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Comparison of the NIR UKIDSS colors for a sample of 5 high-z RL BAL (red dots) and 36 normal RL QSOs (blue dots) matched in redshift. The means of the colors are shown in the plot as red cross for the BALs and as a blue cross for normal QSOs, both with 1-σ error bar. See section 5.2
Source publication
We present the results of a multi-wavelength study of a sample of high-redshift Radio Loud (RL) Broad Absorption Line (BAL) quasars. This way we extend to higher redshift previous studies on the radio properties, and broadband optical colors of these objects. We have se- lected a sample of 22 RL BAL quasars with 3.6 z 4.8 cross-correlating the FIRS...
Citations
... We obtained a total of 664 CDQs (BALs: 165, non-B ALs: 499), 463 LDQs (B ALs: 107, non-B ALs: 356), and 1262 RCQs. Fig. 3 shows the radio luminosity versus redshift comparison of our sample with previous BAL quasar samples ( DiPompeo et al. 2011 ;Bruni et al. 2012 ;Tuccillo et al. 2017 ). The sample in Tuccillo et al. ( 2017 ) consists of 22 BAL sources with 3.6 ≤ z ≤ 4.8, detected both in SDSS DR7 and VLA FIRST surv e ys, and having radio loudness parameter greater than 10. ...
... Fig. 3 shows the radio luminosity versus redshift comparison of our sample with previous BAL quasar samples ( DiPompeo et al. 2011 ;Bruni et al. 2012 ;Tuccillo et al. 2017 ). The sample in Tuccillo et al. ( 2017 ) consists of 22 BAL sources with 3.6 ≤ z ≤ 4.8, detected both in SDSS DR7 and VLA FIRST surv e ys, and having radio loudness parameter greater than 10. Sample provided by Bruni et al. ( 2012 ) comprises 25 BAL quasars found in the SDSS DR4 catalogue with a counterpart in VLA FIRST, having S 1 . ...
In this study, we investigated the orientation model of Broad Absorption Line (BAL) quasars using a sample of sources that are common in Sloan Digital Sky Survey (SDSS) Data Release (DR)-16 quasar catalog and Very Large Array (VLA)-Faint Images of the Radio Sky at Twenty Centimeters (FIRST) survey. Using the radio cut-out images from the FIRST survey, we first designed a deep learning model using convolutional neural networks (CNN) to classify the quasar radio morphologies into the core-only, young jet, single lobe, or triples. These radio morphologies are further sub-classified into core-dominated and lobe-dominated sources. The CNN models can classify the sources with a high precision of >98% for all the morphological sub-classes. The average BAL fraction in the resolved core, core-dominated, and lobe-dominated quasars are consistent with the BAL fraction inferred from radio and infra-red surveys. We also present the distribution of BAL quasars as a function of quasar orientation by using the radio core-dominance as an orientation indicator. A similar analysis is performed for HiBALs, LoBALs, and FeLoBALs. All the radio morphological sub-classes and BAL sub-classes show an increase in BAL fraction at high orientation angles of the jets with respect to the line of sight. Our analysis suggests that BAL quasars are more likely to be found in viewing angles close to the equatorial plane of the quasar. However, a pure orientation model is inadequate, and a combination of orientation and evolution is probably the best way to explain the complete BAL phenomena.
... Fig 3 shows the radio luminosity vs redshift comparison of our sample with previous BAL quasar samples (Tuccillo et al. 2017;Bruni et al. 2012;DiPompeo et al. 2011). The sample in Tuccillo et al. (2017) consists of 22 BAL sources with 3.6 ≤ z ≤ 4.8, detected both in SDSS DR7 and VLA FIRST surveys, and having radio loudness parameter greater than 10. ...
... Fig 3 shows the radio luminosity vs redshift comparison of our sample with previous BAL quasar samples (Tuccillo et al. 2017;Bruni et al. 2012;DiPompeo et al. 2011). The sample in Tuccillo et al. (2017) consists of 22 BAL sources with 3.6 ≤ z ≤ 4.8, detected both in SDSS DR7 and VLA FIRST surveys, and having radio loudness parameter greater than 10. Sample provided by Bruni et al. (2012) Table 4 along with the corresponding BAL fraction values. ...
In this study, we investigated the orientation model of Broad Absorption Line (BAL) quasars using a sample of sources that are common in Sloan Digital Sky Survey (SDSS) Data Release (DR)-16 quasar catalog and Very Large Array (VLA)-Faint Images of the Radio Sky at Twenty Centimeters (FIRST) survey. Using the radio cut-out images from the FIRST survey, we first designed a deep learning model using convolutional neural networks (CNN) to classify the quasar radio morphologies into the core-only, young jet, single lobe, or triples. These radio morphologies are further sub-classified into core-dominated and lobe-dominated sources. The CNN models can classify the sources with a high precision of >98% for all the morphological sub-classes. The average BAL fraction in the resolved core, core-dominated, and lobe-dominated quasars are consistent with the BAL fraction inferred from radio and infra-red surveys. We also present the distribution of BAL quasars as a function of quasar orientation by using the radio core-dominance as an orientation indicator. A similar analysis is performed for HiBALs, LoBALs, and FeLoBALs. All the radio morphological sub-classes and BAL sub-classes show an increase in BAL fraction at high orientation angles of the jets with respect to the line of sight. Our analysis suggests that BAL quasars are more likely to be found in viewing angles close to the equatorial plane of the quasar. However, a pure orientation model is inadequate, and a combination of orientation and evolution is probably the best way to explain the complete BAL phenomena.
... In this section, to probe whether dust is intrinsic to the BAL outflows, we investigate the nature of variation of the infrared fluxes between the Appearing and Disappearing samples (Vivek et al. 2016;Tuccillo et al. 2017). These sources, having undergone an extreme transition of BAL troughs, provide an ideal opportunity to verify the role of dust associated with the BAL outflows. ...
We present a new set of 84 Broad absorption line (BAL) quasars ( 1.7 < zem< 4.4) exhibiting an appearance of C iv BAL troughs over 0.3−4.8 rest-frame years by comparing the Sloan Digital Sky Survey Data Release (SDSSDR)-7, SDSSDR-12, and SDSSDR-14 quasar catalogs. We contrast the nature of BAL variability in this appearing BAL quasar sample with a disappearing BAL quasar sample studied in literature by comparing the quasar’s intrinsic, BAL trough, and continuum parameters between the two samples. We find that appearing BAL quasars have relatively higher redshift and smaller probed timescales as compared to the disappearing BAL quasars. To mitigate the effect of any redshift bias, we created control samples of appearing and disappearing BAL quasars that have similar redshift distribution. We find that the appearing BAL quasars are relatively brighter and have shallower and wider BAL troughs compared to the disappearing BAL sample. The distribution of quasar continuum variability parameters between the two samples is clearly separated, with the appearance of the BAL troughs being accompanied by the dimming of the continuum and vice versa. Spectral index variations in the two samples also point to the anti-correlation between the BAL trough and continuum variations consistent with the ”bluer when brighter” trend in quasars. We show that the intrinsic dust model is less likely to be a favorable scenario in explaining BAL appearance/disappearance. Our analysis suggests that the extreme variations of BAL troughs like BAL appearance/disappearance are mainly driven by changes in the ionization conditions of the absorbing gas.
... In this section, to probe whether dust is intrinsic to the BAL outflows, we investigate the nature of variation of the infrared fluxes between the Appearing and Disappearing samples (Vivek et al. 2016;Tuccillo et al. 2017). These sources, having undergone an extreme transition of BAL troughs, provide an ideal opportunity to verify the role of dust associated with the BAL outflows. ...
We present a new set of 84 Broad absorption line (BAL) quasars ( 1.7 $<$ \zem $<$ 4.4) exhibiting an appearance of \civ BAL troughs over 0.3$-$4.8 rest-frame years by comparing the Sloan Digital Sky Survey Data Release (SDSSDR)-7, SDSSDR-12, and SDSSDR-14 quasar catalogs. We contrast the nature of BAL variability in this appearing BAL quasar sample with a disappearing BAL quasar sample studied in literature by comparing the quasar's intrinsic, BAL trough, and continuum parameters between the two samples. We find that appearing BAL quasars have relatively higher redshift and smaller probed timescales as compared to the disappearing BAL quasars. To mitigate the effect of any redshift bias, we created control samples of appearing and disappearing BAL quasars that have similar redshift distribution. We find that the appearing BAL quasars are relatively brighter and have shallower and wider BAL troughs compared to the disappearing BAL sample. The distribution of quasar continuum variability parameters between the two samples is clearly separated, with the appearance of the BAL troughs being accompanied by the dimming of the continuum and vice versa. Spectral index variations in the two samples also point to the anti-correlation between the BAL trough and continuum variations consistent with the "bluer when brighter" trend in quasars. We show that the intrinsic dust model is less likely to be a favorable scenario in explaining BAL appearance/disappearance. Our analysis suggests that the extreme variations of BAL troughs like BAL appearance/disappearance are mainly driven by changes in the ionization conditions of the absorbing gas.
... In previous work, we demonstrated that it is quite difficult to build a unified model for BAL and non-BAL quasars using an equatorial wind rising from a limb-darkened, optically thick accretion disc (M16). This is because the emission line EWs are much smaller at low inclinations than at high inclinations, whereas the observed emission line properties of BAL and non-BAL quasars are very similar ; see also Weymann et al. 1991;DiPompeo et al. 2012;Tuccillo et al. 2017;Yong et al. 2018;Rankine et al. 2019. In this work, we instead illuminate the wind with an isotropic SED of the same spectral shape as M16, which consists of a multi-colour blackbody disc component and an X-ray power-law with spectral index α X = −0.9. ...
The origin, geometry, and kinematics of the broad-line region (BLR) gas in quasars and active galactic nuclei (AGN) are uncertain. We demonstrate that clumpy biconical disc winds illuminated by an AGN continuum can produce BLR-like spectra. We first use a simple toy model to illustrate that disc winds make quite good BLR candidates, because they are self-shielded flows and can cover a large portion of the ionizing flux-density (ϕH-nH) plane. We then conduct Monte Carlo radiative transfer and photoionization calculations, which fully account for self-shielding and multiple scattering in a non-spherical geometry. The emergent model spectra show broad emission lines with equivalent widths and line ratios comparable to those observed in AGN, provided that the wind has a volume filling factor of fV ≲ 0.1. Similar emission line spectra are produced for a variety of wind geometries (polar or equatorial) and for launch radii that differ by an order of magnitude. The line emission arises almost exclusively from plasma travelling below the escape velocity, implying that ‘failed winds’ are important BLR candidates. The behaviour of a line-emitting wind (and possibly any ‘smooth flow’ BLR model) is similar to that of the locally optimally emitting cloud model originally proposed by Baldwin et al. (1995), except that the gradients in ionization state and temperature are large-scale and continuous, rather than within or between distinct clouds. Our models also produce UV absorption lines and X-ray absorption features, and the stratified ionization structure can partially explain the different classes of broad absorption line quasars.
... In previous work, we demonstrated that it is quite difficult to build a unified model for BAL and non-BAL quasars using an equatorial wind rising from a limb-darkened, optically thick accretion disc (M16). This is because the emission line EWs are much smaller at low inclinations than at high inclinations, whereas the observed emission line properties of BAL and non-BAL quasars are very similar ; see also Weymann et al. 1991;DiPompeo et al. 2012;Tuccillo et al. 2017;Yong et al. 2018;Rankine et al. 2019. In this work, we instead illuminate the wind with an isotropic SED of the same spectral shape as M16, which consists of a multi-colour blackbody disc component and an X-ray power-law with spectral index α X = −0.9. ...
The origin, geometry and kinematics of the broad line region (BLR) gas in quasars and active galactic nuclei (AGN) are uncertain. We demonstrate that clumpy biconical disc winds illuminated by an AGN continuum can produce BLR-like spectra. We first use a simple toy model to illustrate that disc winds make quite good BLR candidates, because they are self-shielded flows and can cover a large portion of the ionizing flux-density ($\phi_H$-$n_H$) plane. We then conduct Monte Carlo radiative transfer and photoionization calculations, which fully account for self-shielding and multiple scattering in a non-spherical geometry. The emergent model spectra show broad emission lines with equivalent widths and line ratios comparable to those observed in AGN, provided that the wind has a volume filling factor of $f_V\lesssim0.1$. Similar emission line spectra are produced for a variety of wind geometries (polar or equatorial) and for launch radii that differ by an order of magnitude. The line emission arises almost exclusively from plasma travelling below the escape velocity, implying that `failed winds' are important BLR candidates. The behaviour of a line-emitting wind (and possibly any `smooth flow' BLR model) is similar to that of the locally optimally-emitting cloud (LOC) model originally proposed by Baldwin et al (1995), except that the gradients in ionization state and temperature are large-scale and continuous, rather than within or between distinct clouds. Our models also produce UV absorption lines and X-ray absorption features, and the stratified ionization structure can partially explain the different classes of broad absorption line quasars.
... We have been able to gather at least three flux density measurements for 13 out of the 15 sources, allowing us to constrain the shape, at least in the GHz range, for the majority of them. In order to establish whether or not a GPS peak was present in the radio spectra of these sources, we performed a basic modeling of the data using a log-parabola as a simplified synchrotron emission component, analogously to previous works in the literature (Bruni et al. 2012;Tuccillo et al. 2017). The procedure has the sole purpose of identifying the presence of a peak and not to characterize the different free parameters of the synchrotron components expected from a core spectrum (for which a better sampling would be required). ...
Giant radio galaxies (GRG) are the largest single entities in the universe, having a projected linear size exceeding 0.7 Mpc, which implies that they are also quite old objects. They are not common, representing a fraction of only ∼6% in samples of bright radio galaxies. While a census of about 300 of these objects has been built in the past years, still no light has been shed on the conditions necessary to allow such an exceptional growth, whether of environmental nature or linked to the inner accretion properties. Recent studies found that samples of radio galaxies selected from hard X-ray active galactic nuclei catalogs selected from the International Gamma-Ray Astrophysics Laboratory ( INTEGRAL )/the Imager on Board the INTEGRAL Satellite and Swift /the Burst Alert Telescope (thus at energies >20 keV) present a fraction of GRG four times larger than what is found in radio-selected samples. We present radio observations of 15 nuclei of hard-X-ray-selected GRG, finding for the first time a large fraction (61%) of young radio sources at the center of Mpc-scale structures. Being at the center of GRG, these young nuclei may be undergoing a restarting activity episode, suggesting a link between the detected hard X-ray emission—due to the ongoing accretion—and the reactivation of the jets.
... In the course of catalog updates, we added 121 new sources to the list. These were found in the literature (McMahon et al., 2002;Richards et al., 2009;Yi et al., 2014;Wang et al., 2016;Khorunzhev et al., 2017;Matsuoka et al., 2017;Reed et al., 2017;Tang et al., 2017;Tuccillo et al., 2017;Yi et al., 2017) but not contained in the 3 large catalogs that form the basis of our list. The sky coverage of the full sample is plotted in Figure 1. ...
Active galactic nuclei (AGN) are prominent astrophysical objects that can be observed throughout the whole Universe. To understand the underlying physical processes and the different appearance of AGN types, extensive samples are needed. Nowadays, various AGN catalogs are available at different wavebands. However, at the highest redshifts data are still relatively sparse. These data are required for examining AGN properties in the early Universe. This way we can compare the earliest AGN with those seen at lower redshifts, and can study their cosmological evolution. Additionally, because of their high luminosity, AGN may also be used as probes to test cosmological models. With the aim of constructing a complete sample of all known AGN at z ≥ 4, we are currently compiling a photometric catalog from literature sources. We cross-match catalogs particularly at optical and radio wavebands, to build up a sample for detailed high-resolution radio interferometric studies. The continuously updated list now contains nearly 2,600 objects with known spectroscopic redshifts, optical magnitudes, and auxiliary information about observations at other wavebands. About 170 of them are known radio sources for which we collect existing radio interferometric data from the literature.
A substantial fraction of quasars display broad absorption lines (BALs) in their rest-frame ultraviolet spectra. While the origin of BALs is thought to be related to the accretion disc wind, it remains unclear whether the observed ratio of BAL to non-BAL quasars is due to orientation. We conducted observations of 48 BAL quasars and the same number of non-BAL quasars at 322 MHz using the Giant Metrewave Radio Telescope. Combined with previous flux measurements ranging from MHz to GHz frequencies, we compared continuum radio spectra between the two quasar groups. These data offer insights into low-frequency radio properties that have been difficult to investigate with previous observations only at GHz frequencies. Our results present that 73 ± 13 per cent of the BAL quasars exhibit steep or peaked spectra, a higher proportion than 44 ± 14 per cent observed in the non-BAL quasars. In contrast, there are no discernible differences between the two quasar groups in the radio luminosity, peak frequency, and spectral index distributions of sources with steep or peaked spectra and sources with flat or inverted spectra. Generally, as the jet axis and line of sight become closer to parallel, quasars exhibit flat or inverted spectra rather than steep or peaked ones. Therefore, these results suggest that BAL quasars are more frequently observed farther from the jet axis than non-BAL quasars. However, given that a certain proportion of BAL quasars exhibit flat or inverted spectra, more than the simple orientation scenario is required to elucidate the radio properties of BAL quasars.
