Journal articles: 'Quasar absorption lines'

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Harutyunian, Haik A. "Are There Quasars at Non-Cosmological Distances?" Symposium - International Astronomical Union 194 (1999): 428–31. http://dx.doi.org/10.1017/s0074180900162485.

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In Dravskikh & Dravskikh (1996) the results of a statistical analysis of quasar luminosity as a function of redshift, if it is assumed to be cosmological, are given (see Fig.1). Three quasar samples were analyzed separately: •quasars with absorption lines;•quasars associated with galaxies or association-quasars not having absorption lines (from Burbidge et al. 1996);•other quasars not included in the first two groups.

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Combes, F., N. Gupta, G. I. G. Jozsa, and E. Momjian. "Discovery of CO absorption at z = 0.05 in G0248+430." Astronomy & Astrophysics 623 (March 2019): A133. http://dx.doi.org/10.1051/0004-6361/201935057.

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Absorption lines in front of distant quasars are quite rare in the millimeter domain. They can, however, bring very useful and complementary information to emission lines. We report here the detection with NOEMA of CO(1–0) and CN(1–0) lines in absorption, and the confirmation of CO emission in the quasar/galaxy pair Q0248+430/G0248+430. The system G0248+430 corresponds to two merging galaxies (a Seyfert and a LINER) at z = 0.0519 with a tidal tail just on the line of sight to the background quasar Q0248+430 at z = 1.313. Optical (CaII, NaI), H I 21 cm, and OH-1667 MHz absorption lines associated with the tidal tail of the foreground system have previously been detected toward the quasar, while four CO lines at different rotation J levels have been detected in emission from the foreground galaxies. New H I 21 cm line observations with the upgraded GMRT array are also presented. We discuss the molecular content of the merging galaxies, and the physical conditions in the absorbing interstellar medium of the tidal tail.

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Aldcroft, T., J. Bechtold, P. Smith, C. Foltz, and G. Schmidt. "Optical Polarization and Line Variability in Quasars with Associated Absorption." International Astronomical Union Colloquium 163 (1997): 681–82. http://dx.doi.org/10.1017/s0252921100043396.

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AbstractThe physical origin of associated absorption lines (zabs ≈ zqso) which are observed in radio-loud quasar is generally not well understood. Two observable properties, line variability and quasar optical polarization, can serve to constrain the possibilities. To this end, we have obtained high-resolution spectra (1 Å) and broad-band optical polarizations for over 30 radio-loud quasars with known CIV associated absorption. The quasars are at redshifts between about 1 and 2, and were previously observed spectroscopically at similar resolution between 1985 – 1986 by Foltz et al (1987). The associated CIV absorption systems include a variety of velocity profiles from weak single lines to very complex multi-component systems to the BAL-like profile of PHL 1157+0128. In this poster we show the first strong evidence for line variability in z > 1 radio-loud quasars. We find that in general the variability is less than ~ 30%. The optical polarization of CIV absorbed quasars is consistent with all radio-loud quasars.

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Capellupo, Daniel M., Fred Hamann, Joseph C. Shields, Tom A. Barlow, and Paola Rodriguez. "Variability in Quasar Broad Absorption Line Outflows." Proceedings of the International Astronomical Union 5, S267 (August 2009): 394. http://dx.doi.org/10.1017/s1743921310006782.

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Broad absorption lines (BALs) in quasar spectra identify high-velocity outflows that likely exist in all quasars and could play a major role in feedback to galaxy evolution (e.g., Di Matteo et al. 2005). Studying the variability in these BALs can help us understand the structure, evolution, and basic physical properties of these outflows. We are investigating BAL variability in a sample of 25 luminous quasars at 1.2 < z < 2.9 with multi-epoch observations that cover time scales from less than around a month to 7.7 years in the quasar rest-frame. We investigate changes in the C iv λ1549 BALs, and we see a variety of phenomena, including some BALs that either appeared or disappeared completely and other BALs that did not change at all over the whole observation period.

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Culliton, Chris, Jane Charlton, Mike Eracleous, Rajib Ganguly, and Toru Misawa. "Probing quasar winds using intrinsic narrow absorption lines." Monthly Notices of the Royal Astronomical Society 488, no. 4 (August 7, 2019): 4690–731. http://dx.doi.org/10.1093/mnras/stz1642.

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ABSTRACT We use the spectra of 73 quasars (1.5 ≲ z ≲ 5) from the VLT UVES archive to catalogue and study narrow absorption lines (NALs) that are physically associated with (intrinsic to) the quasars. We identify 410 NAL systems containing C iv, N v, and/or Si iv doublets. Based on the assumption that only systems intrinsic to the quasar can exhibit partial coverage of the background source(s), we identify 34 reliably intrinsic NAL systems and 11 systems that are potentially intrinsic, as well as 4 mini-broad absorption lines (BALs) and 1 BAL. The minimum fraction of quasars with at least one intrinsic system is shown to be 38 per cent. We identify intrinsic NALs with a wide range of properties, including apparent ejection velocity, coverage fraction, and ionization level. There is a continuous distribution of properties, rather than discrete families, ranging from partially covered C iv systems with black Ly α and with a separate low-ionization gas phase to partially covered N v systems with partially covered Ly α and without detected low-ionization gas. Even more highly ionized associated and intrinsic absorption systems (O vi, Ne viii, and Mg x doublets) have been presented in separate studies; these may represent an extension of the above sequence. We also use the properties of the NALs in conjunction with recent models of accretion disc winds that predict the origins of the absorbing gas in order to determine the model that best characterizes our sample. Additionally, we construct a model describing the spatial distributions, geometries, and varied ionization structures of intrinsic NALs.

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Sargent, Wallace L. W. "Quasar Absorption Lines: Evolution and Clustering." Symposium - International Astronomical Union 130 (1988): 333–42. http://dx.doi.org/10.1017/s0074180900136228.

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A large new sample of absorption redshifts derived from the C IV doublet in the spectra of 56 QSOs has been used to study the evolution and clustering tendencies of the heavy element absorbers (thought to be galaxies). The new data have been compared with more extensive existing data for the more common Lyman α forest lines (thought to be produced by intergalactic clouds). Little or no clustering is observed in the Lyman α forest lines; moreover, there is no evidence for voids in their distribution. Clustering has been detected in the heavy element redshifts on scales Δv ≥ 200 km s−1 where relative motions of clouds within galaxies are unlikely to dominate. The degree of clustering inferred at z ≈ 2 is of the order expected on the simplest model for the evolution of galaxy clustering in cosmic time. The recent discovery of similar concentrations of absorption features extending over Δz ∼ 0.2 in the spectra of widely separated QSOs on the sky provides evidence for very large structures, probably filaments or sheets of galaxies, extending over 100 Mpc (co-moving). The Lyman α forest and heavy element redshifts evolve very differently. The Lyman lines show a rapid increase in density with increasing z, while the C IV doublets show a decrease. This result emphasizes that there are two discrete populations of absorbers. The decrease in C IV line density may be due to the effects of the onset of stellar nucleosynthesis in galaxies.

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Bechtold, Jill. "Evolution of the EUV Background from Quasar Absorption Line Studies." Symposium - International Astronomical Union 168 (1996): 237–44. http://dx.doi.org/10.1017/s0074180900110125.

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The integrated extreme ultraviolet (EUV) radiation from quasars and other high redshift sources provides an ambient ionizing radiation field which may photoionize the gas seen as quasar absorption lines. In particular, the observed evolution of the Lyα forest clouds probably results in part from the evolution of the EUV metagalactic field. Estimates of the EUV field as a function of redshift can be made from measuring the “proximity effect” in quasar spectra; uncertainties in these estimates may be large. Given the uncertainties, the estimated EUV field at z≈3 derived from the proximity effect is in reasonable agreement with the expected contribution from luminous quasars.

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Richards, Gordon T., S. A. Laurent‐Muehleisen, Robert H. Becker, and Donald G. York. "Quasar Absorption Lines as a Function of Quasar Orientation Measures." Astrophysical Journal 547, no. 2 (February 2001): 635–48. http://dx.doi.org/10.1086/318414.

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Lu, Wei-Jian, and Ying-Ru Lin. "Velocity shift of Mg ii and Al iii broad absorption lines in quasar SDSS J134444.33+315007.6." Monthly Notices of the Royal Astronomical Society: Letters 499, no. 1 (September 23, 2020): L58—L61. http://dx.doi.org/10.1093/mnrasl/slaa158.

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ABSTRACT We report, for the first time, a synchronized velocity shift of Mg ii and Al iii broad absorption lines (BALs) in quasar SDSS J134444.33+315007.6 (hereafter, J1344+3150). We found this quasar from a sample of 134 Mg ii BAL quasars with multi-epoch observations. This quasar contains three low-ionization BAL systems, the fastest of which at ${\sim} -17\, 000\, \rm km\, s^{-1}$ shows a kinematic shift of ${\sim} -1101$ and $\sim -1170\, \rm km\, s^{-1}$ in its Mg ii and Al iii ions, respectively, during a rest-frame time of about 3.21 yr. Meanwhile, this quasar also shows other various variation characteristics, including an obvious weakening in its continuum, a coordinated enhancement in multiple emission lines (Mg ii, C iii, and Al iii), and a coordinated enhancement in three Al iii absorption troughs. These variation characteristics convincingly indicate that the BAL outflows of J1344+3150 are under the influence from the background radiation energy. Thus, we infer that the velocity shift displayed in system A in the quasar J1344+3150 may indicate an actual line-of-sight acceleration of an outflow due to the radiation pressure from the central source.

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Chartas, George, and Sarah Strickland. "Wide-Angle Quasar Feedback." Proceedings of the International Astronomical Union 11, S319 (August 2015): 58. http://dx.doi.org/10.1017/s1743921315010145.

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AbstractWe present results from the detection of relativistic winds launched near the innermost stable circular orbits of supermassive black holes. A recent detection of a powerful wind in the X-ray-bright narrow absorption line (NAL) z=1.51 quasar HS 0810+2554 strengthens the case that quasars play a significant role in feedback. In both deep Chandra and XMM-Newton observations of HS 0810 we detected blueshifted absorption lines implying outflowing velocities ranging from 0.1c and 0.4c. The presence of both an emission line at 6.8 keV and an absorption line at 7.8 keV in the spectral line profile of HS 0810 is a characteristic feature of a P-Cygni profile supporting the presence of an expanding outflowing highly ionized Fe absorber. A hard excess component is detected in the XMM-Newton observation of HS 0810 possibly originating from reflection off the disk. Modelling of the XMM-Newton spectrum constrains the inclination angle to be < 35° (68% confidence). The presence of relativistic winds in both low inclination angle NAL quasars as well as in high inclination angle BAL quasars implies that the solid angle of quasar winds may be quite large. The larger solid angle of quasar winds would also indicate that their contribution to the regulation of the host galaxy may be more important than previously thought.

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Itoh, Daisuke, Toru Misawa, Takashi Horiuchi, and Kentaro Aoki. "Search for intrinsic NALs in BAL/mini-BAL quasar spectra." Monthly Notices of the Royal Astronomical Society 499, no. 3 (September 21, 2020): 3094–110. http://dx.doi.org/10.1093/mnras/staa2793.

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ABSTRACT Some fraction of narrow absorption lines (NALs) are physically associated to the quasar/host-galaxy materials (i.e. intrinsic NALs) like those of broad absorption lines (BALs) and mini-BALs. The relation between these three types of absorption lines has not been understood yet, however one interpretation is that these absorption features correspond to different inclination angles. In this study, we search for intrinsic NALs in 11 BAL/mini-BAL quasar spectra retrieved from VLT/UVES public archive, in order to test a possible relation of intrinsic NALs and BALs/mini-BALs in the geometry models. We use partial coverage analysis to separate intrinsic NALs from ones which are associated to cosmologically intervening materials like foreground galaxies and intergalactic medium (i.e. intervening NALs). We identify one reliable and two possible intrinsic NAL systems out of 36 NAL systems in 9 BAL/mini-BAL quasar spectra after removing two quasars without clear BAL features. In spite of a small sample size, we placed a lower limit on the fraction of BAL/mini-BAL quasars that have at least one intrinsic C iv NAL ($\sim 33^{+33}_{-18}{{\ \rm per\ cent}}$). This can be interpreted that intrinsic NAL absorbers exist everywhere regardless of inclination angle. We found that one of the intrinsic NAL systems detected in SDSS J121549.80−003432.1 is located at a large radial distance of R > 130 kpc, using a method of photoionization model with ground/excited-state lines. Considering the wide range of intrinsic NAL absorber distribution in inclination angles and radial distances, it suggests that origins and geometry of them are more complicated than we expected.

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12

Tytler, David. "The Ecology of Quasar Absorption Systems." Symposium - International Astronomical Union 171 (1996): 299–302. http://dx.doi.org/10.1017/s007418090023252x.

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Gas along the lines of sight to QSOs produces narrow absorption lines from ions of the most abundant elements: H, He, C, N, O, Si, S, Mg and Fe. Most lines have rest wavelengths of a few hundred Å but some have wavelengths λ ≥ 900 Å, sufficient that they can be redshifted into the optical. The absorbing gas is normally transparent, except for Lyman continuum absorption, and dust extinction at the highest columns, so we can see hundreds of gas clouds along a line of sight. We see more absorption from higher redshifts, because the universe was denser then and the absorbing “clouds” have roughly constant proper size.

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Klimenko, V. V., P. Petitjean, and A. V. Ivanchik. "Observational estimate of the partial covering probability of quasar emission regions by distant H2 absorption clouds." Monthly Notices of the Royal Astronomical Society 493, no. 4 (March 4, 2020): 5743–60. http://dx.doi.org/10.1093/mnras/staa614.

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ABSTRACT We have searched high spectral resolution spectra of quasars known to exhibit high redshift (z > 1.7) intervening H2-bearing damped Lyman-α (DLA) systems for partial coverage of the quasar emission by intervening H2 clouds. Partial coverage manifests itself by the presence of non-zero residual flux in the core of saturated H2 absorption lines. The residual flux can be observed either only at the bottom of absorption lines redshifted on top of quasar emission lines, in which case part of the broad line region (BLR) is not covered, or in all absorption lines, in case some continuum source is not covered. Among 35 H2 absorption clouds in 14 quasar spectra obtained with the VLT-UVES or Keck-HIRES spectrographs, we detect partial coverage of the BLR for 13 clouds. This result suggests that the probability of partial coverage of the QSO BLR by a distant H2 absorption cloud is about 40 per cent. For four systems towards Q 0013−0029, Q 0405−4418, Q 0812+3208, and J 2100−0641, partial coverage is detected for the first time. We determine the theoretical probability of partial coverage of the BLR by a distant H2 cloud as a function of the ratio between the cloud and the BLR sizes. Using this model, we obtain an estimate of the characteristic BLR radius of $50^{+19}_{-23}\,\rm{light \,days}$. This is similar to the estimate of the BLR size obtained by reverberation-mapping analysis $({\sim}100\,\rm{light\, days})$.

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Shaver, P. A. "Quasar Pairs." Symposium - International Astronomical Union 119 (1986): 475–80. http://dx.doi.org/10.1017/s0074180900153227.

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This paper summarizes various uses which have been made of QSO pairs. Statistical studies using pairs show that the sky distribution of QSOs of arbitrary redshifts is random, and that QSOs of similar redshifts are clustered on a linear scale similar to that of galaxies today. Close pairs are used to set limits on the masses of QSOs. And absorption line studies of QSO pairs support the extrinsic hypothesis for the origin of the narrow absorption lines and the cosmological interpretation of the redshift, they demonstrate the presence of absorbing matter around QSOs, and they set limits on the sizes of the absorbers.

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Chen, Zhi-Fu, and Da-Sheng Pan. "Collective Properties of Quasar Narrow Associated Absorption Lines." Astrophysical Journal 848, no. 2 (October 13, 2017): 79. http://dx.doi.org/10.3847/1538-4357/aa8d66.

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Turner, Edwin L., and Satoru Ikeuchi. "Quasar absorption lines with a nonzero cosmological constant." Astrophysical Journal 389 (April 1992): 478. http://dx.doi.org/10.1086/171224.

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Fynbo, J. P. U., P. Møller, K. E. Heintz, J. N. Burchett, L. Christensen, S. J. Geier, P. Jakobsson, et al. "Gaia-assisted discovery of a detached low-ionisation BAL quasar with very large ejection velocities." Astronomy & Astrophysics 634 (February 2020): A111. http://dx.doi.org/10.1051/0004-6361/201936957.

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We report on the discovery of a peculiar broad absorption line (BAL) quasar identified in our Gaia-assisted survey of red quasars. The systemic redshift of this quasar was difficult to establish because of the absence of conspicuous emission lines. Based on deep and broad BAL troughs of at least Si IV, C IV, and Al III, a redshift of z = 2.41 was established under the assumption that the systemic redshift can be inferred from the red edge of the BAL troughs. However, we observe a weak and spatially extended emission line at 4450 Å that is most likely due to Lyman-α emission, which implies a systemic redshift of z = 2.66 if correctly identified. There is also evidence for the onset of Lyman-α forest absorption bluewards of 4450 Å and evidence for Hα emission in the K band consistent with a systemic redshift of z = 2.66. If this redshift is correct, the quasar is an extreme example of a detached low-ionisation BAL quasar. The BALs must originate from material moving with very large velocities ranging from 22 000 km s−1 to 40 000 km s−1. To our knowledge, this is the first case of a systemic-redshift measurement based on extended Lyman-α emission for a BAL quasar. This method could also be useful in cases of sufficiently distant BL Lac quasars without systemic-redshift information.

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Kunert-Bajraszewska, M., M. Cegłowski, C. Roskowiński, and M. Gawroński. "Extragalactic jets of broad absorption line (BAL) quasars." Proceedings of the International Astronomical Union 10, S313 (September 2014): 244–45. http://dx.doi.org/10.1017/s1743921315002264.

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AbstractFast outflows of the ionized plasma, probably lunched in proximity of Supermassive Black Hole, are responsible for blue-shifted Broad Absorption Lines (BALs) in quasar spectrum. Outflows together with powerful jets produced in AGN are important feedback processes. Therefore, understanding physics behind BAL outflows might be a key to comprehend Galaxy Evolution as a whole. Discovery of the existence of radio-loud BAL quasars gave us another opportunity to study the BAL phenomenon, this time on the ground on radio emission. The radio emission is an additional tool to understand the BAL quasars, their orientation and age, by the VLBI imaging (detection of radio jets and their direction, size determination), the radio-loudness parameter distribution and variability study.

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Kunert-Bajraszewska, Magdalena, and Marcin P. Gawroński. "Radio Structures of Compact Quasars with Broad Absorption Lines." Proceedings of the International Astronomical Union 5, S267 (August 2009): 114. http://dx.doi.org/10.1017/s1743921310005752.

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AbstractBroad absorption lines (BALs), seen in a small fraction of both the radio-quiet and radio-loud quasar populations, are probably caused by the outflow of gas with high velocities and are part of the accretion process. The presence of BALs is due to a geometrical effect and/or it is connected with the quasar evolution. Using the final release of FIRST survey combined with a catalog of BAL QSOs from SDSS/DR3, we have constructed a new sample of compact radio-loud BAL QSOs, which constitutes the majority of radio-loud BAL QSOs. The main goal of this project is to study the origin of BALs by analysis of the BAL QSOs radio morphology, orientation, and jet evolution using the European VLBI Network (EVN) at 1.6 GHz and the Very Long Baseline Array (VLBA) at 5 and 8.4 GHz.

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Chen, Zhi-Fu, Shuang-Xi Yi, Ting-Ting Pang, Ting-Feng Yi, Zhi-Wen Wang, Xiao-Hua Mo, and Chun-Qun Liu. "The Correlated Variations of Absorption Lines and Quasar Continuum." Astrophysical Journal Supplement Series 243, no. 1 (June 24, 2019): 2. http://dx.doi.org/10.3847/1538-4365/ab2464.

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Hall, Patrick B. "A Quasar with Broad Absorption in the Balmer Lines." Astronomical Journal 133, no. 4 (February 20, 2007): 1271–74. http://dx.doi.org/10.1086/511272.

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Narayanan, Desika, Fred Hamann, Tom Barlow, E. M. Burbidge, Ross D. Cohen, Vesa Junkkarinen, and Ron Lyons. "Variability Tests for Intrinsic Absorption Lines in Quasar Spectra." Astrophysical Journal 601, no. 2 (February 2004): 715–22. http://dx.doi.org/10.1086/380781.

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Arrigoni Battaia, F., A. Obreja, J. X. Prochaska, J. F. Hennawi, H. Rahmani, E. Bañados, E. P. Farina, Z. Cai, and A. Man. "Discovery of intergalactic bridges connecting two faint z ∼ 3 quasars." Astronomy & Astrophysics 631 (October 11, 2019): A18. http://dx.doi.org/10.1051/0004-6361/201936211.

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We used the Multi-Unit Spectroscopic Explore (MUSE) on the Very Large Telescope (VLT) to conduct a survey of z ∼ 3 physical quasar pairs at close separation (<30″) with a fast observation strategy (45 min on source). Our aim is twofold: (i) to explore the Lyα glow around the faint-end of the quasar population; and (ii) to take advantage of the combined illumination of a quasar pair to unveil large-scale intergalactic structures (if any) extending between the two quasars. In this work we report the results for the quasar pair SDSS J113502.03−022110.9 – SDSS J113502.50−022120.1 (z = 3.020, 3.008; i = 21.84, 22.15), separated by 11.6″ (or 89 projected kpc). MUSE reveals filamentary Lyα structures extending between the two quasars with an average surface brightness of SBLyα = 1.8 × 10−18 erg s−1 cm−2 arcsec−2. Photoionization models of the constraints in the Lyα, He IIλ1640, and C IVλ1548 line emissions show that the emitting structures are intergalactic bridges with an extent between ∼89 kpc, the quasars’ projected distance, and up to ∼600 kpc. Our models rule out the possibility that the structure extends for ∼2.9 Mpc, that is, the separation inferred from the uncertain systemic redshift difference of the quasars if the difference was only due to the Hubble flow. At the current spatial resolution and surface brightness limit, the average projected width of an individual bridge is ∼35 kpc. We also detect one strong absorption in H I, N V, and C IV along the background sight-line at higher z, which we interpret to be due to at least two components of cool (T ∼ 104 K), metal enriched (Z > 0.3 Z⊙), and relatively ionized circumgalactic or intergalactic gas surrounding the quasar pair. Two additional H I absorbers are detected along both quasar sight-lines at ∼−900 and −2800 km s−1 from the system; the latter has associated C IV absorption only along the foreground quasar sight-line. The absence of galaxies in the MUSE field of view at the redshifts of these two absorbers suggests that they trace large-scale structures or expanding shells in front of the quasar pair. Combining longer exposures and higher spectral resolution when targeting similar quasar pairs has the potential to firmly constrain the physical properties of gas in large-scale intergalactic structures.

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Briggs, F. H. "VLBI Studies of High-Redshift 21cm Absorption Lines." Symposium - International Astronomical Union 129 (1988): 211. http://dx.doi.org/10.1017/s0074180900134503.

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VLBI experiments can contribute to our understanding of absorbing gas observed in the spectra of high-redshift quasars by measuring the spatial extent of the absorbers. An optical survey conducted by Wolfe, Turnshek, Smith, and Cohen (1986) has turned up a class of absorbers characterized by large HI column density and a rich spectrum of metal absorption lines. In these respects the absorbers resemble spiral galaxies, but their occurence is too frequent for interception probabilities based on galaxy cross sections at the present epoch. Recent radio observations to determine the nature of such an absorber at z=2.04 in the spectrum of PKS0458-020 include both continuum observations at 606 and 1590 MHz to define the structure of the background quasar as well as spectral line VLBI at 467 MHz. The observations reveal structure in the continuum source on a wide range of angular scales, making the source nearly ideal for spectral line VLBI on a range of baselines. Early spectroscopic results show that the absorber must have a spatial extent of galaxian size, consistent with the hypothesis that these absorbers are galaxies. The further implication is that galaxies must have been larger and richer in gas at the epoch around z=2 in order to provide the likelihood of interception that is observed optically. (A complete description of the result is in preparation by Briggs, Wolfe, Liszt, Davis and Turner.)

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Hamann, Fred, Serena Perrotta, and Nadia Zakamska. "Outflows & Feedback from Extremely Red Quasars." Proceedings of the International Astronomical Union 15, S359 (March 2020): 232–37. http://dx.doi.org/10.1017/s1743921320004330.

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AbstractFeedback from accreting supermassive black holes is often invoked in galaxy evolution models to inhibit star formation, truncate galaxy growth, and establish the observed black-hole/bulge mass correlation. We are studying outflows and feedback in a unique sample of extremely red quasars (ERQs) during the peak epoch of galaxy formation (at redshifts 2.3 < z < 3.4). We identified ERQs in the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey (BOSS) quasar catalog based on their extremely red i–W3 colors, but we find that ERQs typically have a suite of other extreme properties including 1) a high incidence of blueshifted broad absorption lines, 2) broad emission lines with unusually large rest equivalent widths (REWs), peculiar “wingless” profiles, and frequent large blueshifts (reaching ˜8740 km s-1), and 3) characteristically very broad and blueshifted [OIII] 4959,5007Å lines that trace ionized outflows at speeds up to ˜6700 km s-1. We propose that these ERQs represent a young quasar population with powerful outflows on the precipice of causing important disruptive feedback effects in their host galaxies.

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Furlanetto, Steven R. "Quasar absorption lines at high redshift: through a glass darkly." Proceedings of the International Astronomical Union 1, no. C199 (March 2005): 349–56. http://dx.doi.org/10.1017/s1743921305002802.

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LIEBSCHER, DIERCK-EKKEHARD. "NARROW QUASAR ABSORPTION LINES AND THE HISTORY OF THE UNIVERSE." International Journal of Modern Physics D 03, no. 04 (December 1994): 723–29. http://dx.doi.org/10.1142/s0218271894000836.

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In order to get an estimation of the parameters of the cosmological model the statistics of narrow absorption lines in quasar spectra is evaluated. To this end a phenomenological model of the evolution of the corresponding absorbers in density, size, number and dimension is presented and compared with the observed evolution in the spectral density of the lines and their column density seen in the equivalent width. In spite of the wide range of possible models, the Einstein-deSitter model is shown to be unlikely because of the implied fast evolution in mass.

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Misawa, Toru, Jane C. Charlton, and Michael Eracleous. "MONITORING THE VARIABILITY OF INTRINSIC ABSORPTION LINES IN QUASAR SPECTRA, ,." Astrophysical Journal 792, no. 1 (August 18, 2014): 77. http://dx.doi.org/10.1088/0004-637x/792/1/77.

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Boissé, P., and J. Bergeron. "Improved Ni II oscillator strengths from quasar absorption systems." Astronomy & Astrophysics 622 (February 2019): A140. http://dx.doi.org/10.1051/0004-6361/201834308.

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Aims. We wish to improve the accuracy of oscillator strength values for several Ni II UV transitions and measure for the first time the f-value of a few other weak transitions for which no laboratory nor astronomical measurement is presently available. Methods. Four quasars displaying five damped Lyman α systems with relatively strong Ni II lines were selected. From the analysis of the excellent high resolution spectra available, we determined the relative f-value of Ni II transitions by comparing the strength of the corresponding absorption profiles. To quantify the latter, we used the apparent optical depth method for resolved features, equivalent width measurements for optically thin lines and line fitting with VPFIT. Absolute f-values were then derived by relating our determinations to the available laboratory measurements. Results. Thanks to the good signal-to-noise ratio of the spectra and to the suitable properties of the absorption systems investigated, we are able to significantly improve the determination of the f-value for 13 Ni II transitions falling in the 1317–1804 Å interval. Our results are found to be consistent with other earlier determinations for ten of these transitions; our median relative accuracy for these f-values is 6.5%. For three weak transitions near 1502, 1773, and 1804 Å, which have not been detected previously in astronomical spectra, we can get a first measurement of their f-value. Conclusions. Our work illustrates that, thanks to the redshift and the absence of variations of physical constants on cosmological scales, the analysis of absorption lines induced by remote gas in quasar spectra can nowadays provide valuable constraints on atomic data in the UV range.

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Hutsemékers, D., D. Sluse, and P. Kumar. "Spatially separated continuum sources revealed by microlensing in the gravitationally lensed broad absorption line quasar SDSS J081830.46+060138.0." Astronomy & Astrophysics 633 (January 2020): A101. http://dx.doi.org/10.1051/0004-6361/201936973.

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Gravitational microlensing is a powerful tool for probing the inner structure of distant quasars. In this context, we have obtained spectropolarimetric observations of the two images of the broad absorption line (BAL) quasar SDSS J081830.46+060138.0 (J0818+0601) at redshift z ≃ 2.35. We first show that J0818+0601 is actually gravitationally lensed, and not a binary quasar. A strong absorption system detected at z = 1.0065 ± 0.0002 is possibly due to the lensing galaxy. Microlensing is observed in one image and it magnifies the emission lines, the continuum, and the BALs differently. By disentangling the part of the spectrum that is microlensed from the part that is not microlensed, we unveil two sources of continuum that must be spatially separated: a compact one, which is microlensed, and an extended one, which is not microlensed and contributes to two thirds of the total continuum emission. J0818+0601 is the second BAL quasar in which an extended source of rest-frame ultraviolet continuum is found. We also find that the images are differently polarized, suggesting that the two continua might be differently polarized. Our analysis provides constraints on the BAL flow. In particular, we find that the outflow is seen with a nonzero onset velocity, and stratified according to ionization.

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Stone, Robert B., and Gordon T. Richards. "Narrow, intrinsic C iv absorption in quasars as it relates to outflows, orientation, and radio properties." Monthly Notices of the Royal Astronomical Society 488, no. 4 (August 5, 2019): 5916–34. http://dx.doi.org/10.1093/mnras/stz2111.

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Abstract This work provides evidence that a large fraction of C iv narrow absorption lines (NALs) seen along the line of sight to distant quasars are due to accretion disc winds, while also seeking to understand the relationship between NALs and certain quasar-intrinsic properties. We extend the results from past work in the literature using ${\sim}105\, 000$ NALs from a sample of ${\sim}58\, 000$ SDSS quasars. The primary results of this work are summarized as follows: (1) the velocity distribution (dN/dβ) of NALs is not a function of radio loudness (or even detection) once marginalized by optical/UV luminosity; (2) there are significant differences in the number and distribution of NALs as a function of both radio spectral index and optical/UV luminosity, and these two findings are not entirely interdependent; (3) improvements in quasar systemic redshift measurements and differences in the NAL distribution as a combined function of optical luminosity and radio spectral index together provide evidence that a significant portion of NALs are due to outflows; (4) the results are consistent with standard models of accretion disc winds governed by the LUV–αox relationship and line-of-sight orientation indicated by radio spectral index, and (5) possibly support a magnetically arrested disc model as an explanation for the semistochastic nature of strong radio emission in a fraction of quasars.

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Timlin, John D., W. N. Brandt, Q. Ni, B. Luo, Xingting Pu, D. P. Schneider, M. Vivek, and W. Yi. "The correlations between optical/UV broad lines and X-ray emission for a large sample of quasars." Monthly Notices of the Royal Astronomical Society 492, no. 1 (December 6, 2019): 719–41. http://dx.doi.org/10.1093/mnras/stz3433.

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ABSTRACT We present Chandra observations of 2106 radio-quiet quasars in the redshift range 1.7 ≤ z ≤ 2.7 from the Sloan Digital Sky Survey (SDSS), through data release 14 (DR14), that do not contain broad absorption lines in their rest-frame ultraviolet (UV) spectra. This sample adds over a decade worth of SDSS and Chandra observations to our previously published sample of 139 quasars from SDSS DR5 that is still used to correlate X-ray and optical/UV emission in typical quasars. We fit the SDSS spectra for 753 of the quasars in our sample that have high-quality (exposure time ≥ 10 ks and off-axis observation angle ≤ 10 arcmin) X-ray observations, and analyse their X-ray-to-optical spectral energy distribution properties (αox and Δαox) with respect to the measured C iv and Mg ii emission-line rest-frame equivalent width (EW) and the C iv emission-line blueshift. We find significant correlations (at the ≥99.99 per cent level) between αox and these emission-line parameters, as well as between Δαox and $\rm{C \, \small{IV}}$ EW. Slight correlations are found between Δαox and $\rm{C \, \small{IV}}$ blueshift, $\rm{Mg \, \small{II}}$ EW, and the $\rm{C \, \small{IV}}$ EW to $\rm{Mg \, \small{II}}$ EW ratio. The best-fitting trend in each parameter space is used to compare the X-ray weakness (Δαox) and optical/UV emission properties of typical quasars and weak-line quasars (WLQs). The WLQs typically exhibit weaker X-ray emission than predicted by the typical quasar relationships. The best-fitting relationships for our typical quasars are consistent with predictions from the disc–wind quasar model. The behaviour of the WLQs compared to our typical quasars can be explained by an X-ray ‘shielding’ model.

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Hamann, Fred, Todd M. Tripp, David Rupke, and Sylvain Veilleux. "On the emergence of thousands of absorption lines in the quasar PG 1411+442: a clumpy high-column density outflow from the broad emission-line region?" Monthly Notices of the Royal Astronomical Society 487, no. 4 (June 10, 2019): 5041–61. http://dx.doi.org/10.1093/mnras/stz1408.

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Abstract Quasar outflows are fundamental components of quasar environments that might play an important role in feedback to galaxy evolution. We report on the emergence of a remarkable new outflow absorption-line system in the quasar PG1411+442 (redshift ∼0.089) detected in the UV and visible with the Hubble Space Telescope Cosmic Origins Spectrograph and the Gemini Multi-Object Spectrograph, respectively. This new ‘transient’ system contains thousands of lines, including Fe ii and Fe ii∗ from excited states up to 3.89 eV, H i∗ Balmer lines, Na i D λλ5890, 5896, and the first detection of He i∗ λ5876 in a quasar. The transient absorber is spatially inhomogeneous and compact, with sizes ≲0.003 pc, based on covering fractions on the quasar continuum source ranging from ∼0.45 in strong UV lines to ∼0.04 in Na i D. cloudy photoionization simulations show that large total column densities log NH(cm−2) ≳ 23.4 and an intense radiation field ≲0.4 pc from the quasar are needed to produce the observed lines in thick zones of both fully ionized and partially ionized gas. The densities are conservatively log nH(cm−3) ≳ 7 based on Fe ii∗, H i∗, and He i∗ but they might reach log nH(cm−3) ≳ 10 based on Na i D. The transient lines appear at roughly the same velocity shift, v ∼ −1900 km s−1, as a ‘mini-BAL’ outflow detected previously, but with narrower Doppler widths, b ∼ 100 km s−1, and larger column densities in more compact outflow structures. We propose that the transient lines identify a clumpy outflow from the broad emission-line region that, at its current speed and location, is still gravitationally bound to the central black hole.

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Rao, Sandhya M., David A. Turnshek, and Eric M. Monier. "Neutral Gas Phase Metallicities Associated with Dwarf Galaxies." Proceedings of the International Astronomical Union 14, S344 (August 2018): 309–12. http://dx.doi.org/10.1017/s1743921318006646.

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AbstractAbsorption line spectroscopy of foreground gas in the spectra of background quasars has revealed some clear cases where neutral gas is present and associated with dwarf galaxies. Spectroscopy of Lyα and low-ionization metal lines can be combined to derive neutral gas phase metallicities. The damped Lyα absorbers (DLAs) in quasar spectra are the clearest cases of absorption by predominantly neutral gas regions. Here we present some results on neutral gas phase metallicities for cases where the DLA is clearly associated with a dwarf galaxy. We find that the neutral gas phase metallicities in these systems are similar to those in other DLAs. We argue that there may be many unrecognized cases where a DLA is actually associated with a dwarf galaxy even though there is a luminous galaxy within 100 kpc of the quasar sightline.

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Bergeron, J., and P. Boissé. "Extent and structure of intervening absorbers from absorption lines redshifted on quasar emission lines." Astronomy & Astrophysics 604 (July 31, 2017): A37. http://dx.doi.org/10.1051/0004-6361/201730906.

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Val'tts, I. E. "Comparison of unidentified absorption lines of quasar spectra with unidentified lines of stellar spectra." Astrophysics 30, no. 1 (1989): 14–18. http://dx.doi.org/10.1007/bf01004082.

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Wang, T. G., J. X. Wang, W. Brinkmann, and M. Matsuoka. "How Saturated Are Absorption Lines in the Broad Absorption Line Quasar PG 1411+442?" Astrophysical Journal 519, no. 1 (July 1, 1999): L35—L38. http://dx.doi.org/10.1086/312105.

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Savage, Blair D., Bart Wakker, Buell T. Jannuzi, John N. Bahcall, Jacqueline Bergeron, Alec Boksenberg, George F. Hartig, et al. "The Hubble Space Telescope Quasar Absorption Line Key Project. XV. Milky Way Absorption Lines." Astrophysical Journal Supplement Series 129, no. 2 (August 2000): 563–610. http://dx.doi.org/10.1086/313420.

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Pan, Cai-Juan, Cheng-Yu Su, Mu-Sheng Li, and Wei-Rong Huang. "Identification of Metal Absorption Lines on Quasar Spectra of SDSS DR9." Journal of Astrophysics and Astronomy 35, no. 3 (September 2014): 529–31. http://dx.doi.org/10.1007/s12036-014-9277-x.

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Garcı́a, L. A., and E. V. Ryan-Weber. "CAN UVB VARIATIONS RECONCILE SIMULATED QUASAR ABSORPTION LINES AT HIGH REDSHIFT?" Revista Mexicana de Astronomía y Astrofísica 56, no. 1 (April 1, 2020): 97–107. http://dx.doi.org/10.22201/ia.01851101p.2020.56.01.11.

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In this work we present new calculations of the observables associated with synthetic metal and HI absorption lines in the spectra of high redshift quasars, in-spired by questions and limitations raised in work with a uniform Haardt-Madau 2012 ultraviolet background (UVB). We introduce variations at z ≈ 6 to the UVB and HI self–shielding and explore the sensitivity of the absorption features to modifications of the hardness of the UVB. We find that observed SiIV and low ionization states (e.g. CII, SiII, OI) are well represented by a soft UV ionizing field at z = 6, but this same prescription, fails to reproduce the statistical properties of the observed CIV ion absorber population. We conclude that small variations in the UVB (not greater than a dex below Haardt-Madau 2012 emissivity at 1 Ryd) and HI SSh at z ≈ 6 play a major role in improving the estimation of metal ions and HI statistics at high z.

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Wildy, C., M. R. Goad, and J. T. Allen. "SDSS J1138+3517: a quasar showing remarkably variable broad absorption lines." Monthly Notices of the Royal Astronomical Society 448, no. 3 (February 28, 2015): 2397–411. http://dx.doi.org/10.1093/mnras/stv142.

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Boissé, P., J. Bergeron, J. X. Prochaska, C. Péroux, and D. G. York. "Time variations of narrow absorption lines in high resolution quasar spectra." Astronomy & Astrophysics 581 (September 2015): A109. http://dx.doi.org/10.1051/0004-6361/201526289.

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陆, 美美. "Equivalent Width Measurement of 17 CIV Mini-BAL Quasar Absorption Lines." Astronomy and Astrophysics 07, no. 01 (2019): 11–19. http://dx.doi.org/10.12677/aas.2019.71002.

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Tian, Qiguo, Xiheng Shi, Lei Hao, Yipeng Zhou, Zhenzhen Li, Peng Jiang, Shengmiao Wu, Chenwei Yang, Shaohua Zhang, and Hongyan Zhou. "Ultradense Gas Tracked by Unshifted Broad Absorption Lines in a Quasar." Astrophysical Journal 914, no. 1 (June 1, 2021): 13. http://dx.doi.org/10.3847/1538-4357/abf82d.

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45

Okoshi, Katsuya, Yosuke Minowa, Nobunari Kashikawa, Suzuka Koyamada, and Toru Misawa. "Multiple Absorption Systems in the Lines of Sight to Quadruply Lensed Quasar H1413+1143 As a Probe of the Circumgalactic medium around Dwarf Galaxy." Proceedings of the International Astronomical Union 14, S344 (August 2018): 305–8. http://dx.doi.org/10.1017/s1743921318006683.

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AbstractWe present the first measurement of differences in MgII absorption strength in multiple intervening absorbers, which are also identified as (sub-)Damped Lyman alpha absorption systems, in the four spectra of the quadruply lensed quasar H1413+1143, often referred to the “Cloverleaf”, from highly spatial resolution and high signal-to-noise spectroscopy with an optical multi-mode spectrograph, the Kyoto tridimentional spectrograph II on board the Subaru telescope. The detection of significant MgII absorptions in multiple components in the spatially-resolved spectra suggests that chemical enrichment differs at least on scale of about 10 kpc within the separation of sightlines. For, a DLA system at redshift zabs = 1.66, the rest equivalent widths of MgII absorption lines change by factors up to 6, which is similar to those of HI absorption lines. This suggests that (inhomogeneous) cold absorbers which give rise to strong HI/MgII absorptions dwell on a scale within 10 kpc in the circumgalactic medium (CGM).

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46

Ubachs, W., E. J. Salumbides, M. T. Murphy, H. Abgrall, and E. Roueff. "H2/HD molecular data for analysis of quasar spectra in search of varying constants." Astronomy & Astrophysics 622 (February 2019): A127. http://dx.doi.org/10.1051/0004-6361/201834782.

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Context. Absorption lines of H2 and HD molecules observed at high redshift in the line of sight towards quasars are a test ground to search for variation of the proton-to-electron mass ratio μ. For this purpose, results from astronomical observations are compared with a compilation of molecular data of the highest accuracy, obtained in laboratory studies as well as in first-principles calculations. Aims. A comprehensive line list is compiled for H2 and HD absorption lines in the Lyman (B1Σu+ − X1Σg+) and Werner (C1Πu − X1Σg+) band systems up to the Lyman cutoff at 912 Å. Molecular parameters listed for each line i are the transition wavelength λi, the line oscillator strength fi, the radiative damping parameter of the excited state Γi, and the sensitivity coefficient Ki for a variation of the proton-to-electron mass ratio. Methods. The transition wavelengths λi for the H2 and HD molecules are determined by a variety of advanced high-precision spectroscopic experiments involving narrowband vacuum ultraviolet lasers, Fourier-transform spectrometers, and synchrotron radiation sources. Results for the line oscillator strengths fi, damping parameters Γi, and sensitivity coefficients Ki are obtained in theoretical quantum chemical calculations. Results. A new list of molecular data is compiled for future analyses of cold clouds of hydrogen absorbers, specifically for studies of μ-variation from quasar data. The list is applied in a refit of quasar absorption spectra of B0642–5038 and J1237+0647 yielding constraints on a variation of the proton-to-electron mass ratio Δμ/μ consistent with previous analyses.

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Noterdaeme, P., S. Balashev, J. K. Krogager, R. Srianand, H. Fathivavsari, P. Petitjean, and C. Ledoux. "Proximate molecular quasar absorbers." Astronomy & Astrophysics 627 (June 27, 2019): A32. http://dx.doi.org/10.1051/0004-6361/201935371.

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We present results from a search for strong H2 absorption systems proximate to quasars (zabs ≈ zem) in the Sloan Digital Sky Survey (SDSS) Data Release 14. The search is based on the Lyman-Werner band signature of damped H2 absorption lines without any prior on the associated metal or neutral hydrogen content. This has resulted in the detection of 81 systems with N(H2) ∼ 1019 − 1020 cm−2 located within a few thousand km s−1 from the quasar. Compared to a control sample of intervening systems, this implies an excess of proximate H2 systems by about a factor of 4 to 5. The incidence of H2 systems increases steeply with decreasing relative velocity, reaching an order of magnitude higher than expected from intervening statistics at Δv < 1000 km s−1. The most striking feature of the proximate systems compared to the intervening ones is the presence of Ly − α emission in the core of the associated damped H I absorption line in about half of the sample. This puts constraints on the relative projected sizes of the absorbing clouds to those of the quasar line emitting regions. Using the SDSS spectra, we estimate the H I, metal and dust content of the systems, which are found to have typical metallicities of one tenth Solar, albeit with a large spread among individual systems. We observe trends between the fraction of leaking Ly − α emission and the relative absorber-quasar velocity as well as with the excitation of several metal species, similar to what has been seen in metal-selected proximate DLAs. With the help of theoretical H I-H2 transition relations, we show that the presence of H2 helps to break the degeneracy between density and strength of the UV field as main sources of excitation and hence provides unique constraints on the possible origin and location of the absorbing clouds. We suggest that most of these systems originate from galaxies in the quasar group, although a small fraction of them could be located in the quasar host as well. We conclude that follow-up observations are still required to investigate the chemical and physical conditions in individual clouds and to assess the importance of AGN feedback for the formation and survival of H2 clouds.

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Huang, Hong-Yan, Cai-Juan Pan, Wei-Jian Lu, Yi-Ping Qin, Ying-Ru Lin, Wei-Rong Huang, Yu-Tao Zhou, et al. "Correlation between the ionizing continuum and the variable C iv broad absorption line in multi-epoch observations of SDSS J141007.74+541203.3." Monthly Notices of the Royal Astronomical Society 487, no. 2 (June 13, 2019): 2818–23. http://dx.doi.org/10.1093/mnras/stz1454.

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Abstract Correlations between the variations of quasar absorption lines and the ionizing continuum have been confirmed recently in systematic studies. However, no convincing individual case is reported. We present a statistical analysis of the variable C iv broad absorption line (BAL) in the quasar SDSS J141007.74+541203.3, which has been observed with 44 epochs by the Sloan Digital Sky Survey Data Release 14. Grier et al. have concluded that the most likely cause of the variability of the BAL in SDSS J141007.74+541203.3 is a rapid response to changes in the incident ionizing continuum. In this paper, we confirm the anticorrelation between the equivalent width of BALs and the flux of the continuum based on the spectra of this quasar, which show significant variations. This serves as further independent evidence for the conclusions of Grier et al.

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Misawa, Toru, Michael Eracleous, Jane C. Charlton, and Akito Tajitsu. "Time‐Variable Complex Metal Absorption Lines in the Quasar HS 1603+3820." Astrophysical Journal 629, no. 1 (August 10, 2005): 115–30. http://dx.doi.org/10.1086/431342.

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Loeb, Abraham, and Daniel J. Eisenstein. "Probing Early Clustering with LY alpha Absorption Lines beyond the Quasar Redshift." Astrophysical Journal 448 (July 1995): 17. http://dx.doi.org/10.1086/175938.

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Journal articles on the topic 'Quasar absorption lines'

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