NGC 5548

{{Short description|Type I Seyfert galaxy in the constellation Boötes}} {{Infobox galaxy | name = [[New General Catalogue|NGC]] 5548 | image = Supermassive black hole at the heart of NGC 5548.jpg | image_size = 300px | caption = NGC 5548 image by Hubble.<ref>{{cite news|title=Swiftly moving gas streamer eclipses supermassive black hole|url=http://www.spacetelescope.org/news/heic1413/|access-date=20 June 2014|work=ESA/Hubble Press Release}}</ref> | credit = | epoch = [[J2000]] | pronounce =  | constellation name = [[Boötes]] | ra = {{RA|14|17|59.513}}<ref name="ApJ131_1163"/> | dec = {{DEC|+25|08|12.45}}<ref name="ApJ131_1163"/> | z = {{nowrap|0.01651 ± 0.00189}}<ref name="Adelman-McCarthy2009"/> | h_radial_v = 5,178<ref name="Springob2005"/> km/s | gal_v = | dist_ly = {{nowrap|244.6 [[light year|Mly]] (75.01 [[parsec|Mpc]])}}<ref name="Crook2007"/> | group_cluster = | type = SA0/a pec<ref name="AAA526_A43"/> | mass =  | mass_light_ratio =  | stars = | appmag_v = 13.283<ref name="WisniewskiKleinmann1968"/> | absmag_v = | size_v = {{nowrap|1.7′ × 1.5′}}<ref name="Springob2005"/> | notes = Seyfert galaxy; [[radio jets|radio jet]]<ref name="NED"/> | names = [[Markarian galaxies|Mrk]] 1509, [[Uppsala General Catalogue|UGC]] 9149<ref name="NED"/> | references = }} '''NGC 5548''' is a Type I [[Seyfert galaxy]] with a bright, [[active galactic nucleus|active nucleus]].<ref name="AAA551_L6"/> This activity is caused by matter flowing onto a 65 million [[solar mass]] ({{Solar mass|link=y}}) [[supermassive black hole]] at the core.<ref name="AAA662_205"/> [[Galaxy morphological classification|Morphologically]], this is an unbarred [[lenticular galaxy]] with tightly-wound [[spiral arm]]s, while shell and [[tidal tail]] features suggest that it has undergone a cosmologically-recent merger or interaction event.<ref name="AAA526_A43"/> NGC 5548 is approximately 245<ref name="Crook2007"/> million [[light years]] away and appears in the constellation [[Boötes]]. The [[apparent visual magnitude]] of NGC 5548 is approximately 13.3 in the [[UBV photometric system|V band]].<ref name="WisniewskiKleinmann1968"/>

In 1943, this galaxy was one of twelve [[nebulae]] listed by American astronomer [[Carl Keenan Seyfert]] that showed broad [[emission line]]s in their [[Galactic nuclei|nuclei]].<ref name="Seyfert1943"/> Members of this class of objects became known as [[Seyfert galaxy|Seyfert galaxies]], and they were noted to have a higher than normal surface brightness in their nuclei.<ref name="BurbidgePrendergast1963"/> Observation of NGC 5548 during the 1960s with [[radio telescope]]s showed an enhanced level of [[Radio astronomy|radio emission]].<ref name="Tovmassian1966"/> [[Spectrogram]]s of the nucleus made in 1966 showed that the energized region was confined to a volume a few [[parsec]]s across, where temperature were around {{val|14000|u=K}} and the plasma had a dispersion velocity of ±450 km/s.<ref name="DibaiEsipovPronik1968"/>

Among astronomers, the accepted explanation for the active nucleus in NGC 5548 is the accretion of matter onto a [[supermassive black hole]] (SMBH) at the core. This object is surrounded by an orbiting disk of accreted matter drawn in from the surroundings. As material is drawn into the outer parts of this disk, it becomes [[Photoionization|photoionized]], producing broad emission lines in the optical and [[ultraviolet]] bands of the [[electromagnetic spectrum]]. A wind of ionized matter, organized in filamentary structures at distances of 1–14 light days from the center, is flowing outward in the direction perpendicular to the accretion disk plane.<ref name="AAA551_L6"/>

The mass of the central black hole can be estimated based on the properties of the emission lines in the core region. Combined measurements yield an estimated mass of {{val|6.54|+0.26|-0.25|e=7|ul=M_solar}}. In other words, it is some 65 million times the mass of the [[Sun]]. This result is consistent with other methods of estimating the mass of the SMBH in the nucleus of NGC 5548.<ref name="AAA662_205"/> Matter is falling onto this black hole at the estimated rate of {{val|0.03|u=M_solar}} per year, whereas mass is flowing outward from the core at or above the rate of {{val|0.92|u=M_solar}} each year.<ref name="Crenshaw2009"/> The inner part of the accretion disk surrounding the SMBH forms a thick, hot [[Stellar corona|corona]] spanning several light hours that is emitting [[X-ray astronomy|X-rays]]. When this radiation reaches the [[optically thick]] part of the accretion disk at a radius of around 1–2 light days, the X-rays are converted into heat.<ref name="ApJ639_46"/>

==References== {{reflist|colwidth=24em|refs= <ref name="ApJ131_1163">{{cite journal |doi=10.1086/498708 |last1=Skrutskie |first1=Michael F. |last2=Cutri |first2=Roc M. |last3=Stiening |first3=Rae |last4=Weinberg |first4=Martin D. |last5=Schneider |first5=Stephen E. |last6=Carpenter |first6=John M. |last7=Beichman |first7=Charles A. |last8=Capps |first8=Richard W. |last9=Chester |first9=Thomas |last10=Elias |first10=Jonathan H. |last11=Huchra |first11=John P. |last12=Liebert |first12=James W. |last13=Lonsdale |first13=Carol J. |last14=Monet |first14=David G. |last15=Price |first15=Stephan |last16=Seitzer |first16=Patrick |last17=Jarrett |first17=Thomas H. |last18=Kirkpatrick |first18=J. Davy |last19=Gizis |first19=John E. |last20=Howard |first20=Elizabeth V. |last21=Evans |first21=Tracey E. |last22=Fowler |first22=John W. |last23=Fullmer |first23=Linda |last24=Hurt |first24=Robert L. |last25=Light |first25=Robert M. |last26=Kopan |first26=Eugene L. |last27=Marsh |first27=Kenneth A. |last28=McCallon |first28=Howard L. |last29=Tam |first29=Robert |last30=Van Dyk |first30=Schuyler D. |last31=Wheelock |first31=Sherry L. |title=The Two Micron All Sky Survey (2MASS) |journal=The Astronomical Journal |date=1 February 2006 |volume=131 |issue=2 |pages=1163–1183 |bibcode=2006AJ....131.1163S |s2cid=18913331 |issn=0004-6256 |doi-access=free }}</ref>

<ref name="Adelman-McCarthy2009">{{Citation | author = Adelman-McCarthy, J. K. | title = The SDSS Photometric Catalog, Release 7 | work = VizieR On-line Data Catalog: II/294 |date=June 2009 | bibcode = 2009yCat.2294....0A | postscript= . |display-authors=etal}}</ref>

<ref name="WisniewskiKleinmann1968">{{Citation | last1 = Wisniewski | first1 = W. Z. | last2 = Kleinmann | first2 = D. E. | title = 16. Multicolor photometry of Seyfert galaxies and measurement at 1.55 microns of the jet in M 87 | journal = Astronomical Journal | volume = 73 | pages = 866–867 |date=November 1968 | doi = 10.1086/110721 | bibcode = 1968AJ.....73..866W | postscript= . }}</ref>

<ref name="Springob2005">{{Citation | last1 = Springob | first1 = Christopher M. | last2 = Haynes | first2 = Martha P. | last3 = Giovanelli | first3 = Riccardo | last4 = Kent | first4 = Brian R. | display-authors = 1 | title = A Digital Archive of H I 21 Centimeter Line Spectra of Optically Targeted Galaxies | journal = The Astrophysical Journal Supplement Series | volume = 160 | issue = 1 | pages = 149–162 |date=September 2005 | doi = 10.1086/431550 | bibcode = 2005ApJS..160..149S | postscript= . |arxiv = astro-ph/0505025 | s2cid = 14911447 }} See footnote 2.</ref>

<ref name="Seyfert1943">{{Citation | last1 = Seyfert | first1 = Carl K. | title = Nuclear Emission in Spiral Nebulae | journal = Astrophysical Journal | volume = 97 | page = 28 |date=January 1943 | doi = 10.1086/144488 | bibcode = 1943ApJ....97...28S | postscript= . }} See footnote 2.</ref>

<ref name="BurbidgePrendergast1963">{{Citation | last1 = Burbidge | first1 = E. Margaret | last2 = Burbidge | first2 = G. R. | last3 = Prendergast | first3 = K. H. | title = The Rotation and Physical Conditions in the Seyfert Galaxy NGC 7469 | journal = Astrophysical Journal | volume = 137 | page = 1022 |date=May 1963 | doi = 10.1086/147580 | bibcode = 1963ApJ...137.1022B | postscript= . }}</ref>

<ref name="Crook2007">{{Citation | last1 = Crook | first1 = Aidan C. | last2 = Huchra | first2 = John P. | last3 = Martimbeau | first3 = Nathalie | last4 = Masters | first4 = Karen L. | last5 = Jarrett | first5 = Tom | last6 = Macri | first6 = Lucas M. | display-authors = 1 | title = Groups of Galaxies in the Two Micron All Sky Redshift Survey | journal = The Astrophysical Journal | volume = 655 | issue = 2 | pages = 790–813 |date=February 2007 | doi = 10.1086/510201 | bibcode = 2007ApJ...655..790C | arxiv = astro-ph/0610732 | s2cid = 11672751 | postscript= . }}</ref>

<ref name="AAA526_A43">{{Citation | last1 = Slavcheva-Mihova | first1 = L. | last2 = Mihov | first2 = B. | title = Optical multiband surface photometry of a sample of Seyfert galaxies. I. Large-scale morphology and local environment analysis of matched Seyfert and inactive galaxy samples | journal = Astronomy and Astrophysics | volume = 526 | page = A43 |date=February 2011 | doi = 10.1051/0004-6361/200913243 | bibcode = 2011A&A...526A..43S | postscript= . |arxiv = 1011.1772 | s2cid = 119263271 }} See Table 1.</ref>

<ref name="Tovmassian1966">{{Citation | last1 = Tovmassian | first1 = H. M. | title = On the radio emission from some peculiar galaxies | journal = Australian Journal of Physics | volume = 19 | issue = 4 | page = 565 |date=August 1966 | bibcode = 1966AuJPh..19..565T | postscript= . | doi=10.1071/ph660565 | doi-access= free }}</ref>

<ref name="DibaiEsipovPronik1968">{{Citation | last1 = Dibai | first1 = É. A. | last2 = Esipov | first2 = V. F. | last3 = Pronik | first3 = V. I. | title = The Nucleus of the Seyfert Galaxy NGC 5548 | journal = Soviet Astronomy | volume = 11 | page = 553 |date=February 1968 | bibcode = 1968SvA....11..553D | postscript= . }}</ref>

<ref name="Crenshaw2009">{{Citation | last1 = Crenshaw | first1 = D. M. | last2 = Kraemer | first2 = S. B. | last3 = Schmitt | first3 = H. R. | last4 = Kaastra | first4 = J. S. | last5 = Arav | first5 = N. | last6 = Gabel | first6 = J. R. | last7 = Korista | first7 = K. T. | display-authors = 1 | title = Mass Outflow in the Seyfert 1 Galaxy NGC 5548 | journal = The Astrophysical Journal | volume = 698 | issue = 1 | pages = 281–292 |date=June 2009 | doi = 10.1088/0004-637X/698/1/281 | bibcode = 2009ApJ...698..281C | arxiv = 0902.2310 | s2cid = 62879296 | postscript= . }}</ref>

<ref name="NED">{{Citation | title = NED results for object NGC 5548 | work = NASA/IPAC Extragalactic Database | url = http://ned.ipac.caltech.edu/ | access-date= 2013-05-27 | postscript= . }}</ref>

<ref name="AAA551_L6">{{Citation | last1 = Kollatschny | first1 = W. | last2 = Zetzl | first2 = M. | title = Accretion disk wind as explanation for the broad-line region structure in NGC 5548 | journal = Astronomy & Astrophysics | volume = 551 | page = L6 |date=March 2013 | doi = 10.1051/0004-6361/201220923 | bibcode = 2013A&A...551L...6K | arxiv = 1301.7704 | s2cid = 119117740 | postscript= . }}</ref>

<ref name="AAA662_205">{{Citation | last1 = Bentz | first1 = Misty C. | last2 = Denney | first2 = Kelly D. | last3 = Cackett | first3 = Edward M. | last4 = Dietrich | first4 = Matthias | last5 = Fogel | first5 = Jeffrey K. J. | last6 = Ghosh | first6 = Himel | last7 = Horne | first7 = Keith D. | last8 = Kuehn | first8 = Charles | last9 = Minezaki | first9 = Takeo | last10 = Onken | first10 = Christopher A. | last11 = Peterson | first11 = Bradley M. | last12 = Pogge | first12 = Richard W. | last13 = Pronik | first13 = Vladimir I. | last14 = Richstone | first14 = Douglas O. | last15 = Sergeev | first15 = Sergey G. | last16 = Vestergaard | first16 = Marianne | last17 = Walker | first17 = Matthew G. | last18 = Yoshii | first18 = Yuzuru | display-authors = 1 | title = NGC 5548 in a Low-Luminosity State: Implications for the Broad-Line Region | journal = Astronomy & Astrophysics | volume = 662 | issue = 1 | pages = 205–212 |date=June 2007 | doi = 10.1086/516724 | bibcode = 2007ApJ...662..205B | arxiv = astro-ph/0702644 | s2cid = 14081378 | postscript= . }}</ref>

<ref name="ApJ639_46">{{Citation | last1 = Suganuma | first1 = Masahiro | last2 = Yoshii | first2 = Yuzuru | last3 = Kobayashi | first3 = Yukiyasu | last4 = Minezaki | first4 = Takeo | last5 = Enya | first5 = Keigo | last6 = Tomita | first6 = Hiroyuki | last7 = Aoki | first7 = Tsutomu | last8 = Koshida | first8 = Shintaro | last9 = Peterson | first9 = Bruce A. | display-authors = 1 | title = Reverberation Measurements of the Inner Radius of the Dust Torus in Nearby Seyfert 1 Galaxies | journal = The Astrophysical Journal | volume = 639 | issue = 1 | pages = 46–63 |date=March 2006 | doi = 10.1086/499326 | bibcode = 2006ApJ...639...46S | arxiv = astro-ph/0511697 | s2cid = 7671684 | postscript= . }}</ref> }}

==External links== {{commonscat}} *{{WikiSky}} *{{Citation | title = NGC 5548: Chandra Reads the Cosmic Bar Code of Gas Around a Giant Black Hole | work = Chandra X-ray Observatory | publisher = Harvard-Smithsonian Center for Astrophysics | date = February 20, 2009 | url = http://chandra.harvard.edu/photo/2000/0170/ | access-date= 2013-05-27 | postscript= . }} *{{Citation | title = Seyfert Galaxy NGC 5548 versus normal galaxy NGC 3277 | work = UA astronomical image gallery | publisher = The University of Alabama |date=July 1999 | url = http://www.astr.ua.edu/gifimages/ngc5548.html | access-date= 2013-05-27 | postscript= . }}

[[Category:NGC objects|5548]] [[Category:Unbarred lenticular galaxies]] [[Category:Seyfert galaxies]] [[Category:Markarian galaxies|Markarian 1509]] [[Category:Boötes]]