Supermassive Authors : Ignacio Martn-Navarro, Jean P.

Supermassive Black Hole Control Star Formationin Large GalaxiesMenzi Ngcamphalala NGCMEN001 September 15, 2018Source Article :Title : Black-hole-regulated star formation in massive galaxiesAuthors : Ignacio Martn-Navarro, Jean P. Brodie, Aaron J. Romanowsky,Tomas Ruiz-Lara Glenn van de VenFirst Author’s Institution : University of California ObservatoriesStatus : nature International journal of science1 IntroductionWhen the galaxy evolves the formation of stars process get shutted down. Anew investigation disclosed that using a mass of a black hole that is from thecenter of a galaxy, turn o of the star formation can be determined how shortlycan it take place, since it is known that there is a central supermassive blackhole in every massive galaxy. The shut down is thought to occur when theenergy from a compact region at the center of a galaxy that has much higherluminosity of the electromagnetic spectrum (AGN) ow into a galaxy, so thisoccur by dissipating and heating the gas that would condense as it cool into astar.

Prof Jean Brodie said that this evidence is the rst direct observational,where the eect of black hole on the process of star formation history of thegalaxy can be seen. The new results disclosed that every generation of a galaxyis aected, this is because throughout the life of a galaxy there is a continuousinteraction between the star formation and black hole activity.2 MethodMartin-Navarro determined the star formation histories of the galaxies by ana-lyzing the detailed spectra of their light acquired by the Hobby-Eberly Telescopemassive galaxy survey.

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Astronomers use spectroscopy to measure and separatedierent wavelengths of light from an ob ject. Martin-Navarro analyzed thespectrum of each galaxy by using computational techniques, he then retrievedits star formation history by tting the spectroscopic data in the best combina-tion of stellar populations. He mentioned that this helps to show the amount1Figure 1: The intensity of a supermassive black hole is shown in this gureof Centaurus A, one of the dynamic galactic nuclei nearest to Earth. Thepicture consolidate information from a few telescopes at various wavelengths,demonstrating jets and lobes controlled by the supermassive black hole at thecenter of the galaxy.of light that is from stellar population of dierent ages. The usual size of theunder-massive is RU Me = 2:49 0:37 kpc and over-massive black-hole galaxiesis ROMe = 2:69 0:34 kpc are consistent with average population of galaxieswith the known masses of ( RBHe = 2:71 0:22 kpc ). The mass of suppermas-sive black hole scales is shown in gure 2 with the stellar speed dispersion oftheir host galaxies. Figure 2 express how over-massive and under-massive arelying below and above the line of best tting.

Over-massive have more massivecentral black holes, while under-massive have black-hole galaxies with light sup-permassive black holes. The method where by observed spectrum of a galaxyis decomposed as a temporal series of single population models is called StellarContent and Kinematics via Maximum A Posteriori likelihood (STECKMAP).STECKMAP was used to measure star formation history. Wavelengths between460 and 550 nmwas used for spectroscopic analysis. The Hobby{Eberly Tele-scope Massive Galaxy Survey (HETMGS) was used with long-slit optical spectrato conduct analysis of stellar population, depending on a slit-width but valuesof data resolution varied between 4 :8 and 7 :5. Infared K-band photometry wasused to calculate the size of all galaxies (in a homogenous way).The ma jority of ob jects (about 85%) classied as over-massive or under-massive using our best-tting relation are also over-massive or under-massive3 ResultsAfter Martin determined the star formation histories of galaxies by analyzingthe spectrum of each galaxy, he then found the noticeable dierences when hecompared the histories of the star formation of galaxies with dierent massesof black holes. The dierences only corresponded with the mass of a blackhole not the size, or shape of galaxy.

The results also showed that for galaxies2Figure 2: The stellar speed scattering of galaxies rmly associates with the massof their supermassive black holes . Data points relates toward the 74 HETMGSgalaxies with estimated black hole masses and high-quality spectra.Galaxiesmore than +0 :2 dex over this best-tting connection have black holes moremassive than anticipated for their speed scattering, and consequently are calledover-massive black holes galaxies (red). On the other hand, black hole facilitat-ing less-massive black holes than the normal populace (by 0 :2 dex or past) arecalled under-massive black holes (blue).with similar mass of stars but unique mass of a black hole in the center, thosegalaxies with greater black holes were extinguished before and speedier thanthose with littler black holes. The star formation kept going longer in thosegalaxies with little central black holes. The luminosity of a supermassive blackhole appear when it actively guzzling up the matter from its host inner regionsof the galaxy.

AGN highly varies and are dependent on black hole size, accretionrate of new material that falls into a black hole. Martin further explained thatthey used the mass of a black hole as a proxy for the energy that AGN putinto the galaxy. More energetic feedback from AGN results from the accretionunto more massive black hole. The stellar speed scattering of galaxies rmlyassociates with the mass of their supermassive black holes . Data points relatestoward the 74 HETMGS galaxies with estimated black hole masses and high-quality spectra. They have made utilization of the connection between blackholes mass and star formation histories to demonstrate that the evolution ofstar formation in massive galaxies over inestimable time is driven by black holeactivities. Interestingly, black-hole masses and star formation seem to be relatedas early as z 5.

Figure 3 show the evolution of star formation over cosmic time is stronglycoupled to the mass of the central black hole. Galaxies with over-massive blackholes experienced more intense star formation rates in the very early Universe(look-back times of 10 Gyr or more) than did galaxies with less-massive blackholes. The measurements shown in Figure 3 probe the star formation processes3Figure 3: This gure show how star formation rates and cumulative stellar masshave evolved in over-massive (red), in standard (orange) and in under-massive(blue) black-hole galaxies. Figure a, show the evolution of the star formationrate (SFR) as a function of look-back time; while b, the cumulative mass dis-tribution for the three types of galaxy.

The dierences in formation timescalessuch as those shown in this gure do not depend on galaxy environment. Thisgure represent the Evolution of star formation over cosmic time.4within massive haloes since the early Universe. Interestingly, black-hole massesand star formation seem to be related as early as z 5. Figure 3 shows thatthe evolution of star formation over cosmic time is strongly coupled to a mass ofthe central black hole.

Masses of black holes was measured using many dierentmethods but without detailed information on the stellar population properties.Their nal sample consisted of all HETMGS galaxies for which there are directmeasurements of black-hole masses, and for which they can also determine theirstar formation histories. There are 74 in total, probing total stellar masses fromM 1x 10 10M to M2x 10 12M:4 ConclusionAaron Romanowsky said the exact nature of the feedback from black holes thatterminates formation of stars process is still unknown. Romanowsky further saidblack hole can put energy out into the galaxy in the dierent ways, there aremany ideas from (theorists) that talk about how the quenching of star formationhappens, there still more work that need to be done in order to t the newobservations into models. Their outcomes show that there might be a causalorigin for the watched scaling relations between galaxy properties and blackhole mass, oering observational help for AGN-based extinguishing mechanism.

The quantity of over-massive, standard and under-massive black hole galaxies iscomparable, at 25, 24 and 25 ob jects, separately. Star formation in over-massiveblack-hole galaxies was quenched earlier, with these galaxies reaching 95% oftheir nal mass about 4 Gyr earlier, on average, than under-massive black-holegalaxies, as shown by the cumulative mass distributions in gure 3.5


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