Observing Supermassive Black Holes Across Cosmic Time: From Phenomenology to Physics

Merloni, A.

doi:10.1007/978-3-319-19416-5_4

Cited by 22 publications

(13 citation statements)

References 157 publications

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“…Furthermore, the modest Xray selection biases are well understood and can be reliably modelled to allow for robust measurements on the evolution of AGN and the growth of BHs (e.g. Gilli, Comastri, & Hasinger 2007;Georgantopoulos et al 2013;Ueda et al 2014;Aird et al 2015;Buchner et al 2015;Miyaji et al 2015;Merloni 2016). However, significant uncertainties remain on the contributions to the cosmic BH growth from LLAGN and CT AGN.…”

Section: Selection Of Agn In the X-ray Band: Identification Challengesmentioning

confidence: 99%

Active galactic nuclei: what’s in a name?

Padovani

Alexander

Assef

et al. 2017

Astron Astrophys Rev

609

429

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Active Galactic Nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty orders of magnitude in frequency. The rich phenomenology of AGN has resulted in a large number of different "flavours" in the literature that now comprise a complex and confusing AGN "zoo". It is increasingly clear that these classifications are only partially related to intrin- sic differences between AGN, and primarily reflect variations in a relatively small number of astrophysical parameters as well the method by which each class of AGN is selected. Taken together, observations in different electromagnetic bands as well as variations over time provide complementary windows on the physics of different sub-structures in the AGN. In this review, we present an overview of AGN multi-wavelength properties with the aim of painting their "big picture" through observations in each electromagnetic band from radio to γ-rays as well as AGN variability. We address what we can learn from each observational method, the impact of selection effects, the physics behind the emission at each wavelength, and the potential for future studies. To conclude we use these observations to piece together the basic architecture of AGN, discuss our current understanding of unification models, and highlight some open questions that present opportunities for future observational and theoretical progress.

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Section: Selection Of Agn In the X-ray Band: Identification Challengesmentioning

confidence: 99%

Active galactic nuclei: what’s in a name?

Padovani

Alexander

Assef

et al. 2017

Astron Astrophys Rev

609

429

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“…Here, n 0 is the particle number density, q the electron charge and m its mass. Thus, light is delayed with respect to GWs, by an amount δt directly proportional to the total distance they both traversed δt = dρ 0 q 2 8π 0 c m 2 ω 2 = 6.7 ρ 0 1 GeV/cm 3 6GHz ω 2 days , (39) where in the last equality we substituted numbers for the very latest observation of GWs with an electromagnetic counterpart [22]. These numbers could be interesting: given the observed time delay of several days for radio waves, one may get constraints for models where DM consists of mili-charged matter (i.e., models where q and m may be a fraction of the electron charge and mass).…”

Section: The Dm Environmentmentioning

confidence: 99%

Black holes, gravitational waves and fundamental physics: a roadmap

Barack,

Cardoso,

Nissanke

et al. 2018

Preprint

100

159

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m 1 / M 36.2 +5.2 −3.8 14.2 +8.3 −3.7 23 +18 −6 31.2 +8.4 −6.0 12 +7 −2 30.5 +5.7 −3.0(1.36, 1.60) m 2 / M * In astrophysics "metallicity" refers to the global content of heavy elements above those produced by primordial nucleosynthesis * 1/2 ∼ 10 5 pc −3 in GCs and ∼ 1pc −3 in the field.Estimates using Monte Carlo method to simulate realistic GCs yield merger rates of at least R GC ∼ 5 Gpc −3 yr −1 [153,154], falling below the current limits on the observed rates. Rate estimates from results of direct N -body simulations also yield a similar value of R GC ∼ 6.5 Gpc −3 yr −1 [192]. In particular, these papers have shown that the low-mass GCs below 10 5 M have a negligible contribution to the rates. However, they also show that initially more massive GCs (more massive than 10 6 M ) contribute significantly to the rates. [154] argue that actual merger rates from BHs originating in GCs could be 3 to 5 times larger than their estimated value of ∼ 5 Gpc −3 yr −1 due to uncertainties in initial GC mass function, initial mass function of stars in GCs, maximum initial stellar mass and evolution of BH progenitors. Furthermore, BBH merger rates can be significant in young clusters with masses ∼ 10 4 M [193,194].A simple robust upper limit may be derived by assuming that all BHs merge once in each GC in a Hubble time: * By convention, "nPN" refers to EOM terms that are O(1/c 2n ) smaller than the Newtonian acceleration, or, in the radiation field, smaller by that factor relative to the standard quadrupolar field. * Though this term does not seem to be part of action ( 25), it actually corresponds to the choice G 5 ∝ ln |X| [1413]. * All the limits of this section apply to candidates that represent all the DM. The bounds are less stringent for fractional components.

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“…Quasars display striking similarities such as broad emission lines and continua that follow an approximate power law relationship in the near-UV and optical wavelengths (Merloni 2016, and references therein). However, the exact properties of the continuum and emission lines vary across the population of quasars in a manner that is poorly understood (Richards et al 2011;Shen & Ho 2014;Baskin et al 2015, for instance).…”

Section: Introductionmentioning

confidence: 99%

Spectral Evolution in High Redshift Quasars From the Final Baryon Oscillation Spectroscopic Survey Sample

Jensen

Vivek

Dawson

et al. 2016

ApJ

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We report on the diversity in quasar spectra from the Baryon Oscillation Spectroscopic Survey. After filtering the spectra to mitigate selection effects and Malmquist bias associated with a nearly flux-limited sample, we create high signal-to-noise ratio composite spectra from 58,656 quasars (   z 2.1 3.5), binned by luminosity, spectral index, and redshift. With these composite spectra, we confirm the traditional Baldwin effect (BE, i.e., the anticorrelation of C IV equivalent width (EW) and luminosity) that follows the relation µ , and −0.41±0.005 for z=2.25, 2.46, and 2.84, respectively. In addition to the redshift evolution in the slope of the BE, we find redshift evolution in average quasar spectral features at fixed luminosity. The spectroscopic signature of the redshift evolution is correlated at 98% with the signature of varying luminosity, indicating that they arise from the same physical mechanism. At a fixed luminosity, the average C IV FWHM decreases with increasing redshift and is anti-correlated with C IV EW. The spectroscopic signature associated with C IV FWHM suggests that the trends in luminosity and redshift are likely caused by a superposition of effects that are related to black hole mass and Eddington ratio. The redshift evolution is the consequence of a changing balance between these two quantities as quasars evolve toward a population with lower typical accretion rates at a given black hole mass.

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Observing Supermassive Black Holes Across Cosmic Time: From Phenomenology to Physics

Cited by 22 publications

References 157 publications

Active galactic nuclei: what’s in a name?

Active galactic nuclei: what’s in a name?

Black holes, gravitational waves and fundamental physics: a roadmap

Spectral Evolution in High Redshift Quasars From the Final Baryon Oscillation Spectroscopic Survey Sample

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