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Astronomers are investigating a curious case of a supernova associated with gamma radiation



  Astronomers are investigating a curious case of a supernova associated with gamma radiation
LBT r-band image of the host galaxy in GRB 1
71010A. GRB's radio position is marked with a red cross. Credit: Melandri et al., 2019.

Using a set of space- and ground-based telescopes, an international team of astronomers conducted a detailed study of supernova SN 2017htp associated with gamma-ray burst GRB 171010A. The results of the study, presented in an article published October 26 on arXiv.org, could shed more light on such phenomena.

Astronomers generally agree that gamma-ray (GRB) short-term coincidence coincides with powerful supernovae (SNe), called hypernovae, which occur when a massive star collapses into a black hole. The first conclusive evidence for the SN-GRB connection came in 2003, when an SN-like spectrum emerged from the spectrum of the optical transient of GRB 030329.

But the connection between GRB and SNe is still not fully understood. Studies show that not all powerful supernovae produce gamma rays, which is why some GRBs may not be associated with deaths from massive stars at all. Therefore, detailed investigations of SN-GRB compounds may be helpful in determining the true nature of these phenomena.

Now a group of astronomers led by Andrea Melandri of the Brera Observatory in Italy is reporting the discovery of a new GRB-SN connection. They found that GRB 171010A, an old-ray burst identified in October 2017 at a red shift of 0.33, is associated with the type Ib / c nuclear collapse supernova SN 2017htp, which was discovered in November 2017 at a similar red shift.

"We present a new case of such a relationship at z = 0.33 between GRB 171010A and SN 2017htp (…) We analyzed the optical photometry and spectroscopy of GRB 171010A and SN 2017htp over almost four months since its discovery, "astronomers wrote in the magazine.

Examining the properties of the new GRB-SN connection, astronomers found that about 0.33 nickel solar masses are required to reproduce the maximum brightness of the SN 2017htp, with an ejecta mass of about 4.1 solar masses and a kinetic energy at about 8.1 sixdecillion erg. These results are consistent with other previously observed GRB-SN compounds.

Furthermore, the study revealed the characteristics of the GRB 171010A region and part of the GRB host galaxy. It turned out that the galaxy has a diameter of about half the milk path, making it the second largest GRB host known to date. The researchers noted that although GRB 171010A values ​​are larger in size than most GRB host galaxies, its spectral properties are typical of such objects.

The star formation rate of the GRB star-forming region was estimated to be about 0.2 solar masses per year, while its metallicity (12 + log (O / H)) was measured to a level of about 8.15. According to the thesis, these values ​​are in line with those reported for other GRB-SN connections.

"The observed properties of the GRB star-forming region are similar to those in the star-forming regions that host other GRBs with an associated type Ic-BL SN and with available spatially resolved observations," the magazine states.

In closing remarks, astronomers emphasized that their study seems to confirm that the metallicity in the GRB environment is generally low, even in high metallicity. host galaxies.


Dusty star-forming galaxy MAMBO-9 examined in detail


More information:
GRB 171010A / SN 2017htp: a GRB-SN at z = 0.33, arXiv: 1910.14160 [astro-ph.HE] arxiv.org/abs/1910.14160

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Astronomers investigate a curious case of a supernova in connection with gamma radiation (2019, November 11)
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