Discovery of VHE Gamma-Ray Emission from the BL Lac S2 0109+22

I am very happy to announce this discovery as the first discovery that i was involved in.

The MAGIC collaboration reports the discovery of very high energy (VHE; E>100 GeV) gamma-ray emission from the BL Lac S2 0109+22 (z=0.265 RA: 01h12m05.8s Dec:+22d44m39s, J2000). The object was observed with the MAGIC telescopes for 5.3 hours from 2015/07/22 to 2015/07/25. The preliminary analysis of the first three nights of MAGIC data showed an excess with a statistical significance of ~5 standard deviations. The VHE flux of this detection was estimated to be (1.6+/-0.7)e-11 ph/cm2/s above 100 GeV, about 3% of the flux from the Crab nebula. The daily flux shows a marked enhancement on the night of 25 July up to (9.7+/-1.5)e-11 ph/cm^2/s, ~15% of the Crab flux at E>100 GeV, corresponding to an excess with >7 sigma statistical significance. S2 0109+22 is classified as an intermediate-synchrotron peaked BL Lac object. The multi-year optical and radio historical coverage showed optical variations with typical timescales from weeks to months.

See more:
http://www.astronomerstelegram.org/?read=7844  

BL Lacertae activity at VHE gamma-rays

The MAGIC telescopes have detected Very High Energy gamma-ray flux from BL Lacertae. The preliminary analysis indicates a highly significant signal above 200 GeV. The emission is variable, with a flux of 0.4 and 0.1 times the flux of the Crab nebula above 200 GeV in the nights 14/15 and 16/17, respectively. The flux level is similar to the flaring state reported in Arlen et al. 2013. The observations were triggered by the high activity measured at optical and gamma-ray energies. X-ray ToO observations with the Swift satellite did not show any substantial enhancement in the X-ray flux.
For more information see: http://www.astronomerstelegram.org/?read=7660

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

https://www.doria.fi/handle/10024/98928

VHE Gamma-Ray Emission from H1722+119

H1722+119 is a BL Lac object, that was listed as candidate TeV blazar in Costamante & Ghisellini (2002) based on its X-ray and radio properties. Its redshift is uncertain; Sbarufatti et al. 2006 give z>0.17. The source has been detected by Fermi-LAT, in the Second Fermi Catalogue with F(>1 GeV) (3.7+-0.3)e-09 cm^-2 s^-1 and with spectral index 1.92+-0.06.

H1722+119 was observed for five nights by the MAGIC telescopes starting May 17th 2013 and collecting 11 hours of good quality data. A preliminary analysis yields a detection of the source with a statistical significance of more than 5 standard deviations. The VHE flux of this detection is about 2% of the flux from the Crab nebula above 140 GeV. The previous VHE gamma-ray observations of the source produced an upper limit of 4.2% Crab nebula flux above 140 GeV (Aleksic et al. 2011).

The MAGIC observations were triggered by the extended optical high state of the source, reported by the Tuorla blazar monitoring program (http://users.utu.fi/kani/1m). At the beginning of May 2013 the source reached an R-band magnitude of 14.65, the brightest ever observed since 2005, when the monitoring started. We also analyzed the Fermi-LAT data, finding indication of a spectral index harder than reported in the Second Fermi Catalog. A Swift-XRT ToO observation was performed on 20th May.

MAGIC will continue the observations of the source as soon as the moon conditions allow it again and multiwavelength observations are encouraged.

The MAGIC contact persons for these observations are J. Cortina (cortina@ifae.es) and E. Lindfors (elilin@utu.fi).

MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located at the Canary island of La Palma, Spain, and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 20 TeV. 

http://www.astronomerstelegram.org/?read=5080

BL Lacs already detected in VHE gamma-ray

Among VHE gamma-ray detected sources in sky, BL Lac objects are the most numerous ones. Up to now (24 April 2013 ) 47 out of 163 objects in VHE gamma-ray sky are BL Lacs ^[1].

Below table show list of detected BL Lac objects in VHE gamma-ray.

Object Name	RA	Dec	Type	Redshift
SHBL J001355.9-185406	00 13 52.0	-18 53 29	HBL	0.095
KUV 00311-1938	00 33 34.2	-19 21 33	HBL
1ES 0033+595	00 35 52.63	+59 50 04.56	HBL
RGB J0136+391	01 36 32.5	+39 06 00	HBL
RGB J0152+017	01 52 33.5	+01 46 40.3	HBL	0.08
3C66A	02 22 41.6	+43 02 35.5	IBL	0.41
1ES 0229+200	02 32 53.2	+20 16 21	HBL	0.14
PKS 0301-243	03 03 26.5	-24 07 11	HBL
IC 310	03 16 43.0	+41 19 29	HBL	0.0189
RBS 0413	03 19 47	+18 45 42	HBL	0.19
1ES 0347-121	03 49 23.0	-11 58 38	HBL	0.188
1ES 0414+009	04 16 52.96	+01 05 20.4	HBL	0.287
PKS 0447-439	04 49 28.2	-43 50 12	HBL
1ES 0502+675	05 07 56.2	+67 37 24	HBL	0.341
VER J0521+211	05 21 55	+21 11 24	IBL
PKS 0548-322	05 50 38.4	-32 16 12.9	HBL	0.069
RX J0648.7+1516	06 48 45.6	+15 16 12	HBL	0.179
1ES 0647+250	06 50 46.5	+25 03 00	HBL	0.45
RGB J0710+591	07 10 26.4	59 09 00	HBL	0.125
S5 0716+714	07 21 53.4	+71 20 36	IBL	0.31
1ES 0806+524	08 09 59	+52 19 00	HBL	0.138
1RXS J101015.9-311909	10 10 15.03	-31 18 18.4	HBL	0.142639
1ES 1011+496	10 15 04.1	+49 26 01	HBL	0.212
1ES 1101-232	11 03 36.5	-23 29 45	HBL	0.186
Markarian 421	11 04 19	+38 11 41	HBL	0.031
Markarian 180	11 36 26.4	+70 09 27	HBL	0.045
1ES 1215+303	12 17 52.1	+30 07 01	HBL	0.13
1ES 1218+304	12 21 26.3	+30 11 29	HBL	0.182
W Comae	12 21 31.7	+28 13 59	IBL	0.102
1ES 1312-423	13 15 03.4	-42 36 50	HBL	0.105
PKS 1424+240	14 27 00	+23 47 40	IBL
H 1426+428	14 28 32.6	+42 40 21	HBL	0.129
1ES 1440+122	14 42 48.3	+12 00 40	HBL
AP Lib	15 17 41.8	-24 22 19	LBL	0.049
PG 1553+113	15 55 44.7	+11 11 41	HBL	0.5
Markarian 501	16 53 52.2	+39 45 37	HBL	0.034
1ES 1727+502	17 28 18.6	+50 13 10	HBL	0.055
1ES 1741+196	17 43 57.8	+19 35 09	HBL	0.083
HESS J1943+213	19 43 55	+21 18 08	HBL
1ES 1959+650	19 59 59.8	+65 08 55	HBL	0.048
MAGIC J2001+435	20 01 13.5	+43 53 02.8	IBL
PKS 2005-489	20 09 27.0	-48 49 52	HBL	0.071
PKS 2155-304	21 58 52.7	-30 13 18	HBL	0.116
BL Lacertae	22 02 43.3	+42 16 40	IBL	0.069
B3 2247+381	22 50 06.6	+38 25 58	HBL	0.1187
1ES 2344+514	23 47 04.9	+51 42 17	HBL	0.044
H 2356-309	23 59 09.42	-30 37 22.7	HBL	0.165