We collect 119 γ-ray-loud blazars (97 flat spectrum radio quasars (FSRQs) and 22 BL Lacertae objects (BL Lacs)), and investigate possible correlations between their γ-ray emission (maximum, minimum and average value...We collect 119 γ-ray-loud blazars (97 flat spectrum radio quasars (FSRQs) and 22 BL Lacertae objects (BL Lacs)), and investigate possible correlations between their γ-ray emission (maximum, minimum and average values) at 1 GeV and the radio emission at 8.4 GHz. Our main results are as follows. For the lower state γ-ray data, there is no correlation between the γ-ray and radio flux density; For the high state γ-ray data, there are good correlations for the whole 119 blazars and 97 FSRQs, and a weak correlation for the 22 BL Lac objects; For the average γ-ray data, there are good correlations. According to our analysis, we propose that the γ-rays are associated with the radio emission from the jet, and that the γ-ray emission is likely from the SSC process in this case.展开更多
Observations suggest that γ-ray loud blazars are strongly beamed. The Fermi mission has detected many of blazars, which provide us with a good opportunity to investigate the emission mechanism and the beaming effect ...Observations suggest that γ-ray loud blazars are strongly beamed. The Fermi mission has detected many of blazars, which provide us with a good opportunity to investigate the emission mechanism and the beaming effect in the γ-ray region. We compiled the X-ray observations for 138 Fermi blazars （54 flat spectrum radio quasars, 36 low-peaked BL Lacertae objects, and 48 high-peaked BL Lacertae objects） and calculated their Doppler factors, δγ. It is interesting that the calculated Doppler factors, δγ, are strongly correlated with the γ-ray luminosity.展开更多
The pictures from the James Webb Space Telescope (JWST) suggest that massive galaxies were already at the beginning of the expansion of the Universe because there was too short time to create them. It is consistent wi...The pictures from the James Webb Space Telescope (JWST) suggest that massive galaxies were already at the beginning of the expansion of the Universe because there was too short time to create them. It is consistent with the new cosmology presented within the Scale-Symmetric Theory (SST). The phase transitions of the initial inflation field described in SST lead to the Protoworld—its core was built of dark matter (DM). We show that the DAMA/LIBRA annual-modulation amplitude forced by the change of the Earth’s velocity (i.e. baryonic-matter (BM) velocity) in relation to the spinning DM field in our Galaxy’s halo should be very low. We calculated that in the DM-BM weak interactions are created single and entangled spacetime condensates with a lowest mass/energy of 0.807 keV—as the Higgs boson they can decay to two photons, so we can indirectly detect DM. Our results are consistent with the averaged DAMA/LIBRA/COSINE-100 curve describing the dependence of the event rate on the photon energy in single-hit events. We calculated the mean dark-matter-halo (DMH) mass around quasars, we also described the origin of the plateaux in the rotation curves for the massive spiral galaxies, the role of DM-loops in magnetars, the origin of CMB, the AGN-jet and galactic-halo production, and properties of dark energy (DE).展开更多
The method used in our previous papers is adopted to estimate four basic parameters （the central black hole mass （M）, the boosting factor （or Doppler factor） （6）, the propagation angle （Φ） and the distance a...The method used in our previous papers is adopted to estimate four basic parameters （the central black hole mass （M）, the boosting factor （or Doppler factor） （6）, the propagation angle （Φ） and the distance along the axis to the site of the γ-ray production （d）） for 59 γ-ray loud blazars （20 BL Lacertae objects and 39 flat spectrum radio quasars）. The central black hole masses estimated for this sample are in a range of from 107 Me to 109 MG. In the case of black hole mass, there is no clear difference between BL Lacertae objects and flat spectrum radio quasars, which is consistent with the previous results suggesting that the central black hole masses do not play an important role in the evolutionary sequence of blazars.展开更多
Based on the idea of hypothetical 4-dimensial substance with an inverse population of energy levels, a model of accelerated expansion of the Universe has been developed, which describes Hubble diagrams with great accu...Based on the idea of hypothetical 4-dimensial substance with an inverse population of energy levels, a model of accelerated expansion of the Universe has been developed, which describes Hubble diagrams with great accuracy for type Ia supernovae, quasars and gamma-ray burst sources at the Hubble parameter value of 67.7 km/s/Mpc, coinciding with the value obtained from analysis of inhomogeneities of relic radiation. Calculations at the Hubble parameter value of 73.5 km/s/Mpc, obtained using the ΛCDM model based on the analysis of data on type Ia supernovae and cepheids, differ markedly from the observed data. An explanation of the two values of the Hubble constant is proposed. It is shown that in this model, the magnitude of 13.8 billion years characterizes not the age of the Universe, but the time of propagation of light from those galaxes whose acceleration of removal has a minimal value. Based on the recently discovered curvature of the Universe, estimates are given of the lower limits of its size and lifetime, which turned out to be at least 270 billon years. The probability of transition from the excited state to the underlying energy levels of a hypothetical 4-dimensial substance, as well as the low of increasing energy density as a result of transitions to the underlying levels of this substance, is determined.展开更多
Recently, a unicentric model of the observable universe (UNIMOUN) was proposed. Accordingly, big bangs are common events in our infinitely large, flat, homogeneous and isotropic parent universe. Their progenitors are ...Recently, a unicentric model of the observable universe (UNIMOUN) was proposed. Accordingly, big bangs are common events in our infinitely large, flat, homogeneous and isotropic parent universe. Their progenitors are clusters of cosmically dead and massive neutron stars that merged after reaching the ultimate lowest quantum energy state, where the matter is in an incompressible superconducting gluon-quark superfluid state and zero-entropy, hence granting the resulting progenitors measurable sizes and immunity to collapsing into black holes. Our big bang happened to occur in our neighbourhood, thereby enduing the universe, the observed homogeneity and isotropy. As the enclosed mass of the progenitor was finite, the dynamically expanding curved spacetimes embedded the fireball started flattening to finally diffuse into the flat spacetime of the parent universe. By means of general relativistic numerical hydrodynamical calculations, we use the H-metric to follow the time-evolution of the spacetime embedding the progenitor during the hadronization and the immediately following epochs. Based thereon, we find that the kinetic energy of newly created normal matter increases with distance in a self-similar manner, imitating thereby outflows of nearly non-interacting particles. On cosmic time scales, this behaviour yields a Hubble parameter, H(t), which decreases slowly with the distance from the big bang event. Given the sensitivity of the data of the Cosmic Microwave Background (CMB) from Planck to the underlying cosmological model, we conclude that UNIMOUN is a viable alternative to ΛCMD-cosmologies.展开更多
The redshift range from 2.2 to 3 is known as the ＇redshift desert＇ of quasars because quasars with redshifts in this range have similar optical colors as normal stars and are thus difficult to find in optical sky su...The redshift range from 2.2 to 3 is known as the ＇redshift desert＇ of quasars because quasars with redshifts in this range have similar optical colors as normal stars and are thus difficult to find in optical sky surveys. A quasar candidate, SDSS J085543.40-001517.7, which was selected by a recently proposed criterion involving near-IR Y - K and optical g - z colors, was identified spectroscopically as a new quasar with a redshift of 2.427 by the Guoshoujing Telescope （LAMOST） commissioning observation in 2009 December and confirmed by the observation made with the NAOC/Xinglong 2.16 m telescope in 2010 March. This quasar was not identified in the SDSS spectroscopic survey. Comparing with other SDSS quasars, we found that this new quasar, with an i magnitude of 16.44, is apparently the brightest one in the redshift range from 2.3 to 2.7. From its spectral properties, we derived its central black hole mass to be （1.4 - 3.9） × 10^110 M⊙ and its bolometric luminosity to be 3.7 × 10^48 erg s^-1, which indicates that this new quasar is intrinsically very bright and belongs to the class of the most luminous quasars in the universe. Our identification supports the notion that quasars in the redshift desert can be found by the quasar selection criterion involving the near-IR colors. More missing quasars are expected to be uncovered by future LAMOST spectroscopic surveys, which is important to the study of the cosmological evolution of quasars at redshifts higher than 2.2.展开更多
We selected 457 blazars （193 fiat spectrum radio quasars, 61 low- synchrotron peaked blazars, 69 intermediate-synchrotron peaked blazars and 134 high-synchrotron peaked blazars） from the second Fermi-LAT catalog （2...We selected 457 blazars （193 fiat spectrum radio quasars, 61 low- synchrotron peaked blazars, 69 intermediate-synchrotron peaked blazars and 134 high-synchrotron peaked blazars） from the second Fermi-LAT catalog （2FGL） of γ- ray sources, which have X-ray observations. We calculated the lower limits for their Doppler factors, δγ, and compared the lower limits with the available Doppler factors and the apparent superluminal velocities in the literature.展开更多
We have collected an up-to-date sample of 123 superluminal sources （84 quasars, 27 BL Lac objects and 12 galaxies） and calculated the apparent velocities （βapp） for 224 components in the sources with the A-CDM mo...We have collected an up-to-date sample of 123 superluminal sources （84 quasars, 27 BL Lac objects and 12 galaxies） and calculated the apparent velocities （βapp） for 224 components in the sources with the A-CDM model. We checked the relationships between their proper motions, redshifts,βapp and 5 GHz flux densities. Our analysis shows that the radio emission is strongly boosted by the Doppler effect. The superluminal motion and the relativistic beaming boosting effect are, to some extent, the same in active galactic nuclei.展开更多
Active galactic nuclei （AGNs） have two major classes, namely radio loud AGNs and radio quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which display extreme observational properties, such as rap...Active galactic nuclei （AGNs） have two major classes, namely radio loud AGNs and radio quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which display extreme observational properties, such as rapid variability, high luminosity, high and variable polarization, and superluminal motion. All of those observational properties are probably due to a relativistic beaming effect with the jet pointing close to the line of sight. Observations suggest that the orientation can be expressed by a core-dominance parameter, R. The R, to some extent, is associated with the beaming effect. Blazars are believed to be unified with Fanaroff ＆ Riley type I/II （FRI/II） radio galaxies. In this work, we collected relevant observations from the literature for a sample of 1223 AGNs including 77 BL Lacertae objects, 495 quasars, 460 galaxies, 119 FRs and 72 unidentified sources, and calculated the core-dominance parameters and spectral indexes, discussed the relationship between the two parameters, and gave some discussions. Our analysis suggests that the core-dominance parameters in BL Lacertae objects are larger than those in quasars and galaxies, and the radio spectral indexes in BL Lacertae objects are lower than those in quasars and galaxies. We also found that the core-dominance parameter-spectral index correlation exists for a large sample presented in this work, which may come from a relativistic beaming effect.展开更多
We present preliminary analyses of spectra of quasar candidates in two Guoshoujing Telescope （GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope - LAMOST） test fields near M 31 where ...We present preliminary analyses of spectra of quasar candidates in two Guoshoujing Telescope （GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope - LAMOST） test fields near M 31 where one is close to the optical center of the disk and the other is towards the northeastern outskirts of the halo, obtained during the early stage of the GSJT commissioning in the last season of 2009. Both fields contain background low-redshift quasar candidates selected from the SDSS photometry. In total, 14 new quasars with redshifts up to 2 and i magnitudes between 16.7 and 19.2, are discovered, including 7 within the 2.5° central region of M 31. We briefly discuss the potential applications of these newly discovered bright quasars.展开更多
Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and...Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from spectroscopy with the Yunnan Faint Object Spectrograph and Camera (YFOSC) at the Lijiang 2.4 m telescope in February, 2012. These quasars are in the list of z > 3.6 quasar candidates selected by using our proposed J K/i Y criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as z > 3.6 quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that z > 4 quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.展开更多
We report the discovery of eight new quasars in one extragalactic field （a five-degree field centered at RA=08^h58^m08.2^s, Dec=01°32′29.7″） with the Guoshoujing Telescope （LAMOST） commissioning observation...We report the discovery of eight new quasars in one extragalactic field （a five-degree field centered at RA=08^h58^m08.2^s, Dec=01°32′29.7″） with the Guoshoujing Telescope （LAMOST） commissioning observations made on 2009 December 18. These quasars, with i magnitudes from 16.44 to 19.34 and redshifts from 0.898 to 2.773, were not identified in the SDSS spectroscopic survey, though six of them with redshifts less than 2.5 were selected as quasar targets in SDSS. Except for one source without near-IR Y-band data, seven of these eight new quasars satisfy a newly proposed quasar selection criterion involving both near-IR and optical colors. Two of them were found in the ＇redshift desert＇ for quasars （z from 2.2 to 3）, indicating that the new criterion is efficient for uncovering missing quasars with similar optical colors to stars. Although LAMOST encountered some problems during the commissioning observations, we were still able to identify 38 other known SDSS quasars in this field, with i magnitudes from 16.24 to 19.10 and redshifts from 0.297 to 4.512. Our identifications imply that a substantial fraction of quasars may be miss- ing in previous quasar surveys. The implication of our results to the future LAMOST quasar survey is discussed.展开更多
The gamma function is a good approximation to the luminosity function of astrophysical objects, and a truncated gamma distribution would permit a more rigorous analysis. This paper examines the generalized gamma distr...The gamma function is a good approximation to the luminosity function of astrophysical objects, and a truncated gamma distribution would permit a more rigorous analysis. This paper examines the generalized gamma distribution (GG) and then introduces the scale and the new double truncation. The magnitude version of the truncated GG distribution with scale is adopted in order to fit the luminosity function (LF) for galaxies or quasars. The new truncated GG LF is applied to the five bands of SDSS galaxies, to the 2dF QSO Redshift Survey in the range of redshifts between 0.3 and 0.5, and to the COSMOS QSOs in the range of redshifts between 3.7 and 4.7. The average absolute magnitude versus redshifts for SDSS galaxies and QSOs of 2dF was modeled adopting a redshift dependence for the lower and upper absolute magnitude of the new truncated GG LF.展开更多
By modeling the broadband spectral energy distributions （SEDs） of a typical flat spectrum radio quasar （FSRQ, 3C 279） and two GeV narrow-line Seyfert 1 galaxies （NLSls, PMN J0948＋0022 and 1H 0323＋342） in diffe...By modeling the broadband spectral energy distributions （SEDs） of a typical flat spectrum radio quasar （FSRQ, 3C 279） and two GeV narrow-line Seyfert 1 galaxies （NLSls, PMN J0948＋0022 and 1H 0323＋342） in different flux stages with one-zone leptonic models, we find a universal correlation between their Doppler factors （δ） and peak luminosities （Lc） of external Compton scattering bumps. Compiling a combined sample of FSRQs and GeV NLSls, it is found that both FSRQs and GeV NLSls in different stages and in different sources follow the same δ-Lc correlation well. This indicates that the variations of observed luminosities may be essentially due to the Doppler boosting effect. The universal δ-Lo relation between FSRQs and GeV NLS 1 s in different stages may be further evidence that the particle acceleration and radiation mechanisms for the two kinds of sources are similar. In addition, by replacing Lc with the observed luminosity in the Fermi/LAT band （LLAT）, this correlation holds and it may serve as an empirical indicator of δ. We estimate the δ values with LLAT for 484 FSRQs in the Fermi/LAT Catalog and they range from 3 to 41, with a median of 16, which are statistically consistent with the values derived by other methods.展开更多
With the 1.26 m National Astronomical Observatory-Guangzhou University Infrared/Optical Telescope(NAGIOT) at Xinglong Station of National Astronomical Observatories, Chinese Academy of Sciences, we obtained 419 groups...With the 1.26 m National Astronomical Observatory-Guangzhou University Infrared/Optical Telescope(NAGIOT) at Xinglong Station of National Astronomical Observatories, Chinese Academy of Sciences, we obtained 419 groups of simultaneous observations at g, r and i bands, for the first time,targeting quasar 3 C 454.3 during 15 nights from 2016 October 23 to 2016 December 15. Based on our observations, we investigate the optical variabilities, the relation between brightness and color index, and the periodicity variability. The presented analyses demonstrate that: 1. The maximum variations at the g, r and i bands are △mg|max= 1.015 ± 0.042 mag,△mr|max= 1.188 ± 0.050 mag and △mi|max= 1.305 ± 0.057 mag respectively. 2. During our 15 night monitoring program, intra-day variability was detected on one night(Nov. 2). Also, the brightness increased by A = 15.86% over 50.8 min,then decreased by A = 22.42% over 40.1 min. After a small bright state, its brightness increased again by18.1% over 55 min at the g band. Similar phenomena happened at r and i bands. The intra-day variabilities at the three bands on 2016 November 2 indicate a period of 105 min, which implies a black hole mass of MBH =(0.3 ~ 1.85)× 10^9 M⊙. 3. There is an anti-correlation between color index and magnitude,suggesting the source becomes redder when it brightens.展开更多
In this work, we collected a sample of 69 TeV blazars from TeVCat, obtained their multi-wavelength observations, and fitted their spectral energy distributions by using a second degree poly-nomial function. The struct...In this work, we collected a sample of 69 TeV blazars from TeVCat, obtained their multi-wavelength observations, and fitted their spectral energy distributions by using a second degree poly-nomial function. The structure parameters of synchrotron bumps for 68 blazars and those of inverse- Compton bumps for 56 blazars were derived. Then, we conducted statistical analysis on the parame-ters （curvature, peak frequency, peak luminosity, bolometric luminosity and X/γ-ray spectral indexes）. From our analysis and discussions, we can conclude the following： （1） There is a clear positive correla-tion between the synchrotron peak frequency, log （Vp）^s, and the inverse-Compton peak frequency, log （Vp）^IC, and between the synchrotron peak luminosity, log （Vp）^sL（Vp）^s, and the inverse-Compton peak luminosity,log（Vp）^IC L（Vp）^IC. （2） The correlation between the peak frequency and the curvature of synchrotron bump is clearly different from that of the inverse-Compton bump, which further indicates that there are differ-ent emission mechanisms between them. （3） There is a correlation between log （Vp）^IC and γ-ray spectral index, αγ, for the TeV blazars： log （Vp）^IC = -（4.59 ± 0.30）αγ ＋ （32.67 ±0.59）, which is consistent with previous work. （4） An ＂L-shape＂ relation is found between log（Vp）^s Up and αx for both TeV blazars and Fermi blazars. A significant correlation between log（Vp）^s and X-ray photon index （αx） is found for the TeV blazars with high synchrotron peak frequency： log（Vp）^s = -（3.20 ± 0.34）αx ＋ （24.33 ± 0.79）, while the correlation is positive for low synchrotron peaked TeV sources. （5） In the αx -αγ diagram, there is also an ＂L-shape.＂ The anti-correlation is consistent with results available in the literature, and we also find a positive correlation between them. （6） Inverse-Compton dominant sources have luminous bolometric luminosities.展开更多
We study the growth of black holes and stellar population in spheroids at high redshift using several （sub）mm-loud QSO samples. Applying the same criteria established in an earlier work, we find that, similar to IR ...We study the growth of black holes and stellar population in spheroids at high redshift using several （sub）mm-loud QSO samples. Applying the same criteria established in an earlier work, we find that, similar to IR QSOs at low redshift, the far-infrared emission of these （sub）mm-loud QSOs mainly originates from dust heated by starbursts. By combining low-z IR QSOs and high-z （sub）mm-loud QSOs, we find a trend that the star formation rate （M＊） increases with the accretion rate （Mace）. We compare the values of M＊/Macc for submm emitting galaxies （SMGs）, far-infrared ultraluminous/hypeduminous QSOs and typical QSOs, and construct a likely evolution scenario for these objects. The （sub）mm-loud QSO transition phase has both high Macc and M＊ and hence is important for establishing the correlation between the masses of black holes and spheroids.展开更多
Blazars are characterized by large intensity and spectral variations across the electromagnetic spectrum It is believed that jets emerging from them are almost aligned with the line-of-sight. The major- ity of identif...Blazars are characterized by large intensity and spectral variations across the electromagnetic spectrum It is believed that jets emerging from them are almost aligned with the line-of-sight. The major- ity of identified extragalactic sources in γ-ray catalogs of EGRET and Fermi are blazars. Observationally, blazars can be divided into two classes： fiat spectrum radio quasars （FSRQs） and BL Lacs. BL Lacs usually exhibit lower γ-ray luminosity and harder power law spectra at γ-ray energies than FSRQs. We attempt to explain the high energy properties of FSRQs and BL Lacs from Fermi γ-ray space telescope observations. It was argued previously that the difference in accretion rates is mainly responsible for the large mismatch in observed luminosity in ＂7-ray. However, when intrinsic luminosities are derived by correcting for beaming effects, this difference in 7-ray luminosity between the two classes is significantly reduced. In order to ex- plain this difference in intrinsic luminosities, we propose that spin plays an important role in the luminosity distribution dichotomy of BL Lacs and FSRQs. As the outflow power of a blazar increases with increasing spin of a central black hole, we suggest that the spin plays a crucial role in making BL Lac sources low luminous and slow rotators compared to FSRQ sources.展开更多
基金Supported by the National Natural Science Foundation of China.
文摘We collect 119 γ-ray-loud blazars (97 flat spectrum radio quasars (FSRQs) and 22 BL Lacertae objects (BL Lacs)), and investigate possible correlations between their γ-ray emission (maximum, minimum and average values) at 1 GeV and the radio emission at 8.4 GHz. Our main results are as follows. For the lower state γ-ray data, there is no correlation between the γ-ray and radio flux density; For the high state γ-ray data, there are good correlations for the whole 119 blazars and 97 FSRQs, and a weak correlation for the 22 BL Lac objects; For the average γ-ray data, there are good correlations. According to our analysis, we propose that the γ-rays are associated with the radio emission from the jet, and that the γ-ray emission is likely from the SSC process in this case.
基金supported by the National Natural Science Foundation of China (Grant No. 11173009)the National Basic Research Program of China (973 program, 2007CB815405)+3 种基金the Bureau of Education of Guangzhou Municipality (No.11 Sui-Jiao-Ke[2009])Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(GDUPS) (2009)Yangcheng Scholar Funded Scheme (10A027S)the Joint Laboratory for Optical Astronomy of Chinese Academy of Sciences
文摘Observations suggest that γ-ray loud blazars are strongly beamed. The Fermi mission has detected many of blazars, which provide us with a good opportunity to investigate the emission mechanism and the beaming effect in the γ-ray region. We compiled the X-ray observations for 138 Fermi blazars （54 flat spectrum radio quasars, 36 low-peaked BL Lacertae objects, and 48 high-peaked BL Lacertae objects） and calculated their Doppler factors, δγ. It is interesting that the calculated Doppler factors, δγ, are strongly correlated with the γ-ray luminosity.
文摘The pictures from the James Webb Space Telescope (JWST) suggest that massive galaxies were already at the beginning of the expansion of the Universe because there was too short time to create them. It is consistent with the new cosmology presented within the Scale-Symmetric Theory (SST). The phase transitions of the initial inflation field described in SST lead to the Protoworld—its core was built of dark matter (DM). We show that the DAMA/LIBRA annual-modulation amplitude forced by the change of the Earth’s velocity (i.e. baryonic-matter (BM) velocity) in relation to the spinning DM field in our Galaxy’s halo should be very low. We calculated that in the DM-BM weak interactions are created single and entangled spacetime condensates with a lowest mass/energy of 0.807 keV—as the Higgs boson they can decay to two photons, so we can indirectly detect DM. Our results are consistent with the averaged DAMA/LIBRA/COSINE-100 curve describing the dependence of the event rate on the photon energy in single-hit events. We calculated the mean dark-matter-halo (DMH) mass around quasars, we also described the origin of the plateaux in the rotation curves for the massive spiral galaxies, the role of DM-loops in magnetars, the origin of CMB, the AGN-jet and galactic-halo production, and properties of dark energy (DE).
基金Supported by the National Natural Science Foundation of China.(Nos. 10573005 and 10633010) the 973 project (No. 2007CB815405)
文摘The method used in our previous papers is adopted to estimate four basic parameters （the central black hole mass （M）, the boosting factor （or Doppler factor） （6）, the propagation angle （Φ） and the distance along the axis to the site of the γ-ray production （d）） for 59 γ-ray loud blazars （20 BL Lacertae objects and 39 flat spectrum radio quasars）. The central black hole masses estimated for this sample are in a range of from 107 Me to 109 MG. In the case of black hole mass, there is no clear difference between BL Lacertae objects and flat spectrum radio quasars, which is consistent with the previous results suggesting that the central black hole masses do not play an important role in the evolutionary sequence of blazars.
文摘Based on the idea of hypothetical 4-dimensial substance with an inverse population of energy levels, a model of accelerated expansion of the Universe has been developed, which describes Hubble diagrams with great accuracy for type Ia supernovae, quasars and gamma-ray burst sources at the Hubble parameter value of 67.7 km/s/Mpc, coinciding with the value obtained from analysis of inhomogeneities of relic radiation. Calculations at the Hubble parameter value of 73.5 km/s/Mpc, obtained using the ΛCDM model based on the analysis of data on type Ia supernovae and cepheids, differ markedly from the observed data. An explanation of the two values of the Hubble constant is proposed. It is shown that in this model, the magnitude of 13.8 billion years characterizes not the age of the Universe, but the time of propagation of light from those galaxes whose acceleration of removal has a minimal value. Based on the recently discovered curvature of the Universe, estimates are given of the lower limits of its size and lifetime, which turned out to be at least 270 billon years. The probability of transition from the excited state to the underlying energy levels of a hypothetical 4-dimensial substance, as well as the low of increasing energy density as a result of transitions to the underlying levels of this substance, is determined.
文摘Recently, a unicentric model of the observable universe (UNIMOUN) was proposed. Accordingly, big bangs are common events in our infinitely large, flat, homogeneous and isotropic parent universe. Their progenitors are clusters of cosmically dead and massive neutron stars that merged after reaching the ultimate lowest quantum energy state, where the matter is in an incompressible superconducting gluon-quark superfluid state and zero-entropy, hence granting the resulting progenitors measurable sizes and immunity to collapsing into black holes. Our big bang happened to occur in our neighbourhood, thereby enduing the universe, the observed homogeneity and isotropy. As the enclosed mass of the progenitor was finite, the dynamically expanding curved spacetimes embedded the fireball started flattening to finally diffuse into the flat spacetime of the parent universe. By means of general relativistic numerical hydrodynamical calculations, we use the H-metric to follow the time-evolution of the spacetime embedding the progenitor during the hadronization and the immediately following epochs. Based thereon, we find that the kinetic energy of newly created normal matter increases with distance in a self-similar manner, imitating thereby outflows of nearly non-interacting particles. On cosmic time scales, this behaviour yields a Hubble parameter, H(t), which decreases slowly with the distance from the big bang event. Given the sensitivity of the data of the Cosmic Microwave Background (CMB) from Planck to the underlying cosmological model, we conclude that UNIMOUN is a viable alternative to ΛCMD-cosmologies.
基金supported by the National Natural Science Foundation of China (Grant No.10525313)the National Key Basic Research Science Foundation of China(2007CB815405)+1 种基金the Open Project Program of the Key Laboratory of Optical Astronomy,NAOC,CASThe Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST,now called the Guoshoujing Telescope) is a National Major Scientific Project built by the Chinese Academy of Sciences
文摘The redshift range from 2.2 to 3 is known as the ＇redshift desert＇ of quasars because quasars with redshifts in this range have similar optical colors as normal stars and are thus difficult to find in optical sky surveys. A quasar candidate, SDSS J085543.40-001517.7, which was selected by a recently proposed criterion involving near-IR Y - K and optical g - z colors, was identified spectroscopically as a new quasar with a redshift of 2.427 by the Guoshoujing Telescope （LAMOST） commissioning observation in 2009 December and confirmed by the observation made with the NAOC/Xinglong 2.16 m telescope in 2010 March. This quasar was not identified in the SDSS spectroscopic survey. Comparing with other SDSS quasars, we found that this new quasar, with an i magnitude of 16.44, is apparently the brightest one in the redshift range from 2.3 to 2.7. From its spectral properties, we derived its central black hole mass to be （1.4 - 3.9） × 10^110 M⊙ and its bolometric luminosity to be 3.7 × 10^48 erg s^-1, which indicates that this new quasar is intrinsically very bright and belongs to the class of the most luminous quasars in the universe. Our identification supports the notion that quasars in the redshift desert can be found by the quasar selection criterion involving the near-IR colors. More missing quasars are expected to be uncovered by future LAMOST spectroscopic surveys, which is important to the study of the cosmological evolution of quasars at redshifts higher than 2.2.
基金Supported by the National Natural Science Foundation of China
文摘We selected 457 blazars （193 fiat spectrum radio quasars, 61 low- synchrotron peaked blazars, 69 intermediate-synchrotron peaked blazars and 134 high-synchrotron peaked blazars） from the second Fermi-LAT catalog （2FGL） of γ- ray sources, which have X-ray observations. We calculated the lower limits for their Doppler factors, δγ, and compared the lower limits with the available Doppler factors and the apparent superluminal velocities in the literature.
基金the NSFC(Grants 10573005 and 10633010)the 973 project(2007CB815405)
文摘We have collected an up-to-date sample of 123 superluminal sources （84 quasars, 27 BL Lac objects and 12 galaxies） and calculated the apparent velocities （βapp） for 224 components in the sources with the A-CDM model. We checked the relationships between their proper motions, redshifts,βapp and 5 GHz flux densities. Our analysis shows that the radio emission is strongly boosted by the Doppler effect. The superluminal motion and the relativistic beaming boosting effect are, to some extent, the same in active galactic nuclei.
基金supported by the National Natural Science Foundationof China (NSFC, Grant Nos. 10633010, 11173009)the National Basic Research Program (973 program, 2007CB815405)+3 种基金the Bureau of Education of Guangzhou Municipality (No.11 Sui-Jiao-Ke[2009])Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(GDUPS)(2009)Yangcheng Scholar Funded Scheme (10A027S)the Joint Laboratory for Optical Astronomy of Chinese Academy of Sciences
文摘Active galactic nuclei （AGNs） have two major classes, namely radio loud AGNs and radio quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which display extreme observational properties, such as rapid variability, high luminosity, high and variable polarization, and superluminal motion. All of those observational properties are probably due to a relativistic beaming effect with the jet pointing close to the line of sight. Observations suggest that the orientation can be expressed by a core-dominance parameter, R. The R, to some extent, is associated with the beaming effect. Blazars are believed to be unified with Fanaroff ＆ Riley type I/II （FRI/II） radio galaxies. In this work, we collected relevant observations from the literature for a sample of 1223 AGNs including 77 BL Lacertae objects, 495 quasars, 460 galaxies, 119 FRs and 72 unidentified sources, and calculated the core-dominance parameters and spectral indexes, discussed the relationship between the two parameters, and gave some discussions. Our analysis suggests that the core-dominance parameters in BL Lacertae objects are larger than those in quasars and galaxies, and the radio spectral indexes in BL Lacertae objects are lower than those in quasars and galaxies. We also found that the core-dominance parameter-spectral index correlation exists for a large sample presented in this work, which may come from a relativistic beaming effect.
基金The Guoshoujing Telescope(GSJT)is a National Major Scientific Project built by the Chinese Academy of SciencesFunding for the project has been provided by the National Development and Reform Commission
文摘We present preliminary analyses of spectra of quasar candidates in two Guoshoujing Telescope （GSJT, formerly named the Large Sky Area Multi-Object Fiber Spectroscopic Telescope - LAMOST） test fields near M 31 where one is close to the optical center of the disk and the other is towards the northeastern outskirts of the halo, obtained during the early stage of the GSJT commissioning in the last season of 2009. Both fields contain background low-redshift quasar candidates selected from the SDSS photometry. In total, 14 new quasars with redshifts up to 2 and i magnitudes between 16.7 and 19.2, are discovered, including 7 within the 2.5° central region of M 31. We briefly discuss the potential applications of these newly discovered bright quasars.
基金the National Natural Science Foundation of China (Grant No. 11033001)
文摘Quasars with redshifts greater than 4 are rare, and can be used to probe the structure and evolution of the early universe. Here we report the discovery of six new quasars with i-band magnitudes brighter than 19.5 and redshifts between 2.4 and 4.6 from spectroscopy with the Yunnan Faint Object Spectrograph and Camera (YFOSC) at the Lijiang 2.4 m telescope in February, 2012. These quasars are in the list of z > 3.6 quasar candidates selected by using our proposed J K/i Y criterion and the photometric redshift estimations from the SDSS optical and UKIDSS near-IR photometric data. Nine candidates were observed by YFOSC, and five among six new quasars were identified as z > 3.6 quasars. One of the other three objects was identified as a star and the other two were unidentified due to the lower signal-to-noise ratio of their spectra. This is the first time that z > 4 quasars have been discovered using a telescope in China. Thanks to the Chinese Telescope Access Program (TAP), the redshift of 4.6 for one of these quasars was confirmed by the Multiple Mirror Telescope (MMT) Red Channel spectroscopy. The continuum and emission line properties of these six quasars, as well as their central black hole masses and Eddington ratios, were obtained.
基金supported by the National Natural Science Foundation of China (Grant No.10525313)the National Key Basic Research Science Foundation of China (2007CB815405)The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST,now called the Guoshoujing Telescope) is a National Major Scientific Project built by the Chinese Academy of Sciences
文摘We report the discovery of eight new quasars in one extragalactic field （a five-degree field centered at RA=08^h58^m08.2^s, Dec=01°32′29.7″） with the Guoshoujing Telescope （LAMOST） commissioning observations made on 2009 December 18. These quasars, with i magnitudes from 16.44 to 19.34 and redshifts from 0.898 to 2.773, were not identified in the SDSS spectroscopic survey, though six of them with redshifts less than 2.5 were selected as quasar targets in SDSS. Except for one source without near-IR Y-band data, seven of these eight new quasars satisfy a newly proposed quasar selection criterion involving both near-IR and optical colors. Two of them were found in the ＇redshift desert＇ for quasars （z from 2.2 to 3）, indicating that the new criterion is efficient for uncovering missing quasars with similar optical colors to stars. Although LAMOST encountered some problems during the commissioning observations, we were still able to identify 38 other known SDSS quasars in this field, with i magnitudes from 16.24 to 19.10 and redshifts from 0.297 to 4.512. Our identifications imply that a substantial fraction of quasars may be miss- ing in previous quasar surveys. The implication of our results to the future LAMOST quasar survey is discussed.
文摘The gamma function is a good approximation to the luminosity function of astrophysical objects, and a truncated gamma distribution would permit a more rigorous analysis. This paper examines the generalized gamma distribution (GG) and then introduces the scale and the new double truncation. The magnitude version of the truncated GG distribution with scale is adopted in order to fit the luminosity function (LF) for galaxies or quasars. The new truncated GG LF is applied to the five bands of SDSS galaxies, to the 2dF QSO Redshift Survey in the range of redshifts between 0.3 and 0.5, and to the COSMOS QSOs in the range of redshifts between 3.7 and 4.7. The average absolute magnitude versus redshifts for SDSS galaxies and QSOs of 2dF was modeled adopting a redshift dependence for the lower and upper absolute magnitude of the new truncated GG LF.
基金supported by the National Basic Research Program of China (973 Program) (grant 2014CB845800)the National Natural Science Foundation of China (grants 11573034, 11533003, 11373036 and 11133002)+1 种基金the Strategic Priority Research Program “The Emergence of Cosmological Structures” of the Chinese Academy of Sciences (grant XDB09000000)the Guangxi Science Foundation (2013GXNSFFA019001)
文摘By modeling the broadband spectral energy distributions （SEDs） of a typical flat spectrum radio quasar （FSRQ, 3C 279） and two GeV narrow-line Seyfert 1 galaxies （NLSls, PMN J0948＋0022 and 1H 0323＋342） in different flux stages with one-zone leptonic models, we find a universal correlation between their Doppler factors （δ） and peak luminosities （Lc） of external Compton scattering bumps. Compiling a combined sample of FSRQs and GeV NLSls, it is found that both FSRQs and GeV NLSls in different stages and in different sources follow the same δ-Lc correlation well. This indicates that the variations of observed luminosities may be essentially due to the Doppler boosting effect. The universal δ-Lo relation between FSRQs and GeV NLS 1 s in different stages may be further evidence that the particle acceleration and radiation mechanisms for the two kinds of sources are similar. In addition, by replacing Lc with the observed luminosity in the Fermi/LAT band （LLAT）, this correlation holds and it may serve as an empirical indicator of δ. We estimate the δ values with LLAT for 484 FSRQs in the Fermi/LAT Catalog and they range from 3 to 41, with a median of 16, which are statistically consistent with the values derived by other methods.
基金partially supported by the National Natural Science Foundation of China (Grant Nos. U1531245, 11733001, U1831119, 11873073, 11173009, U1431112, 11733006 and 11873073)the Natural Science Foundation of Guangdong Province (2017A030313011)+1 种基金supports for Astrophysics Key Subjects of Guangdong Province and Guangzhou CityScience and Technology Program of Guangzhou (201707010401)
文摘With the 1.26 m National Astronomical Observatory-Guangzhou University Infrared/Optical Telescope(NAGIOT) at Xinglong Station of National Astronomical Observatories, Chinese Academy of Sciences, we obtained 419 groups of simultaneous observations at g, r and i bands, for the first time,targeting quasar 3 C 454.3 during 15 nights from 2016 October 23 to 2016 December 15. Based on our observations, we investigate the optical variabilities, the relation between brightness and color index, and the periodicity variability. The presented analyses demonstrate that: 1. The maximum variations at the g, r and i bands are △mg|max= 1.015 ± 0.042 mag,△mr|max= 1.188 ± 0.050 mag and △mi|max= 1.305 ± 0.057 mag respectively. 2. During our 15 night monitoring program, intra-day variability was detected on one night(Nov. 2). Also, the brightness increased by A = 15.86% over 50.8 min,then decreased by A = 22.42% over 40.1 min. After a small bright state, its brightness increased again by18.1% over 55 min at the g band. Similar phenomena happened at r and i bands. The intra-day variabilities at the three bands on 2016 November 2 indicate a period of 105 min, which implies a black hole mass of MBH =(0.3 ~ 1.85)× 10^9 M⊙. 3. There is an anti-correlation between color index and magnitude,suggesting the source becomes redder when it brightens.
基金supported by the National Natural Science Foundation of China(11733001 and U1531245)Guangdong Innovation Team(2014KCXTD014)+1 种基金Natural Science Foundation of Guangdong Province(2017A030313011)support from Astrophysics Key Subjects of Guangdong Province and Guangzhou City
文摘In this work, we collected a sample of 69 TeV blazars from TeVCat, obtained their multi-wavelength observations, and fitted their spectral energy distributions by using a second degree poly-nomial function. The structure parameters of synchrotron bumps for 68 blazars and those of inverse- Compton bumps for 56 blazars were derived. Then, we conducted statistical analysis on the parame-ters （curvature, peak frequency, peak luminosity, bolometric luminosity and X/γ-ray spectral indexes）. From our analysis and discussions, we can conclude the following： （1） There is a clear positive correla-tion between the synchrotron peak frequency, log （Vp）^s, and the inverse-Compton peak frequency, log （Vp）^IC, and between the synchrotron peak luminosity, log （Vp）^sL（Vp）^s, and the inverse-Compton peak luminosity,log（Vp）^IC L（Vp）^IC. （2） The correlation between the peak frequency and the curvature of synchrotron bump is clearly different from that of the inverse-Compton bump, which further indicates that there are differ-ent emission mechanisms between them. （3） There is a correlation between log （Vp）^IC and γ-ray spectral index, αγ, for the TeV blazars： log （Vp）^IC = -（4.59 ± 0.30）αγ ＋ （32.67 ±0.59）, which is consistent with previous work. （4） An ＂L-shape＂ relation is found between log（Vp）^s Up and αx for both TeV blazars and Fermi blazars. A significant correlation between log（Vp）^s and X-ray photon index （αx） is found for the TeV blazars with high synchrotron peak frequency： log（Vp）^s = -（3.20 ± 0.34）αx ＋ （24.33 ± 0.79）, while the correlation is positive for low synchrotron peaked TeV sources. （5） In the αx -αγ diagram, there is also an ＂L-shape.＂ The anti-correlation is consistent with results available in the literature, and we also find a positive correlation between them. （6） Inverse-Compton dominant sources have luminous bolometric luminosities.
基金Supported by the National Natural Science Foundation of China.
文摘We study the growth of black holes and stellar population in spheroids at high redshift using several （sub）mm-loud QSO samples. Applying the same criteria established in an earlier work, we find that, similar to IR QSOs at low redshift, the far-infrared emission of these （sub）mm-loud QSOs mainly originates from dust heated by starbursts. By combining low-z IR QSOs and high-z （sub）mm-loud QSOs, we find a trend that the star formation rate （M＊） increases with the accretion rate （Mace）. We compare the values of M＊/Macc for submm emitting galaxies （SMGs）, far-infrared ultraluminous/hypeduminous QSOs and typical QSOs, and construct a likely evolution scenario for these objects. The （sub）mm-loud QSO transition phase has both high Macc and M＊ and hence is important for establishing the correlation between the masses of black holes and spheroids.
基金partially supported by projects SB/S2HEP-001/2013funded by DST(DB)+1 种基金ISRO/RES/2/367/10-11funded by ISRO,India
文摘Blazars are characterized by large intensity and spectral variations across the electromagnetic spectrum It is believed that jets emerging from them are almost aligned with the line-of-sight. The major- ity of identified extragalactic sources in γ-ray catalogs of EGRET and Fermi are blazars. Observationally, blazars can be divided into two classes： fiat spectrum radio quasars （FSRQs） and BL Lacs. BL Lacs usually exhibit lower γ-ray luminosity and harder power law spectra at γ-ray energies than FSRQs. We attempt to explain the high energy properties of FSRQs and BL Lacs from Fermi γ-ray space telescope observations. It was argued previously that the difference in accretion rates is mainly responsible for the large mismatch in observed luminosity in ＂7-ray. However, when intrinsic luminosities are derived by correcting for beaming effects, this difference in 7-ray luminosity between the two classes is significantly reduced. In order to ex- plain this difference in intrinsic luminosities, we propose that spin plays an important role in the luminosity distribution dichotomy of BL Lacs and FSRQs. As the outflow power of a blazar increases with increasing spin of a central black hole, we suggest that the spin plays a crucial role in making BL Lac sources low luminous and slow rotators compared to FSRQ sources.
