Study and Analysis of Absorption Spectra of Quasars

Study and Analysis of Absorption Spectra of Quasars Bushra Q. AL-Abudi 1 and Nuha S. Fouad 1, University of Baghdad, College of Science, Department of Astronomy and Space, Baghdad-Iraq ABSTRACT A quasi-stellar radio source (quasar) is a very energetic and distant active galactic nucleus. Quasars are extremely luminous and were first identified as being high red shift sources of electromagnetic energy, including radio waves and visible light, that were point-like, similar to stars, rather than extended sources similar to galaxies. The simplest way to explain the quasar's red shifts is to assume that they are extremely distant bodies that follow Hubble's law. In this paper, eight single and four double quasars have been detected from SDSS.The single quasars are: SDSS J10010.8+555349.8, SDSS J095918.70+00951.5,SDSS J093857.01+4181., SDSS J141647.1+51115.5, SDSS J141030.6+511113.8, SDSS J005006.35-005319.,SDSS J00055.33-000655.6 and SDSS J851.3+01143.3,the double quasars are SDSS J115518.9+19394., SDSS J1606.14+1034.0, SDSS J133907.13+131039.6 and J15418.94+3536.5. For both types quasars, chemical composition are determined and the redshift are measured from the absorption spectra, it found that the single quasars spans a redshift range of 0.335 z 6.47. the; and double quasars spans a redshift of 1.01 z 3.64. Applying Hubble's law to these values of redshift, some features of absorption line of quasars are measured and analyzed. Key words: Quasar, Absorption line Spectra, single Quasar; Double Quasars 1. INTRODUCTION Quasars growing supermassive black holes in the centers of massive galaxies are the subset of active galactic nuclei (AGNs) that constitute the most luminous objects in the universe. They radiate substantial power across much of the electromagnetic spectrum, with the source of radiation in each frequency regime originating from a different location with respect to the supermassive black hole. The shape of a quasar s spectral energy distribution (SED) can reveal much about the structure of the black hole-accretion disk system[1].quasars were observed during the first half of the 0th century as radio-sources, but their nature remained unclear for decades. In the late 50s, radio observations revealed that these sources were characterized by very small angular sizes: they were star-like objects, or quasi stellar radio sources, later contracted into quasars. The optical counter-parts of some of these radio sources were observed for the first time in the 60s. Their starlike nature was quickly contradicted by their atypical spectral properties. By 1974, the spectra of over two hundred quasars had been analyzed, and all of them having very large redshifts. The simplest way to explain the quasar s redshifts is to assume that they are extremely distant bodies that follow Hubble s law; in such a way that they are the most distant objects known. Moreover, if the redshifts of quasars are caused by the expansion of the Universe, they are very luminous bodies indeed [, 3]. The quasar absorption lines are crucial to our understanding of the Universe since the absorption lines provide a wealth of information on the gaseous Universe from high redshift to present day. The absorption lines can also allow us to probe them metallicity and ionization state of the gas. Owing to the advent of large spectroscopic surveys such as the Sloan Digital Sky Survey (SDSS), tens of thousands of quasar absorption lines can be identified [4]. In this paper, we will study and analysis the absorption spectra of single and double quasars. This paper is organized as follows. Section presents the features of absorption lines spectra. For each quasar; chemical composition were determined and features of absorption line spectra were measured and analyzed in section 3..Section 4 is devoted to conclusions.. The REDSHIFTS and FEATURES of ABSORPTION LINE SPECTRA The redshift of a quasar is usually denoted by the letter z; that is to say [5]. z (1) 0 where is the shift in wavelength of a spectral line, and 0 is the wavelength that line had when it left the quasar. The redshifts can also be expressed as a velocity by means of the Doppler shift formula. However, if the velocity is small compared to the velocity of light, the following simple form of that formula is normally used. v c () 0 Volume 3, Issue 5, May 014 Page 49

v 0 (3) c where v is the velocity, and c the velocity of light. If formula () is converted for the explicit calculation of the redshift Δ formula (3), we can recognize that at a given velocity, the amount of the shift Δ is proportional to the rest wavelength 0 of the corresponding spectral line.the classical method to estimate the distance D is based here on the Hubble s law [6]. v c z H D (4) Where Hubble parameter H (t) is 73 km s -1 Mpc- 1 (t) By converting of formula (4), we get the distance D in (Mpc) c z D (5) H (t) Formula (5) also expresses that the distance D increases proportional to the Redshift z. Given that the quasars have very large redshifts; showing that these objects are moving at relativistic recession velocities; it is necessary to use the exact formula for the relativistic Doppler shift [6]. (1 (1 v c v c ) ) 1 1 1 (6) On the other hand, there is another relativistic transformation equation for the volume of the material bodies. Since the transverse dimensions do not change because of the motion, the volume V of a body decreases according to the following formula [6]. v V V 0 1 (7) c Where Vo is the proper volume of the body. It is well known from Optics that the ratio of the image size q, to the object size p is what is called the magnification M; so that, M=q/p. According to the relativistic transformation equation 7, it could be considered that V is the volume image, and Vo is the volume object; in such a way that [6]. v M 1 (8) c And also we can calculate Redshift as lookback Time from the following equation [6]. tn t (9) ( 1 z) 3 Where t n 13.73 Gyr (i) Also from Redshift we can determine the Post-recombination Density n H using the following equation [6]. n H 1.6 x10-7 (1+z) 3 Cm -3 (10) At recombination (z ~1000): n H ~ 00 cm -3, at reionization (z ~ 7): n H ~ 10-4 cm -3. Also from Redshift we can determine the Atomic Hydrogen Abundance X(H) using the following equation [6]. X(H) = 4Χ10 8 (1+z) 3 << 1 (11) Gunn and Peterson (GP) calculate the observed absorption optical depth from Redshift of Quasar as following equation [6]. Ʈ GP.6Χ10 4 X(H) (1+z) 3/ (1) In this work, We selected eight single quasars and four double quasars from the Sloan Digital Sky Survey (SDSS) to measure the Redshift of quasars [7]. 3. SPECTRAL ANALYSIS of SINGLE QUASARS Eight single quasars have been detected from SDSS and found Object ID (objid), Right ascension (Ra) and Declination (Dec) as shown in table 1. Figures 1-8 show the absorption spectrum lines of the eight single quasars. Volume 3, Issue 5, May 014 Page 50

Table 1: Object ID, Right ascension, and Declination for Selected Single Quasars Quasar Name objid Ra Dec SDSS J10010.8+555349.8 1376583043505768 150.33678577 55.8971917 SDSS J095918.70+00951.5 137651753997107470 149.8793113.16430995 SDSS J093857.01+4181. 13765787356677409 144.73756498 41.475799 SDSS J141647.1+51115.5 13765910933077046 14.19674395 5.1876498 SDSS J141030.6+511113.8 SDSS J005006.35-005319. SDSS J00055.33-000655.6 SDSS J851.3+01143.3 13765913167066499 137657189836980651 137657190905873463 13767859593301413, 1.67594 1.5645863 1.46805 337.1346871 51.18717501-0.88869374-0.11546 1.430848 Fig.1: Absorption Spectrum line of Quasar SDSS J10010.8+555349.8 Fig.: Absorption Spectrum line of Quasar SDSS J095918.70+00951.5 Fig3: Absorption Spectrum of Quasar SDSS J093857.01+4181. Volume 3, Issue 5, May 014 Page 51

Fig.4: Absorption Spectrum of Quasar SDSS J141647.1+51115.5 Fig.5: Absorption Spectrum of Quasar SDSS J141030.6+511113.8 Fig.6: Absorption Spectrum line of Quasar SDSS J005006.35-005319. Fig.7: Absorption Spectrum line of Quasar SDSS J00055.33-000655.6 Volume 3, Issue 5, May 014 Page 5

Fig8: Absorption Spectrum line of Quasar SDSS J851.3+01143.3 We matching the wavelengths of the absorption lines in the spectrum λ obs ( ) of quasars at a value of flux F(λ), with those observed from the pure source in the laboratory λ rest () [7] Tables -9 reflects the extrapolated chemical elements for these single Quasars. By applying the equations which are mentioned previously, we found the features measured from absorption spectra as illustrated in Tables 10-17. The relationship between the optical depths as a function of different values of redshift is shown in figure9. The linear relationship between Recession velocities as a function of distance is shown in figure 10. The slope determines the value of the Hubble constant. By drawing the relationship between the Look back times as a function of the redshift for different quasars as shown in figure 11, it clear that whenever the redshift is less whenever the value of look back time is higher. Table : The chemical composition of Quasar SDSS J10010.8+555349.8 Chemical Element F(λ) λ obs () λ rest () O II 65.8 4975 378.8 Ne II 59.783 516.5 3868.7 H Ɣ 57.6171 5800 4840.48 O III 58.653 675 5006.8 Table 3: The chemical composition of Quasar SDSS J095918.70+00951.5 Chemical Element F(λ) obs. rest C III 6.9331 4100.89 1909 Mg 5.18 6036.46 851.6 O II 6.5909 8040.93 378.8 H Ɣ 4.66 884.7 4101.75 Ne II 3.7 8354.13 3868 Table4: The chemical composition of Quasar SDSS J093857.01+4181. Chemical Elements F(λ) obs C IV 183.3 4550.949 1550.77 He II 118.8148 4838.77 1640.5 C III 113.646 5633.4 1909 Mg 75.99 880.111 851.6 Table 5: The chemical composition of Quasar SDSS J141647.1+51115.5 Chemical Element F(λ) obs Lyα 63.39 3831.5 115.67 C IV 5.463 4875 1550.77 1 C III 15.816 601.5 1909 5 Mg 11.905 8831.5 851.6 Volume 3, Issue 5, May 014 Page 53

Table 6: The chemical composition of Quasar SDSS J141030.6+511113.8 Chemical Element F(λ) obs rest Lyα 33.77 513.4 115.67 C IV 17.54 6559. 1550.77 C III 3.81 8046.36 1909 Table7: The chemical composition of Quasar SDSS J005006.35-005319. Chemical Element F(λ) obs Lyα 6.5077 6446.97 115.67 C IV 3.53 8155.307 1550.77 He II 3.4374 8579.39 1640.5 Table 8: The chemical composition of Quasar SDSS J00055.33-000655.6 Chemical Element F(λ) obs HeI.988 3797.659 537.09 Lyα 6.5549 879.431 115.67 S IV+OIV.1964 10348.94 1507.93 Table 9: The chemical composition of Quasar SDSS J851.3+01143.3 Chemical Element F(λ) obs HeI 65.6089 4369.49 584.33 N I 07.97 6705.0 885.67 Lyα.773 8978.77 115.67 Table10: The features measured of absorption line of quasar SDSS J10010.8+555349.8 Line V(Km/Sec) D(Mpc) M T(Gyr) n(h) X(H) Ʈ(GP) O II 0.334 10060 005. 0.945 8.909 0.415 3.80 x10-7 9.50x10-8 0.003 Ne II 0.3344 10030 006.4 0.94 8.906 0.416 3.801x10-7 9.50 x10-8 0.003 H Ɣ 0.198 59460 1189. 0.980 10.647 0..75 x10-7 9.88 x10-8 0.00 O III 0.343 10960 059. 0.939 8.80 0.430 3.877 x10-7 9.7 x10-8 0.003 Average 0.305 90750 1815 0.951 9.31 0.371 3.80 x10-7 9.64 x10-8 0.003 Table 11: The features measured of absorption line of Quasar SDSS J095918.70+00951.5 Line V (km/ sec) D(Mpc) M T(Gyr) n(h) (cm -3 ) X(H) Ʈ(GP) C III 1.148 344400 6888 0.564 4.360.809 1.586X 10-6 3.965X 10-7 0.03 Mg 1.116 335070 6701.4 0.497 4.457 3.55 1.517 X10-6 3.794X 10-7 0.030 O II 1.156 34690 6938.4 0.580 4.335.713 1.604 X10-6 4.011 X10-7 0.033 H Ɣ 1.155 346740 6934.8 0.579 4.337.719 1.603 X10-6 4.007x X10-7 0.033 Ne II 1.159 347940 6958.8 0.587 4.35.676 1.61 X10-6 4.030 X10-7 0.033 Average 1.147 34414 6884.8 0.561 4.363.834 1.584 X10-6 3.961 X10-7 0.03 Volume 3, Issue 5, May 014 Page 54

Line Table 1: The features measured of absorption line of Quasar SDSS J093857.01+4181. V (Km/ Sec) D(Mpc) M T(Gyr) Table13: The features measured of absorption line of Quasar SDSS J141647.1+51115.5 n(h) (cm -3 ) X(H) Ʈ(GP) C IV 1.934 58038 11607.6 1.656.731 0.77 4.043X 10-6 1.010 X10-6 0.13 He II 1.949 58488 11697.6 1.673.710 0.76 4.105 X10-6 1.06 X10-6 0.135 C III 1.951 58530 11706 1.675.708 0.761 4.111 X10-6 1.07 X10-6 0.135 Mg 1.903 57111 114. 1.619.774 0.79 3.9171X10-6 0.979 X10-6 0.16 Average 1.934 580417.5 11608.35 1.656.731 0.77 4.044X 10-6 1.011X 10-6 0.13 Line V D(Mpc) T(Gyr) n(h) (cm (Km/Sec) M X(H) ) Ʈ(GP) Lyα.151 645480 1909.6 1.905.454 0.654 5.008 X10-6 1.5X10-6 0.18 C IV.143 643080 1861.6 1.896.463 0.658 4.970 X10-6 1.4 X10-6 0.180 C III.149 644880 1897.6 1.90.456 0.655 4.998 X10-6 1.49 X10-6 0.181 Mg.096 69070 1581.4 1.843.519 0.680 4.75 X10-6 1.188 X10-6 0.168 Average.135 64067.5 181.55 1.886.473 0.66 4.93 X10-6 1.3X10-6 0.178 Table 14: The features measured of absorption line of Quasar SDSS J141030.6+511113.8 Line V(Km/Sec) D(Mpc) M T(Gyr) n(h) (Cm -3 ) X(H) Ʈ(GP) Lyα 3.88 986550 19731 3.13 1.546 0.3689 1.61X10-5 3.154 X10-6 0.78 C IV 3.9 968880 19377.6 3.070 1.5784 0.377 1.10X10-5 3.06 X10-6 0.684 C III 3.15 964500 1990 3.055 1.5866 0.379 1.198 X10-5.995 X10-6 0.673 Average 3.44 973310 19466. 3.086 1.570333 0.375 1.3 X10-5 3.058 X10-6 0.695 Table 15: The features measured of absorption line of Quasar SDSS J005006.35-005319. Line V (Km/Sec) D(Mpc) M T(Gyr) n(h) (Cm -3 ) X(H) Ʈ(GP) Lyα 4.303 190960 5819. 4.1854 1.143 0.67.386X10-5 5.96X10-6 1.894 C IV 4.58 177670 5553.4 4.1398 1.1385 0.70.37 X10-5 5.81 X10-6 1.84 He II 4.9 168910 5378. 4.1098 1.148 0.7.88 X10-5 5.7 X10-6 1.779 Average 4.63 179180 5583.6 4.145 1.1369 0.69.333 X10-5 5.83 X10-6 1.83 Table16: The features measured of absorption line of Quasar SDSS J00055.33-000655.6 Line V(Km/Sec) D(Mpc) M T(Gyr) n(h) (Cm -3 ) X(H) Ʈ(GP) 18148.58 3649.6 He I 6.071 5.988 0.730 0.180 5.658 X10-5 1.414 X10-5 6.916 3 5 18547.3 37084.5 Lyα 6.180 6.099 0.713 0.177 5.94 X10-5 1.481 X10-5 7.409 3 4 S 1758903.6 35178.0 5.863 5.777 0.763 0.187 5.17 X10-5 1.93 X10-5 6.044 IV+OIV 5 7 1811537.69 3630.7 Average 6.038 5.955 0.735 0.18 5.584 X10-5 1.396 X10-5 6.790 3 5 Volume 3, Issue 5, May 014 Page 55

Table 17: The features measured of absorption line of Quasar SDSS J851.3+01143.3 Line V(Km/Sec) D(Mpc) M T(Gyr) n(h) (cm -3 ) X(H) Ʈ(GP) He I 6.477 1943333.39 38866.67 6.400 0.671 0.168 6.69 X10-5 1.67 X10-5 8.89 N I 6.570 1971168.7 3943.37 6.494 0.659 0.165 6.94 X10-5 1.735 X10-5 9.399 Lyα 6.385 1915758.388 38315.17 6.307 0.684 0.171 6.446 X10-5 1.611 X10-5 8.410 Average 6.478 194340.166 38868.4 6.400 0.671 0.168 6.693 X10-5 1.673 X10-5 8.900 Fig9: Relationship between Optical depth and Redshift. Fig.10: Relationship between Velocity and Distance Fig.11: Relation between Look back time and Redshift 4. SPECTRAL ANALYSIS of DOUBLE QUASARS Four double quasars have been detected from SDSS and found Object ID (objid), Right ascension (Ra) and Declination (Dec) as shown in table 18. Figures 1-15 show the absorption spectrum lines of these quasars. Tables 19- reflect the extrapolated chemical elements for these quasars. The features measured from absorption spectra are illustrated in Tables 3-6. Also, we can find that the relationship between the optical depth as a function of different values of redshift of some simple of double quasars, as shown in figure 16. Figure 17 illustrates the linear relationship between recession velocities as a function of distance. By drawing the relationship between the Look back times as a function of the redshift of different quasars, we find that whenever the redshift is less whenever the value of look back time is higher (see figure 18). Table 18: Object ID, Right ascension, and Declination for Selected Double Quasars Quasar Name objid Ra Dec SDSS J115518.9+19394. 137668976646948, 178.86193 19.661753 58774576439787545 SDSS J1606.14+1034.0 13766836697004166, 45.1089899 1.06167583 587746457009944, SDSS J133907.13+131039.6 587738568175058991, 04.77974079 13.17767316 13766489399963687, SDSS J15418.94+3536.5 58774014361174098, 13766773558607885, 193.57895411.59348404 Volume 3, Issue 5, May 014 Page 56

Fig. (1): Absorption Spectrum line of Quasar SDSS J115518.9+19394. Fig13: Absorption Spectrum line of Quasar SDSS J1606.14+1034.0 Fig.14: Absorption Spectrum line of Quasar SDSS J133907.13+131039.6 Fig.15: Absorption Spectrum line of Quasar SDSS J15418.94+3536.5 Volume 3, Issue 5, May 014 Page 57

Table (19): The chemical composition of Quasar SDSS J115518.9+19394. Chemical Element F(λ) obs C III 147.67 385.033 1909 C II 76.17 4669.705 36 Mg II 87.05 5606.311 800 Ne IV 7.35 4900.14 439.5 Ne V 48.5 6847.68 3346.79 Table (0): The chemical composition of Quasar SDSSJ1606.14+1034.0 Chemical Element F(λ) obs C III 18.54 4104.76 1909 Mg II 13.15 5985.41 795.5 Ne IV 9.101 57. 439.5 C II 9.45 4989 36 He I 5.9816 845.161 4388 Table (1): The chemical composition of Quasar SDSSJ133907.13+131039.6 Chemical Element F(λ) obs Lyα 59.57 393.99 115.4 N V 41.43 4005.3 139.4 O I 8.3 419.036 1305.53 C II 6.5 493.13 1335.3 C IV 9.58 4968.9 1545.86 Table (): The chemical composition of Quasar SDSSJ15418.94+3536.5 Chemical Element F(λ) obs Lyα 8.0571 5613.03 115.4 N V 10.65 570.76 139.4 C IV 8.95 7110.45 1545.86 C III 5.8913 8715.4 1909 O IV 5.8913 4760.76 1033.3 Table (3): The features measured of Quasar SDSS J115518.9+19394. Line V(Km/Sec) D(Mpc) M T(Gyr) n(h) (cm-3) X(H) Ʈ(GP) C III 1.017 305348.97 6106.965 0.189 4.790 9.647 1.314X10-6 3.86 X10-7 0.04 C II 1.007 3083.534 6045.670 0.13 4.86 15.5 1.94 X10-6 3.36 X10-7 0.03 Mg II 1.00 300676.178 6013.53 0.064 4.846 9.167 1.84 X10-6 3.10 X10-7 0.03 Ne IV 1.008 30599.713 6051.994 0.131 4.8 14.9 1.96 X10-6 3.41 X10-7 0.03 Ne V 1.046 313813.36 676.64 0.306 4.691 5.669 1.370 X10-6 3.46 X10-7 0.06 Average 1.016 304944.191 6098.883 0.16 4.795 14.793 1.311 X10-6 3.79 X10-7 0.04 Table (4): The features measured of Quasar SDSSJ1606.14+1034.0 n(h) (Cm- Line V(Km/Sec) D(Mpc) M T(Gyr) X(H) Ʈ(GP) 3) C III 1.150 345064.431 6901.88 0.568 4.354.783 1.590X10-6 3.976X10-7 0.035 Mg II 1.141 3436.38 6846.54 0.549 4.38.895 1.570X10-6 3.96X10-7 0.0319 Volume 3, Issue 5, May 014 Page 58

Ne IV 1.14 3480.50 6856.405 0.553 4.377.883 1.574X10-6 3.935X10-7 0.030 C II 1.144 343465.176 6869.303 0.557 4.370.847 1.578X10-6 3.947 X10-7 0.03 He I 0.879 63707.45 574.149 0.476 5.330 1.85 1.061X10-6.653 X10 - Avera ge 7 0.0177 1.091 37476.709 6549.534 0.541 4.563.65 1.475X10-6 3.687X10-7 0.093 Table (5): The features measured of Quasar SDSS J133907.13+131039.6 n(h) (Cm- Line V(Km/Sec) D(Mpc) M T(Gyr) X(H) Ʈ(GP) 3) Lyα.35 670773.0 13415.46 1.999.358 0.618 5.41X10-6 1.355X10-6 0.05 N V.31 669461.1 13389. 1.994.363 0.6 5.399X10-6 1.349X10-6 0.03 O I.31 669499.5 13389.99 1.995.363 0.619 5.400X10-6 1.350X10-6 0.03 C II.15 664517.0 1390.34 1.975.381 0.67 5.317X10-6 1.39X10-6 0.199 C IV.14 66498.1 1385.96 1.975.38 0.66 5.313X10-6 1.38X10-6 0.199 Average.5 667709.8 13354. 1.988.369 0.6 5.370X10-6 1.34X10-6 0.0 Table (6): The features measured of Quasar SDSS J15418.94+3536.5 Line V(Km/Sec) D(Mpc) M T(Gyr) n(h) (Cm-3) X(H) Ʈ(GP) Lyα 3.618 1085659.6 1713.19 3.477 1.383 0.38 1.576X10-5 3.941 X10-6 1.017 N V 3.615 108470.5 1694.05 3.4745 1.384 0.365 1.573 X10-5 3.933 X10-6 1.014 C IV 3.599 1079901.8 1598.04 3.457 1.391 0.330 1.557 X10-5 3.89 X10-6 0.998 C III 3.565 106960.9 139.06 3.4 1.407 0.334 1.5 X10-5 3.806 X10-6 0.965 O IV 3.607 10800.7 1644.01 3.465 1.388 0.330 1.564 X10-5 3.91 X10-6 1.005 Average 3.601 1080413.5 1608.7 3.459 1.391 0.337 1.558 X10-5 3.897 X10-6 1.000 Fig.16: Relation between Optical depth and Redshift Fig.17: Relation between Velocity and Distance Volume 3, Issue 5, May 014 Page 59

Fig18: Relation between Lookback time and Redshift 5. CONCLUSIONS In this paper, the absorption spectra of eight single and four double quasars were studied and analyzed, We found that mostly elements of spectra single quasars are (O II, O III, Mg, H Ɣ, Ne II, C III, He II, and sometime He I, N I), but mostly elements of spectra double quasars are (C II, C III, Mg II, Ne IV, N V, and Sometimes O I, O IV, Ne V). From the results, it is found that the single quasars span a redshift range of 0.335 z 6.47and the double quasars span a redshift of 1.01 z 3.64. The features of absorption line, speed, distance, relativistic redshift, magnification, post-recombination density, look back time and Gunn-Peterson Optical depth were calculated. The value of magnification always less than one if speed of quasar is less than the speed of light (if v<c always M<1)..Also the results indicated that whenever the redshift is less whenever the value of look back time is higher and the value of optical depth is less. References [1] Allison. R. Hill, S. C. Gallagher, R. P. Deo, E. Peeters and Gordon. T. Richards," Characterizing Quasars in the Midinfrared: High Signal-to-Noise Spectral Templates", Mon. Not. R. Astron. Soc., 013. [] Valentina D., " Quaser Absorption Spectra: Probes Of The Baryonic Gas At High Redshift ", Ph.D. thesis submitted to Isis-international school for advanced studies,1999. [3] Gisella D. "A comprehensive analysis of optical and near-infrared spectroscopy of z_6 quasars",ph.d thesis submitted to Combined Faculties of the Natural Sciences and Mathematics,University of Heidelberg, Germany,011. [4] Huang, W.-R., Chen,.-F., Qin,Y.-P.,. Li, Liao M.-S, He, R.-H., Han W.-W., F., hong, Y.-Q., Gan J.-Q. and hou,w. "Identification of MgII Absorption Line Systems from SDSS Quasar Catalogue" J. Astrophys. Astr., 3, 77 80, 011. [5] Liddle, A., "An Introduction to Modern Cosmology second Edition ", West Sussex PO19 8SQ, 003. [6] "Quasar Absorption Lines" http://astro.berkeley.edu/~ay16/08/notes/lecture6-08.pdf,1996. [7] Sloan Digital Sky Survey http://www.sdss.org Authors Bushra Q. Al-Abudi received Ph.D. degree in Astronomy in 00 from University of Baghdad, College of Science, Department of Astronomy and Space. Currently she is professor in Astronomy department and her research interests include spectroscopy and photometry analysis of binary stars. Nuha S. Fouad received B.Sc. degrees in Astronomy in 01 from university of Baghdad, College of Science, Department of Astronomy and Space. Currently she is M.Sc. student in Astronomy department. Volume 3, Issue 5, May 014 Page 60