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Title: OPTICAL POLARIMETRY OF THE BLAZAR CGRaBS J0211+1051 FROM MOUNT ABU INFRARED OBSERVATORY

Abstract

We report the detection of high polarization in the first detailed optical linear polarization measurements on the BL Lac object CGRaBS J0211+1051, which flared in {gamma}-rays on 2011 January 23 as reported by Fermi. The observations were made during 2011 January 30-February 3 using a photo-polarimeter mounted at the 1.2 m telescope of Mount Abu Infrared Observatory. CGRaBS J0211+1051 was detected to have a {approx}21.05% {+-} 0.41% degree of polarization (DP) with a steady position angle (P.A.) at 43 Degree-Sign on 2011 January 30. During January 31 and February 1, while polarization shows some variation, the P.A. remained steady through the night. Several polarization flashes occurred during February 2 and 3 resulting in changes in the DP by more than 4% at short timescales ({approx}17-45 minutes). The intra-night variability shown by the source appears to be related to the turbulence in the relativistic jet. A mild wavelength dependence of polarization is not ruled out during the nights of February 2 and 3. The source exhibited significant inter-night variations in the DP (changing by about 2%-9%) and P.A. (changing by 2 Degree-Sign -22 Degree-Sign ) during the five nights of observations. A sudden change in the P.A. accompanied by a risemore » in the DP could be indicative of the fresh injection of plasma in the jet. The detection of a high and variable DP suggests that the source is a low-energy peaked blazar.« less

Authors:
; ; ;  [1]
  1. Astronomy and Astrophysics Division, Physical Research Laboratory, Ahmedabad 380009 (India)
Publication Date:
OSTI Identifier:
22011774
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 746; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BL LACERTAE OBJECTS; FREQUENCY DEPENDENCE; GALAXIES; GALAXY NUCLEI; PLASMA; POLARIMETERS; POLARIMETRY; POLARIZATION; RELATIVISTIC RANGE; TELESCOPES; TURBULENCE

Citation Formats

Chandra, Sunil, Baliyan, Kiran S., Ganesh, Shashikiran, and Joshi, Umesh C., E-mail: baliyan@prl.res.in. OPTICAL POLARIMETRY OF THE BLAZAR CGRaBS J0211+1051 FROM MOUNT ABU INFRARED OBSERVATORY. United States: N. p., 2012. Web. doi:10.1088/0004-637X/746/1/92.
Chandra, Sunil, Baliyan, Kiran S., Ganesh, Shashikiran, & Joshi, Umesh C., E-mail: baliyan@prl.res.in. OPTICAL POLARIMETRY OF THE BLAZAR CGRaBS J0211+1051 FROM MOUNT ABU INFRARED OBSERVATORY. United States. doi:10.1088/0004-637X/746/1/92.
Chandra, Sunil, Baliyan, Kiran S., Ganesh, Shashikiran, and Joshi, Umesh C., E-mail: baliyan@prl.res.in. Fri . "OPTICAL POLARIMETRY OF THE BLAZAR CGRaBS J0211+1051 FROM MOUNT ABU INFRARED OBSERVATORY". United States. doi:10.1088/0004-637X/746/1/92.
@article{osti_22011774,
title = {OPTICAL POLARIMETRY OF THE BLAZAR CGRaBS J0211+1051 FROM MOUNT ABU INFRARED OBSERVATORY},
author = {Chandra, Sunil and Baliyan, Kiran S. and Ganesh, Shashikiran and Joshi, Umesh C., E-mail: baliyan@prl.res.in},
abstractNote = {We report the detection of high polarization in the first detailed optical linear polarization measurements on the BL Lac object CGRaBS J0211+1051, which flared in {gamma}-rays on 2011 January 23 as reported by Fermi. The observations were made during 2011 January 30-February 3 using a photo-polarimeter mounted at the 1.2 m telescope of Mount Abu Infrared Observatory. CGRaBS J0211+1051 was detected to have a {approx}21.05% {+-} 0.41% degree of polarization (DP) with a steady position angle (P.A.) at 43 Degree-Sign on 2011 January 30. During January 31 and February 1, while polarization shows some variation, the P.A. remained steady through the night. Several polarization flashes occurred during February 2 and 3 resulting in changes in the DP by more than 4% at short timescales ({approx}17-45 minutes). The intra-night variability shown by the source appears to be related to the turbulence in the relativistic jet. A mild wavelength dependence of polarization is not ruled out during the nights of February 2 and 3. The source exhibited significant inter-night variations in the DP (changing by about 2%-9%) and P.A. (changing by 2 Degree-Sign -22 Degree-Sign ) during the five nights of observations. A sudden change in the P.A. accompanied by a rise in the DP could be indicative of the fresh injection of plasma in the jet. The detection of a high and variable DP suggests that the source is a low-energy peaked blazar.},
doi = {10.1088/0004-637X/746/1/92},
journal = {Astrophysical Journal},
number = 1,
volume = 746,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2012},
month = {Fri Feb 10 00:00:00 EST 2012}
}
  • The source CGRaBS J0211+1051 (MG1 J021114+1051, z = 0.20) flared up on 2011 January 23 in high-energy γ-rays as reported by the Large Area Telescope (LAT) on board Fermi. This event was followed by increased activity at the UV, optical, and radio frequencies as detected by the observing facilities worldwide. The source also showed a high and variable optical polarization based on which it was proposed to be a low-energy peaked BL Lac object (LBL). The present work reports first comprehensive multi-wavelength study of this source using data in the radio, optical, UV, X- and γ-rays, and optical polarization. Usingmore » these multi-wavelength data on the source, we have estimated various parameters and verified its classification vis-a-vis blazar sequence. Multi-waveband light curves are used to discuss the flaring events of 2011 January in an attempt to address the nature of the source and pinpoint the possible physical processes responsible for the emission. The light curves show variations in the high-energy γ-rays to be correlated with X-ray, UV, and optical variations, perhaps indicating their co-spatial origin. Our optical data, quasi-simultaneous with UV (Swift-UVOT) and X-ray (Swift-XRT) data, enabled us to trace the low-energy (synchrotron) component of the spectral energy distribution (SED) for CGRaBS J0211+1051 for the first time. The SED shows the synchrotron peak to lie at ∼1.35 × 10{sup 14} Hz, confirming that CGRaBS J0211+1051 is an LBL. Some other parameters, such as the local magnetic field (∼5.93 G) and black hole mass (∼2.4 × 10{sup 8} M {sub ☉}), are also estimated which are in agreement with their typical values for the blazars. Based on the present study, identification of the Fermi/LAT source, 2FGL J0211.2+1050, with its BL Lac counterpart CGRaBS J0211+1051 is confirmed.« less
  • We present a summary of data obtained with the 350 {mu}m polarimeter, Hertz, at the Caltech Submillimeter Observatory. We give tabulated results and maps showing polarization vectors and intensity contours. The summary includes over 4300 individual measurements in 56 Galactic sources and two galaxies. Of these measurements, 2153 have P {>=} 3{sigma} {sub p} statistical significance. The median polarization of the entire data set is 1.46%.
  • Optical and NIR polarization and flux density measurements of the IR luminous galaxy IRAS 23060 + 0505 are presented. The flux density in an 8-arcsec diameter aperture follows an approximate power law, while the polarized flux density spectrum steepens from a spectral index of 2.48 in the NIR to 6.0 shortward of 0.8 microns. The wavelength dependence of degree of polarization is unusual, rising very steeply from 1 to 2 percent in the blue to a level of about 8 percent in the I band and then falling slowly through the NIR. A number of different models have been developedmore » as an aid to interpreting the wavelength dependence of polarization and flux density observed for 23060 + 0505. Scattering of radiation from a continuum source largely obscured from the direct sight is the most likely explanation for the observed polarization. 44 refs.« less
  • We present a large collection of photometric data on the blazar PKS 0537-441 in the VRIJHK bands taken in 2004-2009. At least three flare-like episodes with months duration and >3 mag amplitude are apparent. The spectral energy distribution is consistent with a power law, and no indication of a thermal component is found. We searched for short timescale variability, and an interesting event was identified in the J band, with a duration of {approx}25 minutes.