J. M. Rodríguez-Espinosa

Violent star formation in NGC 2363

This is an electronic version of an article published in The Astrophysical Journal. Gonzalez-Delgado, R.M. et al. Violent star formation in NGC 2363. The Astrophysical Journal 437 (1994): 239-261

Dust in active galactic nuclei - Mid-infrared T-ReCS/Gemini spectra using the new RedCan pipeline

Context. The unified model of active galactic nuclei (AGN) claims that the properties of AGN depend on the viewing angle of the observer with respect to a toroidal distribution of dust surrounding the nucleus. Both the mid-infrared (MIR) attenuation and continuum luminosity are expected to be related to dust associated with the torus. Therefore, isolating the nuclear component is essential for studying the MIR emission of AGN. Aims. This work is aimed at studying the MIR emission of AGN with the highest spatial resolution available to date, isolating its contribution from extended emission. We would like to address three fundamental questions: (1) how important is the AGN contribution to the MIR spectrum; (2) where dust attenuation arises; and (3) how does spatial resolution affect these issues. Methods. We compiled all the T-ReCS spectra (Gemini Observatory) available in the N-band for 22 AGN: 5 Type-1 and 17 Type-2 AGN. The high angular resolution of the T-ReCS spectra allowed us to probe physical regions of 57 pc (median). We used a novel pipeline called RedCan capable of producing flux- and wavelength-calibrated spectra for the CanariCam (GTC) and T-ReCS (Gemini) instruments. We measured the fine-structure [S IV] at 10.5 μm and the PAH at 11.3 μm line strengths, together with the silicate absorption/emission features. We also compiled Spitzer/IRS spectra to understand how spatial resolution influences the results. We complemented our sample with the results of 19 VISIR/VLT spectra (Paranal Observatory) and 20 nearby, highly obscured AGN (N_H > 1.5 × 10^(24) cm^(-2)) Spitzer spectra. Results. The 11.3 μm PAH feature is only clearly detected in the nuclear spectra of two AGN, while it is more common in the Spitzer data. For those two objects, the AGN emission in NGC 7130 accounts for more than 80% of the MIR continuum at 12 μm, while in the case of NGC 1808 the AGN does not dominate the MIR emission. This is confirmed by the correlation between the MIR and X-ray continuum luminosities. The [S IV] emission line at 10.5 μm, which is believed to originate in the narrow line region, is detected in most AGN. We have found an enhancement of the optical depth at 9.7 μm (τ_(9.7)) in the high-angular resolution data for higher values of N_H. Clumpy torus models reproduce the observed values only if the host-galaxy properties are taken into account.

Nuclear obscuration in LINERs

Context. Most of the optically classified low-ionisation, narrow emission-line regions (LINERs) nuclei host an active galactic nucleus (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. Aims. The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e. hydrogen column densities of NH > 1:5 10 24 cm 2 ) and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. Methods. We have compiled all the available low spectral-resolution, mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PG QSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and StarBurst (SB) nuclei. We studied the AGN compared to the starburst content in our sample using di erent indicators: the equivalent width of the polycyclic aromatic hydrocarbon at 6.2 m, the strength of the silicate feature at 9.7 m, and the steepness of the mid-IR spectra. We classified the spectra as SB-dominated and AGN-dominated, according to these diagnostics and compared the average mid-IR spectra of the various classes. Moreover, we studied the correlation between the 12 m luminosity, L (12 m), and the 2 10 keV energy band X-ray luminosity, LX(2 10 keV). Results. In 25 out of the 40 LINERs (i.e. 62.5%), the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is di erent from the average spectra of the other optical classes, showing a rather flat spectrum at 6 28 m. We find that the average spectrum of AGN-dominated LINERs with X-ray luminosities LX(2 10 keV) > 10 41 erg/s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. LX(2 10 keV) < 10 41 erg/s) show flat spectra di erent from any of the other optical classes. The correlation between L (12 m) and LX(2 10 keV) for AGN nicely extends towards low luminosities only if SB-dominated LINERs are excluded and if the 2 10 keV band X-ray luminosity is corrected in Compton-thick LINER candidates. Conclusions. We find that LINERs proposed as Compton-thick candidates at X-ray wavelengths may be confirmed according to the X-ray to mid-IR luminosity relation. We show evidence that the dusty-torus disappear when their bolometric luminosity is below Lbol ’ 10 42 erg/s. We suggest that the dominant emission at mid-IR of faint LINERs might be a combination of an elliptical galaxy host (characterised by the lack of gas), a starburst, a jet, and/or ADAF emission. Alternatively, the mid-IR emission of some of these faint LINERs could be a combination of elliptical galaxy plus carbon-rich planetary nebulae. To reconcile the Compton-thick nature of a large number of LINERs without dusty-torus signatures, we suggest that the material producing the Compton-thick X-ray obscuration is free of dust.Context. Most of the optically classified low ionisation narrow emission-line regions (LINERs) nuclei host an active galactic nuclei (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. Aims. The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e hydrogen column densities of NH > 1:5 10 24 cm 2 ); and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. Methods. We have compiled all the available low spectral resolution mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PG QSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and Starburst (SBs) nuclei. We have studied the AGN versus the starburst content in our sample using di erent indicators: the equivalent width (EW) of the polycyclic aromatic hydrocarbon (PAH) at 6:2 m, the strength of the silicate feature at 9.7 m, and the steepness of the mid-IR spectra. We have classified the spectra as SB-dominated and AGNdominated, according to these diagnostics. We have compared the average mid-IR spectra of the various classes. Moreover, we have studied the correlation between the 12 m luminosity, L (12 m), and the 2-10 keV energy band X-ray luminosity, LX(2 10 keV). Results. In 25 out of the 40 LINERs (i.e., 62.5%) the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is di erent from the average spectra of the other optical classes, showing a rather flat spectrum at 6 28 m. We have found that the average spectrum of AGN-dominated LINERs with X-ray luminosities LX(2 10 keV) > 10 41 erg=s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. LX(2 10 keV) < 10 41 erg=s) show flat spectra di erent from any of the other optical classes. The correlation between L (12 m) and LX(2 10 keV) for AGN nicely extends toward low luminosities only if SB-dominated LINERs are excluded and the 2-10 keV band X-ray luminosity is corrected in Compton-thick LINER candidates. Conclusions. We have found that LINERs proposed as Compton-thick candidates at X-ray wavelengths may be confirmed according to the X-ray to mid-IR luminosity relation. We show evidence in favour of the dusty-torus disappearance when their bolometric luminosity is below Lbol’ 10 42 erg=s. We suggest that the dominant emission at mid-IR of faint LINERs might be a combination of an elliptical galaxy host (characterised by the lack of gas), a starburst, a jet, and/or ADAF emission. Alternatively, the mid-IR emission of some of these faint LINERs could be a combination of elliptical galaxy plus carbon-rich planetary nebulae. In order to reconcile the Compton-thick nature of a large fraction of LINERs with the lack of dusty-torus signatures, we suggest that the material producing the Compton-thick X-ray obscuration is free of dust.

Nuclear obscuration in LINERs - Clues from Spitzer/IRS spectra on the Compton thickness and the existence of the dusty torus

Context. Most of the optically classified low-ionisation, narrow emission-line regions (LINERs) nuclei host an active galactic nucleus (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. Aims. The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e. hydrogen column densities of NH > 1:5 10 24 cm 2 ) and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. Methods. We have compiled all the available low spectral-resolution, mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PG QSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and StarBurst (SB) nuclei. We studied the AGN compared to the starburst content in our sample using di erent indicators: the equivalent width of the polycyclic aromatic hydrocarbon at 6.2 m, the strength of the silicate feature at 9.7 m, and the steepness of the mid-IR spectra. We classified the spectra as SB-dominated and AGN-dominated, according to these diagnostics and compared the average mid-IR spectra of the various classes. Moreover, we studied the correlation between the 12 m luminosity, L (12 m), and the 2 10 keV energy band X-ray luminosity, LX(2 10 keV). Results. In 25 out of the 40 LINERs (i.e. 62.5%), the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is di erent from the average spectra of the other optical classes, showing a rather flat spectrum at 6 28 m. We find that the average spectrum of AGN-dominated LINERs with X-ray luminosities LX(2 10 keV) > 10 41 erg/s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. LX(2 10 keV) < 10 41 erg/s) show flat spectra di erent from any of the other optical classes. The correlation between L (12 m) and LX(2 10 keV) for AGN nicely extends towards low luminosities only if SB-dominated LINERs are excluded and if the 2 10 keV band X-ray luminosity is corrected in Compton-thick LINER candidates. Conclusions. We find that LINERs proposed as Compton-thick candidates at X-ray wavelengths may be confirmed according to the X-ray to mid-IR luminosity relation. We show evidence that the dusty-torus disappear when their bolometric luminosity is below Lbol ’ 10 42 erg/s. We suggest that the dominant emission at mid-IR of faint LINERs might be a combination of an elliptical galaxy host (characterised by the lack of gas), a starburst, a jet, and/or ADAF emission. Alternatively, the mid-IR emission of some of these faint LINERs could be a combination of elliptical galaxy plus carbon-rich planetary nebulae. To reconcile the Compton-thick nature of a large number of LINERs without dusty-torus signatures, we suggest that the material producing the Compton-thick X-ray obscuration is free of dust.Context. Most of the optically classified low ionisation narrow emission-line regions (LINERs) nuclei host an active galactic nuclei (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. Aims. The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e hydrogen column densities of NH > 1:5 10 24 cm 2 ); and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. Methods. We have compiled all the available low spectral resolution mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PG QSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and Starburst (SBs) nuclei. We have studied the AGN versus the starburst content in our sample using di erent indicators: the equivalent width (EW) of the polycyclic aromatic hydrocarbon (PAH) at 6:2 m, the strength of the silicate feature at 9.7 m, and the steepness of the mid-IR spectra. We have classified the spectra as SB-dominated and AGNdominated, according to these diagnostics. We have compared the average mid-IR spectra of the various classes. Moreover, we have studied the correlation between the 12 m luminosity, L (12 m), and the 2-10 keV energy band X-ray luminosity, LX(2 10 keV). Results. In 25 out of the 40 LINERs (i.e., 62.5%) the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is di erent from the average spectra of the other optical classes, showing a rather flat spectrum at 6 28 m. We have found that the average spectrum of AGN-dominated LINERs with X-ray luminosities LX(2 10 keV) > 10 41 erg=s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. LX(2 10 keV) < 10 41 erg=s) show flat spectra di erent from any of the other optical classes. The correlation between L (12 m) and LX(2 10 keV) for AGN nicely extends toward low luminosities only if SB-dominated LINERs are excluded and the 2-10 keV band X-ray luminosity is corrected in Compton-thick LINER candidates. Conclusions. We have found that LINERs proposed as Compton-thick candidates at X-ray wavelengths may be confirmed according to the X-ray to mid-IR luminosity relation. We show evidence in favour of the dusty-torus disappearance when their bolometric luminosity is below Lbol’ 10 42 erg=s. We suggest that the dominant emission at mid-IR of faint LINERs might be a combination of an elliptical galaxy host (characterised by the lack of gas), a starburst, a jet, and/or ADAF emission. Alternatively, the mid-IR emission of some of these faint LINERs could be a combination of elliptical galaxy plus carbon-rich planetary nebulae. In order to reconcile the Compton-thick nature of a large fraction of LINERs with the lack of dusty-torus signatures, we suggest that the material producing the Compton-thick X-ray obscuration is free of dust.

MEGARA: the future optical IFU and multi-object spectrograph for the 10.4m GTC telescope

In these proceedings we give a summary of the characteristics and current status of the MEGARA instrument, the future optical IFU and MOS for the 10.4-m Gran Telescopio Canarias (GTC). MEGARA is being built by a Consortium of public research institutions led by the Universidad Complutense de Madrid (UCM, Spain) that also includes INAOE (Mexico), IAA-CSIC (Spain) and UPM (Spain). The MEGARA IFU includes two different fiber bundles, one called LCB (Large Compact Bundle) with a field-of-view of 12.5×11.3 arcsec2 and a spaxel size of 0.62 arcsec yielding spectral resolutions between R=6,800-17,000 and another one called SCB (Small Compact Bundle) covering 8.5×6.7 arcsec2 with hexagonally-shaped and packed 0.42-arcsec spaxels and resolutions R=8,000-20,000. The MOS component allows observing up to 100 targets in 3.5×3.5 arcmin2. Both the IFU bundles and the set of 100 robotic positioners of the MOS will be placed at one of the GTC Folded-Cass foci while the spectrographs (one in the case of the MEGARA-Basic concept) will be placed at the Nasmyth platform. On March 2012 MEGARA passed the Preliminary Design Review and its first light is expected to take place at the end of 2015.

Extinction over the Canarian observatories: the limited influence of Saharan dust

Abstract We present a study of the atmospheric extinction over the observatories of the Canary Islands, based mainly on photometric measurements of the V -band extinction coefficient obtained during 2850 nights at the Carlsberg Automatic Meridian Circle at the Roque de los Muchachos Observatory (La Palma), and complemented with visible and infrared data obtained at the Teide Observatory (Tenerife). The median value of the extinction coefficient in the V -band is found to be 0.113 mag airmass −1 , which compares favourably with the extinction found at other first-quality astronomical sites. Long-term extinction variations due to the effects of the volcanic eruptions of El Chichon (1982) and Mt. Pinatubo (1991) are also described in this study. A detailed description of the seasonal variations provides the opportunity to study the influence of Saharan dust episodes, mostly concentrated in the summer period. This allowed us to estimate how Saharan dust affects astronomical observations. It is concluded that more than 75% of summer nights are not affected by dust, while this number rises over 90% for the rest of the year.

Infrared astronomical characteristics of the Roque de los Muchachos Observatory: precipitable water vapour statistics

We present measurements of the atmospheric water vapour content above the Roque de los Muchachos Observatory (ORM) obtained using the Global Positioning System (GPS). The GPS measurements have been evaluated by comparison with 940-nm radiometer observations. A statistical analysis of the GPS measurements points to the ORM as an observing site with suitable conditions for infrared observations, with a median column of precipitable water vapour (PWV) of 3.8 mm. PWV presents a clear seasonal behaviour, with winter and spring being the best seasons for infrared observations. The percentage of nights showing PWV values less than 3 mm is over 60 per cent in February, March and April. We have also estimated the temporal variability of water vapour content at the ORM. We present a summary of PWV statistical results at different astronomical sites, noting that these values are not directly comparable as a result of the differences in the techniques used to recorded the data.

MEGARA: a new generation optical spectrograph for GTC

MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is an optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) designed for the GTC 10.4m telescope in La Palma. MEGARA offers two IFU fiber bundles, one covering 12.5x11.3 arcsec2 with a spaxel size of 0.62 arcsec (Large Compact Bundle; LCB) and another one covering 8.5x6.7 arcsec2 with a spaxel size of 0.42 arcsec (Small Compact Bundle; SCB). The MEGARA MOS mode will allow observing up to 100 objects in a region of 3.5x3.5 arcmin2 around the two IFU bundles. Both the LCB IFU and MOS capabilities of MEGARA will provide intermediate-to-high spectral resolutions (RFWHM~6,000, 12,000 and 18,700, respectively for the low-, mid- and high-resolution Volume Phase Holographic gratings) in the range 3650-9700ÅÅ. These values become RFWHM~7,000, 13,500, and 21,500 when the SCB is used. A mechanism placed at the pseudo-slit position allows exchanging the three observing modes and also acts as focusing mechanism. The spectrograph is a collimator-camera system that has a total of 11 VPHs simultaneously available (out of the 18 VPHs designed and being built) that are placed in the pupil by means of a wheel and an insertion mechanism. The custom-made cryostat hosts an E2V231-84 4kx4k CCD. The UCM (Spain) leads the MEGARA Consortium that also includes INAOE (Mexico), IAA-CSIC (Spain), and UPM (Spain). MEGARA is being developed under a contract between GRANTECAN and UCM. The detailed design, construction and AIV phases are now funded and the instrument should be delivered to GTC before the end of 2016.

Gran Telescopio Canarias: a 10-m telescope for the ORM

A project to build a large telescope at the Spanish Observatorio del Roque de los Muchachos (ORM), in the island of La Palma, has been underway for several years. Spanish astronomy has progressed steadily to the point where gaining access to large telescope time is key to its continued and future growth. Also the technological situation within Spain is such that building a large telescope is regarded as a scientific and advanced technology endeavor worth investing in. The Gran Telescopio Canarias (GTC) project has thus been granted approval in February this year, with an allocation of 51% of the budget. Current activities of the telescope project are mainly concentrated in the conceptual design and analysis of the telescope optics, including plans for the adaptive optics, its mechanical structure and enclosure, and an active campaign of site testing. We are also carrying out detailed programs aimed at producing and testing prototype models for sensors, actuators and the control system for aligning the primary mirror segments. In the following sections, the current status of the activities being carried out by the telescope project team are described.

Hints on the Gradual Resizing of the Torus in AGNs through Decomposition of Spitzer/IRS Spectra

Several authors have claimed that the less luminous active galactic nuclei (AGN) are not capable of sustaining the dusty torus structure. Thus, a gradual re-sizing of the torus is expected when the AGN luminosity decreases. Our aim is to confront mid-infrared observations of local AGN of different luminosities with this scenario. We decomposed about ~100 IRS/Spitzer spectra of LLAGN and powerful Seyferts in order to decontaminate the torus component from other contributors. We have used the affinity propagation (AP) method to cluster the data into five groups within the sample according to torus contribution to the 5-15 um range (Ctorus) and bolometric luminosity. The AP groups show a progressively higher torus contribution and an increase of the bolometric luminosity, from Group 1 (Ctorus~ 0% and logLbol ~ 41) and up to Group 5 (Ctorus ~80% and log(Lbol) ~44). We have fitted the average spectra of each of the AP groups to clumpy models. The torus is no longer present in Group 1, supporting the disappearance at low-luminosities. We were able to fit the average spectra for the torus component in Groups 3 (Ctorus~ 40% and log(Lbol)~ 42.6), 4 (Ctorus~ 60% and log(Lbol)~ 43.7), and 5 to Clumpy torus models. We did not find a good fitting to Clumpy torus models for Group 2 (Ctorus~ 18% and log(Lbol)~ 42). This might suggest a different configuration and/or composition of the clouds for Group 2, which is consistent with a different gas content seen in Groups 1, 2, and 3, according to the detections of H2 molecular lines. Groups 3, 4, and 5 show a trend to decrease of the width of the torus (which yields to a likely decrease of the geometrical covering factor), although we cannot confirm it with the present data. Finally, Groups 3, 4, and 5 show an increase on the outer radius of the torus for higher luminosities, consistent with a re-sizing of the torus according to the AGN luminosity.