Feedback from active galactic nuclei (AGN) is seen as one of the main contributors to the evolutionary process of galaxies. Especially at high luminosity, many sources seem to harbor a powerful central supermassive black hole that allows for strong jets in radio and/or winds observed in the optical and UV ranges of their electromagnetic spectra.

One class of AGN are the quasars, which are the most powerful and luminous objects in the Universe that can be seen over cosmic epochs, spanning 90% of the age of the Universe. Nowadays, the astronomers make use of a powerful tool to organize the observed quasar spectroscopic diversity, which is the so-called “fourth-dimensional Eigenvector 1” (4DE1). The 4DE1 consists of an empirical formalism based on four independent observational measures (in optical, UV, and X-rays).

The optical plane of the 4DE1, also known as the “Main Sequence” (MS) of quasars act like the “H-R diagram” do for the stellar classification and allows us to separate the quasars into two different populations and also in different spectral types. The main physical drivers of the MS are thought to be (a) the orientation of the source, which can produce an effect of broadening or narrowing on the emission line profile seen in the electromagnetic spectra and (b) the Eddington ratio, which indicates the accretion rateof the source. The exploration of the 4DE1 space together with the quasar MS can significantly contribute to understand how supermassive black holes co-evolve with the host galaxies, a question that is closely linked to their accretion rates and the presence of nuclear outflows and jets.

In this work we have extended the study of the MS to sources at high redshift and high luminosity with a sample of 22 quasars observed in the infrared at the Very Large Telescope (VLT), which is part of the European Southern Observatory (ESO) and is located in cerro Paranal, Chile. The data has a remarkable quality and allows for the analysis of the optical range, due to the displacement of the spectra caused by the distance of the sources. Additional data containing UV spectra were collected from astronomical databases, especially from the Sloan Digital Sky Survey (SDSS).

We study the structure and kinematics of the broad line region (BLR) of the accretion disk and quasar physics through the exploration of rest-frame UV and optical broad emission lines, arising within light weeks of the central continuum source. We have applied a very robust method of decomposition of the emission line profiles as well as of the continuum and FeII contribution, which can be very strong for some high-luminosity quasars and may be related to the chemical evolution of the quasar. We have found that the MS at high-luminosity presents a significant displacement in comparison to the low-luminosity MS, especially due to the broadening of the emission line profiles observed as the luminosity increases.

It is already known that one of the main spectral detectors of outflowing gas are the high-ionization emission lines. Indeed, our study indicates that these lines are the ones that present the strongest outflowing components not only in the optical (like is the case of the [OIII]λλ4959,5007 emission lines) but also in the UV (like CIVλ1549) spectral range. Actually, by performing an interline comparison, we have found that there is a strong trend between optical and UV winds: the quasars that present the strongest optical outflows will also have the strongest UV outflows.

This result mirrors the behaviour observed in low-luminosity quasars, whose high-ionization lines are dominated by an outflow component. It also supports a possible physical connection between an inner outflow on scales of a few hundreds gravitational radii, where the UV CIVλ1549 is emitted, and an outflow at the outer edge of the BLR, where the optical [OIII]λλ4959,5007 likely originates. The main factor governing these outflows is most likely the Eddington ratio, which is directly related to the AGN accretion.

Article: A. Deconto-Machado et al. “High-redshift quasars along the Main Sequence”. Astronomy and Astrophysics, 2023. https://doi.org/10.1051/0004-6361/202243801

Contact:

Instituto de Astrofísica de Andalucía (IAA-CSIC)

Alice Deconto Machado - adeconto@iaa.es

ORIGINAL SOURCE: https://www.iaa.csic.es/en/news/atlas-active-galaxies-shows-outflows-are-common-even-most-dormant-galaxies

The Institute of Astrophysics of Andalusia (IAA-CSIC) studies in depth a sample of LINERs, the least luminous type of active galaxy, and finds that half of them produce gas outflows

Galactic outflows, capable of generating large amounts of energy and transporting gas over large distances, play a fundamental role in the evolution of galaxies. In the case of active galaxies, whose brightness is attributed to the existence of a supermassive black hole surrounded by a disc of matter feeding it, it is common to observe outflows produced by the black hole. However, the properties of these phenomena, which are barely known in less bright active galaxies, have yet to be characterised in detail. A study by researchers at the Institute of Astrophysics of Andalusia (IAA-CSIC) has published the most complete atlas of outflows in a type of low-power active galaxies that are the most abundant in the local universe.

LINERs, an acronym for "low ionisation nuclear emission line region", account for about one third of the galaxies in our environment. Their nuclei emit a specific type of radiation (the emission of weakly ionised or neutral atoms), and their energy shows a higher intensity than galaxies whose energy comes only from stars, but lower than those in which supermassive black holes are very actively consuming material.

In the latter, galactic outflows generate feedback processes that can even stop star formation, but until now it was not even known how frequent they are in LINER galaxies. This could be due to the fact that the particularities of these objects prevent their formation or to an observation bias: these phenomena tend to be found in very powerful active nuclei, where they are easily identified, since the fluxes usually show a scale proportional to the luminosity of the nucleus. active.

"In this work we have imaged ionised gas from a sample of seventy LINER galaxies, making it the largest sample of such studies to date. The outflows are distinguished in the images as extended emission emerging from the galactic nucleus. By combining the information from the images with existing spectroscopic information in the literature, we have quantified for the first time how common outflows are in this type of active galaxy and found that approximately 50% of all LINERs in the local universe show galactic outflows", says Laura Hermosa (IAA-CSIC).

The work has also made it possible to divide the sample into four different types of outflow configurations depending on how the emission is distributed: "core-halo" for unresolved nuclear emission, "disc" for structures similar to small spiral arms or discs, "bubble" for biconical, filamentary or bubble-shaped structures emerging from the core that the team identifies as superoutflow candidates, and "dusty" when large amounts of dust obscure the nuclear emission.

"Moreover, combining the optical information with X-rays, we see a correlation between both emissions for 60% of the sample, which indicates that both emissions are generated in the same spatial region of active galaxies (LINER type), as has already been seen in other higher luminosity galaxies", concludes Laura Hermosa (IAA-CSIC).

Article: L. Hermosa Muñoz et al "A search for ionised gas outflows in an H alpha imaging atlas of nearby LINERs". Astronomy & Astrophysics, 2022 https://doi.org/10.1051/0004-6361/202142629

Contact:

Instituto de Astrofísica de Andalucía (IAA-CSIC)

Unidad de Divulgación y Comunicación

Silbia López de Lacalle - sll@iaa.es - 958230676

https://www.iaa.csic.es

https://divulgacion.iaa.csic.es

ORIGINAL SOURCE: https://www.iac.es/en/outreach/news/caught-act-winds-driven-supermassive-black-holes-directly-impact-star-formation

AUTHORS: Patricia Sonia Barbara Bessiere, Cristina Diosco Ramos Almeida

Patricia Bessiere, a researcher at the Instituto de Astrofísica de Canarias (IAC), has led research which has used data from the KECK telescope in Hawaii to understand the impact that active galactic nuclei have on star formation in their host galaxies. The results are published today in the journal Monthly Notices of the Royal Astronomical Society Letters.

One of the key questions that astronomers are trying to answer is ‘Why do galaxies look the way they do?’. Computer simulations of how galaxies formed and evolved suggest that there should be many more very large galaxies than we actually observe, so what is the missing ingredient in these simulations? What is the process within galaxies that stops too many stars from forming?

We now know that all massive galaxies harbour a super massive black hole at their heart, which is millions or billions of times heavier than our own sun. When the amount of gas from within the galaxy falling onto the black hole abruptly increases, it becomes incredibly hot and vast amounts of energy are released into the galaxy. When a black hole is going through such a phase, it is known as an Active Galactic Nucleus or AGN and astronomers believe that this phenomenon may be the missing ingredient they have been searching for. Some of the energy released by the AGN will have the effect of pushing the gas out of the galaxy, a process known as 'AGN driven winds' or 'AGN feedback', which means that there will be less gas from which to form new stars.

A team of scientists at the IAC have been trying to catch this process in action. Using integral field spectroscopy (IFS) from the KCWI instrument on the Keck telescope in Hawaii, which allows astronomers to simultaneously take many spectra at different locations in the galaxy, they have been able to map both the AGN driven winds and the ages of stars across the inner region of the well studied active galaxy Markarian 34. Taking this approach, they hoped to understand if these winds were having a direct impact on star formation. The results of this study are published today in Monthly Notices of the Royal Astronomical Society Letters as part of the “QSOFEED” project (http://research.iac.es/galeria/cra/qsofeed/) whose aim is to understand how supermassive black holes affect the galaxies that host them.

What the team found shows that that AGN and the winds that they drive have a complex impact on their host galaxies. On one side of the galaxy, they have shown that ahead and at the edges of the wind, new stars are being formed. Patricia Bessiere, who led the study, explains why this may be happening. “Some theoretical studies and computer simulations suggest that, as the AGN driven wind passes through the galaxy, the denser, cooler gas ahead and to the sides is compressed, making the conditions for star formation more favourable. This means that the wind is actually triggering star formation rather than suppressing it.”

However, on the other side of the galaxy, the rate of star formation is found to be unaffected by the passage of the wind. The team suggest that this might be because the wind here is faster and more turbulent meaning that the conditions for star formation are not similarly enhanced. Cristina Ramos Almeida, an IAC researcher and co-author of the study, explains that “what we are seeing here may be evidence of ‘preventive’ feedback, meaning that the wind is disrupting the gas in the galaxy so that it can’t collapse to form new stars”.

“This study demonstrates that the relationship between AGN and their host galaxies is complex and can impact different regions in different ways. The findings of this observational investigation will be important in informing future modelling of galaxy evolution and the role played by AGN”, explains Patricia Bessiere.

To expand our understanding of this relationship, the team now plan to extend their study by observing a larger sample of AGN using the MEGARA instrument, installed on the 10 m Gran Telecopio CANARIAS (GTC). This will allow the team to obtain IFS data which they will use to characterise the spatial distribution of both the winds and the stellar populations. This will help astronomers to understand the details of the relationship between the AGN and star formation and, importantly, how common such interactions are.

Article: P. S. Bessiere, C. Ramos Almeida. Spatially resolved evidence of the impact of quasar driven outflows on recent star formation: The case of Mrk 34. Monthly Notices of the Royal Astronomical Society: Letters, Volume 512, Issue 1, Pages 54–59. DOI: https://doi.org/10.1093/mnrasl/slac01

IAC contacts:

Patricia Bessiere (pbessiere@iac.es)

Cristina Ramos Almeida (cra@iac.es)

ORIGINAL SOURCE: https://www.iaa.csic.es/en/news/first-results-mascot-project-suggest-galaxies-turn-inside-out

The Institute of Astrophysics of Andalusia (IAA-CSIC) participates in MASCOT, a large-scale study of the cold gas in galaxies, an essential element for understanding how galactic evolution works

The apparently immutable galaxies are in a state of flux motivated by various factors that drive their evolution. Among them stands out the formation of stars, which are born from large and cold clouds of molecular gas and whose abundance depends on the available gas. The MASCOT project, promoted by the European Southern Observatory (ESO) and with the participation of the Institute of Astrophysics of Andalusia (IAA-CSIC), was born to study this cold gas, essential for understanding galactic evolution. As a legacy, or public and open release of data, the project has just released its first results, with detailed observations of some two hundred galaxies.

“The galaxies that we observe in the current universe exhibit a wide variety of properties, but they are usually classified as blue and red, that is, galaxies that form stars and dim galaxies where stars are barely being born. Few galaxies show intermediate characteristics and are located in the so-called "green valley", which poses a problem: if the process of galactic evolution were simply a matter of the slow depletion of gas, we would expect to see many more galaxies in the green valley. Thus, some mechanism must be stopping the formation of stars, making the transition from blue to red relatively fast”, says Sara Cazzoli, a researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who participates in the project.

MASCOT, led by Dominika Wylezalek (University of Heidelberg), will study in detail a set of galaxies from the MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) database, a project that observed ten thousand galaxies and provided two-dimensional maps of, for example, the velocity and age of stars in the galaxies, the abundance of elements or the rate of star formation. However, MaNGA did not provide data on the cold phase of the gas. This is the focus of MASCOT, which will study the molecular gas content available for star formation, as well as the relationship between the properties of molecular gas, such as mass and kinematics, and the rate of star formation and composition.

In this first series of data, the scientific team has observed that, by relating the mass of molecular gas to stellar ages, galaxies with less gas tend to show older stellar populations near the galactic center, which is an indication that the quenching of galaxies, or the change from blue to red, occurs from the inside out.

"Feedback due to the activity of supermassive black holes and/or violent star formation is being explored to explain this cooling. These processes can trigger the formation of large gas motions, the galactic superwinds, and thus heat up the cold interstellar medium. This slows down or, in the most extreme cases, stops star formation, first in the centre of galaxies and then in more peripheral areas", says Sara Cazzoli (IAA-CSIC).

The MASCOT study is carried out from the Arizona Radio Observatory (ARO), a twelve-metre antenna capable of detecting cold gas, and this data release represents just over half of the 1400 hours of observation available. The total sample studied will be about 250 to 300 galaxies.

Article: D. Wylezalek et al. "MASCOT - An ESO-ARO legacy survey of molecular gas in nearby SDSS MaNGA galaxies: I. first data release, and global and resolved relations between H2 and stellar content". Monthly Notices of the Royal Astronomical Society, Vol 510, Issue 3, March 2022 https://doi.org/10.1093/mnras/stab3356

Contact:

Instituto de Astrofísica de Andalucía (IAA-CSIC)

Unidad de Divulgación y Comunicación

Silbia López de Lacalle - sll[arroba]iaa.es - 958230676

https://www.iaa.csic.es

https://divulgacion.iaa.csic.es

ORIGINAL SOURCE: https://www.iac.es/en/outreach/news/supermassive-black-holes-change-central-regions-galaxies

Cristina Ramos Almeida, a researcher at the Instituto de Astrofísica de Canarias (IAC), has led research which used data from the ALMA telescope in Chile to understand how supermassive black holes impact the host galaxies they inhabit. The results are published today in the journal Astronomy & Astrophysics.

The supermassive black holes in the centres of galaxies play an important role in regulating their growth, but we still don’t know exactly how this happens or under what circumstances. What we do know is that it occurs during a phase when the black hole is consuming material from the galaxy at a high rate, and its mass is growing quickly. During this phase we say that the galaxy has an active nucleus (or AGN).

These periods of nuclear activity can recur, as long as there is gas available to feed the black hole. One of its effects are the winds of gas driven outwards from the centre of the galaxy by the energy liberated by the active nucleus or other related phenomena. When the gas in these winds is tenuous, they can reach velocities of up to thousands km/s, while for dense gas these velocities only reach hundreds km/s. For the most energetic AGNs, such as some quasars, the winds can drive out all the gas in the centre of a galaxy, preventing further star formation.

To study the dense and cold winds (at temperatures of less than -170º C), it is necessary to use telescopes such as the Atacama Large Millimetre/submillimetre Array (ALMA), which observes radiation at millimetre and submillimetre wavelengths, which lie between the infrared and the radio. ALMA is an interferometer comprising 66 high precision movable antennas, which have a maximum separation of 16 km. This allows the study of galaxies in unprecedented detail in this wavelength range.

Using data from active galaxies obtained with ALMA an article is being published today in the journal Astronomy & Astrophysics by an international team led by IAC researcher Cristina Ramos Almeida. In the article the authors analyse data from a sample of seven highly energetic quasars in the local universe. This work is part of the project “QSOFEED” , whose aim is to understand how supermassive black holes affect the galaxies that host them.

“ALMA has let us study the winds of cold molecular gas from these quasars using emission from the carbon monoxide molecule”, explains Ramos Almeida. “This analysis is important because this cold dense gas is the material from which new stars are formed, and until now there has not been data of this high quality and resolution for a set of dust-obscured quasars in the local universe”. This type of quasar is interesting because it may be a key phase during which the active nucleus is evacuating and consuming gas at a very high rate, which will then give way to a non-obscured phase. Studying these nearby objects is key to understanding what happened in these types of galaxies when the universe had only a quarter of its present age”.

Based on the new data from ALMA the team have discovered that the molecular winds are mainly coplanar with the disc where the majority of the molecular gas is found, and they are relatively compact and slow, reaching maximum velocities of only 200-350 km/s. Nevertheless these winds, together with the action of radio jets in some cases, are responsible for modifying the content and the distribution of the gas in these central regions (the central kiloparsec, which corresponds to ~3300 light years). “Even though the total content of molecular gas in the host galaxies is not significantly changed, the innermost regions are disrupted by the action of these winds” says Anelise Audibert, an IAC researcher who is a co-author of the article.

The next step is to observe a larger sample of obscured quasars with MEGARA, an instrument installed on the Gran Telescopio CANARIAS (GTC), and with ALMA, to characterize its ionized and molecular winds. “We also want to investigate the stellar populations of the host galaxies, to see if the most extreme winds are those which have had the greatest effect on the formation of new stars. This will let us quantify directly the effect of AGN feedback” concludes Patricia Bessiere, an IAC researcher and another co-author of the article, whose research is centred on this aspect of the project.

Artículo: C. Ramos Almeida, M. Bischetti, S. García-Burillo, A. Alonso-Herrero, A. Audibert, C. Cicone, C. Feruglio, C. N. Tadhunter, J. C. S. Pierce, M. Pereira-Santaella, P. S. Bessiere. The diverse cold molecular gas contents, morphologies, and kinematics of type-2 quasars as seen by ALMA. Astronomy & Astrophysics, 658, A155, https://www.aanda.org/component/article?access=doi&doi=10.1051/0004-6361/202141906

IAC contacts:

Cristina Ramos Almeida (cra[at]iac.es)

Anelise Audibert (anelise.audibert[at]iac.es)

Patricia Bessiere (patricia.bessiere[at]iac.es)

ORIGINAL SOURCE: https://www.iaa.csic.es/en/news/observed-first-time-jet-gas-it-emerges-central-star-planetary-nebula

Thanks to MEGARA instrument of the Gran Telescopio Canarias, researchers from the Institute of Astrophysics of Andalusia (IAA-CSIC) have observed and analyzed the jet of NGC 2392, which points to the existence of a companion star

All stars with a mass less than eight times that of the Sun will end their lives as planetary nebulae, formed by a central star -the "bare" core of the star after the expulsion of its outer layers- surrounded by a fluorescent envelope. These nebulae can have spherical, bipolar or highly complex shapes and, although it is still unknown why one shape or another develops, the indications point to the participation of bipolar jets of material launched by the action of a companion star. A group of astronomers led by the IAA-CSIC has traced the bipolar jet of the planetary nebula NGC 2392 to its central star, thus demonstrating that the jet launch process is still active.

After exhausting their fuel, low and intermediate mass stars shed their outer layers, forming an envelope of ionized gas around a white dwarf star: a planetary nebula. "Until just a couple of decades ago it was believed that the morphologies of planetary nebulae were due to the interaction of stellar winds launched in two different evolutionary phases, a model that did not explain the asymmetric or multipolar forms of some of them -points out Martín A. Guerrero, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who is leading the study-. Now we know that very fast and collimated jets of material, which are formed at the end of the star's life, could interact with the envelope expelled in previous stages and draw different morphologies”.

The origin of this paradigm shift dates back to the mid-1980s, when what was called a high-speed “bipolar flow” was discovered precisely in NGC 2392, the nebula object of this study, and which represented the first indication of a jet of material in a planetary nebula. And, although the speed of the material could even be measured, the brightness of the nebula (especially the inner shell) made it impossible to obtain a direct image of the jet.

Up to now. Today we have a technique known as integral field spectroscopy, capable of resolving previously unattainable details and used by state-of-the-art instruments such as MEGARA, which operates at the Gran Telescopio Canarias (GTC). "The extraordinary tomographic capacity of MEGARA has allowed us to separate the terribly weak emission of the jet from the bright nebular emission," says Sara Cazzoli, a researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who is participating in the work.

Thus, almost four decades after the discovery of the jet in NGC 2392, researchers have discovered that it consists of two large globules (and some fainter nodules) emerging from the central star and extending beyond the outer shell of the nebula. The material in the jet shows a velocity of about 206 kilometers per second, an age of about 2600 years and a linear size twice that of the nebula itself.

According to the results, the jet passes through the inner bright shell and, since the jet and the shell show similar speeds, everything indicates that it is the jet that accelerates the gas of the shell and shapes it, and not the weak stellar wind of the star. Furthermore, the MEGARA 3D tomography of the jet reveals that it is currently being collimated, unlike the fossil jets, already inactive, detected in other evolved planetary nebulae.

“Finally, this work supports a result that we obtained in 2019 and that analyzed the high-energy X-rays emanating from the central star. These provide indirect evidence for the existence of an invisible companion revolving around the central star. In this scenario, the jet would emerge from the companion star, quite possibly another white dwarf, and the X-ray emission of an accretion disk around the latter”, concludes Martín A. Guerrero (IAA-CSIC).

Article: M.A. Guerrero, S. Cazzoli et al. "Tomography of the Jet in NGC 2392". The Astrophysical Journal.

Contact:

Instituto de Astrofísica de Andalucía (IAA-CSIC)

Unidad de Divulgación y Comunicación

Silbia López de Lacalle - sll[arroba]iaa.es - 958230676

https://www.iaa.csic.es

https://divulgacion.iaa.csic.es

ORIGINAL SOURCE: https://www.iac.es/en/outreach/news/differences-between-discs-active-and-non-active-galaxies-detected-first-time

A study led by researchers at the Instituto de Astrofísica de Canarias (IAC), making comparison between the discs of several pairs of spiral galaxies, active and non-active, concludes that in the discs of the former the rotational motion of the stars is of greater importance. This study, just accepted for publication in Astronomy & Astrophysics Letters, is the first evidence for large scale dynamical differences between active and non-active galaxies in the local universe. The astronomers participating are from the Instituto de Astrofísica de Canarias (IAC) and the University of La Laguna (ULL); as well as the National Autonomous University of Mexico (UNAM), the Complutense University of Madrid (UCM) and the Instituto de Astrofísica de Andalucia (IAA).

There is now evidence that the supermassive black holes at the centres of the majority of galaxies have a basic influence on their evolution. In some of them, the black hole is ingesting the material surrounding it at a very high rate, emitting a large quantity of energy. In those cases we say that the galaxy has an active nucleus (AGN). The material which feeds the AGN must initially be quite distant from the nucleus, in the disc of the galaxy, rotating around its centre. This gas must, one way or another, have been “braked” in order to fall into the central zone, a process known as loss of angular momentum.

“Studying the mechanisms which control the relation between the active nucleus and the rest of the galaxy -explains Ignacio del Moral Castro, a doctoral student in the IAC and the University of La Laguna (ULL) and first author of the article- is necessary to understand how these objects form and evolve, and to be able to throw light on this question we need to compare active and non-active galaxies. With this purpose, the main idea of my doctoral thesis is centred on the study and comparison of galaxies which are almost twin, but with the difference being nuclear activity”.

The work has consisted of comparing the dynamics of the galactic discs of various active/non-active pairs. The researchers used data from the CALIFA survey (Calar Alto Legacy Integral Field Area). This contains spectroscopic data over complete 2D fields for more than 600 galaxies, taken at the Calar Alto Observatory in Almería, which allow observations of virtually the whole of each galaxy, so that its global characteristics can be studied.

Novel methodology

Previously, in the majority of studies the procedure used was the identification of a sample of active galaxies within a large survey, which were then compared to the rest of the galaxies in the survey having similar properties which do not show nuclear activity. However, this time, the researchers used a novel method: they performed one-to-one comparisons. Firstly, they identified active spiral galaxies in the CALIFA sample, and for each of them they looked for a non-active galaxy which had equivalent global properties, i.e. with the same mass, brightness, orientation and so on, and very similar in appearance.

Using this method the team put forward two scenarios to explain the dynamical differences between active and non-active galaxies. In the first, the explanation would be that it is the trace of the angular momentum transfer between the gas which has fallen into the centre and the material which remains in the disc. The second attributes the difference to the infall of gas from outside, via the capture of small nearby satellite galaxies, in which case, this capture should occur more frequently in the active galaxies. Both scenarios are compatible with this result and they are not mutually exclusive.

“The result surprised us; we really didn’t expect to find this type of differences on a large scale, give that the duration of the active phase is very short in comparison with the lifetime of a galaxy, and with the time needed to produce morphological and dynamical changes”, says Begoña García Lorenzo, and IAC researcher, and a coauthor of the article.

“Up to now we thought that all galaxies go through active phases during their lifetimes, but this result could mean that this is not the case, which would imply a major change to current models”, adds Cristina Ramos Almeida, also an IAC researcher and coauthor of the article.

Article: I. del Moral-Castro, B. García-Lorenzo, C. Ramos Almeida, T. Ruiz-Lara, J. Falcón-Barroso, S.F. Sánchez, P. Sánchez-Blázquez, I. Márquez, and J. Masegosa. “Larger λR in the disc of isolated active spiral galaxies than in their non-active twins”. Astronomy & Astrophysics Letters, 2020, 639, L9. DOI: https://doi.org/10.1051/0004-6361/202038091

Arxiv: https://arxiv.org/abs/2006.12654

Contact at the IAC:

- Ignacio del Moral Castro: imoralc@iac.es

ORIGINAL SOURCE: https://www.iaa.csic.es/en/news/megara-instrument-enters-heart-active-galaxy-ngc-7469

Active galaxy nuclei are among the most energetic objects in the universe, and can continuously emit more than a hundred times the energy of all the stars in a galaxy like ours. Their brightness is attributed to the existence of a supermassive black hole surrounded by a disk of matter that feeds it, but the phenomenon of nuclear activity still raises many questions. The MEGARA instrument, designed to solve hitherto unresolved scientific problems, has just revealed new structures in the regions near the active nuclei of NGC 7469.

NGC 7469, located some 200 million light years away -relatively close in astronomical scales- shows a high rate of star formation, which is attributed to past interactions with its companion galaxy. It is a seyfert galaxy, a type of active galaxy that shows a very bright nucleus, the product of the fall of material towards the supermassive black hole. The black hole has an estimated mass of some twelve million suns.

For a black hole to be active there must be material to feed it and an efficient mechanism to transport the material to the nucleus. Among these mechanisms are the discs, flattened structures that revolve around the black hole and whose material spirals towards the center; the bars, elongated structures that extend on both sides of the nucleus and channel the gas from the arms of the spiral galaxies towards the nucleus; or the winds, very fast flows of gas and dust capable of moving large masses of material.

"Thanks to MEGARA we have been able to study the central region of NGC7469 with an unprecedented resolution. We found that the ionized gas traces three components, two corresponding to discs that co-rotate in the same plane, one thinner than the other, and another one that does not show rotation and is probably associated with the presence of winds", says Sara Cazzoli, researcher at the Institute of Astrophysics of Andalusia (IAA-CSIC) who leads the work.

"One of the great questions regarding active galaxies lies in the very origin of the activity. We know that almost all galaxies with masses similar to that of the Milky Way or larger have supermassive black holes in their nuclei, but some are dormant, such as SgrA*, the central black hole of our galaxy" -says Isabel Márquez, a researcher at the IAA-CSIC who participates in the work-. Studies with such high kinematic resolution are necessary to understand the phenomena related to the feeding and feedback of active galaxies, as well as the role played by the different components".

Knowing what happens in the central regions of active galaxies, or how the gas moves in the different components, requires a state-of-the-art technological capacity. The MEGARA instrument, designed by a consortium led by the Universidad Complutense de Madrid, in which the Institute of Astrophysics of Andalusia (IAA-CSIC) participated, uses IFS technology - an acronym for "integral field spectroscopy" - which makes it possible to take around a thousand spectra per galaxy and obtain a complete 3D panorama of them.

"Due to the brightness of the nuclear regions of active galaxies, smaller telescopes were normally used for their study -says Armando Gil de Paz, a researcher at the Complutense University of Madrid who participates in the work-. However, much of the information is found in clouds of gas that differ from the rest: they move at high speeds and, due to these movements, have their weak emission located at frequencies different from that produced by most of the gas in galaxies. It is what is known as the wings. Observing these wings requires the use of large telescopes and highly efficient instruments such as the Gran Telescopio Canarias and MEGARA, respectively".

Reference: S. Cazzoli et al. "NGC7469 as seen by MEGARA: new results from high-resolution IFU spectroscopy". Monthly Notices of the Astronomical Society, DOI: https://doi.org/10.1093/mnras/staa409

ORIGINAL SOURCE: https://www.iac.es/en/outreach/news/fast-and-furious-detection-powerful-winds-driven-supermassive-black-hole-la-palma

The supermassive black holes in the centres of many galaxies seem to have a basic influence on their evolution. This happens during a phase in which the black hole is consuming the material of the galaxy in which it resides at a very high rate, growing in mass as it does so. During this phase we say that the galaxy has an active nucleus (AGN, for active galactic nucleus).

The effect that this activity has on the host galaxy is known as AGN feedback, and one of its properties are galactic winds: this is gas from the centre of the galaxy being driven out by the energy released by the active nucleus. These winds can reach velocities of up to thousands of kilometres per second, and in the most energetic AGNs, for example the quasars, which can clean out the centres of the galaxies impeding the formation of new stars. It has been shown that the evolution of the star formation over cosmological timescales cannot be explained without the existence of a regulating mechanism.

To study these winds in quasars the EMIR infrared spectrograph on the Gran Telescopio Canarias (GTC) was used. EMIR is an instrument developed completely in the Instituto de Astrofísica de Canarias, which is designed to study the coolest and most distant objects in the universe by analysing infrared light. Since June 2016 this has been installed at a focus of the GTC, after going through an exhaustive test phase in the workshops of the Instrument Division of the IAC headquarters in La Laguna.

The data obtained since then has been used to produce several scientific articles of which the latest is a study of the obscured quasar J1509+0434, published today in the journal Monthly Notices of the Royal Astronomical Society Letters and produced by an international team led by IAC researcher Cristina Ramos Almeida. This quasar is in the local universe, and is an analogue of the more distant and far more numerous quasars in which AGN feedback must be affecting in a major way the formation of new stars.

“EMIR has allowed us to study the winds of ionized and molecular gas from this quasar by using the infrared range. This analysis is very important because they don’t always show similar properties, which tells us a great deal about how these winds are produced and how they affect their host galaxies”, explains Ramos Almeida. The study of this and other local quasars will allow us to understand what was happening in galaxies when they were younger and when they were forming their structures which we see today.

Based on the new data obtained with EMIR, the team has discovered that the ionized wind is faster than the molecular wind, reaching velocities of up to 1,200 km/s. However it would be the molecular wind which is emptying the gas reservoirs of the galaxy (up to 176 solar masses per year). “New observations with ALMA will let us confirm this estimate”, explained José Acosta Pulido, a researcher at the IAC and co-author of this study.

The next step is to observe a complete sample of obscured nearby quasars with EMIR to study their ionized and molecular winds. We also want to investigate the stellar populations of their host galaxies. This will allow us to confirm directly the effect of AGN feedback on the evolution of the galaxies.

Reference: C. Ramos Almeida, J. A. Acosta-Pulido, C. N. Tadhunter, C. González-Fernández, C. Cicone, M. Fernández-Torreiro. A near-infrared study of the multi-phase outflow in the type-2 quasar J1509+0434. Monthly Notices of the Royal Astronomical Society: Letters, Volume 487, Issue 1, June 2019, Pages L18–L23, https://doi.org/10.1093/mnrasl/slz072