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EGS-zs8-1

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EGS-zs8-1
EGS-zs8-1 viewed by theHubble Space Telescope
Observation data (J2000[1]epoch)
ConstellationBoötes[1]/Ursa Major
Right ascension14h20m34.89s[1]
Declination+53° 00′ 15.4″[1]
Redshift7.7[1]
Heliocentric radial velocity2,098,548 km/s (1,303,977 mi/s)
Galactocentric velocity2,098,671 km/s (1,304,054 mi/s)
Distance13.1billionly(4.0 billionpc) (light travel distance)
29.5billionly(9.0 billionpc)
(comoving distance)
Apparent magnitude(V)25.3J
Characteristics
TypeLyman-break galaxy
Mass8×109M☉
Size15 kly (diameter)
Apparent size(V)0.004 x 0.0018
Other designations
GCF2012 8053, CANDELS J142034.88+530015.1, SSTSL2 J142034.90+530015.1, SYM2017 9104

EGS-zs8-1is ahigh-redshiftLyman-break galaxyfound at the northernconstellationofBoötes.[2]In May 2015, EGS-zs8-1 had the highestspectroscopicredshiftof any knowngalaxy,meaning EGS-zs8-1 was the most distant and the oldest galaxy observed.[3][4]In July 2015, EGS-zs8-1 was surpassed byEGSY8p7(EGSY-2008532660).[citation needed]

Description

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Artist's impression of EGS-zs8-1

The redshift of EGS-zs8-1 was measured atz= 7.73, corresponding to alight travel distanceof about 13.040 billion light years fromEarth,and age of 13.04 billion years. The galaxy shows a high rate ofstar formation,so it releases its peak radiation at thevacuum ultravioletpart of theelectromagnetic spectrum,near the 121.567 nm (1,215.67 Å)Lyman-alpha emission linedue to the intense radiation from newly formedblue stars,hence it is classified as aLyman-break galaxy;high-redshiftstarburst galaxiesemitting the Lyman-alpha emission line. Because of thecosmological redshifteffectcaused by theexpansion of the universe,the peak light from the galaxy has becomeredshiftedand has moved into theinfraredpart of theelectromagnetic spectrum.[2]The galaxy has acomoving distanceof about 30 billion light years from Earth.[5]

EGS-zs8-1 was born 670 million years after theBig Bang,during the period ofreionization,and it's 15 percent the size of the Milky Way. The galaxy was found to be larger than its other neighbors in that period when the universe was still very young.[4]Its mass at the time the light was emitted is estimated to have been about 15% of theMilky Way's current mass. The galaxy was making new stars at roughly 80 times the rate of the current Milky Way, or equivalent to 800M☉worth of material turning to stars every year.[5]The light reaching Earth was made by stars in EGS-zs8-1 that were 100 million to 300 million years old at the time they emitted the light.[6]The age of EGS-zs8-1 places it in thereionizationphase of creation, a time when hydrogen outside the galaxies was switching from a neutral to ionized state. According to the galaxy's discoverers, EGS-zs8-1 and other early galaxies were likely the causes of reionization.[7][8]

Discovery

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In 2013,Yaleastronomer Pascal Oesch spotted an unexpected bright object while looking atHubble Space Telescopeimages. He then confirmed the existence of the object using theSpitzer Space Telescope.[4]Redshiftcalculations, using the Multi-Object Spectrometer for Infrared Exploration (MOSFIRE) equipment at theW.M. Keck ObservatoryinHawaii,were then performed to precisely determine the age of the galaxy.[7]Oesch and his colleagues at Yale and theUniversity of California, Santa Cruzannounced the find, which was named EGS-zs8-1, in May 2015 surpassing the previous record for oldest galaxy by about 30 million years.[4]

See also

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Records
Preceded by Most distant galaxy
2015 		Succeeded by

References

[edit]
  1. ^abcde"Astronomers Set a New Galaxy Distance Record - Fast Facts".HubbleSite. 5 May 2015. STScI-2015-22.Retrieved9 May2015.
  2. ^abOesch, P.A.; et al. (3 May 2015). "A Spectroscopic Redshift Measurement for a Luminous Lyman Break Galaxy at z=7.730 using Keck/MOSFIRE".The Astrophysical Journal.804(2): L30.arXiv:1502.05399.Bibcode:2015ApJ...804L..30O.doi:10.1088/2041-8205/804/2/L30.S2CID55115344.
  3. ^Villard, Ray; Chou, Felicia (5 May 2015)."Astronomers Set a New Galaxy Distance Record".HubbleSite.Retrieved7 May2015.
  4. ^abcdBorenstein, Seth (5 May 2015)."Astronomers find farthest galaxy: 13.1 billion light-years".AP News.Retrieved6 May2015.
  5. ^abOverbye, Dennis(5 May 2015)."Astronomers Measure Distance to Farthest Galaxy Yet".The New York Times.Retrieved6 May2015.
  6. ^Cofield, Calla (5 May 2015)."This Galaxy Far, Far Away Is the Farthest One Yet Found".Space.com.Retrieved7 May2015.
  7. ^abStaff (5 May 2015)."Astronomers unveil the farthest galaxy".Phys.org.Retrieved6 May2015.
  8. ^Lemonick, Michael D. (6 May 2015)."Farthest Galaxy Spotted Yet Is 13 Billion Light-Years Away".National Geographic News.Archived fromthe originalon 9 May 2015.Retrieved18 June2015.
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