New High-z Fermi BL Lacs with the Photometric Dropout Technique

Abstract

Determining redshifts for BL Lacertae (BL Lac) objects using the traditional spectroscopic method is challenging due to the absence of strong emission lines in their optical spectra. We employ the photometric dropout technique to determine redshifts for this class of blazars using the combined 13 broad-band filters from Swift-UVOT and the multi-channel imager GROND at the MPG 2.2 m telescope at ESO's La Silla Observatory. The wavelength range covered by these 13 filters extends from far ultraviolet to the near-Infrared. We report results on 40 new Fermi detected BL Lacs with the photometric redshifts determinations for 5 sources, with 3FGL J1918.2-4110 being the most distant in our sample at z=2.16. Reliable upper limits are provided for 20 sources in this sample. Using the highest energy photons for these Fermi-LAT sources, we evaluate the consistency with the Gamma-ray horizon due to the extragalactic background light.

arXiv comment16 pages, 8 figures, ApJ accepted

References in corpus (39)

• Measuring Reddening with SDSS Stellar Spectra and Recalibrating SFD
• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The Swift Ultra-Violet/Optical Telescope
• Accurate photometric redshifts for the CFHT Legacy Survey calibrated using the VIMOS VLT Deep Survey
• The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III
• Evolutionary models for very-low-mass stars and brown dwarfs with dusty atmospheres
• A Unifying View of the Spectral Energy Distributions of Blazars
• Measuring and Modelling the Redshift Evolution of Clustering: the Hubble Deep Field North
• Photometric Calibration of the Swift Ultraviolet/Optical Telescope
• A theoretical unifying scheme for gamma-ray bright blazars
• Extragalactic Background Light Inferred from AEGIS Galaxy SED-type Fractions
• Modeling the Extragalactic Background Light from Stars and Dust
• A low level of extragalactic background light as revealed by gamma-rays from blazars
• Semi-analytic modeling of the EBL and consequences for extragalactic gamma-ray spectra
• The Third Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey
• GROND - a 7-channel imager
• Photometric redshift and classification for the XMM-COSMOS sources
• 2FHL: The Second Catalog of Hard Fermi-LAT Sources
• The Imprint of The Extragalactic Background Light in the Gamma-Ray Spectra of Blazars
• Dissecting Photometric redshift for Active Galactic Nuclei using XMM- and Chandra-COSMOS samples
• The Fermi blazars divide
• The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars
• Spectroscopy of The Largest Ever Gamma-ray Selected BL Lac Sample
• The 2175 A dust feature in a Gamma Ray Burst afterglow at redshift 2.45
• The First Fermi-LAT Catalog of Sources Above 10 GeV
• The relation between broad lines and gamma--ray luminosities in Fermi blazars
• Compton Dominance and the Blazar Sequence
• Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe
• Multiwavelength Observations of the Powerful Gamma-ray Quasar PKS 1510-089: Clues on the Jet Composition
• Detection of the cosmic γ-ray horizon from multiwavelength observations of blazars
• BL Lacertae objects beyond redshift 1.3 - UV-to-NIR photometry and photometric redshift for Fermi/LAT blazars
• Optical spectroscopic observations of $\gamma$-ray blazar candidates VI. Further observations from TNG, WHT, OAN, SOAR and Magellan telescopes
• Photometric redshifts for GRB afterglows from GROND and Swift/UVOT
• The discovery of high power - high synchrotron peak blazars
• Optical spectroscopic observations of gamma-ray blazar candidates II. The 2013 KPNO campaign in the Northern Hemisphere
• Blue Fermi Flat Spectrum Radio Quasars
• A catalogue of absorption-line systems in QSO spectra
• ROSAT Observations of Blazars from a Polarized Radio Selected Sample

Cited by in corpus (16)

• TXS 0506+056, the first cosmic neutrino source, is not a BL Lac
• General Physical Properties of CGRaBS Blazars
• Optical spectroscopy of Blazars for the Cherenkov Telescope Array
• Multiwavelength Study of High-Redshift Blazars
• Detection of a gamma-ray flare from the high-redshift blazar DA 193
• New high-z BL Lacs using the photometric method with Swift and SARA
• Predicting the redshift of gamma-ray loud AGNs using supervised machine learning
• Using Neural Networks to Differentiate Newly Discovered BL Lacs and FSRQs among the 4FGL Unassociated Sources Employing Gamma-ray, X-ray, UV/Optical and IR Data
• Optical Spectroscopy of Blazars for the Cherenkov Telescope Array -- II
• Hunting distant BL Lacs with the photometric technique using Swift and SARA
• Identifying the 3FHL catalog: V. Results of the CTIO-COSMOS optical spectroscopy campaign 2019
• The benefit of simultaneous seven-filter imaging: 10 years of GROND observations
• Classifying blazar candidates from the 3FGL unassociated catalog into BL Lacs and FSRQs using Swift and WISE data
• NuSTAR Observations and multi-wavelength modeling of the high-redshift BL Lac Object 4FGL J2146.5-1344
• XMM-NuSTAR Observation and Multiwavelength SED Modeling of Blazar 4FGL J1520.8-0348
• The Gamma-ray Luminosity Function of Flat-Spectrum Radio Quasars