- Discovery of Very High Energy Gamma-Ray Emission from the
distant FSRQ PKS 1441+25 with the MAGIC telescopes: This source
is the second distant VHE gamma-ray source with the redshift of
0.939 (Shaw et al. 2012, ApJ, 748, 49). It is discovered by
MAGIC on April 20, 2015. MAGIC is a system of two 17m-diameter
Imaging Atmospheric Cherenkov Telescopes designed to perform
gamma-ray astronomy in the energy range from 50 GeV to greater
than 50 TeV. The flux above 80 GeV is estimated to be about
8e-11 cm^-2 s^-1 (16% of Crab Nebula flux). Preliminary analysis
show detection significant of 6 standard deviations during ~2
hours observation in the night between 17 and 18 of April; and
11 standard deviations during ~4 hours observations in the night
between 18 and 19 of April (http://www.astronomerstelegram.org/?read=7416
). The highest optical R-band magnitude is 15.6 and was measured
in the night between 21 and 22 April using KVA telescope
(http://users.utu.fi/kani/1m/PKS_1441+25.html ).
- MAGIC detects an increased activity from FSRQ PKS 1510-089 at very high energy gamma-rays: The redshift of this source is 0.36. The preliminary analysis shows a highly significant signal and a flux of ~20% from that of the Crab nebula above 100 GeV for the data taken from 2015/05/18 to 2015/05/19. This implies an increase by a factor of ~5 with respect to the flux reported previously in 2012. The source is active now in Optical and IR-band as well (http://www.astronomerstelegram.org/?read=7542 ). We are performing optical monitoring in R-band using KVA telescope. The current flare in Optical is the second one after 6 years since the monitoring of this source started in the Tuorla blazar monitoring program (http://users.utu.fi/kani/1m/PKS_1510-089.html )
Showing posts with label gamma-rays. Show all posts
Showing posts with label gamma-rays. Show all posts
Thursday, May 21, 2015
Newest blazar discoveries in VHE gamma-rays band
Wednesday, September 17, 2014
Very High Energy Gamma-Rays emitting BL LAC's Population Study
In this post, you can find my MS thesis abstract following with the link to the complete version. In my thesis, lots of useful astronomical information are available. If you want to use the data please cite my thesis as reference in your publication.
Abstract
Context: BL Lacs are the most numerous extragalactic objects which are detected in Very High Energy (VHE) gamma-rays band. They are a subclass of blazars. Large flux variability amplitude, sometimes happens in very short time scale, is a common characteristic of them. Significant optical polarization is another main characteristics of BL Lacs. BL Lacs' spectra have a continuous and featureless Spectral Energy Distribution (SED) which have two peaks.
Among 1442 BL Lacs in the Roma-BZB catalogue, only 51 are detected in VHE gamma-rays band. BL Lacs are most numerous (more than 50% of 514 objects) objects among the sources that are detected above 10 GeV by FERMI-LAT. Therefore, many BL Lacs are expected to be discovered in VHE gamma-rays band. However, due to the limitation on current and near future technology of Imaging Air Cherenkov Telescope, astronomers are forced to predict whether an object emits VHE gamma-rays or not.
Some VHE gamma-ray prediction methods are already introduced but still are not confirmed. Cross band correlations are the building blocks of introducing VHE gamma-rays prediction method.
Aims: We will attempt to investigate cross band correlations between flux energy density, luminosity and spectral index of the sample. Also, we will check whether recently discovered MAGIC J2001+435 is a typical BL Lac.
Methods: We select a sample of 42 TeV BL Lacs and collect 20 of their properties within five energy bands from literature and Tuorla blazar monitoring program database. All of the data are synchronized to be comparable to each other. Finally, we choose 55 pair of datasets for cross band correlations finding and investigating whether there is any correlation between each pair. For MAGIC J2001+435 we analyze the publicly available SWIFT-XRT data, and use the still unpublished VHE gamma-rays data from MAGIC collaboration. The results are compared to the other sources of the sample.
Results: Low state luminosity of multiple detected VHE gamma-rays is strongly correlated luminosities in all other bands. However, the high state does not show such strong correlations. VHE gamma-rays single detected sources have similar behaviour to the low state of multiple detected ones. Finally, MAGIC J2001+435 is a typical TeV BL Lac. However, for some of the properties this source is located at the edge of the whole sample (e.g. in terms of X-rays flux).
keywords: BL Lac(s), Population study, Correlations finding, Multi wavelengths analysis, VHE gamma-rays, gamma-rays, X-rays, Optical, Radio
Among 1442 BL Lacs in the Roma-BZB catalogue, only 51 are detected in VHE gamma-rays band. BL Lacs are most numerous (more than 50% of 514 objects) objects among the sources that are detected above 10 GeV by FERMI-LAT. Therefore, many BL Lacs are expected to be discovered in VHE gamma-rays band. However, due to the limitation on current and near future technology of Imaging Air Cherenkov Telescope, astronomers are forced to predict whether an object emits VHE gamma-rays or not.
Some VHE gamma-ray prediction methods are already introduced but still are not confirmed. Cross band correlations are the building blocks of introducing VHE gamma-rays prediction method.
Aims: We will attempt to investigate cross band correlations between flux energy density, luminosity and spectral index of the sample. Also, we will check whether recently discovered MAGIC J2001+435 is a typical BL Lac.
Methods: We select a sample of 42 TeV BL Lacs and collect 20 of their properties within five energy bands from literature and Tuorla blazar monitoring program database. All of the data are synchronized to be comparable to each other. Finally, we choose 55 pair of datasets for cross band correlations finding and investigating whether there is any correlation between each pair. For MAGIC J2001+435 we analyze the publicly available SWIFT-XRT data, and use the still unpublished VHE gamma-rays data from MAGIC collaboration. The results are compared to the other sources of the sample.
Results: Low state luminosity of multiple detected VHE gamma-rays is strongly correlated luminosities in all other bands. However, the high state does not show such strong correlations. VHE gamma-rays single detected sources have similar behaviour to the low state of multiple detected ones. Finally, MAGIC J2001+435 is a typical TeV BL Lac. However, for some of the properties this source is located at the edge of the whole sample (e.g. in terms of X-rays flux).
keywords: BL Lac(s), Population study, Correlations finding, Multi wavelengths analysis, VHE gamma-rays, gamma-rays, X-rays, Optical, Radio
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