Quasar Remnants Research Articles

Black Holes and the Supermassive Compact Object at the Galactic Center: Multi-arts of Thought and Nature

Black Holes and the Supermassive Compact Object at the Galactic Center: Multi-arts of Thought and Nature

Ultrahigh energy cosmic ray nuclei from remnants of dead quasars

We re-examine the possibility of ultrahigh energy cosmic rays being accelerated in nearby dormant quasars. We particularize our study to heavy nuclei to accommodate the spectrum and nuclear composition recently reported by the Pierre Auger Collaboration. Particle acceleration is driven by the Blandford–Znajek mechanism, which wires the dormant spinning black holes as Faraday unipolar dynamos. We demonstrate that energy losses are dominated by photonuclear interactions on the ambient photon fields. We argue that the local dark fossils of the past quasar activity can be classified on the basis of how source parameters (mass of the central engine and photon background surrounding the accelerator) impact the photonuclear interaction. In this classification it is possible to distinguish two unequivocal type of sources: those in which nuclei are completely photodisintegrated before escaping the acceleration region and those in which photopion production is the major energy damping mechanism. We further argue that the secondary nucleons from the photodisintegrated nuclei (which have a steep spectral index at injection) can populate the energy region below “the ankle” feature in the cosmic ray spectrum, whereas heavy and medium mass nuclei (with a harder spectral index) populate the energy region beyond “the ankle”, all the way to the high energy end of the spectrum. In addition, we show that five potential quasar remnants from our cosmic backyard correlate with the hot-spot observed by the Telescope Array.

The Co‐Formation of Spheroids and Quasars Traced in their Clustering

We compare observed clustering of quasars and galaxies as a function of redshift, mass, luminosity, & color/morphology, to constrain models of quasar fueling and spheroid-BH co-evolution. High redshift quasars are shown to be drawn from progenitors of local early-type galaxies, with the characteristic quasar luminosity L* reflecting a characteristic mass of 'active' BH/host populations at each redshift. Evolving observed high-z quasar clustering to z=0 predicts a trend of clustering in 'quasar remnants' as a function of stellar mass identical to that observed for early-types. However, quasar clustering does not simply reflect observed early (or late)-type populations; at each redshift, quasars cluster as an 'intermediate' population. Comparing with the age of elliptical stellar populations reveals that this 'intermediate' population represents those ellipticals undergoing or terminating their final significant star formation at each epoch. Assuming that quasar triggering is associated with the formation/termination epoch of ellipticals predicts quasar clustering at all observed redshifts without any model dependence or assumptions about quasar light curves, lifetimes, or accretion rates. This is not true for disks or quasar halos: i.e. quasars do not generically trace star formation, disks, or halo assembly. Quasar clustering at all z is consistent with a constant halo mass ~4x10^{12} M_sun, similar to local 'group scales.' The observations support a scenario in which major mergers trigger quasar activity and dominate bright, high-z quasar populations. We show that measurements of quasar clustering versus luminosity at z~1 can be used to constrain different lower-luminosity AGN fueling mechanisms, and that high-z clustering is sensitive to whether or not systems 'shut down' growth at z>3.

Reconstructing the Cosmic Evolution of Quasars from the Age Distribution of Local Early‐Type Galaxies

We use the spectra of 22,000 nearby early-type galaxies from the Sloan Digital Sky Survey (SDSS) to determine the age distribution of these galaxies as a function of their velocity dispersion sigma_v in the range 100 km/s < sigma_v < 280 km/s. We then combine the inferred age-distributions with the local abundance of spheroids, including early-type galaxies and late-type bulges, to predict the evolution of the quasar luminosity function (LF) in the redshift range 0<z<6. We make the following simple assumptions: (i) the formation of stars in each galaxy, at the epoch identified with the mean mass-weighted stellar age, is accompanied by the prompt assembly of the nuclear supermassive black hole (SMBH); (ii) the mass of the SMBH obeys the M_bh-sigma_v correlation observed in nearby galaxies; (iii) the SMBH radiates at a fraction f_Edd of the Eddington limit for a fixed duration t_Q, and is identified as a luminous quasar during this epoch, (iv) the intrinsic dispersions in the Eddington ratio and the M_bh-sigma_v relation produce a combined scatter of Delta(log L_Q) around the mean logarithmic quasar luminosity <log L_Q> at fixed sigma_v. These assumptions require that the SMBH remnants of quasars with bolometric luminosity below L_bol=10^{12.5} f_Edd L_sun reside predominantly in bulges of late type galaxies. We find that evolution of the observed quasar LF can be fit over the entire redshift range in this simple model, 0<z<6 with the choices of Delta(log L_Q)=0.6-0.9, t_Q= (6-8)x10^7 yr, and <f_Edd>=0.3-0.5. We find no evidence that any of the model parameters evolves with redshift, supporting the strong connection between the formation of stars and nuclear SMBHs in spheroids.

TeV Signatures of Compact UHECR Accelerators

We study numerically particle acceleration by the electric field induced near the horizon of a rotating supermassive (M \sim 10^9-10^{10} M_{\odot}) black hole embedded in the magnetic field B. We find that acceleration of protons to energy E > 10^{20} eV is possible only at extreme values of M and B. We also find that the acceleration is very inefficient and is accompanied by a broad band MeV-TeV radiation whose total power exceeds at least by a factor of 1000 the total power emitted in ultra-high energy cosmic rays (UHECR). This implies that if O(10) nearby quasar remnants were sources of proton events with energy E > 10^{20} eV, then each quasar remnant would overshine e.g. the Crab nebula by more than two orders of magnitude in the TeV energy band. Recent TeV observations exclude this possibility. A model in which O(100) sources are situated at 100-1000 Mpc is not ruled out and can be experimentally tested by present TeV gamma-ray telescopes. Such a model can explain the observed UHECR flux at moderate energies E \sim (4-5) 10^{19} eV.

Nearby quasar remnants and ultrahigh-energy cosmic rays

As recently suggested, nearby quasar remnants are plausible sites of black-hole based compact dynamos that could be capable of accelerating ultrahigh-energy cosmic rays (UHECRs). In such a model, UHECRs would originate at the nuclei of nearby dead quasars, those in which the putative underlying supermassive black holes are suitably spun-up. Based on galactic optical luminosity, morphological type, and redshift, we have compiled a small sample of nearby objects selected to be highly luminous, bulge-dominated galaxies, likely quasar remnants. The sky coordinates of these galaxies were then correlated with the arrival directions of cosmic rays detected at energies $g40 \mathrm{EeV}.$ An apparently significant correlation appears in our data. This correlation appears at closer angular scales than those expected when taking into account the deflection caused by typically assumed IGM or galactic magnetic fields over a charged particle trajectory. Possible scenarios producing this effect are discussed, as is the astrophysics of the quasar remnant candidates. We suggest that quasar remnants be also taken into account in the forthcoming detailed search for correlations using data from the Auger Observatory.

Cosmic ray generation by quasar remnants: constraints and implications

The quasar remnant cores of nearby giant elliptical galaxies NGC 4486 (M87), 1399, 4649 and 4472 are the sites of supermassive (>109 M⊙) black holes. These objects are investigated as to the viability of the conjecture that they could harbour compact dynamos capable of generating the highest energy cosmic rays. For an accretion process involving an equipartition magnetic field near the event horizons of the underlying putative spun-up black holes, the energy achievable in accelerating protons could well be 1020 eV for all these galaxies when only considering the drag induced by curvature radiation. Estimates of the spectral energy distribution (SED) of ambient core photons lead to the conclusion that the energy losses arising from photo-pion production in proton collisions with these target photons are relatively small for all but M87. For M87, the ambient photon field is likely to be a limiting factor. Accretion rates of ∼1 M⊙ yr−1, comparable to the Bondi rates and to the stellar mass-loss rates, are associated with (>1020 eV) cosmic ray generation in the other (electromagnetically dark) galactic core sites. If these sites are found to be sources of such cosmic rays, it would suggest the presence of a global inflow of interstellar gas all the way into the centre of the host galaxy.

Cosmic rays from remnants of quasars?

Considerations of the collision losses for protons traversing the 2.7 K black body microwave radiation field have led to the conclusion that the highest energy cosmic rays, those observed at $\geq 10^{20}$ eV, must come from sources within the present epoch. In light of this constraint, it is here suggested that these particles may be accelerated near the event horizons of spinning supermassive black holes associated with presently inactive quasar remnants. The required emf is generated by the black hole induced rotation of externally supplied magnetic field lines threading the horizon. Producing the observed flux of the highest energy cosmic rays would constitute a negligible drain on the black hole dynamo. Observations with upcoming air shower arrays and space missions may lead to the identification of candidate dormant galaxies which harbor such black holes. Although the highest energy events observed so far are accounted for within the context of this scenario, a spectral upper bound at $\sim 10^{21}$ eV is expected since the acceleration to higher energies appears to be precluded, on general grounds.

The evolutionary unified scheme. 1: Quasars and radio galaxies in the viewing angle-redshift plane

view Abstract Citations (6) References (43) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Evolutionary Unified Scheme. I. Quasars and Radio Galaxies in the Viewing Angle--Redshift Plane Vagnetti, F. ; Spera, R. Abstract We present a study of the distribution of quasars and radio galaxies in the viewing-angle-redshift plane in the framework of the evolutionary unified scheme (Vagnetti, Giallongo, & Cavaliere 1991). Results are presented for some illustrative cases, including a distribution of the Lorentz factors and appropriate luminosity functions for quasars and their host galaxies. A cosmologically increasing <{GAMMA}> is found, in agreement with the previous paper. It is argued that the appearance of sources as quasars or radio galaxies can depend on the viewing angle and on the redshift, due to the balance between the beamed component and the luminosity of the host galaxy. Within the assumptions of our evolutionary unified scheme, we find that low-{GAMMA} objects can be observed as quasars mainly at z ~> 0.3, while a substantial fraction of the low-z radio galaxies could consist of quasar remnants. Publication: The Astrophysical Journal Pub Date: December 1994 DOI: 10.1086/174936 arXiv: arXiv:astro-ph/9405054 Bibcode: 1994ApJ...436..611V Keywords: Bl Lacertae Objects; Galactic Evolution; Quasars; Radio Galaxies; Luminosity; Red Shift; Astrophysics; GALAXIES: BL LACERTAE OBJECTS: GENERAL; GALAXIES: EVOLUTION; GALAXIES: QUASARS: GENERAL; RADIO CONTINUUM: GALAXIES; Astrophysics E-Print: to appear in ApJ full text sources arXiv | ADS |

Quasar populations in a cosmological constant-dominated flat universe

Most physical properties derived for quasars, as single entities or as a population, depend upon the cosmology assumed. In this paper, we calculate the quasar luminosity function and some related quantities for a flat universe dominated by a cosmological constant Lambda (Lambda = 0.9, Omega = 0.1) and compare them with those deduced for a flat universe with zero cosmological constant (Lambda = 0, Omega = 1). We use the ATT quasar survey data (Boyle et al. 1990) as input in both cases. The data are fitted well by a pure luminosity evolution model for both the cosmologies but with different evolutionary parameters. From the luminosity function, we predict (extrapolate) a greater number of quasars at faint apparent magnitudes (twice the number at B = 24, z is less than 2.2) for the Lambda-dominated universe. This population of faint quasars at high redshift would result in a higher incidence of gravitational lensing. The total luminosity of the quasar population and the total mass tied up in black hole remnants of quasars is not sensitive to the cosmology. However, for a Lambda cosmology, this mass is tied up in fewer but more massive black holes.

Remnants of the quasars

Assuming a standard black hole accretion model for quasars, we estimate the present total mass density, rho sub BH, of quasar remnants using recent observations of quasar populations and of typical quasar spectra over a wide wavelength range. We find rho sub BH of greater than about (1.4-2.2) x 10 exp 5 solar masses/cu Mpc for a quasar radiative efficiency of 0.1. This is an upward revision by a factor of 3.0-4.6 from a decade-old estimate by Soltan (1982). A typical bright galaxy is thus expected to contain a central black hole of greater than about 10 exp 7/cu h solar masses. Furthermore, we expect that greater than about 50 percent of rho sub BH is contributed by objects of mass greater than about 10 exp 8/sq h solar masses and greater than about 10 percent by those more massive than about 6 x 10 exp 8/sq h solar masses.

On the extendedness of faint ultraviolet excess quasar candidates

view Abstract Citations (9) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the extendedness of faint ultraviolet excess quasar candidates Edwards, G. ; Borra, E. F. ; Hardy, E. Abstract A search for UV excess quasars based on deep U, J, and F plates taken with the Canada-France-Hawaii telescope has been conducted. The plates were fully digitized and analyzed with automated software. After applying a technique for separating stars from galaxies, the surprising result was obtained that a significant fraction of the quasar candidates are not starlike. The extendedness of most (but not all) of these objects is not detectable by ordinary eye inspection. The possible nature of these objects is briefly discussed, concluding that a simple explanation is that they are compact blue galaxies. In this case, quasar counts based uniquely on the ultraviolet excess criterion have overestimated the surface density of faint quasars (B greater than 21) by more than a factor of 2. The possibility that these objects may be quasar remnants is also raised Publication: The Astrophysical Journal Pub Date: February 1985 DOI: 10.1086/162905 Bibcode: 1985ApJ...289..446E Keywords: Image Processing; Quasars; Radiant Flux Density; Spectral Energy Distribution; Ultraviolet Spectra; Compact Galaxies; Density Distribution; Surface Properties; Astrophysics full text sources ADS |

A cosmological test - Its application to quasars and estimates of Q sub 0

It is shown that knowledge of the local space density of quasar remnants leads to a powerful cosmological test. A plausible identification of quasar remnants and a measure of their local space density are proposed. Local BL Lac objects are assumed to be a subset of local quasar remnants beamed in our direction. Tentative values of q/sub 0/ are derived.

Globular Clusters as Remnants of Quasars

IN the past two years many theories have been advanced for the explanation of the extraordinarily powerfully emitting cosmic energy sources known as quasistellar radio-sources, or quasars for short. Two particular theories have been brought out in an especially detailed form, namely, the gravitational collapse theory of Hoyle and Fowler1 and the spherical galaxy formation theory of Field2.