Markarian 501 (or Mrk 501) is a
galaxy
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...
with a spectrum extending to the highest energy gamma rays.
It is a
blazar
A blazar is an active galactic nucleus (AGN) with a relativistic jet (a jet composed of ionized matter traveling at nearly the speed of light) directed very nearly towards an observer. Relativistic beaming of electromagnetic radiation from the ...
or
BL Lac object
A BL Lacertae object or BL Lac object is a type of active galactic nucleus (AGN) or a galaxy with such an AGN, named after its prototype, BL Lacertae. In contrast to other types of active galactic nuclei, BL Lacs are characterized by rapid and l ...
, which is an
active galactic nucleus
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not pr ...
with a jet that is shooting towards the Earth.
In the
very-high-energy gamma ray
Very-high-energy gamma ray (VHEGR) denotes gamma radiation with photon energies of 100 GeV (gigaelectronvolt) to 100 TeV (teraelectronvolt), i.e., 1011 to 1014 electronvolts. This is approximately equal to
wavelengths between 10−17 and 10−20 ...
region of the spectrum, at
energies
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat ...
above 10
11 eV (0.1 TeV), it is the brightest object in the sky.
The object has a redshift of z = 0.034.
[
The galaxy hosting the blazar was studied and catalogued by ]Benjamin Markarian
Benjamin "Benik" Egishevitch Markarian ( hy, Բենիամին Եղիշեի Մարգարյան) was an Armenian astrophysicist. Markarian's Chain is a group of galaxies which was named after him when he discovered that its members move with a com ...
in 1974. It was first determined to be a very high energy gamma ray emitter in 1996 by John Quinn at the Whipple Observatory.
Galaxy
The elliptical galaxy is located in the constellation of Hercules
Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures.
The Romans adapted the Gr ...
at right ascension
Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth.
When paired w ...
16h 53.9m and declination
In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...
+39° 45'. Its visible size appears to be 1.2 by 1 minute of arc.
Gamma rays
The gamma ray
A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...
s from Mrk 501 are extremely variable, undergoing violent outbursts.
The gamma ray spectrum of Mrk 501 shows two humps. One is below 1 keV and can be considered to be X-ray
An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...
s and the other is above 1 TeV. During flares and outbursts the peaks increase in power and frequency.[ Flares lasting 20 minutes with rise times of 1 minute have been measured by ]MAGIC
Magic or Magick most commonly refers to:
* Magic (supernatural), beliefs and actions employed to influence supernatural beings and forces
* Ceremonial magic, encompasses a wide variety of rituals of magic
* Magical thinking, the belief that unrela ...
. In these flares the higher energy gamma rays (of 1.2 Tev) were delayed 4 minutes over the 0.25 TeV gamma rays. This delay has led to various theories, including that space is bigger at small dimensions with a foamy quantum texture. 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
In a relativistic theory of physics, a Lorentz scalar is an expression, formed from items of the theory, which evaluates to a scalar, invariant under any Lorentz transformation. A Lorentz scalar may be generated from e.g., the scalar product of ve ...
, but could provide a clue for unification theory. Observations of Dr. Floyd Stecker of NASA's Goddard Space Flight Center
The Goddard Space Flight Center (GSFC) is a major NASA space research laboratory located approximately northeast of Washington, D.C. in Greenbelt, Maryland, United States. Established on May 1, 1959 as NASA's first space flight center, GSFC empl ...
of Mrk 501 and Mrk 421 demonstrated that there is no violation of Lorentz invariance. The galaxy is also variable in visible light between magnitude 14.5 and 13.6.
During the discovery observations flashes at the average rate of one in seven minutes were observed. Cosmic ray
Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...
s (that is, fermionic
In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. Generally, it has a half-odd-integer spin: spin , spin , etc. In addition, these particles obey the Pauli exclusion principle. Fermions include all quarks and ...
or 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 10−12 cm−2s−1
Black hole
Blazars are likely to originate from matter falling into a black hole
A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...
and possibly a binary black hole
A binary black hole (BBH) is a system consisting of two black holes in close orbit around each other. Like black holes themselves, binary black holes are often divided into stellar binary black holes, formed either as remnants of high-mass binary ...
. The velocity dispersion (which is the maximum difference in the velocity toward or away from Earth) observed in the galaxy is 372 km/s which predicts a black hole mass of (0.9 − 3.4) × 109 M⊙. However, dispersion of velocity was also measured as 291 and 270 km/s so the central mass may be less. A 23-day variability suggested that an object may be orbiting the central black hole with a 23-day period.
Jet
With very-long-baseline interferometry
Very-long-baseline interferometry (VLBI) is a type of astronomical interferometer, astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telesco ...
, the fine detail of radio waves
Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz (GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (short ...
can be seen down to milliarcsecond
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
(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.[ with further detail at arXiv:astro-ph/0309285]
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 relativistic with 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 MHz, the power level is 1.81 Jy, although this is variable.
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. The symmetrical radio emission extends to 70", which corresponds to 120 to 200 kpc.
Blazar Research
In March 2022, scientists led by Ioannis Liodakis studied Markarian 501 during an average state while discerning how blazers make such a bright light using Imaging X-ray Polarimetry Explorer
Imaging X-ray Polarimetry Explorer, commonly known as IXPE or SMEX-14, is a space observatory with three identical telescopes designed to measure the polarization of cosmic X-rays of black holes, neutron stars, and pulsars. The observatory ...
(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."
Catalog entries
Early designations were 4C 39.49 and B2 1652+39.
The Uppsala General Catalogue
The Uppsala General Catalogue of Galaxies (UGC) is a catalogue of 12,921 galaxies visible from the northern hemisphere. It was first published in 1973.
The catalogue includes essentially all galaxies north of declination -02°30' and to a limiting ...
of Galaxies lists this as UGC 10599.
Other designations: B1652+39 or 1H1652+398 or TeV J1653+397.
Notes
References
External links
TeVCat 2.0: Markarian 501
*
{{Hercules (constellation)
Discoveries by Benjamin Markarian
BL Lacertae objects
Blazars
Principal Galaxies Catalogue objects
Markarian galaxies
Hercules (constellation)