View source for Astronomy:Markarian 501

{{Short description|Elliptical galaxy emitting very-high-energy gamma rays}}
{{Infobox galaxy
| name = Markarian 501
| image = [[File:SDSS Mrk 501.jpg|SDSS Mrk 501]]
|caption = [[Astronomy:Sloan Digital Sky Survey|Sloan Digital Sky Survey]] image of Mrk 501
| epoch = [[Astronomy:J2000|J2000]]
| type = S0 <ref name="mgod">{{cite web
  | website=MARKARIAN2 – Markarian Galaxies Optical Database
  | title=Results for Mrk 501
  | url=http://heasarc.nasa.gov/w3browse/all/markarian2.html
  | archive-url=https://web.archive.org/web/20100623224554/http://heasarc.nasa.gov/W3Browse/all/markarian2.html
  | url-status=dead
  | archive-date=2010-06-23
  | access-date=2011-12-06 }} Data base query page is at [https://web.archive.org/web/20111028222504/http://heasarc.nasa.gov/db-perl/W3Browse/w3table.pl?tablehead=name%3Dmarkarian2&Action=More+Options]. Fill in Mrk 501 for name and click start search at bottom of page.</ref>
| ra = {{RA|16|53|52.21}}<ref name=vizi>{{cite journal|url=http://vizier.u-strasbg.fr/viz-bin/VizieR-4?-c=253.46756950%2B39.76016917&-c.rs=5&-out.add=_r&-sort=_r&-out.max=$4|bibcode=2000A&AS..143...23O|journal= Astronomy & Astrophysics Supplement Series|volume=143|pages=23–32|date=10 April 2000|title=The VizieR database of astronomical catalogues |last1=Ochsenbein|first1=F. |first2=P.|last2=Bauer |first3=J.|last3=Marcout|arxiv = astro-ph/0002122 |doi = 10.1051/aas:2000169 |s2cid=17377096}}</ref>
| dec = {{DEC|39|45|37.6}}<ref name=vizi/>
| dist_ly = 456 [[Astronomy:Light-year|Mly]] (140 [[Astronomy:Parsec|Mpc]]; 4.32x10<sup>24</sup> m)
| z = 9915±25 km/[[Second|s]] or 0.033640 Z
| size_v = 94.86" &times; 71.1" <ref name="mgod" />
| size = ~{{convert|64|kpc|ly|abbr=on|lk=on|order=flip}} (estimated)<ref>{{cite web |url=https://heasarc.gsfc.nasa.gov/db-perl/W3Browse/w3hdprods.pl?files=P&Target=heasarc%5Fmarkarian2%7C%7C%7C%5Funique%5Fid%3D514%7C%7C&Coordinates=Equatorial&Equinox=2000|title=Parameter Display for single row in Markarian Galaxies Optical Database}}</ref><ref name="mgod" />{{efn|name=size|Calculated from apparent size and distance:<math>456 Mly*sin(94.86 arcsec) = 209,683 ly</math>}}
| constellation name = [[Astronomy:Hercules (constellation)|Hercules]]
| notes = brightest object in [[Physics:Very-high-energy gamma ray|very-high-energy gamma ray]]s
| group_cluster = zw1707.6+4045
| names = 4C39.49, PGC 59214, UGC 10599
}}
'''Markarian 501''' (or '''Mrk 501''') is a [[Astronomy:Galaxy|galaxy]] with a spectrum extending to the highest energy gamma rays.<ref name="Aharonian">{{cite journal|last=Aharonian|first=F. A.|title=The time averaged TeV energy spectrum of Mkn 501 of the extraordinary 1997 outburst as measured with the stereoscopic Cherenkov telescope system of HEGRA|journal=Astronomy and Astrophysics|volume=349|pages=11–28|url=https://arxiv.org/PS_cache/astro-ph/pdf/9903/9903386v2.pdf|arxiv=astro-ph/9903386|bibcode=1999A&A...349...11A|year=1999}}</ref> It is a [[Astronomy:Blazar|blazar]] or BL Lac object, which is an [[Active galactic nucleus|active galactic nucleus]] with a jet that is shooting towards the Earth. The object has a redshift of z = 0.034.<ref name=acc/>

Mrk 501 is an extremely variable source of gamma rays, undergoing violent outbursts.<ref name=acc/> During an outburst in 1997, it was the brightest object in the sky in the [[Physics:Very-high-energy gamma ray|very-high-energy gamma ray]] region of the spectrum, at [[Physics:Photon energy|energies]] above 10<sup>11</sup>&nbsp;[[Physics:Electronvolt|eV]] (100 GeV).<ref name="Protheroe">{{Cite arXiv |eprint=astro-ph/9710118 <!-- unsupported parameter |url=https://arxiv.org/PS_cache/astro-ph/pdf/9710/9710118v1.pdf --> |title=Very high energy gamma rays from Markarian 501 |last=Protheroe |first=Ray J. |author2=C.L. Bhat |author3=P. Fleury |author4=E. Lorenz |author5=M. Teshima |author6=T.C. Weekes |date=12 October 1997}}</ref>

The galaxy hosting the blazar was studied and [[Astronomy:Markarian galaxies|catalogued]] by Benjamin Markarian in 1974.<ref name="Markaryan1974">{{cite journal |last=Markaryan |first=B. E. |author2=V. A. Lipovetskii |date=1974 |title=Galaxies with ultraviolet continuum V |journal=Astrophysics |volume=8 |issue=2 |pages=89–99 |issn=0571-7256 |doi=10.1007/BF01002156 |bibcode = 1972Ap......8...89M |s2cid=122248004 }}</ref> It was first determined to be a very high energy gamma ray emitter in 1996 by John Quinn at the Whipple Observatory.<ref name=acc/><ref name="Quinn">{{cite journal
|vauthors=Quinn J, Akerlof CW, Biller S, Buckley J, Carter-Lewis DA, Cawley MF, Catanese M, Connaughton V, Fegan DJ, Finley JP, Gaidos J, Hillas AM, Lamb RC, Krennrich F, Lessard R, McEnery JE, Meyer DI, Mohanty G, Rodgers AJ, Rose HJ, Sembroski G, Schubnell MS, Weekes TC, Wilson C, Zweerink J |display-authors=8
|date=10 January 1996 |title=Detection of Gamma Rays with E > 300 GeV from Markarian 501 |journal=The Astrophysical Journal Letters |volume=465 |issue=2 |pages=L83–L86 |doi=10.1086/309878 |bibcode = 1996ApJ...456L..83Q |doi-access=free }}</ref>

==Galaxy==
The elliptical galaxy is located in the constellation of [[Astronomy:Hercules (constellation)|Hercules]] at [[Right ascension|right ascension]] 16h 53.9m and [[Declination|declination]] +39° 45'. Its visible size appears to be 1.2 by 1 minute of arc.<ref>{{cite web | url=http://www.elisanet.fi/jere.kahanpaa/astro/scan/ugc/ugc10599.htm | title=Object: Galaxy UGC 10599 = Markarian 501}}</ref>

==Gamma rays==
The [[Physics:Gamma ray|gamma ray]]s from Mrk 501 are extremely variable, undergoing violent outbursts.<ref name=acc>{{cite journal |last=Acciari |first=V. A. |collaboration= VERITAS Collaboration and MAGIC Collaboration |title=Spectral Energy Distribution of Markarian 501: Quiescent State vs. Extreme Outburst|journal=Astrophysical Journal|volume=729|issue=2|pages=2 |date=2011|doi=10.1088/0004-637X/729/1/2|bibcode = 2011ApJ...729....2A |arxiv = 1012.2200 |s2cid=15451643 }}</ref>
The gamma ray spectrum of Mrk 501 shows two humps. One is below 1&nbsp;keV and can be considered to be [[Physics:X-ray|X-ray]]s and the other is above 1&nbsp;TeV. During flares and outbursts the peaks increase in power and frequency.<ref name=acc/> Flares lasting 20 minutes with rise times of 1 minute have been measured by [[Astronomy:MAGIC (telescope)|MAGIC]]. In these flares the higher energy gamma rays (of 1.2 Tev) were delayed 4 minutes over the 0.25&nbsp;TeV gamma rays.<ref>{{cite journal|arxiv=astro-ph/0702008|title=Variable VHE gamma-ray emission from Markarian 501 |last=Albert |first=J |collaboration=MAGIC Collaboration |date=5 December 2007 |doi=10.1086/521382 |volume=669 |issue=2 |journal=The Astrophysical Journal|pages=862–883|bibcode=2007ApJ...669..862A|s2cid=118954339 |url=http://eprints.ucm.es/23692/1/MirandaJM66libre.pdf}}</ref> This delay has led to various theories, including that space is bigger at small dimensions with a [[Astronomy:Quantum foam|foamy quantum texture]].<ref>{{cite journal |vauthors=Albert J, Ellis J, Mavromatos NE, Nanopoulos DV, Sakharov AS, ((Sarkisyan EKG)) |year=2008|title=Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope|journal=Physics Letters B|volume=668|issue=4|pages=253–257|doi=10.1016/j.physletb.2008.08.053|bibcode = 2008PhLB..668..253M |arxiv = 0708.2889 |s2cid=5103618}}</ref> The foam would create a variation in the speed of light for higher-energy light gamma-rays and the lower-energy radio waves and visible light. Such a variation would contradict Lorentz invariance, but could provide a clue for [[Physics:Grand Unified Theory|unification theory]]. Observations of Dr. Floyd Stecker of NASA's [[Organization:Goddard Space Flight Center|Goddard Space Flight Center]] of Mrk 501 and Mrk 421 demonstrated that there is no violation of Lorentz invariance.<ref name="Dr. Floyd Stecker">{{cite web|title=Einstein Makes Extra Dimensions Toe The Line|url=http://imagine.gsfc.nasa.gov/docs/features/news/17dec03.html|publisher=[[Organization:NASA|NASA]]|access-date=19 December 2011}}</ref> The galaxy is also variable in visible light between magnitude 14.5 and 13.6.<ref name="Barbieri">{{cite journal|last=Barbieri|first=G|author2=G. Romano|date=1977|title=The optical variability of the galaxy Markarian 501|journal=Acta Astronomica|volume=27|issue=2|pages=195–197|bibcode = 1977AcA....27..195B }}</ref>

During the discovery observations flashes at the average rate of one in seven minutes were observed. [[Astronomy:Cosmic ray|Cosmic ray]]s (that is, fermionic or [[Physics:Massive particle|massive]] cosmic rays, as opposed to photons) were ruled out by the shape and size of the flashes which are small and elliptical for gamma rays. The flux for photons over 300 GeV at this point in time in 1995 was 8.1±1.5 x 10<sup>−12</sup> cm<sup>−2</sup>s<sup>−1</sup><ref name="Quinn"/>

==Black hole==
Blazars are likely to originate from matter falling into a [[Astronomy:Black hole|black hole]] and possibly a [[Astronomy:Binary black hole|binary black hole]]. The velocity dispersion (which is the maximum difference in the velocity toward or away from Earth) observed in the galaxy is 372&nbsp;km/s which predicts a black hole mass of (0.9 − 3.4) × 10<sup>9</sup> [[Astronomy:Solar mass|M<sub>⊙</sub>]]. However, dispersion of velocity was also measured as 291 and 270&nbsp;km/s so the central mass may be less.<ref name="Rieger">{{cite journal|doi=10.1051/0004-6361:20021482|bibcode=2003A&A...397..121R|title=On the central black hole mass in Mkn 501|arxiv=astro-ph/0210326v1|journal=Astronomy and Astrophysics|volume=397|pages=121–125|year=2003|last1=Rieger|first1=F. M.|last2=Mannheim|first2=K.|s2cid=14579804}}</ref> A 23-day variability suggested that an object may be orbiting the central black hole with a 23-day period.<ref name="Rieger"/>

==Jet==
With [[Astronomy:Very-long-baseline interferometry|very-long-baseline interferometry]], the fine detail of [[Astronomy:Radio astronomy|radio waves]] can be seen down to milliarcsecond (mas) resolution. A central very bright single point called the ''core'' is observed. From the core an extremely high-speed blast of plasma emerges in a narrow cone shape as a one-sided jet.

After 30 milliarcseconds, the jet, which is 300 pc long, does a 90° turn and fans out. The inner jet before the kink shows bright edges or a limb-brightened structure less than 10 mas wide. This is probably due to a fast-moving central part to the jet, combined with slower edges.<ref name="Bondi">{{cite web
 |url             = http://www.ira.cnr.it/Research/VLBI.html
 |title           = Very Long Baseline Interferometry Research
 |last            = Bondi
 |first           = M.
 |author2         = L. Feretti
 |author3         = M. Giroletti
 |author4         = K.-H. Mack
 |author5         = F. Mantovani
 |author6         = C. Stanghellini
 |author7         = T. Venturi
 |author8         = D. Dallacasa
 |author9         = C. Fanti
 |author10        = R. Fanti
 |author11        = G. Giovannini
 |author12        = E. Liuzzo
 |author13        = M. Orienti
 |author14        = A. Rossetti
 |display-authors = 8
 |publisher       = Instituto di Radioastronomia
 |access-date      = 6 December 2011
 |url-status         = dead
 |archive-url      = https://web.archive.org/web/20100203210023/http://www.ira.cnr.it/Research/VLBI.html
 |archive-date     = 3 February 2010
}} with further detail at {{cite journal|arxiv=astro-ph/0309285 |doi=10.1086/379663 |title=Parsec‐Scale Properties of Markarian 501 |year=2004 |last1=Giroletti |first1=M. |last2=Giovannini |first2=G. |last3=Feretti |first3=L. |last4=Cotton |first4=W. D. |last5=Edwards |first5=P. G. |last6=Lara |first6=L. |last7=Marscher |first7=A. P. |last8=Mattox |first8=J. R. |last9=Piner |first9=B. G. |last10=Venturi |first10=T. |journal=The Astrophysical Journal |volume=600 |issue=1 |pages=127–140 |bibcode=2004ApJ...600..127G |s2cid=18078543 }}</ref>

Normally, there would be jets of gas shooting out in opposite directions. The observed jet is the one that faces the earth and projects plasma towards Earth. There is also a jet heading away from Earth called a ''counter jet''. Close into the core, this counter jet is so much dimmer than the main jet that it is invisible in radio waves.

The brightness of the counter jet is less than the main jet by a factor of 1250. This implies that the jet is [[Physics:Theory of relativity|relativistic]] with [[Lorentz factor|Γ]] about 15 (that is, the plasma is moving at 99.8% of the speed of light) and at an angle between 15° and 25° from the line of sight from the Earth. At 408&nbsp;MHz, the power level is 1.81 [[Astronomy:Jansky|Jy]], although this is variable.<ref name="Giroletti">{{cite web|url=http://cdsweb.cern.ch/record/641783/files/0309285.pdf|title=Parsec Scale Properties of Markarian 501
|last=Giroletti|first=M.
|author2=G. Giovannini
|author3=L. Feretti
|author4=W.D. Cotton
|author5=P.G. Edwards
|author6=L. Lara
|author7=A.P. Marscher
|author8=J.R. Mattox
|author9=B.G. Piner
|author10=T. Venturi
|display-authors=8
|date=11 September 2003|access-date=6 December 2011}}</ref>

Beyond 10 kpc from the core, the counter jet becomes visible, showing that the jets have become non-relativistic; that is, plasma is no longer moving close to the speed of light.<ref name="Giroletti" /> The symmetrical radio emission extends to 70", which corresponds to 120 to 200 kpc.<ref name="Giroletti" />

==Blazar research==

In March 2022, scientists led by Ioannis Liodakis studied Markarian 501 during an average state while discerning how blazars make such a bright light using [[Astronomy:IXPE|Imaging X-ray Polarimetry Explorer]] (IXPE.) The researchers were "able to show that the particles in these jets are supercharged by shock fronts, resolving a longstanding 'unanswered question' about the dynamics of these brilliant objects."<ref>{{Cite web |title=Scientists Solve Major Mystery of Powerful Energy Beams Pointed at Earth |url=https://www.vice.com/en/article/4ax8db/scientists-solve-major-mystery-of-powerful-energy-beams-pointed-at-earth |access-date=2022-11-23 |website=www.vice.com |date=23 November 2022 |language=en}}</ref><ref>{{Cite journal |last1=Liodakis |first1=Ioannis |last2=Marscher |first2=Alan P. |last3=Agudo |first3=Iván |last4=Berdyugin |first4=Andrei V. |last5=Bernardos |first5=Maria I. |last6=Bonnoli |first6=Giacomo |last7=Borman |first7=George A. |last8=Casadio |first8=Carolina |last9=Casanova |first9=Vı́ctor |last10=Cavazzuti |first10=Elisabetta |last11=Rodriguez Cavero |first11=Nicole |last12=Di Gesu |first12=Laura |last13=Di Lalla |first13=Niccoló |last14=Donnarumma |first14=Immacolata |last15=Ehlert |first15=Steven R. |date=2022-11-23 |title=Polarized blazar X-rays imply particle acceleration in shocks |journal=Nature |volume=611 |issue=7937 |language=en |pages=677–681 |doi=10.1038/s41586-022-05338-0 |pmid=36418451 |pmc=9684068 |arxiv=2209.06227 |bibcode=2022Natur.611..677L |issn=1476-4687|doi-access=free }}</ref>

{{Blockquote|text=We’ve known about these sources from the 60s. They are among the brightest objects in X-rays and for years we did not know how the X-rays are made. We had a few theories, but the radio and optical data we could get are not able to tell us much.|author=Ioannis Liodakis|title=|source=Postdoctoral Researcher, Finnish Centre for Astronomy with ESO}}

==Catalog entries==
Early designations were 4C 39.49 and B2 1652+39.<ref>{{cite book|last1=Ulrich|first1=Marie Helene|last2=Shakeshaft|first2=John R. |title=The Formation and Dynamics of Galaxies|chapter-url=https://books.google.com/books?id=-SKWVtAwNoIC&pg=PA292|date=1974|publisher=Kluwer Academic Publishers|location=Dordrecht, Holland|isbn=978-90-277-0461-0|page=292|chapter=Optical Observations of Nuclei of Galaxies}}</ref>
The [[Astronomy:Uppsala General Catalogue|Uppsala General Catalogue]] of Galaxies lists this as '''UGC 10599'''.<ref>{{cite web|url=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?UGC%2010599|title=UGC 10599|work=VII/26D/catalog Uppsala General Catalogue of Galaxies (UGC) (Nilson 1973)|access-date=9 December 2011}}</ref>

Other designations: '''B1652+39''' or '''1H1652+398''' or '''TeV J1653+397'''.<ref>{{cite web|url=http://tevcat.uchicago.edu/?mode=1;id=76|title=Markarian 501|work=TeVCat|access-date=10 December 2011}}</ref>

==Notes==
{{Notelist}}

[[File:MRK 0501 2MASS.jpg|thumb|Mrk 501 ([[Astronomy:2MASS|2MASS]])]]

==References==
{{Reflist|40em}}

==External links==
*[http://tevcat2.uchicago.edu/sources/FItw4l TeVCat 2.0: Markarian 501]
*{{cite simbad|title= 7C 165211.80+395026.00}}


[[Category:Blazars]]
[[Category:Principal Galaxies Catalogue objects]]
[[Category:Hercules (constellation)]]
[[Category:Radio galaxies]]
[[Category:4C objects|39.49]]

{{Sourceattribution|Markarian 501}}