A new super-lipid X-ray source has been discovered in Galaxy NGC 55

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A new super-lipid X-ray source has been discovered in Galaxy NGC 55

XMM-Newton stacked image of NGC 55. Circles with radius 2000 around the ULXS are plotted with surface brightness profiles from the Filter-RG610 DSS image. The color bar displays the number of counts. Credit: Rupa et al., 2022.

Using ESA’s Texm-Newton and NASA Swift Space Telescopes, an international team of astronomers has observed a nearby galaxy known as NGC 55. They have discovered a new source of transient X-rays in this galaxy. The conclusion was reported in a paper published July 19 on the Arxiv server before printing.


Ultraviolet X-ray sources (ULXS) are point sources in the sky that are extremely bright in X-rays each with more than a million suns emitting wavelengths. They are less luminous than Active Galactic Nuclei, but brighter than any known stellar process. Although several studies of ULXs have been conducted, the fundamental nature of these sources remains unresolved.

Located about 6.5 million light years Far away, NGC 55 (dubbed the Whale Galaxy) is one of the closest galaxies to the local group. that it Mass Estimated at 20 billion solar masses. Previous observations of NGC 55 with XMM-Newton revealed that it hosts at least one ulx.

Now, a group of astronomers led by Alessandra Roppa of the University of Palermo in Italy reports another discovery in NGC 55. They find that an object, designated XMMU J001446.81-391123.48 and classified as a transient X-ray source, reaches a peak luminosity that allows it to be reclassified at It is ULX.

“In this work, we provide evidence for a new (second) Ulx in Galaxy NGC 55, thanks to recent XMM-Newton observations,” the researchers wrote in the paper.

New XMM-Newton’s in-depth observations allowed Robba’s team to find that the XMMU J001446.81-391123.48 reaches peak luminosity above 1.6 erg/s. Therefore, the source was confirmed as a ULX and received the designation NGC 55 ULX-2.

The researchers note that given the transient nature of some ULXS, newly discovered sources are not always new sources. NGC 55 ULX-2 is a good example that in some cases these sources are detected with luminosity less than 1 erg/s of 1 duodecillion before reaching the ULX system.

The study found that unlike many transients, which are characterized by a telephone spectrum, NGC 55 ULX-2 has a soft spectrum. The astronomers added that the X-ray spectrum of ULX-2 is much softer than in previous observations and was classified by them as soft ulx.

According to the research, the temporal behavior of NGC 55 ULX-2 shows that the time scales of flow variances are of the order of one month. This is likely due to small changes in the accretion rate or due to super-orbital modifications, attributed to the front of the accretion disk.

Astronomers also searched in depth for periodic signals from NGC 55 ULX-2. However, no significant coherent signals from this source were detected.


Looking for an ultra-contrast X-ray source NGC 925 ULX-3


more information:
A. Robba et al, a transient super-prime xenogeneic source in NGC 55. Arxiv: 2207.09447v1 [astro-ph.HE]And the arxiv.org/abs/2207.09447

© 2022 Science X Network

the quote: New Ultraluminous X-ray source detected in Galaxy NGC 55 (2022, July 26) retrieved on July 27, 2022 from https://phys.org/news

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