Arxiv – Probing Extragalactic Planets Using Quasar Microlensing (8 pages)<\/a><\/p>\nOver the past two decades, it has been established that planets are ubiquitous in the Milky Way galaxy (e.g., Wolszczan & Frail 1992; Mayor & Queloz 1995; Udry & Santos 2007; Lissauer et al. 2014; Winn & Fabrycky 2015). Extrapolating to the extragalactic regime, it is natural to hypothesize that planets are common in external galaxies as well. However, we lack the observational techniques to test this hypothesis, because compared to their Galactic brethren, extragalactic planets are much farther away and much more difficult to separate from the host stars\/galaxies. Just as gravitational microlensing provides a unique tool to detect planets in the Galaxy (e.g., Mao & Paczynski 1991; Gould & Loeb 1992; Gaudi 2012), it can also provide the capability to detect planets in extragalactic galaxies, by combining microlensing and a galaxy scale gravitational lens.<\/p>\n
They generated a range of magnification maps with \u03b1pl ranging from 0.0001 to 0.001, equivalent to 103<\/sup> \u2013 104<\/sup> planets in the Moon to Jupiter mass range per main sequence star, where the upper boundary is selected to match the recent limit of floating jupiters in the Milky Way (Mr\u00b4oz et al. 2017). Since it is computationally expensive to calculate large magnification maps with a huge number of lenses, they constrain the size of the maps to be 400 \u00d7 400rg with each pixel 0.375 rg, and for each set of parameters, they generate 30 random maps to sample the large scale variation of the magnification pattern.<\/p>\nThis planet to star mass ratio is equivalent to over\u223c 2000 objects per main sequence star in the mass range between Moon and Jupiter, or over \u223c 200 objects in Mars to Jupiter range including 0.08 jupiters. This constraint is consistent with the upper end of the theoretical estimate of \u223c 105<\/sup? between Moon and Jupiter (Strigari et al. 2012), and the recently observed constraint, 0.25 jupiters per main-sequence star, in the Milky Way (Mr\u00b4oz et al. 2017).\n\nPlanets and stars in Galaxy and Universe<\/b><\/p>\nThe Milky Way is the second-largest galaxy in the Local Group, with its stellar disk approximately 100,000 ly (30 kpc) in diameter, and, on average, approximately 1,000 ly (0.3 kpc) thick. As a guide to the relative physical scale of the Milky Way, if the Solar System out to Neptune were the size of a US quarter (24.3 mm (0.955 in)), the Milky Way would be approximately the size of the continental United States. A ring-like filament of stars wrapping around the Milky Way may belong to the Milky Way itself, rippling above and below the relatively flat galactic plane. If so, that would mean a diameter of 150,000\u2013180,000 light-years (46\u201355 kpc).<\/p>\n
The Milky Way contains between 200 and 400 billion stars and at least 100 billion planets. If we assume 300 billion stars and 1,000 Mars to Jupiter size rogue objects.<\/p>\n
The vast number of rogue planets suggests that there are 300 trillion Mars to Jupiter size object in the Milky Way.<\/p>
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If the typical galaxy had 100 billion stars, then there would be 2 x 1023<\/sup> stars in the observable universe.<\/p>\nThere should be 2 x 1026<\/sup> Mars to Jupiter size rogue objects in the observable universe.<\/p>\n","protected":false},"excerpt":{"rendered":"Previously, planets have been detected only in the Milky Way galaxy. Researchers show that quasar microlensing provides a means to probe extragalactic planets in the lens galaxy, by studying the microlensing properties of emission close to the event horizon of the supermassive black hole of the background quasar, using the current generation telescopes. they show … <\/p>\n
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