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Title: Near-infrared and gamma-ray monitoring of TANAMI gamma-ray bright sources

Journal Article · · Astronomy and Astrophysics
 [1];  [2];  [3];  [4];  [5]
  1. INAF-IAPS, via Fosso del Cavaliere 100, Roma (Italy); Universita La Sapienza, Roma (Italy)
  2. Universita di Perugia (Italy)
  3. Nordic Optical Telescope (Spain)
  4. NASA Goddard Space Flight Center, Astrophysics Science Division, Greenbelt, MD (United States); Catholic University of America, Washington, DC (United States). Institute for Astrophysics & Computational Sciences
  5. Univ. Wurzburg (Germany). Institut fur Theoretische Physik und Astrophysik, Lehrstuhl fur Astronomie; Dr. Karl-Remeis-Sternwarte and Erlangen Centre for Astroparticle Physics (Germany)
+ Show Author Affiliations

Context. We present that spectral energy distribution and its variability are basic tools for understanding the physical processes operating in active galactic nuclei (AGN). Aims. In this paper we report the results of a one-year near-infrared (NIR) and optical monitoring of a sample of 22 AGN known to be gamma-ray emitters, aimed at discovering correlations between optical and gamma-ray emission. Methods. We observed our objects with the Rapid Eye Mount (REM) telescope in J,H,K, and R bands nearly twice every month during their visibility window and derived light curves and spectral indexes. We also analyzed the gamma-ray data from the Fermi gamma-ray Space Telescope, making weekly averages. Results. Six sources were never detected during our monitoring, proving to be fainter than their historical Two micron all sky survey (2MASS) level. All of the sixteen detected sources showed marked flux density variability, while the spectral indexes remained unchanged within our sensitivity limits. Steeper sources showed, on average, a larger variability. From the NIR light curves we also computed a variability speed index for each detected source. Only one source (PKS 0208-512) underwent an NIR flare during our monitoring. Half of the sources showed a regular flux density trend on a one-year time scale, but do not show any other peculiar characteristic. The broadband spectral index αro appears to be a good proxy of the NIR spectral index only for BL Lac objects. No clear correlation between NIR and gamma-ray data is evident in our data, save for PKS 0537-441, PKS 0521-360, PKS 2155-304, and PKS 1424-418. In conclusion, the gamma-ray/NIR flux ratio showed a large spread, QSO being generally gamma-louder than BL Lac, with a marked correlation with the estimated peak frequency (νpeak) of the synchrotron emission.

Research Organization:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Organization:
USDOE
Contributing Organization:
Fermi-LAT Collaboration
Grant/Contract Number:
AC02-76SF00515
OSTI ID:
1356584
Journal Information:
Astronomy and Astrophysics, Vol. 555; ISSN 0004-6361
Publisher:
EDP SciencesCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 5 works
Citation information provided by
Web of Science

References (30)

FERMI LARGE AREA TELESCOPE SECOND SOURCE CATALOG journal March 2012
THE LARGE AREA TELESCOPE ON THE FERMI GAMMA-RAY SPACE TELESCOPE MISSION journal May 2009
Relativistic jets as X-ray and gamma-ray sources journal February 1981
Smarts Optical and Infrared Monitoring of 12 Gamma-Ray Bright Blazars journal August 2012
A Search for Intraday Variability in the Blazar PKS 2005-489 journal July 2003
Infrared Colors of the Gamma-Ray-Detected Blazars journal March 2012
UBVRI photoelectric photometry in the fields of fifteen active galaxies journal March 1989
The connection between x-ray- and radio-selected BL Lacertae objects journal May 1995
Relativistic jets as compact radio sources journal August 1979
TANAMI: tracking active galactic nuclei with austral milliarcsecond interferometry: I. First-epoch 8.4 GHz images journal September 2010
Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds journal June 1998
Modeling the Production of Flares in Gamma‐Ray Quasars journal June 2001
GAMMA-RAY LIGHT CURVES AND VARIABILITY OF BRIGHT FERMI -DETECTED BLAZARS journal September 2010
SIMILARITY OF THE OPTICAL-INFRARED AND γ-RAY TIME VARIABILITY OF FERMI BLAZARS journal April 2012
THE SECOND CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE journal December 2011
Roma-BZCAT: a multifrequency catalogue of blazars journal December 2008
A test for partial correlation with censored astronomical data journal February 1996
The Second-Generation Guide star Catalog: Description and Properties journal July 2008
THE SPECTRAL ENERGY DISTRIBUTION OF FERMI BRIGHT BLAZARS journal May 2010
The classification of BL Lacertae objects: the Ca H&K break journal November 2002
Atlas of quasar energy distributions journal November 1994
High-energy neutrinos from extragalactic jets journal May 1995
Emission lines and optical continuum in low-luminosity radio galaxies journal January 2004
The Second-Generation Guide Star Catalog: Description and Properties text January 2008
The Spectral Energy Distribution of Fermi bright blazars text January 2009
Gamma-ray Light Curves and Variability of Bright Fermi-Detected Blazars text January 2010
TANAMI: Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry I. First-Epoch 8.4 GHz Images text January 2010
The classification of BL Lacertae objects: the Ca H&K break text January 2002
A Search for Intraday Variability in the Blazar PKS 2005-489 text January 2003
Emission lines and optical continuum in low-luminosity radio galaxies text January 2003

Cited By (2)

H.E.S.S. discovery of very high energy γ-ray emission from PKS 0625−354 journal February 2018
H.E.S.S. discovery of very high energy $\gamma$-ray emission from PKS 0625-354 text January 2018

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Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BL Lacertae objects: general
radiation mechanisms: non-thermal
gamma rays: galaxies