We present the beginning of a multi-wavelength study of TeV blazars with the WIYN 0.9 meter telescope, the VERITAS/Whipple gamma-ray telescope, and the AMANDA/IceCube neutrino detectors. Corresponding optical and gamma-ray observations were taken of Mrk 421, Mrk 501, and 1ES 1959+650 in April and June of 2006. We aim to determine the flux variability of our sources and locate flaring moments to verify the timing dependence of neutrino occurrences and form a basis for a blinded neutrino analysis for AMANDA-II and IceCube.

Mrk 421

Mrk 501

1ES 1959 +650

Spectral Energy Distribution

Long Term Veritas Data

Future Work

Optical observations using the WIYN 0.9m telescope took place from April 18 - May 10 2006 and from June 15 - June 19 2006 until they were cut short in June when the telescope was hit by lightning. We utilized B and V filters to take our data then plotted the flux versus time. To obtain fluxes, we reduced and calibrated the images using standard comparison stars [1]. In order to see if neutrinos are related to flaring, we plan to determine when flares occur in optical and gamma-rays.

Mrk 421

In these plots, the flux is in units of Janskys, where 1 Jansky = 1e-23 erg s-1 m-2 Hz-1. The Rate for gamma rays in measured in Crabs, where 1 Crab is the TeV rate of the Crab nebula. The Crab nebula is used as the standard because it has had a relatively stable TeV rate over time.

Flux vs Date for Markarian 421

Optical data of B and V bandpasses for Mrk 421.

Rate(crabs) vs date for Markarian 421

Preliminary gamma ray data[9] for Mrk 421.

Mrk 501

Optical data for Markarian 501

Optical data of B and V bandpasses for Mrk 501.

Rate(crabs) vs date for Markarian 501

Preliminary gamma ray data[9] for Mrk 501.

1ES 1959 +650

Optical data for 1ES 1959 +650

Optical data of B and V bandpasses for 1ES 1959 +650

Rate(crabs) vs date for 1ES 1959 +650

Preliminary gamma ray data[9] for 1ES 1959 +650

Spectral Energy Distribution

The optical data will help characterize the spectral energy distribution curves of our sources outside the TeV range. We plotted the flux values for our Mrk 421 optical data next to the theoretical curves of leptonic synchrotron self-compton model for blazar emission. A code developed by the VERITAS collaboration [8] produced these plots, and the parameters for the SSC curve came from a previous study of gamma and X-ray data from Mrk 421 [2].

An SED plot for Mrk 421

An SED plot for Mrk 421 using one-zone synchrotron self-compton model with our optical data superimposed.

SED curve created by Blazejowski[2].

SED Curve created by Blazejowski[2].

Long Term Veritas data

Using a modified version of the statistical method developed by Scargle [6] and first applied to gamma-ray data by Flacconio and Resconi [7], we analyzed long-term VERITAS data for Mrk 421. This analysis characterizes periods of flaring by dividing the light curve into regions of relatively constant flux based on the likelihood that the source will remain at a constant level, thus smoothing out the purely statistical fluctuations to determine times of flaring. We used these data to calculate how often the blazar was above our threshold of 1.5 Crabs, which we chose because Mrk 421 had a flare at the level of 1.5 Crabs during our period of observation. This can be considered a high state of the source when long-term observations are considered.

All data runs of Mrk 421

Four year Whipple data of Mrk 421 with Maximun Likelihood Blocks overlaid. All data runs are used and each data run lasts 28 minuts. The pink line denotes 1.5 crabs and changes from year to year due to changes in the sensitivety of the detector.

Daily averages of Mrk 421

Four year Whipple data of Mrk 421 with Maximun Likelihood Blocks overlaid Data are daily averages of 28 minute data runs.

We first calculated the flaring probability to be 41% by using all data runs. This method showed a bias toward days of high flux because Whipple took more data on days in which the source was in a high state. Therefore, we recalculated the flaring probability using daily averages, yielding a probability of 24%. However, this ignores flares on shorter timescales, which Mrk 421 has had in the past. This discrepancy is unfortunately due to the small duty cycle of TeV photon detectors; hence it may be useful to estimate flaring probabilities by also considering the more continuous X-ray data.

Future Work

AMANDA Data will need to be analyzed for this period. the Whipple and VERITAS telescopes will continue to take data on the blazars and new series of WIYN observations including more blazars is planed for the fall 2006.

Mrk421 1104+3813 Nov 4 - Jan 31 1ES 1959+650 1959+6508 Sept 1 - Jan 31 1ES 2344+614 2347+5142 Sept 1 - Jan 31 1ES 0033+595 0035+5950 Sept 1 - Jan 31 1ES 0806+524 0809+5218 Nov 4 - Jan 31


[1] Villata M et al 1998 Astron. Astrophys. Suppl. Ser. 130 305

[2] Blazejowski et al 2005 ApJ 630 130B

[3] Krennrich et al 2002 ApJ 575 L9

[4] Grube et al 2005 ICRC proceedings

[5] Rebillot et al 2006 ApJ 641 740R

[6] Scargle J D 1998 ApJ 504 405

[7] Resconi E 2006 TeV II proceedings

[8] Krawczynski H,available at

[9] Available at

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