Determining time delay in the gravitationally   lensed system QSO2237+0305

Koptelova, E.; Oknyanskij, V. L.; Shimanovskaya, E. V.

doi:10.1051/0004-6361:20054050

Cited by 25 publications

(29 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A recent analysis by Shalyapin et al (2008) of the g‐ and r ‐band light curves of Q0957+561 confirms the time delay measured by Collier (2001). Evidence of the time delay between the brightness variations in the V and R bands has also been found for the system Q2237+0305 (Koptelova, Oknyanskij & Shimanovskaya 2006). The correlation between variations in the V ‐ and R ‐band light curves of quasars from the massive compact halo object data base was studied by Magdis & Papadakis (2006).…”

Section: Time Delay Measurementssupporting

confidence: 58%

See 1 more Smart Citation

Intrinsic quasar variability and time delay determination in the lensed quasar UM673

Koptelova¹,

Oknyanskij²,

Артамонов³

et al. 2010

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We present the results of time delay measurements between the A and B components of the gravitationally lensed quasar UM673. The measurements are based on the brightness variations of the quasar components observed with the 1.5‐m telescope of the Maidanak Observatory in the V, R and I bands during the 2003–2005 observational period. The amplitudes of variations in the R band are 0.046 and 0.122 mag for Component A and B, respectively. Due to the short visibility period of UM673, about 3 months in a year, the light curves of the quasar components have large annual gaps. It complicates the time delay estimation. From the cross‐correlation analysis, we find that the brightness variations in component B follow the brightness variations in Component A by about 150 days. We also explore the possibility of measuring the wavelength‐dependent time delay between the brightness variations in the V, R and I bands. We find that in agreement with reprocessing model of quasar variability, the brightness variation at longer wavelengths follows the brightness variations at shorter wavelengths. Finally, we show that the combination of the multiband data corrected for the wavelength‐dependent time delay can help to improve the cross‐correlation analysis of the light curves with large annual gaps.

show abstract

Section: Time Delay Measurementssupporting

confidence: 58%

“…If there is a time lag between two different bands, the light curves in these bands should also be shifted to the same epoch of observations (see e.g. Oknyanskij 1999; Collier 2001; Koptelova et al 2006). The visibility period corresponding to the combined light curves can be made larger by correcting for interband time delay.…”

Section: Time Delay Measurementsmentioning

confidence: 99%

Intrinsic quasar variability and time delay determination in the lensed quasar UM673

Koptelova¹,

Oknyanskij²,

Артамонов³

et al. 2010

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…For Q0957+561, Collier (2001) reported a delay of about 3.4 d between the r-band and g-band APO main events (g-band events leading those in the r band), which translates into a rest-frame lag of about 1.4 d, in excellent agreement with predictions of the disc reprocessing scenario. This first delay between optical bands for a GLQ requires an independent confirmation as well as new efforts with other GLQs (e.g., Koptelova et al 2006), and here we try to reach the first goal.…”

Section: Delay Between Optical Bandsmentioning

confidence: 88%

New two-colour light curves of Q0957+561: time delays and the origin of intrinsic variations

Shalyapin¹,

Goicoechea²,

Koptelova³

et al. 2008

A&A

View full text Add to dashboard Cite

Aims. We extend the gr-band time coverage of the gravitationally lensed double quasar Q0957+561. New gr light curves permit us to detect significant intrinsic fluctuations, to determine new time delays, and thus to gain perspective on the mechanism of intrinsic variability in Q0957+561. Methods. We use new optical frames of Q0957+561 in the g and r passbands from January 2005 to July 2007. These frames are part of an ongoing long-term monitoring with the Liverpool robotic telescope. We also introduce two photometric pipelines that are applied to the new gr frames of Q0957+561. The transformation pipeline incorporates zero-point, colour, and inhomogeneity corrections to the instrumental magnitudes, so final photometry to the 1-2% level is achieved for both quasar components. The two-colour final records are then used to measure time delays. Results. The gr light curves of Q0957+561 show several prominent events and gradients, and some of them (in the g band) lead to a time delay between components Δt BA = 417 ± 2 d (1σ). We do not find evidence of extrinsic variability in the light curves of Q0957+561. We also explore the possibility of a delay between a large event in the g band and the corresponding event in the r band. The gr cross-correlation reveals a time lag Δt rg = 4.0 ± 2.0 d (1σ; the g-band event is leading) that confirms a previous claim of the existence of a delay between the g and r band in this lensed quasar. Conclusions. The time delays (between quasar components and between optical bands) from the new records and previous ones in similar bands indicate that most observed variations in Q0957+561 (amplitudes of ∼100 mmag and timescales of ∼100 d) are very probably due to reverberation within the gas disc around the supermassive black hole.

show abstract

“…A multi-epoch multi-band photometry, carried out during several years, was used for the quasar Q2237+0305 by Koptelova et al (2006), who observed the object during five years (1995)(1996)(1997)(1998)(1999)(2000) in the VRI bands. Anguita et al (2008) combined these data with OGLE observations.…”

Section: Introductionmentioning

confidence: 99%

Flux and color variations of the quadruply imaged quasar HE 0435-1223

Ricci

Poels

Elyiv

et al. 2011

A&A

View full text Add to dashboard Cite

Aims. We present VRi photometric observations of the quadruply imaged quasar HE0435-1223, carried out with the Danish 1.54 m telescope at the La Silla Observatory. Our aim was to monitor and study the magnitudes and colors of each lensed component as a function of time. Methods. We monitored the object during two seasons (2008 and 2009) in the VRi spectral bands, and reduced the data with two independent techniques: difference imaging and point spread function (PSF) fitting. Results. Between these two seasons, our results show an evident decrease in flux by ≈0.2-0.4 magnitudes of the four lensed components in the three filters. We also found a significant increase (≈0.05-0.015) in their V − R and R − i color indices. Conclusions. These flux and color variations are very likely caused by intrinsic variations of the quasar between the observed epochs. Microlensing effects probably also affect the brightest "A" lensed component.

show abstract

Determining time delay in the gravitationally lensed system QSO2237+0305

Cited by 25 publications

References 36 publications

Intrinsic quasar variability and time delay determination in the lensed quasar UM673

Intrinsic quasar variability and time delay determination in the lensed quasar UM673

New two-colour light curves of Q0957+561: time delays and the origin of intrinsic variations

Flux and color variations of the quadruply imaged quasar HE 0435-1223

Contact Info

Product

Resources

About