Rapid 'turn-on' of a nuclear transient observed by astronomers

November 19, 2018 by Tomasz Nowakowski, Phys.org report
**Rapid “turn-on” of a nuclear transient observed by astronomers
The observed transient luminosities of PS1-13cbe from the PS1 survey in gr izyP1 filters after correction for Galactic extinction. S: marks the epoch of the LDSS spectrum (MJD 56570). Credit: Katebi et al., 2018.

An international team of astronomers has observed the peculiar activity of a nuclear transient event known as PS1-13cbe. The transient, which occurred in the nucleus of the galaxy SDSS J222153.87+003054.2, experienced a rapid flare-up lasting about 70 days. The finding is reported in a paper published November 8 on arXiv.org.

At a redshift of 0.12355, SDSS J222153.87+003054.2 (or SDSS J2221+0030 for short) is a type 2 Seyfert galaxy. It has a central supermassive black hole (SMBH) with an estimated mass of around 20 million solar masses.

In general, Seyfert host (AGN) that produce spectra line emissions from highly ionized gas. Astronomers classify these galaxies as type 1 or 2, depending on the emission lines shown by their spectra.

However, observations show that various AGN types are observed in the same object at different epochs of time. One explanation of this phenomenon is that some type 2 Seyfert galaxies are actually type 1 with inactive engines. This suggests that type 2 Seyfert galaxies are an evolved version of the type 1.

Some AGNs showcase X-ray absorption variations, and are thus called "changing-look" AGNs. Furthermore, in some Seyfert galaxies, the broad emission lines disappear and, while in others broad emission lines appear, what astronomers describe as a "turn-on" of an AGN. So far, the most rapid "turn-ons" observed last less than one year.

Now, a team of researchers led by Reza Katebi of Ohio University reports a rapid "turn-on" of the nuclear transient PS1-13cbe in the nucleus of the galaxy SDSS J2221+0030. PS1-13cbe was detected on July 9, 2013 in the Pan-STARRS1 (PS1) sky survey. Additional observations of this transient and its host galaxy, that led to the new findings, were conducted by the team using NASA's Swift spacecraft, the 6.5 m Magellan Clay telescope and the 2.4 m Hiltner telescope.

According to the paper, PS1-13cbe brightened in the course of about 70 days and reached a peak total optical luminosity of approximately 10.6 tredecillion erg/s, while its temperature roughly stayed constant. Moreover, this rapid "turn-on" of PS1-13cbe was accompanied by the appearance of broad Balmer lines and hence a transition to a type 1 Seyfert galaxy.

"At the time of the outburst, the galaxy changed type to a Seyfert 1 as broad Hα and Hβ appeared and the continuum brightened in the spectrum taken with LDSS3 +57 days after the peak and then changed its type back to a Seyfert 2 as the broad Hα and Hβ disappeared in the spectrum taken with OSMOS 2 years later and did not reappear in spectra taken three and four years after the outburst," the researchers wrote in the paper.

The allowed Katebi's team to conclude that PS1-13cbe is a "changing-look" AGN that has been powered by instabilities in the accretion disk. They added that the "turn-on" of this AGN is among the shortest observed in a "changing look" active galactic nuclei.

Explore further: Researchers discover a blazar-like narrow-line Seyfert 1 galaxy

More information: Reza Katebi et al. PS1-13cbe: The Rapid "Turn on" of a Seyfert 1. arXiv:1811.03694 [astro-ph.GA]. arxiv.org/abs/1811.03694

Related Stories

Astronomers discover 21 changing-look active galactic nuclei

November 28, 2017

(Phys.org)—A group of astronomers led by Qian Yang of the Peking University in Beijing, China, has detected 21 active galactic nuclei (AGN) of a rare type known as changing-look AGNs. The finding, reported November 22 in ...

Active galactic nuclei and star formation

October 15, 2018

Most galaxies host a supermassive black hole (SMBH) at their nucleus. (A supermassive black hole is one whose mass exceeds a million solar-masses.) A key unresolved issue in galaxy formation and evolution is the role these ...

Prototypical active galaxy Arakelian 120 observed by Swift

October 18, 2016

(Phys.org)—Astronomers using NASA's Swift space observatory, have conducted a long-term monitoring campaign of a prototypical active galaxy, designated Arakelian 120 (Ark 120 for short). These observations reveal crucial ...

What are active galactic nuclei?

November 9, 2016

In the 1970s, astronomers became aware of a compact radio source at the center of the Milky Way Galaxy – which they named Sagittarius A. After many decades of observation and mounting evidence, it was theorized that the ...

Extended emission filaments found in the galaxy Markarian 6

September 27, 2018

Russian astronomers have conducted a study of large-scale morphology and kinematics of the ionized gas in the galaxy Markarian 6. The research, in addition to mapping the ionized gas in the stellar disc, has identified a ...

Recommended for you

Total lunar eclipse woos sky watchers

January 21, 2019

An unusual set of celestial circumstances came together over Sunday night and the wee hours of Monday for sky watchers in Europe, Africa and the Americas, where the moon was fully obscured before lighting up again with a ...

Making stars when the universe was half its age

January 18, 2019

The universe is about 13.8 billion years old, and its stars are arguably its most momentous handiwork. Astronomers studying the intricacies of star formation across cosmic time are trying to understand whether stars and the ...

Saturn hasn't always had rings

January 17, 2019

One of the last acts of NASA's Cassini spacecraft before its death plunge into Saturn's hydrogen and helium atmosphere was to coast between the planet and its rings and let them tug it around, essentially acting as a gravity ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Tuxford
not rated yet Nov 29, 2018
This is an observed example of the central tenant of LaViolette's Continuous Creation model, which predict periodic eruptions of the central core, ejecting new matter therefrom and cosmic ray super waves propagating therefrom, changing the climate of planets like Earth periodically, as documented in the ice core records.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.