frames/hour.frame rate ~10 frames/hour.

The main working band wasThe main working band was

R, the pixel angular size wasR, the pixel angular size was

equal 0.12 equal 0.12 .



Date, March 2001

Totally frames,R band

AverageFWHM,

14 53 0.86

15 57 1.16

16 48 1.18

17 46 1.64

18 40 1.89

20 60 0.89

21 64 1.00

6

Q0957+56Q0957+561,1,all framesall frames

0 0.4 0.8 1.2 1.6 2 2.4 2.8

0

20

40

60

80

Q 0957+561 M aidanak data set

380 fram es

FW H M.



The distribution of seeing estimates (FWHM) (FWHM) for the whole set of frames of Q0957+561

7

1983.1 1983.2 1983.3 1983.40

0.5

1

1.5

2 F W H M v s JDm arch 1 4 .2 0 0 1

FW

HM

, arc

sec

JD -2450000.

Seeing estimates for the set of frames of Q0957+561 obtained on March 14. 2001



Q0957+56Q0957+561,1,

March 14March 14

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CCD image of the field of Q0957+561 A,B obtained with 1.5 m AZT-22 telescope. The seeing FWHM=0.6", denoted standard stars F,G,H and comparison stars S1, S2. and comparison stars S1, S2.

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Presence of the lensing galaxy near B component

Variable seeing, tracking errors,…

Some sources of photometry uncertainty:Some sources of photometry uncertainty:

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Photometry: the Photometry: the approach approach



The method of Optimal Image Subtraction (Alard C., Lupton The method of Optimal Image Subtraction (Alard C., Lupton R.H., 1998, ApJ 503, 325) was developed for the search of R.H., 1998, ApJ 503, 325) was developed for the search of variable objects in crowded star fields, and was pioneered for variable objects in crowded star fields, and was pioneered for photometry of Q2237 components by Wozniak P.R., Alard C. photometry of Q2237 components by Wozniak P.R., Alard C. et al. 2000, ApJ 529, 88. The idea of the method - to determine et al. 2000, ApJ 529, 88. The idea of the method - to determine the optimal convolution kernel, which reduce PSF of the the optimal convolution kernel, which reduce PSF of the reference frame to PSF of current frame, analysing PSF’s reference frame to PSF of current frame, analysing PSF’s difference on all significant pixels. The result of subtraction of the difference on all significant pixels. The result of subtraction of the reference frame, convolved with optimal kernel, from the given reference frame, convolved with optimal kernel, from the given frame, contains only variable part of the flux for all objects in frame, contains only variable part of the flux for all objects in given image. given image.

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Photometry: the Photometry: the approachapproach

Im(x,y)+Bg(x,y) = Ref(x.y)Im(x,y)+Bg(x,y) = Ref(x.y)Ker(u,v)Ker(u,v)



2 2

2( )

2

, , ,

( , ) k

i j k n

u v

jinKer u v A e u v

For centered images For centered images Im(x,yIm(x,y) and ) and Ref(x,y):Ref(x,y):

2

,([ ]( , ) ( , ) ( , )) min

x yR Ker x y Im x y Bg x y

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Referent Referent frameframe



Current frame

Residual imageConvolution kernel

-------------------->>

Illustration of the work of Illustration of the work of image subtraction routineimage subtraction routine

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Q0957+561 A,B photometry for Maidanak data for 7 nights in Q0957+561 A,B photometry for Maidanak data for 7 nights in March 2001. All the light curves are in the same scale but March 2001. All the light curves are in the same scale but arbitrary shifted along Y. “Light curve” for star S1 is also plotted.arbitrary shifted along Y. “Light curve” for star S1 is also plotted.



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1 9 8 3 .1 1 9 8 3 .2 1 9 8 3 .3 1 9 8 3 .41 6 .5 4

1 6 .5

1 6 .4 6

1 6 .4 2

1 6 .3 8

1 6 .3 4

1 9 8 3 .1 1 9 8 3 .2 1 9 8 3 .3 1 9 8 3 .4

1 8 .1

1 8

1 7 .9

A

B

S 1

JD -2 4 5 0 0 0 0 JD -2 4 5 0 0 0 0

1 3 .8 2

1 3 .7 8

1 3 .7 4

1 3 .7

1 3 .6 6

GQ0957+5Q0957+5

61,61,

March 14March 14

Light curves for Q0957+561 A, B, standard star G and comparison star S1Light curves for Q0957+561 A, B, standard star G and comparison star S1

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Q0957+5Q0957+561,61,

March 15March 15

1 9 8 4 .2 1 9 8 4 .3 1 9 8 4 .41 6 .5 4

1 6 .5

1 6 .4 6

1 6 .4 2

1 6 .3 8

1 6 .3 4

1 9 8 4 .2 1 9 8 4 .3 1 9 8 4 .4

1 8 .1

1 8

1 7 .9

A

B

S 1

JD -2 4 5 0 0 0 0 JD -2 4 5 0 0 0 0

1 3 .8 2

1 3 .7 8

1 3 .7 4

1 3 .7

1 3 .6 6

G

.

16

1 9 9 0 .1 1 9 9 0 .2 1 9 9 0 .3 1 9 9 0 .4 1 9 9 0 .51 6 .5 4

1 6 .5 0

1 6 .4 6

1 6 .4 2

1 6 .3 8

1 6 .3 4

1 9 9 0 .1 1 9 9 0 .2 1 9 9 0 .3 1 9 9 0 .4

1 8 .1 0

1 8 .0 0

1 7 .9 0

A

B

S 1

JD -2 4 5 0 0 0 0 JD -2 4 5 0 0 0 0

1 3 .8 2

1 3 .7 8

1 3 .7 4

1 3 .7 0

1 3 .6 6

G

.



Q0957+5Q0957+561,61,

March 21March 21


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The results of The results of FF-test for Q0957+561 A,B components variability-test for Q0957+561 A,B components variability

(95 % significance(95 % significance) )



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Q2237+0305: Q2237+0305: observational dataobservational data

The data were obtained with AZT-22 telescope at MaidanakThe data were obtained with AZT-22 telescope at Maidanak

observatory during the continuous monitoring on July-Augustobservatory during the continuous monitoring on July-August

2000. Totally 549 frames were aquired during 36 nights in R2000. Totally 549 frames were aquired during 36 nights in R

band. The ST-7 CCD camera was used as the light detector,band. The ST-7 CCD camera was used as the light detector,

providing the pixel size 0.12 providing the pixel size 0.12 .

The search for short-time scale variability for Q2237+0305

components was fulfilled by many authors, particularly, by

C.M.Cumming M.M., de Robertis ( 1995, PASP 107, 469.),

HST observations- Blanton M. et al. (MNRAS,298,4, p.1223)



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CCD image of Q2237+0305 obtained with 1.5 m AZT-22 telescope.

R band, the seeing (FWHM) =0.70 .

Q2237+03Q2237+030505

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The brightness records for A-D components of Q2237+0305 and The brightness records for A-D components of Q2237+0305 and the reference star the reference star for seven nights in July-August 2000.for seven nights in July-August 2000.

0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 3 0 01 8 .4

1 8 .2

1 8

1 7 .8

1 7 .6

1 7 .4

1 7 .2

1 7

1 6 .8

1 6 .6

A

C

D

B

J U L 2 4 J U L 2 5 J U L 2 9 A U G 03 A U G 05 A U G 1 3 A U G 20

R m

agni

tude

F ram e N o .

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The light curves of A-D components of Q2237+0305 (night average The light curves of A-D components of Q2237+0305 (night average magnitude) for the continuous monitoring period in July-Aug. 2000.magnitude) for the continuous monitoring period in July-Aug. 2000.

1 6 .8 5

1 6 .8

1 6 .7 5

1 6 .7

1 6 .6 5

1 6 .6

1 7 5 0 1 7 6 0 1 7 7 0 1 7 8 0 1 7 9 0 1 8 0 0

1 8 .3

1 8 .2

1 8 .1

1 8

1 7 .9

1 7 .8

1 7 .7

1 7 .6

1 7 .5

JD -2 4 5 0 0 0 0 JD -2 4 5 0 0 0 0

1 7 5 0 1 7 6 0 1 7 7 0 1 7 8 0 1 7 9 0 1 8 0 0

1 9 .8

1 9 .6

1 9 .4

1 9 .2

1 9

A

B

C

D

R 1

.

Q2237+03Q2237+030505

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Some conclusions.Some conclusions. The analysis of the photometry for sets of images of two GLQ - The analysis of the photometry for sets of images of two GLQ -

Q0957+561 and Q2237+0305 reveal the presence of significant Q0957+561 and Q2237+0305 reveal the presence of significant (comparing to measurement errors) brightness fluctuation for the (comparing to measurement errors) brightness fluctuation for the first system, whereas no such fluctuation was found for the first system, whereas no such fluctuation was found for the second one. The modern CCD detectors and methods of image second one. The modern CCD detectors and methods of image processing assures precise photometrical measurements (1processing assures precise photometrical measurements (1%% or or a little better) of GLQ components with a 1-2 meter class a little better) of GLQ components with a 1-2 meter class telescope, located in a site with a good astroclimate. telescope, located in a site with a good astroclimate.

The important information about lens and source could be The important information about lens and source could be obtained from studying a fine features of light curves which rise obtained from studying a fine features of light curves which rise the question about the ways of future improving of the question about the ways of future improving of measurement precision.measurement precision.



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AcknowledgementsAcknowledgements

The authors are grateful to the Maidanak foundation for providingThe authors are grateful to the Maidanak foundation for providing

AZT-22 telescope of Maidanak observatory by the modern AZT-22 telescope of Maidanak observatory by the modern

scientific-grade CCD camera. scientific-grade CCD camera.

This work was partially supported by Ukrainian Science and This work was partially supported by Ukrainian Science and

Technology Committee grant NN43. Technology Committee grant NN43.



25 years after the discovery: some current topics on lensed qsos

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lensed qsos santander

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