Advertisement

Springer Nature is making Coronavirus research free. View research | View latest news | Sign up for updates

The extragalactic gamma-ray sky in the Fermi era

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 to check access.

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

Notes

  1. 1.

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

  2. 2.

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

  3. 3.

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

  4. 4.

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

  5. 5.

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

  6. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

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

  20. 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

  21. 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

  22. 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

  23. 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

  24. 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

  25. 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

  26. 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

  27. 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

  28. 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

  29. 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

  30. 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

  31. 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

  32. 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

  33. 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

  34. 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

  35. 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

  36. 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

  37. 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

  38. 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

  39. 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

  40. 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

  41. 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)

  42. 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

  43. 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

  44. 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

  45. 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

  46. 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

  47. 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

  48. 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

  49. 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

  50. 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

  51. 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

  52. 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

  53. 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

  54. 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

  55. 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

  56. 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

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

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

  59. 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

  60. 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

  61. 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

  62. 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

  63. 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

  64. 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

  65. 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

  66. 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

  67. 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

  68. 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

  69. 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

  70. 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

  71. 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

  72. 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

  73. 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

  74. 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

  75. 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

  76. 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

  77. 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

  78. 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

  79. 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

  80. 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

  81. 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

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

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

  84. 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

  85. 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

  86. 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

  87. 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

  88. 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

  89. 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

  90. 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

  91. 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

  92. 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

  93. 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

  94. 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

  95. 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

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

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

  98. 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

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

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

  101. 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

  102. 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

  103. 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

  104. 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

  105. 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

  106. 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

  107. 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

  108. 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

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

  110. 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

  111. 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

  112. 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

  113. 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

  114. 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

  115. 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

  116. 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

  117. 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

  118. 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

  119. 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

  120. 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

  121. 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

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

  123. 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

  124. 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

  125. 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

  126. 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

  127. 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

  128. 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

  129. 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

  130. 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

  131. 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

  132. 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

  133. 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

  134. 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

  135. 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

  136. 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

  137. 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

  138. 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

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

  140. 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

  141. 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

  142. 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

  143. 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

  144. 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

  145. 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

  146. 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

  147. 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

  148. 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

  149. 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

  150. 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

  151. 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)

  152. 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

  153. 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

  154. 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

  155. 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

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

  157. 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

  158. 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

  159. 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

  160. 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

  161. 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

  162. 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

  163. 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

  164. 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

  165. 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

  166. 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

  167. 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

  168. 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

  169. 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

  170. 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

  171. 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

  172. 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

  173. 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

  174. 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

  175. 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

  176. 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

  177. 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)

  178. 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

  179. 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

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

  181. 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

  182. 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

  183. 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

  184. 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

  185. 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

  186. 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

  187. 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

  188. 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

  189. 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

  190. 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

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

  192. 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

  193. 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

  194. 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

  195. 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

  196. 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

  197. 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

  198. 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

  199. 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

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

  201. 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

  202. 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

  203. 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

  204. 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

  205. 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

  206. 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

  207. 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

  208. 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

  209. 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

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

  211. 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)

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

  213. 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

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

  215. 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

  216. 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

  217. 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

  218. 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

  219. 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

  220. 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

  221. 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

  222. 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

  223. 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

  224. 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

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

  226. 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

  227. 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

  228. 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

  229. 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

  230. 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

  231. 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

  232. 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

  233. 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

  234. 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

  235. 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

  236. 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

  237. 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

  238. 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

  239. 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

  240. 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

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

  242. 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

  243. 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

  244. 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

  245. 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

  246. 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

  247. 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

  248. 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

  249. 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

  250. 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

  251. 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

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

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

  254. 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

  255. 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

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

  257. 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

  258. 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

  259. 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

  260. 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

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

  262. 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

  263. 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

  264. 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

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

Correspondence to Francesco Massaro.

Rights and permissions

Reprints and Permissions

About this article

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

Keywords

  • Gamma rays
  • Extragalactic astronomy
  • Active galactic nuclei
  • Quasars
  • BL Lac objects
  • Background light