Composite quasar spectra from the sloan digital sky survey

Daniel E. Vanden Berk, Gordon T. Richards, Amanda Bauer, Michael A. Strauss, Donald P. Schneider, Timothy M. Heckman, Donald G. York, Patrick B. Hall, Xiaohui Fan, G. R. Knapp, Scott F. Anderson, James Annis, Neta A. Bahcall, Mariangela Bernardi, John W. Briggs, J. Brinkmann, Robert Brunner, Scott Burles, Larry Carey, Francisco J. Castander & 42 others A. J. Connolly, J. H. Crocker, I. Csabai, Mamoru Doi, Douglas Finkbeiner, Scott Friedman, Joshua A. Frieman, Masataka Fukugita, James E. Gunn, G. S. Hennessy, Željko Ivezić, Stephen Kent, Peter Z. Kunszt, D. Q. Lamb, R. French Leger, Daniel C. Long, Jon Loveday, Robert H. Lupton, Avery Meiksin, Aronne Merelli, Jeffrey A. Munn, Heidi Jo Newberg, Matt Newcomb, R. C. Nichol, Russell Owen, Jeffrey R. Pier, Adrian Pope, Constance M. Rockosi, David J. Schlegel, Walter A. Siegmund, Stephen Smee, Yehuda Snir, Chris Stoughton, Christopher Stubbs, Mark Subbarao, Alexander S. Szalay, G. Szokoly, Christy Tremonti, Alan Uomoto, Patrick Waddell, Brian Yanny, Wei Zheng

Research output: Contribution to journalArticle

1131 Citations (Scopus)

Abstract

We have created a variety of composite quasar spectra using a homogeneous data set of over 2200 spectra from the Sloan Digital Sky Survey (SDSS). The quasar sample spans a redshift range of 0.044 ≤ z ≤ 4.789 and an absolute r′ magnitude range of -18.0 to -26.5. The input spectra cover an observed wavelength range of 3800-9200 Å at a resolution of 1800. The median composite covers a rest-wavelength range from 800 to 8555 Å and reaches a peak signal-to-noise ratio of over 300 per 1 Å resolution element in the rest frame. We have identified over 80 emission-line features in the spectrum. Emission-line shifts relative to nominal laboratory wavelengths are seen for many of the ionic species. Peak shifts of the broad permitted and semiforbidden lines are strongly correlated with ionization energy, as previously suggested, but we find that the narrow forbidden lines are also shifted by amounts that are strongly correlated with ionization energy. The magnitude of the forbidden line shifts is ≲100 km s-1, compared with shifts of up to 550 km s-1 for some of the permitted and semiforbidden lines. At wavelengths longer than the Lyα emission, the continuum of the geometric mean composite is well fitted by two power laws, with a break at ≈5000 Å. The frequency power-law index, αv, is -0.44 from ≈1300 to 5000 Å and -2.45 redward of ≈5000 Å. The abrupt change in slope can be accounted for partly by host-galaxy contamination at low redshift. Stellar absorption lines, including higher order Balmer lines, seen in the composites suggest that young or intermediate-age stars make a significant contribution to the light of the host galaxies. Most of the spectrum is populated by blended emission lines, especially in the range 1500-3500 Å, which can make the estimation of quasar continua highly uncertain unless large ranges in wavelength are observed. An electronic table of the median quasar template is available.

Original languageEnglish
Pages (from-to)549-564
Number of pages16
JournalAstronomical Journal
Volume122
Issue number2
DOIs
Publication statusPublished - Aug 2001

Fingerprint

quasars
wavelength
composite materials
wavelengths
shift
power law
ionization
galaxies
continuums
signal-to-noise ratio
energy
contamination
signal to noise ratios
templates
slopes
stars
electronics

Keywords

  • Quasars: emission lines
  • Quasars: general

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Vanden Berk, D. E., Richards, G. T., Bauer, A., Strauss, M. A., Schneider, D. P., Heckman, T. M., ... Zheng, W. (2001). Composite quasar spectra from the sloan digital sky survey. Astronomical Journal, 122(2), 549-564. https://doi.org/10.1086/321167

Composite quasar spectra from the sloan digital sky survey. / Vanden Berk, Daniel E.; Richards, Gordon T.; Bauer, Amanda; Strauss, Michael A.; Schneider, Donald P.; Heckman, Timothy M.; York, Donald G.; Hall, Patrick B.; Fan, Xiaohui; Knapp, G. R.; Anderson, Scott F.; Annis, James; Bahcall, Neta A.; Bernardi, Mariangela; Briggs, John W.; Brinkmann, J.; Brunner, Robert; Burles, Scott; Carey, Larry; Castander, Francisco J.; Connolly, A. J.; Crocker, J. H.; Csabai, I.; Doi, Mamoru; Finkbeiner, Douglas; Friedman, Scott; Frieman, Joshua A.; Fukugita, Masataka; Gunn, James E.; Hennessy, G. S.; Ivezić, Željko; Kent, Stephen; Kunszt, Peter Z.; Lamb, D. Q.; Leger, R. French; Long, Daniel C.; Loveday, Jon; Lupton, Robert H.; Meiksin, Avery; Merelli, Aronne; Munn, Jeffrey A.; Newberg, Heidi Jo; Newcomb, Matt; Nichol, R. C.; Owen, Russell; Pier, Jeffrey R.; Pope, Adrian; Rockosi, Constance M.; Schlegel, David J.; Siegmund, Walter A.; Smee, Stephen; Snir, Yehuda; Stoughton, Chris; Stubbs, Christopher; Subbarao, Mark; Szalay, Alexander S.; Szokoly, G.; Tremonti, Christy; Uomoto, Alan; Waddell, Patrick; Yanny, Brian; Zheng, Wei.

In: Astronomical Journal, Vol. 122, No. 2, 08.2001, p. 549-564.

Research output: Contribution to journalArticle

Vanden Berk, DE, Richards, GT, Bauer, A, Strauss, MA, Schneider, DP, Heckman, TM, York, DG, Hall, PB, Fan, X, Knapp, GR, Anderson, SF, Annis, J, Bahcall, NA, Bernardi, M, Briggs, JW, Brinkmann, J, Brunner, R, Burles, S, Carey, L, Castander, FJ, Connolly, AJ, Crocker, JH, Csabai, I, Doi, M, Finkbeiner, D, Friedman, S, Frieman, JA, Fukugita, M, Gunn, JE, Hennessy, GS, Ivezić, Ž, Kent, S, Kunszt, PZ, Lamb, DQ, Leger, RF, Long, DC, Loveday, J, Lupton, RH, Meiksin, A, Merelli, A, Munn, JA, Newberg, HJ, Newcomb, M, Nichol, RC, Owen, R, Pier, JR, Pope, A, Rockosi, CM, Schlegel, DJ, Siegmund, WA, Smee, S, Snir, Y, Stoughton, C, Stubbs, C, Subbarao, M, Szalay, AS, Szokoly, G, Tremonti, C, Uomoto, A, Waddell, P, Yanny, B & Zheng, W 2001, 'Composite quasar spectra from the sloan digital sky survey', Astronomical Journal, vol. 122, no. 2, pp. 549-564. https://doi.org/10.1086/321167
Vanden Berk DE, Richards GT, Bauer A, Strauss MA, Schneider DP, Heckman TM et al. Composite quasar spectra from the sloan digital sky survey. Astronomical Journal. 2001 Aug;122(2):549-564. https://doi.org/10.1086/321167
Vanden Berk, Daniel E. ; Richards, Gordon T. ; Bauer, Amanda ; Strauss, Michael A. ; Schneider, Donald P. ; Heckman, Timothy M. ; York, Donald G. ; Hall, Patrick B. ; Fan, Xiaohui ; Knapp, G. R. ; Anderson, Scott F. ; Annis, James ; Bahcall, Neta A. ; Bernardi, Mariangela ; Briggs, John W. ; Brinkmann, J. ; Brunner, Robert ; Burles, Scott ; Carey, Larry ; Castander, Francisco J. ; Connolly, A. J. ; Crocker, J. H. ; Csabai, I. ; Doi, Mamoru ; Finkbeiner, Douglas ; Friedman, Scott ; Frieman, Joshua A. ; Fukugita, Masataka ; Gunn, James E. ; Hennessy, G. S. ; Ivezić, Željko ; Kent, Stephen ; Kunszt, Peter Z. ; Lamb, D. Q. ; Leger, R. French ; Long, Daniel C. ; Loveday, Jon ; Lupton, Robert H. ; Meiksin, Avery ; Merelli, Aronne ; Munn, Jeffrey A. ; Newberg, Heidi Jo ; Newcomb, Matt ; Nichol, R. C. ; Owen, Russell ; Pier, Jeffrey R. ; Pope, Adrian ; Rockosi, Constance M. ; Schlegel, David J. ; Siegmund, Walter A. ; Smee, Stephen ; Snir, Yehuda ; Stoughton, Chris ; Stubbs, Christopher ; Subbarao, Mark ; Szalay, Alexander S. ; Szokoly, G. ; Tremonti, Christy ; Uomoto, Alan ; Waddell, Patrick ; Yanny, Brian ; Zheng, Wei. / Composite quasar spectra from the sloan digital sky survey. In: Astronomical Journal. 2001 ; Vol. 122, No. 2. pp. 549-564.
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TY - JOUR

T1 - Composite quasar spectra from the sloan digital sky survey

AU - Vanden Berk, Daniel E.

AU - Richards, Gordon T.

AU - Bauer, Amanda

AU - Strauss, Michael A.

AU - Schneider, Donald P.

AU - Heckman, Timothy M.

AU - York, Donald G.

AU - Hall, Patrick B.

AU - Fan, Xiaohui

AU - Knapp, G. R.

AU - Anderson, Scott F.

AU - Annis, James

AU - Bahcall, Neta A.

AU - Bernardi, Mariangela

AU - Briggs, John W.

AU - Brinkmann, J.

AU - Brunner, Robert

AU - Burles, Scott

AU - Carey, Larry

AU - Castander, Francisco J.

AU - Connolly, A. J.

AU - Crocker, J. H.

AU - Csabai, I.

AU - Doi, Mamoru

AU - Finkbeiner, Douglas

AU - Friedman, Scott

AU - Frieman, Joshua A.

AU - Fukugita, Masataka

AU - Gunn, James E.

AU - Hennessy, G. S.

AU - Ivezić, Željko

AU - Kent, Stephen

AU - Kunszt, Peter Z.

AU - Lamb, D. Q.

AU - Leger, R. French

AU - Long, Daniel C.

AU - Loveday, Jon

AU - Lupton, Robert H.

AU - Meiksin, Avery

AU - Merelli, Aronne

AU - Munn, Jeffrey A.

AU - Newberg, Heidi Jo

AU - Newcomb, Matt

AU - Nichol, R. C.

AU - Owen, Russell

AU - Pier, Jeffrey R.

AU - Pope, Adrian

AU - Rockosi, Constance M.

AU - Schlegel, David J.

AU - Siegmund, Walter A.

AU - Smee, Stephen

AU - Snir, Yehuda

AU - Stoughton, Chris

AU - Stubbs, Christopher

AU - Subbarao, Mark

AU - Szalay, Alexander S.

AU - Szokoly, G.

AU - Tremonti, Christy

AU - Uomoto, Alan

AU - Waddell, Patrick

AU - Yanny, Brian

AU - Zheng, Wei

PY - 2001/8

Y1 - 2001/8

N2 - We have created a variety of composite quasar spectra using a homogeneous data set of over 2200 spectra from the Sloan Digital Sky Survey (SDSS). The quasar sample spans a redshift range of 0.044 ≤ z ≤ 4.789 and an absolute r′ magnitude range of -18.0 to -26.5. The input spectra cover an observed wavelength range of 3800-9200 Å at a resolution of 1800. The median composite covers a rest-wavelength range from 800 to 8555 Å and reaches a peak signal-to-noise ratio of over 300 per 1 Å resolution element in the rest frame. We have identified over 80 emission-line features in the spectrum. Emission-line shifts relative to nominal laboratory wavelengths are seen for many of the ionic species. Peak shifts of the broad permitted and semiforbidden lines are strongly correlated with ionization energy, as previously suggested, but we find that the narrow forbidden lines are also shifted by amounts that are strongly correlated with ionization energy. The magnitude of the forbidden line shifts is ≲100 km s-1, compared with shifts of up to 550 km s-1 for some of the permitted and semiforbidden lines. At wavelengths longer than the Lyα emission, the continuum of the geometric mean composite is well fitted by two power laws, with a break at ≈5000 Å. The frequency power-law index, αv, is -0.44 from ≈1300 to 5000 Å and -2.45 redward of ≈5000 Å. The abrupt change in slope can be accounted for partly by host-galaxy contamination at low redshift. Stellar absorption lines, including higher order Balmer lines, seen in the composites suggest that young or intermediate-age stars make a significant contribution to the light of the host galaxies. Most of the spectrum is populated by blended emission lines, especially in the range 1500-3500 Å, which can make the estimation of quasar continua highly uncertain unless large ranges in wavelength are observed. An electronic table of the median quasar template is available.

AB - We have created a variety of composite quasar spectra using a homogeneous data set of over 2200 spectra from the Sloan Digital Sky Survey (SDSS). The quasar sample spans a redshift range of 0.044 ≤ z ≤ 4.789 and an absolute r′ magnitude range of -18.0 to -26.5. The input spectra cover an observed wavelength range of 3800-9200 Å at a resolution of 1800. The median composite covers a rest-wavelength range from 800 to 8555 Å and reaches a peak signal-to-noise ratio of over 300 per 1 Å resolution element in the rest frame. We have identified over 80 emission-line features in the spectrum. Emission-line shifts relative to nominal laboratory wavelengths are seen for many of the ionic species. Peak shifts of the broad permitted and semiforbidden lines are strongly correlated with ionization energy, as previously suggested, but we find that the narrow forbidden lines are also shifted by amounts that are strongly correlated with ionization energy. The magnitude of the forbidden line shifts is ≲100 km s-1, compared with shifts of up to 550 km s-1 for some of the permitted and semiforbidden lines. At wavelengths longer than the Lyα emission, the continuum of the geometric mean composite is well fitted by two power laws, with a break at ≈5000 Å. The frequency power-law index, αv, is -0.44 from ≈1300 to 5000 Å and -2.45 redward of ≈5000 Å. The abrupt change in slope can be accounted for partly by host-galaxy contamination at low redshift. Stellar absorption lines, including higher order Balmer lines, seen in the composites suggest that young or intermediate-age stars make a significant contribution to the light of the host galaxies. Most of the spectrum is populated by blended emission lines, especially in the range 1500-3500 Å, which can make the estimation of quasar continua highly uncertain unless large ranges in wavelength are observed. An electronic table of the median quasar template is available.

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KW - Quasars: general

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