Skip to main content
SpringerLink
Log in

The extragalactic gamma-ray sky in the Fermi era

  • Review Article
  • Published:
The Astronomy and Astrophysics Review Aims and scope

Abstract

The Universe is largely transparent to \(\gamma \)-rays in the GeV energy range, making these high-energy photons valuable for exploring energetic processes in the cosmos. After 7 years of operation, the Fermi  Gamma-ray Space Telescope has produced a wealth of information about the high-energy sky. This review focuses on extragalactic \(\gamma \)-ray sources: what has been learned about the sources themselves and about how they can be used as cosmological probes. Active galactic nuclei (blazars, radio galaxies, Seyfert galaxies) and star-forming galaxies populate the extragalactic high-energy sky. Fermi observations have demonstrated that these powerful non-thermal sources display substantial diversity in energy spectra and temporal behavior. Coupled with contemporaneous multifrequency observations, the Fermi results are enabling detailed, time-dependent modeling of the energetic particle acceleration and interaction processes that produce the \(\gamma \)-rays, as well as providing indirect measurements of the extragalactic background light and intergalactic magnetic fields. Population studies of the \(\gamma \)-ray source classes compared to the extragalactic \(\gamma \)-ray background place constraints on some models of dark matter. Ongoing searches for the nature of the large number of \(\gamma \)-ray sources without obvious counterparts at other wavelengths remain an important challenge.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10
Fig. 11
Fig. 12
Fig. 13
Fig. 14
Fig. 15
Fig. 16
Fig. 17
Fig. 18
Fig. 19
Fig. 20
Fig. 21
Fig. 22
Fig. 23

Similar content being viewed by others

Notes

  1. http://www.physics.purdue.edu/MOJAVE/.

  2. http://www.to.astro.it/blazars/webt/.

  3. http://james.as.arizona.edu/~psmith/Fermi/.

  4. http://www.astro.yale.edu/smarts/glast/home.php.

  5. see e.g., https://www.bu.edu/blazars/VLBAproject.html.

  6. http://www.swift.psu.edu/unassociated/.

Abbreviations

AGN(s):

Active galactic nucleus(i)

AGU:

Active galaxy of uncertain type

BCU:

Blazar candidate of uncertain type

CGRO:

Compton Gamma-Ray Observatory

CSS:

Compact steep spectrum radio source

DM:

Dark matter

EBL:

Extragalactic gamma-ray background light

EGB:

Extragalactic gamma-ray background

EC:

External Compton

FR:

Fanaroff–Riley radio source class

FSRQ:

Flat-spectrum radio quasar

GRB:

Gamma-ray burst

HBL:

High-frequency peaked BL Lac object

HSP:

High-synchrotron peaked BL Lac object

QSO:

Quasi-stellar object (a.k.a. quasar)

RG:

Radio galaxy

RLNLSy1:

Radio-loud narrow-line Seyfert of type 1

SED:

Spectral energy distribution

SFR:

Star formation rate

SSC:

Synchrotron self-Compton

SSRQ:

Steep spectrum radio quasar

UGS:

Unidentified/unassociated gamma-ray source

1FGL:

First Fermi gamma-ray LAT point source catalog

2FGL:

Second Fermi gamma-ray LAT point source catalog

3FGL:

Third Fermi gamma-ray LAT point source catalog

1LAC:

First Fermi LAT AGN catalog

2LAC:

Second Fermi LAT AGN catalog

3LAC:

Third Fermi LAT AGN catalog

2PC:

Second LAT pulsar catalog

3EG:

Third EGRET catalog

CRATES:

The combined radio all-sky targeted eight GHz survey

LBAS:

LAT bright AGN sample

Roma-BZCAT:

Roma-multifrequency blazar catalog

WGS:

WISE gamma-ray strip

WIBRaLS:

WISE blazar-like radio-loud source catalog

AGILE:

Astrorivelatore Gamma a Immagini Leggero

ATCA:

Australia Telescope Compact Array

BAT :

Burst Alert Telescope

CGRH:

Cosmic gamma-ray horizon

COS-B:

Celestial Observation Satellite-B

CTA:

Cherenkov Telescope Array

EGRET:

Energetic Gamma-Ray Experiment Telescope

FAVA:

Fermi all-sky variability analysis

FoV:

Field of view

GASP:

GLAST-AGILE support program

GBM:

Gamma-Ray Burst Monitor

GLAST:

Gamma-Ray Large Area Space Telescope

HESS:

High-Energy Stereoscopic System

IBIS:

Imager on-Board the INTEGRAL Satellite

INTEGRAL:

INTErnational Gamma-Ray Astrophysics Laboratory

IR:

Infrared energy range

LAT:

Large Area Telescope

LR:

Likelihood ratio

MAGIC:

Major Atmospheric Gamma-Ray Imaging Cherenkov Telescope

MOJAVE:

Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments

OSO-3:

Orbiting Solar Observatory-3

PSF:

Point spread function

SAS-2:

Small Astronomy Satellite-2

SMARTS:

Small and Medium Aperture Research Telescope System

SOAR:

Southern Astrophysical Research Telescope

UV:

Ultraviolet energy range

VERITAS:

Very Energetic Radiation Imaging Telescope Array System

VLA:

Very Large Array

VLBA:

Very Long Baseline Array

VLBI:

Very long baseline interferometry

WEBT:

Whole Earth Blazar Telescope

References

  • Aartsen MG, Ackermann M, Adams J et al (2014) Observation of high-energy astrophysical neutrinos in three years of IceCube data. Phys Rev Lett 113. doi:10.1103/PhysRevLett.113.101101

  • Abdo AA, Ackermann M, Ajello M et al (2008) Fermi large area telescope view of the core of the radio galaxy Centaurus A. Astrophys J 719:1433–1444. doi:10.1088/0004-637X/719/2/1433

  • Abdo AA, Ackermann M, Ajello M et al (2009a) Bright active galactic nuclei source list from the first three months of the Fermi large area telescope all-sky survey. Astrophys J Suppl Ser 700:597–622. doi:10.1088/0004-637X/700/1/597

    Article  Google Scholar 

  • Abdo AA, Ackermann M, Ajello M et al (2009b) Fermi/large area telescope bright gamma-ray source list. Astrophys J Suppl Ser 183:46–66. doi:10.1088/0067-0049/183/1/46

    Article  ADS  Google Scholar 

  • Abdo AA, Ackermann M, Ajello M et al (2009c) Early Fermi gamma-ray space telescope observations of the quasar 3C 454.3. Astrophys J 699:817–823. doi:10.1088/0004-637X/699/1/817

    Article  ADS  Google Scholar 

  • Abdo AA, Ackermann M, Ajello M et al (2009d) Radio-loud narrow-line Seyfert 1 as a new class of gamma-ray active galactic nuclei. Astrophys J Lett 707:142–147. doi:10.1088/0004-637X/707/2/L142

  • Abdo AA, Ackermann M, Ajello M et al (2009e) A population of gamma-ray millisecond pulsars seen with the Fermi large area telescope. Science 325:848–852. doi:10.1126/science.1176113

  • Abdo AA, Ackermann M, Ajello M et al (2010a) Fermi large area telescope first source catalog. Astrophys J Suppl Ser 188:405–436. doi:10.1088/0067-0049/188/2/405

    Article  ADS  Google Scholar 

  • Abdo AA, Ackermann M, Ajello M et al (2010b) The first catalog of active galactic nuclei detected by the Fermi large area telescope. Astrophys J 715:429–457. doi:10.1088/0004-637X/715/1/429

    Article  ADS  Google Scholar 

  • Abdo AA, Ackermann M, Ajello M et al (2010c) Fermi large area telescope observations of misaligned active galactic nuclei. Astrophys J 720:912–922. doi:10.1088/0004-637X/720/1/912

  • Abdo AA, Ackermann M, Ajello M et al (2010d) Fermi gamma-ray imaging of a radio galaxy. Science 328:725–792. doi:10.1126/science.1184656

  • Abdo AA, Ackermann M, Ajello M et al (2010e) The Fermi-LAT high-latitude survey: source count distributions and the origin of the extragalactic diffuse background. Astrophys J 720:435–453. doi:10.1088/0004-637X/720/1/435

  • Abdo AA, Ackermann M, Ajello M et al (2010f) Detection of gamma-ray emission from the starburst galaxies M82 and NGC 253 with the large area telescope on Fermi. Astrophys J 709:152–157. doi:10.1088/2041-8205/709/2/L152

  • Abdo AA, Ackermann M, Ajello M et al (2010g) Detection of the small magellanic cloud in gamma-rays with Fermi/LAT. Astron Astrophys 523:46–59. doi:10.1051/0004-6361/201014855

  • Abdo AA, Ackermann M, Ajello M et al (2010h) Observations of the large magellanic cloud with Fermi. Astron Astrophys 512:7–21. doi:10.1051/0004-6361/200913474

  • Abdo AA, Ackermann M, Ajello M et al (2010i) Fermi large area telescope observations of local group galaxies: detection of M 31 and search for M 33. Astron Astrophys 523:2–8. doi:10.1051/0004-6361/201015759

  • Abdo AA, Ackermann M, Ajello M et al (2013a) Fermi large area telescope gamma-ray detection of theradio galaxy M87. Astrophys J 768:54–67

  • Abdo AA, Ajello M, Allafort A et al (2013b) The second Fermi large area telescope catalog of gamma-ray pulsars. Astrophys J Suppl Ser 208:17–76. doi:10.1088/0067-0049/208/2/17

  • Abramowski A, Acero F, Aharonian F et al (2012) Astrophys J 746:151–168. doi:10.1088/0004-637X/746/2/151

    Article  ADS  Google Scholar 

  • Abramowski A, Acero F, Aharonian F et al (2013) Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S. Astron Astrophys 550:4–14. doi:10.1051/0004-6361/201220355

    Google Scholar 

  • Acciari VA, Aliu E, Arlen T et al (2010) Veritas 2008–2009 monitoring of the variable gamma-ray source M 87. Astrophys J 716:819–824. doi:10.1088/0004-637X/716/1/819

    Article  ADS  Google Scholar 

  • Acero F, Donato D, Ojha R et al (2013) Hunting for treasures among the Fermi unassociated sources: a multiwavelength approach. Astrophys J 779:133–141. doi:10.1088/0004-637X/779/2/133

    Article  ADS  Google Scholar 

  • Acero F, Ackermann M, Ajello M et al (2015) Fermi large area telescope third source catalog. Astrophys J Suppl Ser 218:23–60. doi:10.1088/0067-0049/218/2/23

    Article  ADS  Google Scholar 

  • Ackermann M, Ajello M, Allafort A et al (2010) Constraints on dark matter annihilation in clusters of galaxies with the Fermi large area telescope. JCAP 05:25. doi:10.1088/1475-7516/2010/05/025

    Article  ADS  Google Scholar 

  • Ackermann M, Ajello M, Allafort A et al (2011a) The second catalog of active galactic nuclei detected by the Fermi large area telescope. Astrophys J 743:171–208. doi:10.1088/0004-637X/743/2/171

  • Ackermann M, Ajello M, Allafort A et al (2011b) The radio/gamma-ray connection in active galactic nuclei in the era of the Fermi large area telescope. Astrophys J 741:30–49. doi:10.1088/0004-637X/741/1/30

  • Ackermann M, Ajello M, Atwood WB et al (2012a) Fermi-LAT observations of the diffuse \(\gamma \)-ray emission: implications for cosmic rays and the interstellar medium. Astrophys J 212:750–784. doi:10.1088/0004-637X/750/1/3

  • Ackermann M, Ajello M, Allafort A et al (2012b) A statistical approach to recognizing source classes for unassociated sources in the first Fermi-LAT catalog. Astrophys J 753:83–105. doi:10.1088/0004-637X/753/1/83

  • Ackermann M, Ajello M, Allafort A et al (2012c) The imprint of the extragalactic background light in the gamma-ray spectra of blazars. Science 338:1190–1192. doi:10.1126/science.1227160

  • Ackermann M, Ajello M, Allafort A et al (2012d) GeV observations of star-forming galaxies with the Fermi large area telescope. Astrophys J 755:164–187. doi:10.1088/0004-637X/755/2/164

  • Ackermann M, Ajello M, Allafort A et al (2012e) Search for gamma-ray emission from X-ray-selected Seyfert galaxies with Fermi-LAT. Astrophys J 747:104–120. doi:10.1088/0004-637X/747/2/104

  • Ackermann M, Ajello M, Allafort A et al (2013a) The first Fermi-LAT catalog of sources above 10 GeV. Astrophys J Suppl Ser 209:34–68. doi:10.1088/0067-0049/209/2/34

  • Ackermann M, Ajello M, Allafort A et al (2013b) Determination of the point-spread function for the Fermi large area telescope from on-orbit data and limits on pair halos of active galactic nuclei. Astrophys J 765:54–72. doi:10.1088/0004-637X/765/1/54

  • Ackermann M, Ajello M, Albert A et al (2013c) The Fermi all-sky variability analysis: a list of flaring gamma-ray sources and the search for transients in our galaxy. Astrophys J 771:57–68. doi:10.1088/0004-637X/771/1/57

  • Ackermann M, Albert A, Anderson B et al (2014a) Dark matter constraints from observations of 25 Milky Way satellite galaxies with the Fermi large area telescope. Phys Rev D 89:2001-1–2001-22. doi:10.1103/PhysRevD.89.042001

  • Ackermann M, Ajello M, Albert A et al (2014b) Search for cosmic-ray-induced gamma-ray emission in galaxy clusters. Astrophys J 787:18–43. doi:10.1088/0004-637X/787/1/18

  • Ackermann M, Albert A, Atwood WB et al (2014c) The spectrum and morphology of the Fermi bubbles. Astrophys J 793:64–97. doi:10.1088/0004-637X/793/1/64

  • Ackermann M, Ajello M, Allafort A et al (2014d) Multifrequency studies of the peculiar quasar 4C +21.35 during the 2010 flaring activity. Astrophys J 786:157–171. doi:10.1088/0004-637X/786/2/157

  • Ackermann M, Ajello M, Atwood WB et al (2015a) The third catalog of active galactic nuclei detected by the Fermi large area telescope. Astrophys J 810:14–47. doi:10.1088/0004-637X/810/1/14

  • Ackermann M, Ajello M, Albert A et al (2015b) The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV. Astrophys J 799:86–110. doi:10.1088/0004-637X/799/1/86

  • Ackermann M, Albert A, Anderson B et al (2015c) Searching for dark matter annihilation from Milky Way dwarf spheroidal galaxies with six years of Fermi-LAT data. Phys Rev Lett (submitted)

  • Agudo I, Marscher AP, Jorstad SG et al (2011) On the location of the \(\gamma \)-ray outburst emission in the BL lacertae object AO 0235+164 through observations across the electromagnetic spectrum. Astrophys J Lett 735:10–16. doi:10.1088/2041-8205/735/1/L10

    Article  ADS  Google Scholar 

  • Agudo I, Marscher AP, Jorstad SG et al (2012) Erratic jet wobbling in the BL lacertae object OJ287 revealed by sixteen years of 7 mm VLBA observations. Astrophys J 747:63–72. doi:10.1088/0004-637X/747/1/63

    Article  ADS  Google Scholar 

  • Aharonian F (2000) TeV gamma rays from BL Lac objects due to synchrotron radiation of extremely high energy protons. New Astron 5:377–395. doi:10.1016/S1384-1076(00)00039-7

    Article  ADS  Google Scholar 

  • Aharonian FA, Akhperjanian AG, Bazer-Bachi AR (2007) An exceptional very high energy gamma-ray flare of PKS 2155-304. Astrophys J 664:71–74. doi:10.1086/520635

    Article  ADS  Google Scholar 

  • Ajello M, Romani RW, Gasparini D et al (2014) The cosmic evolution of Fermi BL lacertae objects. Astrophys J 780:73–96. doi:10.1088/0004-637X/780/1/73

    Article  ADS  Google Scholar 

  • Ajello M, Gasparini D, Sánchez-Conde M et al (2015) The origin of the extragalactic gamma-ray background and implications for dark matter annihilation. Astrophys J 800:L27–L34. doi:10.1088/2041-8205/800/2/L27

    Article  ADS  Google Scholar 

  • Albert J, Aliu E, Anderhub H et al (2013) Variable very high energy \(\gamma \)-ray emission from Markarian 501. Astrophys J 669:862–883. doi:10.1086/521382

    Article  ADS  Google Scholar 

  • Aleksić J, Antonelli LA, Antoranz P (2014) Rapid and multiband variability of the TeV bright active nucleus of the galaxy IC 310. Astron Astrophys 563:91. doi:10.1051/0004-6361/201321938

    Article  ADS  Google Scholar 

  • Arshakian TG, León-Tavares J, Boettcher M et al (2012) Radio-optical-gamma-ray properties of MOJAVE AGN detected by Fermi/LAT. Astron Astrophys 537:32–41. doi:10.1051/0004-6361/201117140

    Article  ADS  Google Scholar 

  • Arsioli B, Fraga B, Giommi P et al (2015) 1WHSP: an IR-based sample of 1000 VHE \(\gamma \)-ray blazar candidates. Å 579:34–44. doi:10.1051/0004-6361/201424148

    Google Scholar 

  • Atwood WB, Abdo AA, Ackermann M et al (2009) The large area telescope on the Fermi gamma-ray space telescope mission. Astrophys J 697:1071–1102. doi:10.1088/0004-637X/697/2/1071

    Article  ADS  Google Scholar 

  • Baltz EA, Berenji B, Bertone G et al (2008) Pre-launch estimates for GLAST sensitivity to dark matter annihilation signals. JCAP 07:13–55. doi:10.1088/1475-7516/2008/07/013

    Article  ADS  Google Scholar 

  • Barnacka A, Glicenstein J-F, Moudden Y (2011) First evidence of a gravitational lensing-induced echo in gamma rays with Fermi LAT. Astron Astrophys 528:3–6. doi:10.1051/0004-6361/201016175

    Article  ADS  Google Scholar 

  • Baumgartner WH, Tueller J, Markwardt CB et al (2008) The 70 month swift-BAT all-sky hard X-ray survey. Astrophys J Suppl Ser 207:19–30. doi:10.1088/0067-0049/207/2/19

    Article  ADS  Google Scholar 

  • Berlin A, Hooper D (2013) Stringent constraints on the dark matter annihilation cross section from subhalo searches with the Fermi gamma-ray space telescope. Phys Rev D 89:6014. doi:10.1103/PhysRevD.89.016014

    Google Scholar 

  • Bertoni B, Hooper D, Linden T (2015) Examining the Fermi-LAT third source catalog in search of dark matter subhalos. Phys Rev D (submitted)

  • Bignami GF, Fichtel CE, Hartman RC, Thompson DJ (1979) Galaxies and gamma-ray astronomy. Astrophys J 232:649–658. doi:10.1086/157323

    Article  ADS  Google Scholar 

  • Bird AJ, Bazzano A, Bassani L et al (2010) The fourth IBIS/ISGRI soft gamma-ray survey catalog. Astrophys J Suppl Ser 186:1–9. doi:10.1088/0067-0049/186/1/1

    Article  ADS  Google Scholar 

  • Blandford RD, Rees MJ (1978) Rees extended and compact extragalactic radio sources: interpretation and theory. Phys Scr 17:265–274. doi:10.1088/0031-8949/17/3/020

    Article  ADS  Google Scholar 

  • Boettcher M, Reimer A, Sweeney K et al (2013) Leptonic and hadronic modeling of Fermi-detected blazars. Astrophys J 768:54–67. doi:10.1088/0004-637X/768/1/54

    Article  ADS  Google Scholar 

  • Bonning E, Urry CM, Bailyn C et al (2012) SMARTS optical and infrared monitoring of 12 gamma-ray bright blazars. Astrophys J 756:13–28. doi:10.1088/0004-637X/756/1/13

    Article  ADS  Google Scholar 

  • Bonnolli G, Tavecchio F, Ghisellini G, Sbarrato T (2015) An emerging population of BL Lacs with extreme properties: towards a class of EBL and cosmic magnetic field probes? Mon Not R Astron Soc 451:611–621. doi:10.1093/mnras/stv953

    Article  ADS  Google Scholar 

  • Broderick AE, Chang P, Pfrommer C (2012) The cosmological impact of luminous TeV blazars. I. Implications of plasma instabilities for the intergalactic magnetic field and extragalactic gamma-ray background. Astrophys J 752:22–44. doi:10.1088/0004-637X/752/1/22

    Article  ADS  Google Scholar 

  • Calderone G, Foschini L, Ghisellini G et al (2011) \(\gamma \)-ray variability of radio-loud narrow-line Seyfert 1 galaxies. Mon Not R Astron Soc 413:2365–2370. doi:10.1111/j.1365-2966.2011.18308.x

    Article  ADS  Google Scholar 

  • Casandjian J-M, Grenier IA (2008) A revised catalogue of EGRET \(\gamma \)-ray sources. Astron Astrophys 489:849–883. doi:10.1051/0004-6361:200809685

    Article  ADS  Google Scholar 

  • Chang P, Broderick AE, Pfrommer C (2006) The cosmological impact of luminous TeV blazars. II. Rewriting the thermal history of the intergalactic medium. Astrophys J 752:23–46. doi:10.1088/0004-637X/752/1/23

    Article  ADS  Google Scholar 

  • Chang P, Broderick AE, Pfrommer C et al (2014) The effect of nonlinear Landau damping on ultrarelativistic beam plasma instabilities. Astrophys J 797:110–115. doi:10.1088/0004-637X/797/2/110

    Article  ADS  Google Scholar 

  • Chatterjee R, Fossati G, Urry CM (2013a) An optical-near-infrared outburst with no accompanying \(\gamma \)-rays in the blazar PKS 0208-512. Astrophys J 763:11–18. doi:10.1088/2041-8205/763/1/L11

  • Chatterjee R, Nalewajko K, Myers AD (2013b) Implications of the anomalous outburst in the blazar PKS 0208-512. Astrophys J 771:25–29. doi:10.1088/2041-8205/771/2/L25

  • Cheung CC, Donato D, Gehrels N et al (2012) Chandra X-ray observations of the two brightest unidentified high galactic latitude Fermi-LAT gamma-ray sources. Astrophys J 756:33–52. doi:10.1088/0004-637X/756/1/33

    Article  ADS  Google Scholar 

  • Cheung CC, Larsson S, Scargle JD et al (2014) Fermi large area telescope detection of gravitational lens delayed \(\gamma \)-ray flares from blazar B0218+357. Astrophys J Lett 728:14–20. doi:10.1088/2041-8205/782/2/L14

    Article  ADS  Google Scholar 

  • Cerruti M, Zech A, Boisson C, Inoue S (2015) A hadronic origin for ultra-high-frequency-peaked BL Lac objects. Mon Not R Astron Soc 448:910–927. doi:10.1093/mnras/stu2691

    Article  ADS  Google Scholar 

  • D’Abrusco R, Massaro F, Ajello M et al (2012) Infrared colors of the gamma-ray-detected blazars. Astrophys J 748:68–82. doi:10.1088/0004-637X/748/1/68

    Article  ADS  Google Scholar 

  • D’Abrusco R, Massaro F, Paggi A et al (2013) Unveiling the nature of unidentified gamma-ray sources. I. A new method for the association of gamma-ray blazars. Astrophys J Suppl Ser 206:12–38. doi:10.1088/0067-0049/206/2/12

    Article  ADS  Google Scholar 

  • D’Abrusco R, Massaro F, Paggi A et al (2014) The WISE blazar-like radio-loud sources: an all-sky catalog of candidate gamma-ray blazars. Astrophys J Suppl Ser 215:14. doi:10.1088/0067-0049/215/1/14

    Article  ADS  Google Scholar 

  • D’Ammando F, Antolini E, Tosti G et al (2013a) Long-term monitoring of PKS 0537-441 with Fermi-LAT and multiwavelength observations. Mon Not R Astron Soc 431:2481–2492. doi:10.1093/mnras/stt344

  • D’Ammando F, Orienti M, Finke J et al (2013b) Multifrequency studies of the narrow-line Seyfert 1 galaxy SBS 0846+513. Mon Not R Astron Soc 436:191–201. doi:10.1093/mnras/stt1560

  • D’Amamndo F, Orienti M, Finke J et al (2015a) The most powerful flaring activity from the NLSy1 PMN J0948+0022. Astrophys J 768:54–67. doi:10.1093/mnras/stu2251

  • D’Amamndo F, Orienti M, Larsson J, Giroletti M (2015b) The first \(\gamma \)-ray detection of the narrow-line Seyfert 1 FBQS J1644+2619. Mon Not R Astron Soc 452:520–524. doi:10.1093/mnras/stv1278

  • D’Ammando F, Orienti M, Tavecchio F et al (2015c) Unveiling the nature of the \(\gamma \)-ray emitting active galactic nucleus PKS 0521-36. Mon Not R Astron Soc 450:3975–3990. doi:10.1093/mnras/stv909

  • Dermer CD (1995) On the beaming statistics of gamma-ray sources. Astrophys J 446:63–66. doi:10.1086/187931

    Article  ADS  Google Scholar 

  • Dermer CD, Giebels B (2015) Active galactic nuclei at \(\gamma \)-ray energies. CRAS 000:00–96 in prep

    Google Scholar 

  • Dermer CD, Schlickeiser R (2002) Transformation properties of external radiation fields, energy-loss rates and scattered spectra, and a model for blazar variability. Astrophys J 575:667–686. doi:10.1086/341431

    Article  ADS  Google Scholar 

  • Dermer CD, Cerruti M, Lott B (2002) Equipartition gamma-ray blazars and the location of the gamma-ray emission site in 3C 279. Astrophys J 782:82–96. doi:10.1088/0004-637X/782/2/82

    Article  ADS  Google Scholar 

  • Dermer CD, Cavadini M, Razzaque S et al (2011) Time delay of cascade radiation for TeV blazars and the measurement of the intergalactic magnetic field. Astrophys J Lett 733:21. doi:10.1088/2041-8205/733/2/L21

    Article  ADS  Google Scholar 

  • Di Mauro M, Donato F, Lamanna G et al (2014a) Diffuse \(\gamma \)-ray emission from unresolved BL Lac objects. Astrophys J 786:129–140. doi:10.1088/0004-637X/786/2/129

  • Di Mauro M, Calore F, Donato F, Ajello M, Latronico L (2014b) Diffuse \(\gamma \)-ray emission from misaligned active galactic nuclei. Astrophys J 780:161–175. doi:10.1088/0004-637X/780/2/161

  • Doert M, Errando M (2014) Search for gamma-ray-emitting active galactic nuclei in the Fermi-LAT unassociated sample using machine learning. Astrophys J 782:41–48. doi:10.1088/0004-637X/782/1/41

    Article  ADS  Google Scholar 

  • Dolag K, Kachelriess M, Ostapchenko S et al (2011) Lower limit on the strength and filling factor of extragalactic magnetic fields. Astrophys J Lett 727:4–7. doi:10.1088/2041-8205/727/1/L4

    Article  ADS  Google Scholar 

  • Domínguez A, Prada F (2013) Measurement of the expansion rate of the universe from \(\gamma \)-ray attenuation. Astrophys J 771:34–38. doi:10.1088/2041-8205/771/2/L34

    Article  Google Scholar 

  • Domínguez A, Finke JD, Prada F et al (2013) Detection of the cosmic \(\gamma \)-ray horizon from multiwavelength observations of blazars. Astrophys J 770:77–92. doi:10.1088/0004-637X/770/1/77

    Article  ADS  Google Scholar 

  • Elmouttie M, Haynes RF, Jones KL et al (1998) Radio continuum evidence for nuclear outflow in the Circinus galaxy. Mon Not R Astron Soc 297:1202–1218. doi:10.1046/j.1365-8711.1998.01592.x

    Article  ADS  Google Scholar 

  • Essay W, Kusenko A (2010a) A new interpretation of the gamma-ray observations of distant active galactic nuclei. Astropart Phys 33:81–85. doi:10.1046/j.1365-8711.1998.01592.x

  • Essay W, Kusenko A (2010b) Secondary photons and neutrinos from cosmic rays produced by distant blazars. Phys Rev Lett 104. doi:10.1103/PhysRevLett.104.141102

  • Falomo R, Pian E, Treves A (2014) An optical view of BL lacertae objects. Astron Astrophys Rev 22:73

    Article  ADS  Google Scholar 

  • Fanaroff BL, Riley JM (1974) The morphology of extragalactic radio sources of high and low luminosity. Mon Not R Astron Soc 167:31P–36P

    Article  ADS  Google Scholar 

  • Fields BD, Pavlidou V, Prodanović T (2011) Cosmic gamma-ray background from star-forming galaxies. Astrophys J 722:66–75. doi:10.1088/2041-8205/722/2/L199

    Google Scholar 

  • Finke J (2013) Blazars in context in the Fermi era. In: 2012 Fermi symposium proceedings, pp 1–7 (eprint arXiv:1303.5095)

  • Finke JD (2013) Compton dominance and the blazar sequence. Astrophys J 763:134–144. doi:10.1088/0004-637X/763/2/134

    Article  ADS  Google Scholar 

  • Finke JD, Dermer CE (2010) On the break in the Fermi-large area telescope spectrum of 3C 454.3. Astrophys J 714:303–307. doi:10.1088/2041-8205/714/2/L303

    Article  ADS  Google Scholar 

  • Finke JD, Razzaque S, Dermer CE (2010) Modeling the extragalactic background light from stars and dust. Astrophys J 712:238–249. doi:10.1088/0004-637X/712/1/238

    Article  ADS  Google Scholar 

  • Foschini L, Angelakis E, Fuhrmann L et al (2012) Radio-to-\(\gamma \)-ray monitoring of the narrow-line Seyfert 1 galaxy PMN J0948+0022 from 2008 to 2011. Astron Astrophys 548:106–119. doi:10.1051/0004-6361/201220225

    Article  ADS  Google Scholar 

  • Foschini L, Berton A, Caccianiga A et al (2015) Properties of flat-spectrum radio-loud narrow-line Seyfert 1 galaxies. Astron Astrophys 575:13. doi:10.1051/0004-6361/201424972

    Article  ADS  Google Scholar 

  • Fossati G, Maraschi L, Celotti A et al (1998) A unifying view of the spectral energy distributions of blazars. Mon Not R Astron Soc 299:433–448. doi:10.1046/j.1365-8711.1998.01828.x

    Article  ADS  Google Scholar 

  • Fuhrmann L, Larsson S, Chaing J et al (2014) Detection of significant cm to sub-mm band radio and \(\gamma \)-ray correlated variability in Fermi bright blazars. Astron J 441:1899–1909. doi:10.1093/mnras/stu540

    Google Scholar 

  • Ghirlanda G, Ghisellini G, Tavecchio F (2011a) Correlation of Fermi large area telescope sources with the 20-GHz Australia telescope compact array radio survey. Mon Not R Astron Soc 407:791–803. doi:10.1111/j.1365-2966.2010.16980.x

  • Ghirlanda G, Ghisellini G, Tavecchio F (2011b) The radio-\(\gamma \)-ray connection in Fermi blazars. Mon Not R Astron Soc 413:852–862. doi:10.1111/j.1365-2966.2010.18173.x

  • Ghisellini G, Tavecchio F (2015) Fermi/LAT broad emission line blazars. Mon Not R Astron Soc 448:1060–1077. doi:10.1093/mnras/stv055

    Article  ADS  Google Scholar 

  • Ghisellini G, Tavecchio F, Chiaberge M (2005) Structured jets in TeV BL Lac objects and radiogalaxies. Implications for the observed properties. Astron Astrophys 432:401–410. doi:10.1051/0004-6361:20041404

    Article  ADS  Google Scholar 

  • Ghisellini G, Maraschi L, Tavecchio F (2009) The Fermi blazars’ divide. Mon Not R Astron Soc 396:105–109. doi:10.1111/j.1745-3933.2009.00673.x

    Article  ADS  Google Scholar 

  • Ghisellini G, Tavecchio F, Foschini L et al (2011) General physical properties of bright Fermi blazars. Mon Not R Astron Soc 402:497–518. doi:10.1111/j.1365-2966.2009.15898.x

    Article  ADS  Google Scholar 

  • Giannios D (2013) Reconnection-driven plasmoids in blazars: fast flares on a slow envelope. Mon Not R Astron Soc 431:355–363. doi:10.1093/mnras/stt167

    Article  ADS  Google Scholar 

  • Giommi P, Padovani P (2015) A simplified view of blazars: contribution to the X-ray and \(\gamma \)-ray extragalactic backgrounds. Mon Not R Astron Soc 000:000–000. doi:10.1093/mnras/stv793

    Google Scholar 

  • Giommi J, Padovani P, Polenta G (2012a) Exploring the relation between (sub-)millimeter radiation and \(\gamma \)-ray emission in blazars with Planck and Fermi. Astrophys J 754:23–37. doi:10.1088/0004-637X/754/1/23

  • Giommi P, Polenta G, Lahteenmaki A et al (2012b) Simultaneous Planck, Swift, and Fermi observations of X-ray and gamma-ray selected blazars. Astron Astrophys 541:160–219. doi:10.1051/0004-6361/201117825

  • Giommi P, Padovani P, Polenta G (2013) A simplified view of blazars: the \(\gamma \)-ray case. Mon Not R Astron Soc 000:000–000. doi:10.1093/mnras/stt305

    Google Scholar 

  • Grenier IA, Casandjian J, Terrier R (2005) Unveiling extensive clouds of dark gas in the solar neighborhood. Science 307:1292. doi:10.1126/science.1106924

    Article  ADS  Google Scholar 

  • Hada K, Giroletti M, Kino M et al (2014) A strong radio brightening at the jet base of M 87 during the elevated very high energy gamma-ray state in 2012. Astrophys J 788:165–177. doi:10.1088/0004-637X/788/2/165

    Article  ADS  Google Scholar 

  • Harris DE, Birretta JA, Junor W et al (2003) Flaring X-ray emission from HST-1, a knot in the M87 jet. Astrophys J 586:41–44. doi:10.1086/374773

    Article  ADS  Google Scholar 

  • Harris DE, Massaro F, Cheung CC et al (2012) An experiment to locate the site of TeV flaring in M87. Astrophys J 743:177–182. doi:10.1088/0004-637X/743/2/177

    Article  ADS  Google Scholar 

  • Hartmann DH (2007) Probing the extragalactic background with GLAST. In: AIP conference proceedings, vol 921. The first glast symposium. doi:10.1063/1.2757259

  • Hartman RC, Bertsch DL, Bloom SD et al (1999) The third EGRET catalog of high-energy gamma-ray sources. Astrophys J Suppl Ser 123:79–202. doi:10.1086/313231

    Article  ADS  Google Scholar 

  • Hassan T, Mirabal N, Contreras JL, Oya I (2013) Gamma-ray active galactic nucleus type through machine-learning algorithms. Mon Not R Astron Soc 428:220–225. doi:10.1093/mnras/sts022

    Article  ADS  Google Scholar 

  • Hayashida M, Stawarz L, Cheung CC et al (2013) Discovery of GeV emission from the Circinus galaxy with the Fermi large area telescope. Astrophys J 779:131–138. doi:10.1088/0004-637X/779/2/131

    Article  ADS  Google Scholar 

  • Healey SE, Romani RW, Taylor GB et al (2007) CRATES: an all-sky survey of flat-spectrum radio sources. Astrophys J Suppl Ser 171:61–71. doi:10.1086/513742

    Article  ADS  Google Scholar 

  • Healey SE, Romani RW, Garret C et al (2008) CGRaBS: an all-sky survey of gamma-ray blazar candidates. Astrophys J Suppl Ser 175:97–104. doi:10.1086/523302

    Article  ADS  Google Scholar 

  • Hovatta T, Lister ML, Kovalev YY et al (2010) The relation between radio polarization and gamma-ray emission in AGN jets. Int J Mod Phys D 19:943–948. doi:10.1142/S0218271810016683

    Article  ADS  Google Scholar 

  • Hovatta T, Lister ML, Aller MF et al (2012) MOJAVE: monitoring of jets in active galactic nuclei with VLBA experiments. VIII. Faraday rotation in parsec-scale AGN jets. Astron J 144:105–139. doi:10.1088/0004-6256/144/4/105

    Article  ADS  Google Scholar 

  • Hovatta T, Aller MF, Aller HD et al (2014) MOJAVE: monitoring of jets in active galactic nuclei with VLBA experiments XI. Spectral distributions. Astron J 147:143. doi:10.1088/0004-6256/147/6/143

    Article  ADS  Google Scholar 

  • Kadler M, Eisenacher D, Ros R et al (2012) The blazar-like radio structure of the TeV source IC 310. Astron Astrophys 538:1. doi:10.1051/0004-6361/201118212

    Article  ADS  Google Scholar 

  • Kataoka J, Stawarz L, Cheung CC et al (2010) \(\gamma \)-ray spectral evolution of NGC 1275 observed with Fermi large area telescope. Astrophys J 715:554–560. doi:10.1088/0004-637X/715/1/554

    Article  ADS  Google Scholar 

  • Kataoka J, Stawarz L, Takahashi Y et al (2011) Broad-line radio galaxies observed with Fermi-LAT: the origin of the GeV \(\gamma \)-ray emission. Astrophys J 740:29–44. doi:10.1088/0004-637X/740/1/29

    Article  ADS  Google Scholar 

  • Kataoka J, Yatsu Y, Kawai N et al (2012) Toward identifying the unassociated gamma-ray source 1FGL J1311.7-3429 with X-ray and optical observations. Astrophys J 757:176–185. doi:10.1088/0004-637X/757/2/176

    Article  ADS  Google Scholar 

  • Katsuta J, Tanaka Y, Stawarz L (2013) Fermi-LAT and Suzaku observations of the radio galaxy Centaurus B. Astron Astrophys 550:66. doi:10.1051/0004-6361/201220270

    Article  ADS  Google Scholar 

  • Komossa S, Voges W, Xu D et al (2006) Radio-loud narrow-line type 1 Quasars. Astron J 132:531–545. doi:10.1086/505043

    Article  ADS  Google Scholar 

  • Kovalev YY (2009) Identification of the early Fermi/LAT gamma-ray bright objects with extragalactic VLBI sources. Astrophys J 707:56–59. doi:10.1088/0004-637X/707/1/L56

    Article  ADS  Google Scholar 

  • Kraushaar WL, Clark GW, Garmire GP et al (1972) High-energy cosmic gamma-ray observations from the OSO-3 satellite. Astrophys J 177:341–363. doi:10.1086/151713

  • Jarrett TH, Chester T, Cutri R et al (2003) The 2MASS large galaxy atlas. Astron J 125:525–554. doi:10.1086/345794

    Article  ADS  Google Scholar 

  • Jorstad S, Marscher AP, Smith PS et al (2008) A tight connection between gamma-ray outbursts and parsec-scale jet activity in the Quasar 3C 454.3. Astrophys J 773:147–173. doi:10.1088/0004-637X/773/2/147

    Article  ADS  Google Scholar 

  • Jorstad SG, Marscher AP, Larionov VM et al (2010) Flaring behavior of the Quasar 3C 454.3 across the electromagnetic spectrum. Astrophys J 715:362–384. doi:10.1088/0004-637X/715/1/362

    Article  ADS  Google Scholar 

  • Inoue Y (2010) Contribution of gamma-ray-loud radio galaxies’ core emissions to the cosmic MeV and GeV gamma-ray background radiation. Astrophys J 733:L199–L203. doi:10.1088/0004-637X/733/1/66

    Google Scholar 

  • Isler JC, Urry CM, Bailyn C et al (2015) The SMARTS multi-epoch optical spectroscopy atlas (SaMOSA): an analysis of emission line variability in southern hemisphere Fermi blazars. Astrophys J 804:7–20. doi:10.1088/0004-637X/804/1/7

    Article  ADS  Google Scholar 

  • Landoni M, Massaro F, Paggi A et al (2015) Optical spectroscopic observations of gamma-ray blazar candidates III. The 2013/2014 campaign in the southern hemisphere. AJ (in press). arXiv:1503.04805

  • Lee KJ, Guillemot L, Yue YL, Kramer M, Champion DL (2012) Application of the Gaussian mixture model in pulsar astronomy—pulsar classification and candidates ranking for the Fermi 2FGL catalogue. Mon Not R Astron Soc 424:2832–2840. doi:10.1111/j.1365-2966.2012.21413.x

    Article  ADS  Google Scholar 

  • Lenain J-P, Ricci C, Turler M et al (2010) Seyfert 2 galaxies in the GeV band: jets and starburst. Astron Astrophys 524:72–79. doi:10.1051/0004-6361/201015644

    Article  ADS  Google Scholar 

  • Leòn Tavares J, Kotilainen J, Chavushyan V et al (2014) The host galaxy of the gamma-ray narrow-line Seyfert 1 galaxy 1H 0323+342. Astrophys J 795:58. doi:10.1088/0004-637X/795/1/58

    Article  ADS  Google Scholar 

  • Linford JD, Taylor GB, Schinzel FK (2012) Gamma-ray loudness, synchrotron peak frequency, and parsec-scale properties of blazars detected by the Fermi large area telescope. Astrophys J 757:25–38. doi:10.1088/0004-637X/757/1/25

    Article  ADS  Google Scholar 

  • Lister ML, Cohen MH, Homan DC et al (2009) MOJAVE: monitoring of jets in active galactic nuclei with VLBA experiments. VI. Kinematics analysis of a complete sample of blazar jets. Astron J 138:1874–1892. doi:10.1088/0004-6256/138/6/1874

    Article  ADS  Google Scholar 

  • Lister ML, Aller M, Aller H et al (2011) \(\gamma \)-ray and parsec-scale jet properties of a complete sample of blazars from the MOJAVE program. Astrophys J 742:27–51. doi:10.1088/0004-637X/742/1/27

    Article  ADS  Google Scholar 

  • Lister ML, Hovatta MF, Aller HD et al (2015) Why haven’t many of the brightest radio loud blazars been detected by Fermi? Astrophys J Lett (in press)

  • López-Caniego M, Gonzàlez-Nuevo J, Massardi M et al (2013) Mining the Herschel-astrophysical terahertz large area survey: submillimetre-selected blazars in equatorial fields. Mon Not R Astron Soc 430:1556–1577. doi:10.1093/mnras/sts680

    Article  Google Scholar 

  • Maeda K, Kataoka J, Nakamori T et al (2011) Unraveling the nature of unidentified high galactic latitude Fermi/LAT gamma-ray sources with Suzaku. Astrophys J 729:103–117. doi:10.1088/0004-637X/729/2/103

    Article  ADS  Google Scholar 

  • Makiya R, Totani T, Kobayashi MAR (2011) Contribution from star-forming galaxies to the cosmic gamma-ray background radiation. Astrophys J 728:158–167. doi:10.1088/0004-637X/728/2/158

    Article  ADS  Google Scholar 

  • Mahony EK, Ghisellini G, Tavecchio F et al (2010) High-frequency radio properties of sources in the Fermi-LAT 1 year point source catalog. Astrophys J 718:587–595. doi:10.1088/0004-637X/718/2/587

    Article  ADS  Google Scholar 

  • Mannheim K, Biermann PL (1992) Gamma-ray flaring of 3C 279—a proton-initiated cascade in the jet? Astron Astrophys 253:21–24

    ADS  Google Scholar 

  • Marscher AP (2014) Turbulent, extreme multi-zone model for simulating flux and polarization variabilityin blazars. Astrophys J 780:87–96. doi:10.1088/0004-637X/780/1/87

  • Marscher AP, Broderick JJ (1981) X-ray and VLBI radio observations of the quasars NRAO 140 and NRAO 530. Astrophys J 249:406–414. doi:10.1086/159301

    Article  ADS  Google Scholar 

  • Marscher AP, Jorstad SG, D’Arcangelo FD et al (2008) The inner jet of an active galactic nucleus as revealed by a radio-to-\(\gamma \)-ray outburst. Nature 452:966–969. doi:10.1038/nature06895

    Article  ADS  Google Scholar 

  • Marscher AP, Jorstad SG, Larionov VM et al (2010) Probing the inner jet of the Quasar PKS 1510-089 with multi-waveband monitoring during strong gamma-ray activity. Astrophys J Lett 710:126–131. doi:10.1088/2041-8205/710/2/L126

    Article  ADS  Google Scholar 

  • Marscher AP (2014) Turbulent, extreme multi-zone model for simulating flux and polarization variability in blazars. Astrophys J 780:87–96. doi:10.1088/0004-637X/780/1/87

    Article  ADS  Google Scholar 

  • Masetti M, Sbarufatti B, Parisi P et al (2013) BL lacertae identifications in a ROSAT-selected sample of Fermi unidentified objects. Astron Astrophys 559:58–74. doi:10.1051/0004-6361/201322611

    Article  ADS  Google Scholar 

  • Massaro E, Perri M, Giommi P et al (2004) Log-parabolic spectra and particle acceleration in the BL Lac object Mkn 421: spectral analysis of the complete BeppoSAX wide band X-ray data set. Astron Astrophys 413:489–503. doi:10.1051/0004-6361:20031558

    Article  ADS  Google Scholar 

  • Massaro E, Tramacere A, Perri M et al (2006) Log-parabolic spectra and particle acceleration in blazars. III. SSC emission in the TeV band from Mkn501. Astron Astrophys 448:861–871. doi:10.1051/0004-6361:20053644

    Article  ADS  Google Scholar 

  • Massaro E, Giommi P, Leto C et al (2009) Roma-BZCAT: a multifrequency catalogue of blazars. Astron Astrophys 495:691–696. doi:10.1051/0004-6361:200810161

    Article  ADS  Google Scholar 

  • Massaro E, Giommi P, Leto C et al (2011a) Multifrequency catalogue of blazars (3rd edn). In: Massaro E, Giommi P, Leto C, Marchegiani P, Maselli A, Perri M, Piranomonte S (eds) ARACNE Editrice, Rome

  • Massaro F, D’Abrusco R, Ajello M et al (2011b) Identification of the infrared non-thermal emission in blazars. Astrophys J Lett 740:48–53. doi:10.1088/2041-8205/740/2/L48

  • Massaro F, Ajello M et al (2011c) Fueling lobes of radio galaxies: statistical particle acceleration and the extragalactic \(\gamma \)-ray background. Astrophys J Lett 729:12–16. doi:10.1088/2041-8205/729/1/L12

  • Massaro F, Paggi A, Cavaliere A (2011d) X-ray and TeV emissions from high-frequency-peaked BL Lac objects. Astrophys J Lett 742:32–36. doi:10.1088/2041-8205/742/2/L32

  • Massaro F, D’Abrusco R, Tosti G et al (2012a) The WISE gamma-ray strip parameterization: the nature of the gamma-ray active galactic nuclei of uncertain type. Astrophys J 750:138–148. doi:10.1088/0004-637X/750/2/138

  • Massaro F, D’Abrusco R, Tosti G et al (2012b) Unidentified gamma-ray sources: hunting gamma-ray blazars. Astrophys J 752:61–68. doi:10.1088/0004-637X/752/1/61

  • Massaro F, D’Abrusco R, Paggi A et al (2013a) Unveiling the nature of unidentified gamma-ray sources. II. Radio, infrared, and optical counterparts of the gamma-ray blazar candidates. Astrophys J Suppl Ser 206:13–28. doi:10.1088/0067-0049/206/2/13

  • Massaro F, D’Abrusco R, Giroletti M et al (2013b) Unveiling the nature of the unidentified gamma-ray sources. III. Gamma-ray blazar-like counterparts at low radio frequencies. Astrophys J Suppl Ser 207:4–19. doi:10.1088/0067-0049/207/1/4

  • Massaro F, D’Abrusco R, Paggi A et al (2013c) Unveiling the nature of the unidentified gamma-ray sources. V. Analysis of the radio candidates with the kernel density estimation. Astrophys J Suppl Ser 209:10–17. doi:10.1088/0067-0049/209/1/10

  • Massaro F, Giroletti M, Paggi A et al (2013d) Blazar spectral properties at 74 MHz. Astrophys J Suppl Ser 208:15–21. doi:10.1088/0067-0049/208/2/15

  • Massaro F, Masetti N, D’Abrusco R et al (2014) Optical spectroscopic observations of blazars and gamma-ray blazar candidates in the sloan digital sky survey data release nine. Astron J 148:66. doi:10.1088/0004-6256/148/4/66

    Article  ADS  Google Scholar 

  • Massaro F, Landoni M, D’Abrusco R et al (2015a) Optical spectroscopic observations of gamma-ray blazar candidates. II. The 2013 KPNO campaign in the northern hemisphere. Astron J 575:124 (pii 2015A&A.575A.124M)

  • Massaro F, D’Abrusco R, Landoni M et al (2015b) Refining the associations of the Fermi large area telescope source catalogs. Astrophys J Suppl Ser 217:2–28. doi:10.1088/0067-0049/217/1/2

  • Massaro E, Maselli A, Leto C et al (2015c) The 5th edition of the Roma-BZCAT. A short presentation. Astrophys Space Sci (in press). arXiv:1502.07755

  • Mattox JR, Schachter J, Molnar L et al (1997) The identification of EGRET sources with flat-spectrum radio sources. Astrophys J 481:95–115

    Article  ADS  Google Scholar 

  • Meegan C, Lichti G, Bhat PN et al (2009) The Fermi gamma-ray burst monitor. Astrophys J 702:791–804. doi:10.1088/0004-637X/702/1/791

    Article  ADS  Google Scholar 

  • Meyer ET, Fossati G, Georganopoulos M (2011) From the blazar sequence to the blazar envelope: revisiting the relativistic jet dichotomy in radio-loud active galactic nuclei. Astrophys J 740:98–112. doi:10.1088/0004-637X/740/2/98

    Article  ADS  Google Scholar 

  • Michelson PF, Atwood WB, Ritz S (2010) Gamma-ray space telescope: high-energy results from the first year. Rep Prog Phys 73:7–32. doi:10.1088/0034-4885/73/7/074901

    Article  Google Scholar 

  • Migliori G, Siemiginowska A, Kelly BC (2014) Jet emission in young radio sources: a Fermi large area telescope gamma-ray view. Astrophys J 780:165–179. doi:10.1088/0004-637X/780/2/165

    Article  ADS  Google Scholar 

  • Miniati F, Elyiv A (2013) Relaxation of blazar-induced pair beams in cosmic voids. Astrophys J 770:54–62. doi:10.1088/0004-637X/770/1/54

    Article  ADS  Google Scholar 

  • Mirabal N, Halpern JP (2009) 0FGL J1830.3+0617: a Fermi blazar near the galactic plane. Astrophys J Lett 701:129–132. doi:10.1088/0004-637X/701/2/L129

    Article  ADS  Google Scholar 

  • Mirabal N, Frías-Martinez V, Hassan T et al (2012) Fermi’s SIBYL: mining the gamma-ray sky for dark matter subhaloes. Mon Not R Astron Soc 424:64–68. doi:10.1111/j.1745-3933.2012.01287.x

    Article  ADS  Google Scholar 

  • Nalewajko K, Begelman MC (2012) The effect of poloidal velocity shear on the local development of current-driven instabilities. Mon Not R Astron Soc 425:2480–2486. doi:10.1111/j.1365-2966.2012.22117.x

    Article  ADS  Google Scholar 

  • Nalewajko K, Begelman MC, Cerutti B et al (2012) Energetic constraints on a rapid gamma-ray flare in PKS 1222+216. Mon Not R Astron Soc 425:2519–2529. doi:10.1111/j.1365-2966.2012.21721.x

    Article  ADS  Google Scholar 

  • Nalewajko K, Begelman MC, Sikora M (2014) Constraining the location of gamma-ray flares in luminous blazars. Astrophys J 789:161–180. doi:10.1088/0004-637X/789/2/161

    Article  ADS  Google Scholar 

  • Neronov A, Vovk I (2010) Evidence for strong extragalactic magnetic fields from Fermi observations of TeV blazars. Science 328. doi:10.1126/science.1184192

  • Neronov A, Semikoz D, Vovk Ie (2010) Very high-energy \(\gamma \)-ray emission from IC 310. Astron Astrophys 519:6. doi:10.1051/0004-6361/201014499

    Article  ADS  Google Scholar 

  • Neronov A, Vovk I, Malyshev D (2015) Central engine of a gamma-ray blazar resolved through the magnifying glass of gravitational microlensing. Nature 11:664–667. doi:10.1038/nphys3376

    Google Scholar 

  • Nolan PL, Abdo AA, Ackermann M, Ajello M et al (2012) Fermi large area telescope second source catalog. Astrophys J Suppl Ser 199:31–77. doi:10.1088/0067-0049/199/2/31

    Article  ADS  Google Scholar 

  • Nori M, Giroletti M, Massaro M et al (2014) Unveiling the nature of unidentified gamma-ray sources. VI. Gamma-ray blazar candidates in the WISH survey and their radio properties. Astrophys J Suppl Ser 212:3. doi:10.1088/0067-0049/212/1/3

    Article  ADS  Google Scholar 

  • O’Dea CP (1998) The compact steep-spectrum and Gigahertz peaked-spectrum radio sources. Pub Astron Soc Pac 110:493–532. doi:10.1086/316162

    Article  ADS  Google Scholar 

  • Ojha R, Kadler M, Boeck M et al (2010) TANAMI: tracking active galactic nuclei with austral milliarcsecond interferometry. I. First epoch 8.4 GHz images. Astron Astrophys 519:45–59. doi:10.1051/0004-6361/200912724

    Article  ADS  Google Scholar 

  • Orienti M, D’Ammando F, Giroletti M et al (2014) Exploring the multiband emission of TXS 0536+145: the most distant \(\gamma \)-ray flaring blazar. Mon Not R Astron Soc 444:3040–3051. doi:10.1093/mnras/stu1644

    Article  ADS  Google Scholar 

  • Osmer PS, Porter AC, Green RF et al (1994) Luminosity effects and the emission-line properties of quasars with 0 less than \(Z\) less than 3.8. Astrophys J 436:678–695. doi:10.1086/174942

    Article  ADS  Google Scholar 

  • Padovani P, Ghisellini G, Fabian AC (1993) Radio-loud AGN and the extragalactic gamma-ray background. Mon Not R Astron Soc 206:21–24

    Google Scholar 

  • Paggi A, Massaro F, Cavaliere A et al (2009) SSC radiation in BL Lacertae sources, the end of the tether. Astron Astrophys 504:821–828. doi:10.1051/0004-6361/200912237

    Article  ADS  Google Scholar 

  • Paggi A, Massaro F, D’Abrusco R et al (2013) Unveiling the nature of the unidentified gamma-ray sources. IV. The Swift catalog of potential X-ray counterparts. Astrophys J Suppl Ser 209:9–37. doi:10.1088/0067-0049/209/1/9

    Article  ADS  Google Scholar 

  • Paggi A, Milisavljevic D, Masetti N et al (2014) Optical spectroscopic observations of gamma-ray blazar candidates. I. Preliminary results. Astron J 147:112. doi:10.1088/0004-6256/147/5/112

    Article  ADS  Google Scholar 

  • Paliya VS, Stalin CS, Ravikumar CD (2015) Fermi monitoring of radio-loud narrow-line Seyfert 1 galaxies. Astron J 149:41. doi:10.1088/0004-6256/149/2/41

    Article  ADS  Google Scholar 

  • Petrov L, Mahony EK, Edwards PG et al (1978) Australia telescope compact array observations of Fermi unassociated sources. Mon Not R Astron Soc 432:1294–1302. doi:10.1093/mnras/stt550

    Article  ADS  Google Scholar 

  • Raiteri CM, Villata M, Aller MF et al (2011) The long-lasting activity of 3C 454.3. GASP-WEBT and satellite observations in 2008–2010. Astron Astrophys 534. doi:10.1051/0004-6361/201117026

  • Raiteri CM, Villata M, Smith PS et al (2012) Variability of the blazar 4C 38.41 (B3 1633+382) from GHz frequencies to GeV energies. Astron Astrophys 545:18. doi:10.1051/0004-6361/201219492

    Article  Google Scholar 

  • Raiteri CM, Villata M, D’Ammando F et al (2013) The awakening of BL Lacertae: observations by Fermi, Swift and the GASP-WEBT. Mon Not R Astron Soc 436:1530–1545. doi:10.1093/mnras/stt1672

    Article  ADS  Google Scholar 

  • Raiteri CM, Villata M, Carnerero MI et al (2014) Infrared properties of blazars: putting the GASP-WEBT sources into context. Mon Not R Astron Soc 442:629–646. doi:10.1093/mnras/stu886

    Article  ADS  Google Scholar 

  • Rando R, Buson S (2015) Fermi LAT: more than six years of insights and new puzzles. Riv Nuovo Cim 38:209–269

    ADS  Google Scholar 

  • Ray PS, Abdo AA, Parent D et al (2012) Radio searches of Fermi LAT sources and blind search pulsars: the Fermi pulsar search consortium. arXiv:1205.3089 (2011 Fermi symposium proceedings—eConf C110509)

  • Reimer O (2005) On the origin of unidentified EGRET gamma-ray sources. AIPC 745:184–198. doi:10.1063/1.1878408

    ADS  Google Scholar 

  • Reimer A (2007) The redshift dependence of gamma-ray absorption in the environments of strong-line AGNs. Astrophys J 665:1023–1029. doi:10.1086/519766

    Article  ADS  Google Scholar 

  • Reimer A (2012) On the physics of hadronic blazar emission models. J Phys Conf Ser 355. doi:10.1088/1742-6596/355/1/012011

  • Reimer O, Torres D (2007) Identification of high energy gamma-ray sources and source populations in the era of deep all-sky coverage. Astrophys Space Sci 309:57–62. doi:10.1007/s10509-007-9469-9

    Article  ADS  Google Scholar 

  • Reynolds SP (1982) Theoretical studies of compact radio sources—part two—inverse-compton radiation from anisotropic photon and electron distributions—general results and spectra from relativistic flows. Astrophys J 256:38–53. doi:10.1086/159882

    Article  ADS  Google Scholar 

  • Ricci F, Massaro F, Landoni M et al (2015) Optical spectroscopic observations of gamma-ray blazar candidates IV. Results of the 2014 follow-up campaign. Astron J (in press). arXiv:1503.05196

  • Salamon MH, Stecker FW (1998) Absorption of high-energy gamma rays by interactions with extragalactic starlight photons at high redshifts and the high-energy gamma-ray background. Astrophys J 493:547–554. doi:10.1086/305134

    Article  ADS  Google Scholar 

  • Sbarrato T, Ghisellini G, Maraschi L, Colpi M (2012) The relation between broad lines and \(\gamma \)-ray luminosities in Fermi blazars. Mon Not R Astron Soc 421:1764–1778. doi:10.1111/j.1365-2966.2012.20442.x

    Article  ADS  Google Scholar 

  • Schinzel FK, Petrov L, Taylor GB et al (2015) New associations of gamma-ray sources from the Fermi second source catalog. Astrophys J Suppl Ser 217:4. doi:10.1088/0067-0049/217/1/4

    Article  ADS  Google Scholar 

  • Schlickeiser R, Ibscher D, Supsar M (2012) Plasma effects on fast pair beams in cosmic voids. Astrophys J 758:102–113. doi:10.1088/0004-637X/758/2/102

    Article  ADS  Google Scholar 

  • Shaw MS, Romani RW, Cotter G et al (2013a) Spectroscopy of the largest ever gamma-ray-selected BL Lac sample. Astrophys J 764:135–148. doi:10.1088/0004-637X/764/2/135

  • Shaw MS, Filippenko AV, Romani RW et al (2013b) Photometrically triggered keck spectroscopy of fermi BL Lacertae objects. Astron J 146:127–134. doi:10.1088/0004-6256/146/5/127

  • Sikora M, Begelman MC, Rees MJ (1994) Comptonization of diffuse ambient radiation by a relativistic jet: the source of gamma rays from blazars? Astrophys J 421:153–162. doi:10.1086/173633

    Article  ADS  Google Scholar 

  • Sijbring D, de Bruyn AG (1994) Multifrequency radio continuum observations of head-tail galaxies in the Perseus cluster. Astron Astrophys 331:901–915

    ADS  Google Scholar 

  • Sironi L, Giannios D (2014) Relativistic pair beams from TeV blazars: a source of reprocessed GeV emission rather than intergalactic heating. Astrophys J 787:49–65. doi:10.1088/0004-637X/787/1/49

    Article  ADS  Google Scholar 

  • Sironi L, Petropoulou M, Giannios D (2015) Relativistic jets shine through shocks or magnetic reconnection? Mon Not R Astron Soc 450:183–191. doi:10.1093/mnras/stv641

    Article  ADS  Google Scholar 

  • Smith PS, Williams GG, Schmidt GD et al (2007) Highly polarized optically selected BL Lacertae objects. Astrophys J 663:118–124. doi:10.1086/517992

    Article  ADS  Google Scholar 

  • Sowards-Emmerd D, Romani RW, Michelson PF (2003) The gamma-ray blazar content of the northern sky. Astrophys J 590:109–122. doi:10.1086/374981

    Article  ADS  Google Scholar 

  • Sowards-Emmerd D, Romani RW, Michelson PF et al (2005) A northern survey of gamma-ray blazar candidates. Astrophys J 626:95–103. doi:10.1086/429902

    Article  ADS  Google Scholar 

  • Sreekumar P, Bertsch DL, Hartman RC (2012) GeV emission from the nearby radio galaxy Centaurus A. Aph 11:221. doi:10.1016/S0927-6505(99)00054-7

    ADS  Google Scholar 

  • Stecker FW, Venters TM (2011) Components of the extragalactic gamma-ray background. Astrophys J 736:40–53. doi:10.1088/0004-637X/736/1/40

    Article  ADS  Google Scholar 

  • Stecker FW, Salamon MH, Malkan MA (1993) The high-energy diffuse cosmic gamma-ray background radiation from blazars. Astrophys J 410:71–74. doi:10.1086/186882

    Article  ADS  Google Scholar 

  • Stecker FW, Baring MG, Summerlin EJ (2007) Blazar \(\gamma \)-rays, shock acceleration, and the extragalactic background light. Astrophys J 667:29–32. doi:10.1086/522005

    Article  ADS  Google Scholar 

  • Stern BE, Poutanen J (2011) Variation of the \(\gamma \gamma \) opacity by the He II Lyman continuum constrains the location of the \(\gamma \)-ray emission region in the blazar 3C 454.3. Mon Not R Astron Soc 417:11–15. doi:10.1111/j.1745-3933.2011.01107.x

    Article  ADS  Google Scholar 

  • Stickel M, Padovani P, Urry CM et al (1991) The complete sample of 1 Jansky BL Lacertae objects. I—Summary properties. Astrophys J 374:413–439. doi:10.1086/170133

    Article  ADS  Google Scholar 

  • Stocke JT, Morris SL, Gioia IM et al (1991) The Einstein observatory extended medium-sensitivity survey. II—The optical identifications. Astrophys J Suppl Ser 76:813–874. doi:10.1086/191582

    Article  ADS  Google Scholar 

  • Stroh MC, Falcone AD (2013) Swift X-ray telescope monitoring of Fermi-LAT gamma-ray sources of interest. Astrophys J Suppl Ser 207:28–40. doi:10.1088/0067-0049/207/2/28

    Article  ADS  Google Scholar 

  • Strong A, Bignami GF (1983) Gamma-ray observations toward NGC 1275 and the origin of the emission in the infrared, X-rays, and gamma-rays. Astrophys J 274:549–557. doi:10.1086/161469

    Article  ADS  Google Scholar 

  • Su M, Slatyer TR, Finkbeiner D (2010) Giant gamma-ray bubbles from Fermi-LAT: active galactic nucleus activity or bipolar galactic wind? Astrophys J 724:1044–1082. doi:10.1088/0004-637X/724/2/1044

    Article  ADS  Google Scholar 

  • Sutherland W, Saunders W (1992) On the likelihood ratio for source identification. Mon Not R Astron Soc 259:413–420

    Article  ADS  Google Scholar 

  • Swanenburg BN, Hermsen W, Bennett K et al (1978) COS B observation of high-energy gamma radiation from 3C273. Nature 275:298. doi:10.1038/275298a0

    Article  ADS  Google Scholar 

  • Takahashi Y, Kataoka J, Nakamori T et al (2012) Suzaku X-ray follow-up observations of seven unassociated Fermi-LAT gamma-ray sources at high galactic latitudes. Astrophys J 747:64–80. doi:10.1088/0004-637X/747/1/64

    Article  ADS  Google Scholar 

  • Takeuchi Y, Kataoka J, Stawarz L (2012) Suzaku X-ray imaging of the extended lobe in the giant radio galaxy NGC 6251 associated with the Fermi-LAT source 2FGL J1629.4+8236. Astrophys J 749:66–73. doi:10.1088/0004-637X/749/1/66

    Article  ADS  Google Scholar 

  • Takeuchi Y, Kataoka J, Maeda K et al (2013) Multiband diagnostics of unidentified 1FGL sources with Suzaku and Swift X-ray observations. Astrophys J Suppl Ser 208:25–58. doi:10.1088/0067-0049/208/2/25

    Article  ADS  Google Scholar 

  • Tanaka YT, Doi A, Inoue Y et al (2015) Six years of Fermi-LAT and multi-wavelength monitoring of the broad-line radio galaxy 3c 120: jet dissipation at sub-parsec scales from the central engine. Astrophys J 799:18–23. doi:10.1088/2041-8205/799/2/L18

    Article  ADS  Google Scholar 

  • Tavani M, Barbiellini G, Argan A et al (2008) The AGILE space mission. Nucl Instrum Methods Phys Res Sect A 588:52–62. doi:10.1016/j.nima.2008.01.023

    Article  ADS  Google Scholar 

  • Tavecchio F, Ghisellini G (2008) Spine-sheath layer radiative interplay in subparsec-scale jets and the TeV emission from M87. Mon Not R Astron Soc 385:98–102. doi:10.1111/j.1745-3933.2008.00441.x

    Article  ADS  Google Scholar 

  • Tavecchio F, Ghisellini G, Foschini L et al (2010) The intergalactic magnetic field constrained by Fermi/large area telescope observations of the TeV blazar 1ES0229+200. Mon Not R Astron Soc 406:70–74. doi:10.1111/j.1745-3933.2010.00884.x

    ADS  Google Scholar 

  • Tavecchio F, Ghisellini G, Bonnolii G, Foschini L (2011) Extreme TeV blazars and the intergalactic magnetic field. Mon Not R Astron Soc 414:3566–3576. doi:10.1111/j.1365-2966.2011.18657.x

    Article  ADS  Google Scholar 

  • Taylor GB, Healey SE, Helmboldt JF (2007) Characteristics of EGRET blazars in the VLBA imaging and polarimetry survey (VIPS). Astrophys J 671:1355–1364. doi:10.1086/523264

    Article  ADS  Google Scholar 

  • Thompson DJ (2008) Gamma ray astrophysics: the EGRET results. Rep Prog Phys 71:116901–116924. doi:10.1088/0034-4885/71/11/116901

    Article  ADS  Google Scholar 

  • Thompson DJ, Fichtel CE (1982) Extragalactic gamma radiation—use of galaxy counts as a galactic tracer. Astron Astrophys 109:352–354

    ADS  Google Scholar 

  • Thompson DJ, Bertsch DL, Fichtel CE et al (1993) Calibration of the energetic gamma-ray experiment telescope (EGRET) for the compton gamma-ray observatory. Astrophys J Suppl Ser 86:629–656. doi:10.1086/191793

    Article  ADS  Google Scholar 

  • Tramacere A, Massaro E, Taylor AM (2011) Stochastic acceleration and the evolution of spectral distributions in synchro-self-compton sources: a self-consistent modeling of blazars’ flares. Astrophys J 739:66–81. doi:10.1088/0004-637X/739/2/66

    Article  ADS  Google Scholar 

  • Urry MC, Padovani P (1995) Unified schemes for radio-loud active galactic nuclei. Pub Astron Soc Pac 107:803–845. doi:10.1086/133630

    Article  ADS  Google Scholar 

  • Villata M, Raiteri CM, Gurwell MA et al (2009) The GASP-WEBT monitoring of 3C 454.3 during the 2008 optical-to-radio and \(\gamma \)-ray outburst. Astron Astrophys 504:9–12. doi:10.1051/0004-6361/200912732

    Article  ADS  Google Scholar 

  • Venters TM, Pavlidou V (1978) Probing the intergalactic magnetic field with the anisotropy of the extragalactic gamma-ray background. Mon Not R Astron Soc 432:3485–3494. doi:10.1093/mnras/stt697

    Article  ADS  Google Scholar 

  • Venters MT, Pavlidou V (2011) The effect of blazar spectral breaks on the blazar contribution to the extragalactic gamma-ray background. Astrophys J 737:80–86. doi:10.1088/0004-637X/737/2/80

    Article  ADS  Google Scholar 

  • Venters MT, Pavlidou V, Reyes CL (2009) The extragalactic background light absorption feature in the blazar component of the extragalactic gamma-ray background. Astrophys J 703:1939–1946. doi:10.1088/0004-637X/703/2/1939

    Article  ADS  Google Scholar 

  • Vovk I, Neronov A (2015) Microlensing constraint on the size of the gamma-ray emission region in blazar B0218+357 (eprint arXiv:1507.01092)

  • Wright EL, Eisenhardt PRM, Mainzer EK et al (2010) The wide-field infrared survey explorer (WISE): mission description and initial on-orbit performance. Astron J 140:1868–1881. doi:10.1088/0004-6256/140/6/1868

    Article  ADS  Google Scholar 

  • Zhou H, Wang T, Yuan W et al (2007) A narrow-line Seyfert 1-blazar composite nucleus in 2MASX J0324+3410. Astrophys J 658:13–16. doi:10.1086/513604

    Article  ADS  Google Scholar 

  • Zdziarski AA, Boettcher M (2015) Hadronic models of blazars require a change of the accretion paradigm. Mon Not R Astron Soc 450:21–25. doi:10.1093/mnrasl/slv039

    Article  ADS  Google Scholar 

Download references

Acknowledgments

This review would not have been possible without the dedicated efforts of scientists, engineers, and technicians who have made the Fermi Gamma-ray Space Telescope mission so successful. We extend thanks to all those who contributed. Special thanks to Justin Finke, Filippo D’Ammando and Seth Digel for valuable comments on the manuscript. F. Massaro wishes to thank M. Ajello, R. D’Abrusco, D. Gasparrini, M. Giroletti, L. Latronico, N. Masetti, A. Paggi, H. Smith and G. Tosti for their support during the last 4 years spent working on Fermi blazars. The work by is supported by the Programma Giovani Ricercatori—Rita Levi Montalcini—Rientro dei Cervelli (2012). This review is also supported by the NASA grants NNX12AO97G and NNX13AP20G. Part of this work is based on archival data, software or on-line services provided by the ASI Science Data Center. This research has made use of data obtained from the high-energy Astrophysics Science Archive Research Center (HEASARC) provided by NASA’s Goddard Space Flight Center; the SIMBAD database operated at CDS, Strasbourg, France; the NASA/IPAC Extragalactic Database (NED) operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. TOPCAT (http://www.star.bris.ac.uk/~mbt/topcat/) (Taylor 2005) for the preparation and manipulation of the tabular data and the images. The Aladin Java applet (http://aladin.u-strasbg.fr/aladin.gml) was used to create the finding charts reported in this paper (Bonnarel 2000). It can be started from the CDS (Strasbourg, France), from the CFA (Harvard, USA), from the ADAC (Tokyo, Japan), from the IUCAA (Pune, India), from the UKADC (Cambridge, UK), or from the CADC (Victoria, Canada).

Author information

Authors and Affiliations

  1. Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, 10125, Turin, Italy

    Francesco Massaro

  2. NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA

    David J. Thompson & Elizabeth C. Ferrara

Authors
  1. Francesco Massaro
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. David J. Thompson
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Elizabeth C. Ferrara
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Francesco Massaro.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Massaro, F., Thompson, D.J. & Ferrara, E.C. The extragalactic gamma-ray sky in the Fermi era. Astron Astrophys Rev 24, 2 (2016). https://doi.org/10.1007/s00159-015-0090-6

Download citation

  • Received:

  • Published:

  • DOI: https://doi.org/10.1007/s00159-015-0090-6

Keywords

Search

Navigation