Journal articles: 'AGN luminosity function'

1

Kulkarni, Girish, Gábor Worseck, and Joseph F. Hennawi. "Evolution of the AGN UV luminosity function from redshift 7.5." Monthly Notices of the Royal Astronomical Society 488, no. 1 (June 3, 2019): 1035–65. http://dx.doi.org/10.1093/mnras/stz1493.

Full text

Abstract:

ABSTRACTDeterminations of the ultraviolet (UV) luminosity function of active galactic nuclei (AGN) at high redshifts are important for constraining the AGN contribution to reionization and understanding the growth of supermassive black holes. Recent inferences of the luminosity function suffer from inconsistencies arising from inhomogeneous selection and analysis of data. We address this problem by constructing a sample of more than 80 000 colour-selected AGN from redshift $z$ = 0 to 7.5 using multiple data sets homogenized to identical cosmologies, intrinsic AGN spectra, and magnitude systems. Using this sample, we derive the AGN UV luminosity function from redshift $z$ = 0 to 7.5. The luminosity function has a double power-law form at all redshifts. The break magnitude M* shows a steep brightening from M* ∼ −24 at $z$ = 0.7 to M* ∼ −29 at $z$ = 6. The faint-end slope β significantly steepens from −1.9 at $z$ < 2.2 to −2.4 at $z$ ≃ 6. In spite of this steepening, the contribution of AGN to the hydrogen photoionization rate at $z$ ∼ 6 is subdominant (<3 per cent), although it can be non-negligible (∼10 per cent) if these luminosity functions hold down to M1450 = −18. Under reasonable assumptions, AGN can reionize He ii by redshift $z$ = 2.9. At low redshifts ($z$ < 0.5), AGN can produce about half of the hydrogen photoionization rate inferred from the statistics of H i absorption lines in the intergalactic medium. Our analysis also reveals important systematic errors in the data, which need to be addressed and incorporated in the AGN selection function in future in order to improve our results. We make various fitting functions, codes, and data publicly available.

APA, Harvard, Vancouver, ISO, and other styles

2

Merloni, Andrea, and Sebastian Heinz. "Cosmological evolution of the AGN kinetic luminosity function." Proceedings of the International Astronomical Union 2, S238 (August 2006): 65–70. http://dx.doi.org/10.1017/s174392130700470x.

Full text

Abstract:

AbstractWe present a first attempt to derive the cosmological evolution of the kinetic luminosity function of AGN based on the joint evolution of the flat spectrum radio and hard X-ray selected AGN luminosity functions. An empirical correlation between jet power and radio core luminosity is found, which is consistent with the theoretical assumption that, below a certain Eddington ratio, SMBH accrete in a radiatively inefficient way, while most of the energy output is in the form of kinetic energy.We show how the redshift evolution of the kinetic power density from such a low-ṁ mode of accretion makes it a good candidate to explain the so-called “radio mode” of AGN feedback as outlined in many galaxy formation schemes.

APA, Harvard, Vancouver, ISO, and other styles

3

Runburg, Jack, Duncan Farrah, Anna Sajina, Mark Lacy, Jenna Lidua, Evanthia Hatziminaoglou, W. N. Brandt, et al. "Consistent Analysis of the AGN LF in X-Ray and MIR in the XMM-LSS Field." Astrophysical Journal 924, no. 2 (January 1, 2022): 133. http://dx.doi.org/10.3847/1538-4357/ac37b8.

Full text

Abstract:

Abstract The luminosity function of active galactic nuclei (AGN) probes the history of supermassive black hole assembly and growth across cosmic time. To mitigate selection biases, we present a consistent analysis of the AGN luminosity functions (LFs) derived for both X-ray and mid-infrared (MIR) selected AGN in the XMM-Large Scale Structure field. There are 4268 AGN used to construct the MIR luminosity function (IRLF) and 3427 AGN used to construct the X-ray luminosity function (XLF), providing the largest census of the AGN population out to z = 4 in both bands with significant reduction in uncertainties. We are able for the first time to see the knee of the IRLF at z > 2 and observe a flattening of the faint-end slope as redshift increases. The bolometric luminosity density, a proxy for the cosmic black hole accretion history, computed from our LFs, shows a peak at z ≈ 2.25, consistent with recent estimates of the peak in the star formation rate density (SFRD). However, at earlier epochs, the AGN luminosity density is flatter than the SFRD. If confirmed, this result suggests that the build up of black hole mass outpaces the growth of stellar mass in high-mass systems at z ≳ 2.5. This is consistent with observations of redshift z ∼ 6 quasars that lie above the local M − σ relationship. The luminosity density derived from the IRLF is higher than that from the XLF at all redshifts. This is consistent with the dominant role of obscured AGN activity in the cosmic growth of supermassive black holes.

APA, Harvard, Vancouver, ISO, and other styles

4

Melini, Gabriele, Fabio La Franca, and Fabrizio Fiore. "Feedback from AGN: The Kinetic/Radio Luminosity Function." Proceedings of the International Astronomical Union 5, S267 (August 2009): 402. http://dx.doi.org/10.1017/s1743921310006861.

Full text

Abstract:

We have measured the probability distribution function of the ratio RX = log L1.4/LX, where L1.4/LX = ν Lν(1.4 GHz)/LX(2–10 keV), between the 1.4 GHz and the unabsorbed 2–10 keV luminosities and its dependence on LX and z. We have used a complete sample of ~1800 hard X-ray selected AGN, observed in the 1.4 GHz band, cross-correlated in order to exclude FR II-type objects, and thus obtain a contemporaneous measure of the radio and X-ray emission. The distribution P(RX|LX,z) is shown in Figure 1. Convolution of the distribution P(RX|LX,z) with the 2–10 keV X-ray AGN luminosity function from La Franca et al. (2005) and the relations between radio power and kinetic energy from Best et al. (2006) and Willott et al. (1999) allows us to derive the AGN kinetic power and its evolution. As shown in Figure 1, our results are in good agreement with the predictions of the most recent models of galaxy formation and evolution (e.g., Croton et al. 2006), where AGN radio feedback is required to quench the star formation.

APA, Harvard, Vancouver, ISO, and other styles

5

Meurs, E. J. A. "A nuclear Luminosity Function for Seyferts." Symposium - International Astronomical Union 175 (1996): 541–42. http://dx.doi.org/10.1017/s007418090008178x.

Full text

Abstract:

Relations between various classes of AGN should show up when examining their LFs. For Seyfert galaxies, such studies have been affected by the prevalence of (essentially) integrated magnitudes. Proper nuclear magnitudes have been determined in an effort of CCD imaging, which enable an appropriate comparison with QSOs.

APA, Harvard, Vancouver, ISO, and other styles

6

Liu, Chenxu, Karl Gebhardt, Erin Mentuch Cooper, Yechi Zhang, Donald P. Schneider, Robin Ciardullo, Dustin Davis, et al. "The Active Galactic Nuclei in the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX). II. Luminosity Function." Astrophysical Journal 935, no. 2 (August 1, 2022): 132. http://dx.doi.org/10.3847/1538-4357/ac8054.

Full text

Abstract:

Abstract We present the Lyα emission line luminosity function (LF) of the active galactic nuclei (AGN) in the first release of the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX) AGN catalog. The AGN are selected either by emission line pairs characteristic of AGN or by a single broad emission line, free of any photometric preselections (magnitude/color/morphology). The sample consists of 2346 AGN spanning 1.88 < z < 3.53, covering an effective area of 30.61 deg2. Approximately 2.6% of the HETDEX AGN are not detected at >5σ confidence at r ∼ 26 in the deepest r-band images we have searched. The Lyα line luminosity ranges from ∼1042.3 to 1045.9 erg s−1. Our Lyα LF shows a turnover luminosity with opposite slopes on the bright end and the faint end: The space density is highest at L Ly α ∗ = 10 43.4 erg s−1. We explore the evolution of the AGN LF over a broader redshift range (0.8 < z < 3); constructing the rest-frame ultraviolet (UV) LF with the 1450 Å monochromatic luminosity of the power-law component of the continuum (M1450) from M 1450 ∼ −18 to −27.5. We divide the sample into three redshift bins (z ∼ 1.5, 2.1, and 2.6). In all three redshift bins, our UV LFs indicate that the space density of AGN is highest at the turnover luminosity M 1450 * with opposite slopes on the bright end and the faint end. The M 1450 LFs in the three redshift bins can be well fit with a luminosity evolution and density evolution model: the turnover luminosity ( M 1450 * ) increases, and the turnover density (Φ*) decreases with increasing redshift.

APA, Harvard, Vancouver, ISO, and other styles

7

Fotopoulou, S., J. Buchner, I. Georgantopoulos, G. Hasinger, M. Salvato, A. Georgakakis, N. Cappelluti, et al. "The 5–10 keV AGN luminosity function at 0.01." Astronomy & Astrophysics 587 (March 2016): A142. http://dx.doi.org/10.1051/0004-6361/201424763.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Miyaji, T., G. Hasinger, and M. Schmidt. "Soft X-ray AGN luminosity function from ROSAT surveys." Astronomy and Astrophysics 369, no. 1 (April 2001): 49–56. http://dx.doi.org/10.1051/0004-6361:20010102.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Hasinger, G. "The X-Ray Background and the AGN Luminosity Function." Symposium - International Astronomical Union 183 (1999): 200–209. http://dx.doi.org/10.1017/s007418090013253x.

Full text

Abstract:

ROSAT deep and shallow surveys have provided an almost complete inventory of the constituents of the soft X-ray background which led to a population synthesis model for the whole X-ray background with interesting cosmological consequences. According to this model the X-ray background is the “echo” of mass accretion onto supermassive black holes, integrated over cosmic time. A new determination of the soft X-ray luminosity function of active galactic nuclei (AGN) is consistent with pure density evolution, and the comoving volume density of AGN at redshift 2–3 approaches that of local normal galaxies. This indicates that many larger galaxies contain black holes and it is likely that the bulk of the black holes was produced before most of the stars in the universe. However, only X-ray surveys in the harder energy bands, where the maximum of the energy density of the X-ray background resides, will provide the acid test of this picture.

APA, Harvard, Vancouver, ISO, and other styles

10

Ceraj, L., V. Smolčić, I. Delvecchio, M. Novak, G. Zamorani, J. Delhaize, E. Schinnerer, E. Vardoulaki, and N. Herrera Ruiz. "The VLA-COSMOS 3 GHz Large Project: Star formation properties and radio luminosity functions of AGN with moderate-to-high radiative luminosities out to z∼ 6." Astronomy & Astrophysics 620 (December 2018): A192. http://dx.doi.org/10.1051/0004-6361/201833935.

Full text

Abstract:

We have studied a sample of 1604 moderate-to-high radiative luminosity active galactic nuclei (HLAGN) selected at 3 GHz within the VLA-COSMOS 3 GHz Large Project. These were classified by combining multiple AGN diagnostics: X-ray data, mid-infrared data and broadband spectral energy distribution fitting. We decomposed the total radio 1.4 GHz luminosity (L1.4 GHz, TOT) into the emission originating from star formation and AGN activity by measuring the excess in L1.4 GHz, TOT relative to the infrared-radio correlation of star-forming galaxies. To quantify the excess, for each source we calculated the AGN fraction (fAGN) defined as the fractional contribution of AGN activity to L1.4 GHz, TOT. The majority of the HLAGN, (68.0 ± 1.5)%, are dominated by star-forming processes (fAGN ≤ 0.5), while (32.0 ± 1.5)% are dominated by AGN-related radio emission (0.5 < fAGN ≤ 1). We used the AGN-related 1.4 GHz emission to derive the 1.4 GHz AGN luminosity functions of HLAGN. By assuming pure density and pure luminosity evolution models we constrained their cosmic evolution out to z ∼ 6, finding Φ*(z)∝(1 + z)(2.64 ± 0.10)+(−0.61 ± 0.04)z and L*(z)∝(1 + z)(3.97 ± 0.15)+(−0.92 ± 0.06)z. These evolutionary laws show that the number and luminosity density of HLAGN increased from higher redshifts (z ∼ 6) up to a maximum in the redshift range 1 < z < 2.5, followed by a decline toward local values. By scaling the 1.4 GHz AGN luminosity to kinetic luminosity using the standard conversion, we estimate the kinetic luminosity density as a function of redshift. We compare our result to the semi-analytic models of radio mode feedback, and find that this feedback could have played an important role in the context of AGN-host co-evolution in HLAGN which shows evidence of AGN-related radio emission (fAGN > 0).

APA, Harvard, Vancouver, ISO, and other styles

11

Stone, Meredith, Alexandra Pope, Jed McKinney, Lee Armus, Tanio Díaz-Santos, Hanae Inami, Allison Kirkpatrick, and Sabrina Stierwalt. "Measuring Star Formation and Black Hole Accretion Rates in Tandem Using Mid-infrared Spectra of Local Infrared Luminous Galaxies." Astrophysical Journal 934, no. 1 (July 1, 2022): 27. http://dx.doi.org/10.3847/1538-4357/ac778b.

Full text

Abstract:

Abstract We present the results of a stacking analysis performed on Spitzer/Infrared Spectrograph high-resolution mid-infrared (mid-IR) spectra of luminous infrared galaxies (LIRGs) in the Great Observatories All-Sky LIRG Survey. By binning in relation to mid-IR active galactic nucleus (AGN) fraction and stacking spectra, we detect bright emission lines [Ne ii] and [Ne iii], which trace star formation, and fainter emission lines [Ne v] and [O iv], which trace AGN activity, throughout the sample. We find that the [Ne ii] luminosity is fairly constant across all AGN fraction bins, while the [O iv] and [Ne v] luminosities increase by over an order of magnitude. Our measured average line ratios, [Ne v]/[Ne ii] and [O iv]/[Ne ii], at low AGN fraction are similar to H II galaxies, while the line ratios at high AGN fraction are similar to LINERs and Seyferts. We decompose the [O iv] luminosity into star formation and AGN components by fitting the [O iv] luminosity as a function of the [Ne ii] luminosity and the mid-IR AGN fraction. The [O iv] luminosity in LIRGs is dominated by star formation for mid-IR AGN fractions ≲0.3. With the corrected [O iv] luminosity, we calculate black hole accretion rates (BHARs) ranging from 10−5 M ⊙ yr−1 at low AGN fractions to 0.2 M ⊙ yr−1 at the highest AGN fractions. We find that using the [O iv] luminosity, without correcting for star formation, can lead to overestimation of the BHAR by up to a factor of 30 in starburst-dominated LIRGs. Finally, we show that the BHAR/star formation rate ratio increases by more than three orders of magnitude as a function of mid-IR AGN fraction in LIRGs.

APA, Harvard, Vancouver, ISO, and other styles

12

Kulkarni, Girish, Tirthankar Roy Choudhury, Ewald Puchwein, and Martin G. Haehnelt. "Evolution of the Quasar Luminosity Function: Implications for EoR-21cm." Proceedings of the International Astronomical Union 12, S333 (October 2017): 246–49. http://dx.doi.org/10.1017/s1743921317011140.

Full text

Abstract:

AbstractWe present predictions for the spatial distribution of 21 cm brightness temperature fluctuations from high-dynamic-range simulations for AGN-dominated reionization histories that have been tested against available Lyα and CMB data. We model AGN by extrapolating the observed Mbh–σ relation to high redshifts and assign them ionizing emissivities consistent with recent UV luminosity function measurements. AGN-dominated reionization histories increase the variance of the 21 cm emission by a factor of up to ten compared to similar reionization histories dominated by faint galaxies, to values close to 100 mK2 at scales accessible to experiments (k ≲ 1 cMpc−1h). This is lower than the sensitivity reached by ongoing experiments by only a factor of about two or less. AGN dominated reionization should be easily detectable by LOFAR (and later HERA and SKA1) at their design sensitivity.

APA, Harvard, Vancouver, ISO, and other styles

13

Harikane, Yuichi, Yoshiaki Ono, Masami Ouchi, Chengze Liu, Marcin Sawicki, Takatoshi Shibuya, Peter S. Behroozi, et al. "GOLDRUSH. IV. Luminosity Functions and Clustering Revealed with ∼4,000,000 Galaxies at z ∼ 2–7: Galaxy–AGN Transition, Star Formation Efficiency, and Implication for Evolution at z > 10." Astrophysical Journal Supplement Series 259, no. 1 (March 1, 2022): 20. http://dx.doi.org/10.3847/1538-4365/ac3dfc.

Full text

Abstract:

Abstract We present new measurements of rest-UV luminosity functions and angular correlation functions from 4,100,221 galaxies at z ∼ 2–7 identified in the Subaru/Hyper Suprime-Cam survey and CFHT Large Area U-band Survey. The obtained luminosity functions at z ∼ 4–7 cover a very wide UV luminosity range of ∼ 0.002 – 2000 L UV * combined with previous studies, confirming that the dropout luminosity function is a superposition of the active galactic nucleus (AGN) luminosity function dominant at M UV ≲ −24 mag and the galaxy luminosity function dominant at M UV ≳ −22 mag, consistent with galaxy fractions based on 1037 spectroscopically identified sources. Galaxy luminosity functions estimated from the spectroscopic galaxy fractions show the bright-end excess beyond the Schechter function at ≳2σ levels, possibly made by inefficient mass quenching, low dust obscuration, and/or hidden AGN activity. By analyzing the correlation functions at z ∼ 2–6 with HOD models, we find a weak redshift evolution (within 0.3 dex) of the ratio of the star formation rate (SFR) to the dark matter accretion rate, SFR / M ̇ h , indicating the almost constant star formation efficiency at z ∼ 2–6, as suggested by our earlier work at z ∼ 4–7. Meanwhile, the ratio gradually increases with decreasing redshift at z < 5 within 0.3 dex, which quantitatively reproduces the cosmic SFR density evolution, suggesting that the redshift evolution is primarily driven by the increase of the halo number density due to the structure formation, and the decrease of the accretion rate due to the cosmic expansion. Extrapolating this calculation to higher redshifts assuming the constant efficiency suggests a rapid decrease of the SFR density at z > 10 with ∝ 10−0.5(1+z), which will be directly tested with the James Webb Space Telescope.

APA, Harvard, Vancouver, ISO, and other styles

14

Koulouridis, E., L. Faccioli, A. M. C. Le Brun, M. Plionis, I. G. McCarthy, M. Pierre, A. Akylas, et al. "The XXL Survey." Astronomy & Astrophysics 620 (November 20, 2018): A4. http://dx.doi.org/10.1051/0004-6361/201730789.

Full text

Abstract:

Modern cosmological simulations heavily rely on feedback from active galactic nuclei (AGN) in order to stave off overcooling in massive galaxies, and galaxy groups and clusters. Given that AGN are a key component of such simulations, an important independent test is whether or not the simulations capture the broad demographics of the observed AGN population. However, to date, comparisons between observed and simulated AGN populations have been relatively limited. Here, we have used the cosmo-OWLS suite of cosmological hydrodynamical simulations to produce realistic synthetic catalogs of X-ray AGN out to z = 3, with the aim of comparing the catalogs to the observed X-ray AGN population in the XXL survey and other recent surveys. We focused on the unabsorbed X-ray luminosity function (XLF), the Eddington ratio distribution, the black hole mass function, and the projected clustering of X-ray AGN. To compute the unabsorbed XLF of the simulated AGN, we used recent empirically-determined (luminosity-dependent) bolometric corrections, in order to convert the simulated bolometric luminosity into an observable X-ray luminosity. We show that, using these corrections, the simulated AGN sample accurately reproduces the observed XLF over 3 orders of magnitude in X-ray luminosity in all redshift bins from z = 0 out to z = 3. To compare to the observed Eddington ratio distribution and the clustering of AGN, we produced detailed “XMM-Newton-detected” catalogs of the simulated AGN. This requires the production of synthetic X-ray images extracted from light cones of the simulations, which self-consistently contain both the X-ray AGN and the emission from diffuse, hot gas within galaxies, galaxy groups, and clusters and that fold in the relevant instrumental effects of XMM-Newton. We apply a luminosity- and redshift-dependent obscuration function for the AGN and employ the same AGN detection algorithm as used for the real XXL survey. We demonstrate that the detected population of simulated AGN reproduces the observed Eddington ratio distribution and projected clustering from XXL quite well. Based on these comparisons, we conclude that the simulations have a broadly realistic population of AGN and that our synthetic X-ray AGN catalogs should be useful for interpreting additional trends (e.g. environmental dependencies) and as a helpful tool for quantifying AGN contamination in galaxy group and cluster X-ray surveys.

APA, Harvard, Vancouver, ISO, and other styles

15

Beckmann, V., S. Soldi, C. R. Shrader, N. Gehrels, and N. Produit. "The Hard X‐Ray 20–40 keV AGN Luminosity Function." Astrophysical Journal 652, no. 1 (November 20, 2006): 126–35. http://dx.doi.org/10.1086/507510.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Yuan, Zunli, Jiancheng Wang, Ming Zhou, and Jirong Mao. "A MIXTURE EVOLUTION SCENARIO OF THE AGN RADIO LUMINOSITY FUNCTION." Astrophysical Journal 820, no. 1 (March 17, 2016): 65. http://dx.doi.org/10.3847/0004-637x/820/1/65.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Kaiser, C. R., and P. N. Best. "Luminosity function, sizes and FR dichotomy of radio-loud AGN." Monthly Notices of the Royal Astronomical Society 381, no. 4 (November 11, 2007): 1548–60. http://dx.doi.org/10.1111/j.1365-2966.2007.12350.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Aird, J., K. Nandra, A. Georgakakis, E. S. Laird, C. C. Steidel, and C. Sharon. "The X-ray luminosity function of AGN at z ∼ 3." Monthly Notices of the Royal Astronomical Society 387, no. 2 (June 2008): 883–96. http://dx.doi.org/10.1111/j.1365-2966.2008.13286.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Leiter, Darryl, and Elihu Boldt. "Can AGN (Active Galactic Nuclei) Alone Make the Cosmic X-ray Background?" Symposium - International Astronomical Union 159 (1994): 378. http://dx.doi.org/10.1017/s0074180900175709.

Full text

Abstract:

Recent ROSAT X-ray observations of AGN have yielded important new information about the analytic structure of the AGN X-ray luminosity function and its evolution out to z = 3. Using the luminosity evolution obtained within the cosmological context of Ω=0, we find[ that AGN could readily make up the CXB (cosmic X-ray background). However, in this case we find that accounting for the CXB with accretion-powered AGN emission is incompatible with the observed mass function for present-epoch black hole galactic nuclei (both active and dormant). On the other hand, we find that the luminosity evolution obtained with ROSAT for such AGN within the cosmological context of Ω=1 is indeed compatible with the present-epoch black hole galactic nuclei mass function. This apparently acceptable solution, though, definitely falls short of accounting for all the CXB, even when considering unified models for AGN. This difficulty can be resolved by noting that the underlying supermassive black holes which already exist at the onset of the canonical AGN phenomenon of supply-limited accretion must have undergone a previous growth phase where the accretion would be expected to be Eddington-limited. In this likely scenario (i.e., for Ω=1) the residual CXB, that over and above the foreground of canonical AGN, can be naturally explained by the characteristic X-ray emission from highly compact PAG (precursor active galaxy) sources associated with these numerous black holes, at redshifts just beyond the earliest AGN.

APA, Harvard, Vancouver, ISO, and other styles

20

Symeonidis, M., and M. J. Page. "AGN and star formation across cosmic time." Monthly Notices of the Royal Astronomical Society 503, no. 3 (March 3, 2021): 3992–4007. http://dx.doi.org/10.1093/mnras/stab598.

Full text

Abstract:

ABSTRACT We investigate the balance of power between stars and AGN across cosmic history, based on the comparison between the infrared (IR) galaxy luminosity function (LF) and the IR AGN LF. The former corresponds to emission from dust heated by stars and AGN, whereas the latter includes emission from AGN-heated dust only. We find that at all redshifts (at least up to z ∼ 2.5), the high-luminosity tails of the two LFs converge, indicating that the most IR-luminous galaxies are AGN-powered. Our results shed light to the decades-old conundrum regarding the flatter high-luminosity slope seen in the IR galaxy LF compared to that in the UV and optical. We attribute this difference to the increasing fraction of AGN-dominated galaxies with increasing total IR luminosity (LIR). We partition the LIR−z parameter space into a star formation-dominated and an AGN-dominated region, finding that the most luminous galaxies at all epochs lie in the AGN-dominated region. This sets a potential ‘limit’ to attainable star formation rates, casting doubt on the abundance of ‘extreme starbursts’: if AGN did not exist, LIR > 1013 L⊙ galaxies would be significantly rarer than they currently are in our observable Universe. We also find that AGN affect the average dust temperatures (Tdust) of galaxies and hence the shape of the well-known LIR−Tdust relation. We propose that the reason why local ULIRGs are hotter than their high-redshift counterparts is because of a higher fraction of AGN-dominated galaxies amongst the former group.

APA, Harvard, Vancouver, ISO, and other styles

21

Rowan-Robinson, Michael. "Models for Infrared and Submillimetre Counts and Backgrounds." Symposium - International Astronomical Union 204 (2001): 265–80. http://dx.doi.org/10.1017/s0074180900226168.

Full text

Abstract:

A simple and versatile parametrized approach to the star formation history allows a quantitative investigation of the constraints from far infrared and submillimetre counts and background intensity measurements.The models include four spectral components: infrared cirrus, an M 82-like starburst, an Arp 220-like starburst and an AGN dust torus. The 60 μm luminosity function is determined for each chosen rate of evolution using the PSCz redshift data for 15000 galaxies. The proportions of each spectral type as a function of 60 μm luminosity are chosen for consistency with IRAS and SCUBA colour-luminosity relations, and with the fraction of AGN as a function of luminosity found in 12 μm samples.A good fit to the observed counts at 0.44, 2.2, 15, 60, 90, 175 and 850 μm can be found with pure luminosity evolution in all 3 cosmological models investigated: Ω0 = 1, Ω0 = 0.3 (Λ = 0), and Ω0 = 0.3, Λ = 0.7. All 3 models also give an acceptable fit to the integrated background spectrum. The total mass-density of stars generated in all 3 cosmological models is consistent with that observed.

APA, Harvard, Vancouver, ISO, and other styles

22

Ho, Luis C., Alexei V. Filippenko, and Wallace L. W. Sargent. "Low-Luminosity Seyfert Nuclei." International Astronomical Union Colloquium 159 (1997): 429–33. http://dx.doi.org/10.1017/s0252921100040665.

Full text

Abstract:

AbstractWe describe a new sample of Seyfert nuclei discovered during the course of an optical spectroscopic survey of nearby galaxies. The majority of the objects, many recognized as AGNs for the first time, have luminosities much lower than those of classical Seyferts and populate the faint end of the AGN luminosity function. A significant fraction of the nuclei emit broad Hα emission qualitatively similar to the broad lines seen in classical Seyfert 1 nuclei and QSOs.

APA, Harvard, Vancouver, ISO, and other styles

23

Kaiser, Christian R., and Philip N. Best. "Erratum: Luminosity function, sizes and FR dichotomy of radio-loud AGN." Monthly Notices of the Royal Astronomical Society 384, no. 4 (March 2008): 1742. http://dx.doi.org/10.1111/j.1365-2966.2008.12694.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Aird, J., K. Nandra, E. S. Laird, A. Georgakakis, M. L. N. Ashby, P. Barmby, A. L. Coil, et al. "The evolution of the hard X-ray luminosity function of AGN." Monthly Notices of the Royal Astronomical Society 401, no. 4 (February 1, 2010): 2531–51. http://dx.doi.org/10.1111/j.1365-2966.2009.15829.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Vallini, L., C. Gruppioni, F. Pozzi, C. Vignali, and G. Zamorani. "CO luminosity function fromHerschel-selected galaxies and the contribution of AGN." Monthly Notices of the Royal Astronomical Society: Letters 456, no. 1 (November 24, 2015): L40—L44. http://dx.doi.org/10.1093/mnrasl/slv173.

Full text

APA, Harvard, Vancouver, ISO, and other styles

26

Hasinger, G. "The X-ray background and the AGN X-ray luminosity function." Astronomische Nachrichten: News in Astronomy and Astrophysics 319, no. 1-2 (1998): 37–41. http://dx.doi.org/10.1002/asna.2123190120.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Green, Richard F. "AGN and the Demographics of Supermassive Black Holes." International Astronomical Union Colloquium 184 (2002): 335–42. http://dx.doi.org/10.1017/s0252921100030980.

Full text

Abstract:

AbstractHigh angular resolution observations from WFPC and STIS now allow well-constrained dynamical measurement of the masses of supermassive black holes (SMBH) in nearby galaxies. An initial statistical analysis by Magorrian et al. showed that 97% of bulges host SMBH. Black hole mass is correlated moderately with bulge luminosity and strongly with the velocity dispersion of the whole bulge, suggesting that black hole formation may be an intrinsic aspect of bulge formation. Black hole masses for AGN determined from reverberation mapping fall on the same relationship with bulge velocity dispersion as those determined from stellar dynamical measurements. The prospect is therefore that the large-scale distribution of black hole masses in distant quasars may be determined through relatively straightforward measurement. Integral constraints show consistency between the total AGN luminosity density and the total volume density in SMBH contained in galaxy bulges. The strong peak of the high-luminosity quasar luminosity function at early cosmic time is consistent with the association of the build-up of SMBH through accretion and bulge formation. Alternate scenarios requiring substantial build-up of the most massive black holes at later cosmic times are more difficult to reconcile with the evolution of the LF.

APA, Harvard, Vancouver, ISO, and other styles

28

Ramón-Pérez, Marina, Ángel Bongiovanni, Ana María Pérez García, Jordi Cepa, Maritza A. Lara-López, José A. de Diego, Emilio Alfaro, et al. "The OTELO survey." Astronomy & Astrophysics 631 (October 14, 2019): A10. http://dx.doi.org/10.1051/0004-6361/201833295.

Full text

Abstract:

Aims. We take advantage of the capability of the OTELO survey to obtain the Hα luminosity function (LF) at z ∼ 0.40. Because of the deepest coverage of OTELO, we are able to determine the faint end of the LF, and thus better constrain the star formation rate and the number of galaxies at low luminosities. The AGN contribution to this LF is estimated as well. Methods. We make use of the multiwavelength catalogue of objects in the field compiled by the OTELO survey, which is unique in terms of minimum flux and equivalent width. We also take advantage of the pseudo-spectra built for each source, which allow the identification of emission lines and the discrimination of different types of objects. Results. The Hα luminosity function at z ∼ 0.40 is obtained, which extends the current faint end by almost 1 dex, reaching minimal luminosities of log10Llim = 38.5 erg s−1 (or ∼0.002 M⊙ yr−1). The AGN contribution to the total Hα luminosity is estimated. We find that no AGN should be expected below a luminosity of log10L = 38.6 erg s−1. From the sample of non-AGN (presumably, pure SFG) at z ∼ 0.40 we estimated a star formation rate density of ρSFR = 0.012 ± 0.005 M⊙ yr−1 Mpc−3.

APA, Harvard, Vancouver, ISO, and other styles

29

Kauffmann, Guinevere, and Timothy M. Heckman. "The formation of bulges and black holes: lessons from a census of active galaxies in the SDSS." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1828 (January 12, 2005): 621–43. http://dx.doi.org/10.1098/rsta.2004.1516.

Full text

Abstract:

We examine the relationship between galaxies, supermassive black holes and AGN using a sample of 23 000 narrow–emission–line (‘type 2’) active galactic nuclei (AGN) drawn from a sample of 123 000 galaxies from the Sloan Digital Sky Survey. We have studied how AGN host properties compare with those of normal galaxies and how they depend on the luminosity of the active nucleus. We find that AGN reside in massive galaxies and have distributions of sizes and concentrations that are similar to those of the early–type galaxies in our sample. The host galaxies of low–luminosity AGN have stellar populations similar to normal early types. The hosts of highluminosity AGN have much younger mean stellar ages, and a significant fraction have experienced recent starbursts. High–luminosity AGN are also found in lower–density environments. We then use the stellar velocity dispersions of the AGN hosts to estimate black hole masses and their [OIII]λ5007 emission–line luminosities to estimate black hole accretion rates.We find that the volume averaged ratio of star formation to black hole accretion is ∼1000 for the bulge–dominated galaxies in our sample. This is remarkably similar to the observed ratio of stellar mass to black hole mass in nearby bulges. Most of the present–day black hole growth is occurring in black holes with masses less than 3 × 10 7 M ⊙. Our estimated accretion rates imply that low–mass black holes are growing on a time–scale that is comparable with the age of the Universe. Around 50% this growth takes place in AGN that are radiating within a factor of five of the Eddington luminosity. Such systems are rare, making up only 0.2% of the lowmass black hole population at the present day. The remaining growth occurs in lower luminosity AGN. The growth time–scale increases by more than an order of magnitude for the most massive black holes in our sample. We conclude that the evolution of the AGN luminosity function documented in recent optical and X–ray surveys is driven by a decrease in the characteristic mass scale of actively accreting black holes.

APA, Harvard, Vancouver, ISO, and other styles

30

Piana, Olmo, Pratika Dayal, and Tirthankar Roy Choudhury. "The impact of black hole feedback on the UV luminosity and stellar mass assembly of high-redshift galaxies." Monthly Notices of the Royal Astronomical Society 510, no. 4 (December 24, 2021): 5661–75. http://dx.doi.org/10.1093/mnras/stab3757.

Full text

Abstract:

ABSTRACT We employ the Delphi semi-analytical model to study the impact of black hole growth on high-redshift galaxies, both in terms of the observed ultraviolet (UV) luminosity and of the star formation rate. To do this, first, we assess the contribution of active galactic nuclei (AGN) to the total galaxy UV luminosity as a function of stellar mass and redshift. We find that for MUV ≲ −24 mag and z ≈ 5−6, the galaxies for which the black hole UV luminosity outshines the stellar UV emission become the majority, and we estimate their duty cycle. Secondly, we study the evolution of the AGN and stellar luminosity functions (LFs), finding that it is driven both by changes in their characteristic luminosities (i.e. evolution of the intrinsic brightness of galaxies) and in their normalizations (i.e. evolution of the number densities of galaxies), depending on the luminosity range considered. Finally, we follow the mass assembly history for three different halo mass bins, finding that the magnitude of AGN-driven outflows depends on the host halo mass. We show that AGN feedback is most effective when the energy emitted by the accreting black hole is approximately $1{{\ \rm per\ cent}}$ of the halo binding energy, and that this condition is met in galaxies in haloes with $M_\mathrm{h} \sim 10^{11.75} \, {\rm \rm M_\odot }$ at z = 4. In such cases, AGN feedback can drive outflows that are up to 100 times more energetic than supernovae-driven outflows, and the star formation rate is a factor of 3 lower than for galaxies of the same mass without black hole activity.

APA, Harvard, Vancouver, ISO, and other styles

31

Masini, Alberto, Annalisa Celotti, and Samuele Campitiello. "Toward measuring the spin of obscured supermassive black holes." Astronomy & Astrophysics 658 (February 2022): A68. http://dx.doi.org/10.1051/0004-6361/202142451.

Full text

Abstract:

Context. Mass and spin are two fundamental properties of astrophysical black holes. While some established indirect methods are adopted to measure both these properties of active galactic nuclei (AGN) when viewed relatively face-on, very few suggested methods exist to measure these properties when AGN are highly inclined and potentially obscured by large amounts of gas. Aims. In this context we explore the accuracy and performance of a recently proposed method to estimate the spin of AGN by fitting the accretion disk spectral energy distribution, when adapted for highly inclined and obscured systems, and in particular to a sample of six local water megamasers. For these sources the accretion rate and inclination angle are both known, allowing us to rely only on the AGN bolometric luminosity to infer their spin. Methods. Using the bolometric luminosity as a proxy for the accretion disk peak luminosity, we derived the expected bolometric luminosity as a function of spin. Then, we measured the bolometric luminosity of each source through X-ray spectroscopy, and compared it with the expected value to constrain the spin of the AGN. Results. The quality of the constraints depend critically on the accuracy of the measured bolometric luminosity, which is difficult to estimate in heavily obscured systems. Three out of six sources do not show consistency between the expected and measured bolometric luminosities, while the other three (four, when considering the [OIII] line as tracer of the bolometric luminosity) are formally consistent with high spin values. Conclusions. Our results suggest that this method, although promising (and possibly considered as a future calibrator for other methods) needs better observational data and further theoretical modeling to be successfully applied to obscured AGN and to infer robust results.

APA, Harvard, Vancouver, ISO, and other styles

32

Schirra, Adrian P., Mélanie Habouzit, Ralf S. Klessen, Francesca Fornasini, Dylan Nelson, Annalisa Pillepich, Daniel Anglés-Alcázar, Romeel Davé, and Francesca Civano. "Bringing faint active galactic nuclei (AGNs) to light: a view from large-scale cosmological simulations." Monthly Notices of the Royal Astronomical Society 508, no. 4 (October 5, 2021): 4816–43. http://dx.doi.org/10.1093/mnras/stab2863.

Full text

Abstract:

ABSTRACT The sensitivity of X-ray facilities and our ability to detect fainter active galactic nuclei (AGNs) will increase with the upcoming Athena mission and the AXIS and Lynx concept missions, thus improving our understanding of supermassive black holes (BHs) in a luminosity regime that can be dominated by X-ray binaries. We analyse the population of faint AGNs ($L_{\rm x, 2{-}10 \, keV}\leqslant 10^{42}\, \rm erg\,s^{ -1}$) in the Illustris, TNG100, EAGLE, and SIMBA cosmological simulations, and find that the properties of their host galaxies vary from one simulation to another. In Illustris and EAGLE, faint AGNs are powered by low-mass BHs located in low-mass star-forming galaxies. In TNG100 and SIMBA, they are mostly associated with more massive BHs in quenched massive galaxies. We model the X-ray binary (XRB) populations of the simulated galaxies, and find that AGNs often dominate the galaxy AGN + XRB hard X-ray luminosity at z > 2, while XRBs dominate in some simulations at z < 2. Whether the AGN or XRB emission dominates in star-forming and quenched galaxies depends on the simulations. These differences in simulations can be used to discriminate between galaxy formation models with future high-resolution X-ray observations. We compare the luminosity of simulated faint AGN host galaxies to observations of stacked galaxies from Chandra. Our comparison indicates that the simulations post-processed with our X-ray modelling tend to overestimate the AGN + XRB X-ray luminosity; luminosity that can be strongly affected by AGN obscuration. Some simulations reveal clear AGN trends as a function of stellar mass (e.g. galaxy luminosity drop in massive galaxies), which are not apparent in the observations.

APA, Harvard, Vancouver, ISO, and other styles

33

Schirra, Adrian P., Mélanie Habouzit, Ralf S. Klessen, Francesca Fornasini, Dylan Nelson, Annalisa Pillepich, Daniel Anglés-Alcázar, Romeel Davé, and Francesca Civano. "Bringing faint active galactic nuclei (AGNs) to light: a view from large-scale cosmological simulations." Monthly Notices of the Royal Astronomical Society 508, no. 4 (October 5, 2021): 4816–43. http://dx.doi.org/10.1093/mnras/stab2863.

Full text

Abstract:

ABSTRACT The sensitivity of X-ray facilities and our ability to detect fainter active galactic nuclei (AGNs) will increase with the upcoming Athena mission and the AXIS and Lynx concept missions, thus improving our understanding of supermassive black holes (BHs) in a luminosity regime that can be dominated by X-ray binaries. We analyse the population of faint AGNs ($L_{\rm x, 2{-}10 \, keV}\leqslant 10^{42}\, \rm erg\,s^{ -1}$) in the Illustris, TNG100, EAGLE, and SIMBA cosmological simulations, and find that the properties of their host galaxies vary from one simulation to another. In Illustris and EAGLE, faint AGNs are powered by low-mass BHs located in low-mass star-forming galaxies. In TNG100 and SIMBA, they are mostly associated with more massive BHs in quenched massive galaxies. We model the X-ray binary (XRB) populations of the simulated galaxies, and find that AGNs often dominate the galaxy AGN + XRB hard X-ray luminosity at z > 2, while XRBs dominate in some simulations at z < 2. Whether the AGN or XRB emission dominates in star-forming and quenched galaxies depends on the simulations. These differences in simulations can be used to discriminate between galaxy formation models with future high-resolution X-ray observations. We compare the luminosity of simulated faint AGN host galaxies to observations of stacked galaxies from Chandra. Our comparison indicates that the simulations post-processed with our X-ray modelling tend to overestimate the AGN + XRB X-ray luminosity; luminosity that can be strongly affected by AGN obscuration. Some simulations reveal clear AGN trends as a function of stellar mass (e.g. galaxy luminosity drop in massive galaxies), which are not apparent in the observations.

APA, Harvard, Vancouver, ISO, and other styles

34

Grimmett, L. P., J. R. Mullaney, E. P. Bernhard, C. M. Harrison, D. M. Alexander, F. Stanley, V. A. Masoura, and K. Walters. "A binning-free method reveals a continuous relationship between galaxies’ AGN power and offset from main sequence." Monthly Notices of the Royal Astronomical Society 495, no. 1 (May 16, 2020): 1392–402. http://dx.doi.org/10.1093/mnras/staa1255.

Full text

Abstract:

ABSTRACT Studies investigating the relationship between active galactic nucleus (AGN) power and the star formation rates (SFRs) of their host galaxies often rely on averaging techniques – such as stacking – to incorporate information from non-detections. However, averages, and especially means, can be strongly affected by outliers and can therefore give a misleading indication of the ‘typical’ case. Recently, a number of studies have taken a step further by binning their sample in terms of AGN power (approximated by the 2–10 keV luminosity of the AGN), and investigating how the SFR distribution differs between these bins. These bin thresholds are often weakly motivated, and binning implicitly assumes that sources within the same bin have similar (or even identical) properties. In this paper, we investigate whether the distribution of host SFRs – relative to the locus of the star-forming main sequence (i.e. RMS) – changes continuously as a function of AGN power. We achieve this by using a hierarchical Bayesian model that completely removes the need to bin in AGN power. In doing so, we find strong evidence that the RMS distribution changes with 2–10 keV X-ray luminosity. The results suggest that higher X-ray luminosity AGNs have a tighter physical connection to the star-forming process than lower X-ray luminosity AGNs, at least within the 0.8 < z < 1.2 redshift range considered here.

APA, Harvard, Vancouver, ISO, and other styles

35

Yuan, Zunli, Jiancheng Wang, Ming Zhou, and Jirong Mao. "EFFECT OF SPECTRAL INDEX DISTRIBUTION ON ESTIMATING THE AGN RADIO LUMINOSITY FUNCTION." Astrophysical Journal 829, no. 2 (September 27, 2016): 95. http://dx.doi.org/10.3847/0004-637x/829/2/95.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Cool, Richard J., Daniel J. Eisenstein, Christopher S. Kochanek, Michael J. I. Brown, Nelson Caldwell, Arjun Dey, William R. Forman, et al. "THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY." Astrophysical Journal 748, no. 1 (February 28, 2012): 10. http://dx.doi.org/10.1088/0004-637x/748/1/10.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Santos, Daryl Joe D., Tomotsugu Goto, Seong Jin Kim, Ting-Wen Wang, Simon C.-C. Ho, Tetsuya Hashimoto, Ting-Chi Huang, et al. "Environmental effects on AGN activity via extinction-free mid-infrared census." Monthly Notices of the Royal Astronomical Society 507, no. 2 (August 16, 2021): 3070–88. http://dx.doi.org/10.1093/mnras/stab2352.

Full text

Abstract:

ABSTRACT How does the environment affect active galactic nucleus (AGN) activity? We investigated this question in an extinction-free way by selecting 1120 infrared (IR) galaxies in the AKARI North Ecliptic Pole Wide field at redshift z ≤ 1.2. A unique feature of the AKARI satellite is its continuous nine-band IR filter coverage, providing us with an unprecedentedly large sample of IR spectral energy distributions (SEDs) of galaxies. By taking advantage of this, for the first time, we explored the AGN activity derived from SED modelling as a function of redshift, luminosity, and environment. We quantified AGN activity in two ways: AGN contribution fraction (ratio of AGN luminosity to the total IR luminosity), and AGN number fraction (ratio of number of AGNs to the total galaxy sample). We found that galaxy environment (normalized local density) does not greatly affect either definitions of AGN activity of our IRG/LIRG samples (log LTIR ≤ 12). However, we found a different behaviour for ULIRGs (log LTIR > 12). At our highest redshift bin (0.7 ≲ z ≲ 1.2), AGN activity increases with denser environments, but at the intermediate redshift bin (0.3 ≲ z ≲ 0.7), the opposite is observed. These results may hint at a different physical mechanism for ULIRGs. The trends are not statistically significant (p ≥ 0.060 at the intermediate redshift bin, and p ≥ 0.139 at the highest redshift bin). Possible different behaviour of ULIRGs is a key direction to explore further with future space missions (e.g. JWST, Euclid, SPHEREx).

APA, Harvard, Vancouver, ISO, and other styles

38

Trebitsch, Maxime, Marta Volonteri, and Yohan Dubois. "Modelling a bright z = 6 galaxy at the faint end of the AGN luminosity function." Monthly Notices of the Royal Astronomical Society 494, no. 3 (April 20, 2020): 3453–63. http://dx.doi.org/10.1093/mnras/staa1012.

Full text

Abstract:

ABSTRACT Recent deep surveys have unravelled a population of faint active galactic nuclei (AGNs) in the high-redshift Universe, leading to various discussions on their nature and their role during the Epoch of Reionization. We use cosmological radiation hydrodynamics simulations of a bright galaxy at z ∼ 6 (${M_\star } \gtrsim 10^{10}\, {\rm M}_{\odot }$) hosting an actively growing supermassive black hole to study the properties of these objects. In particular, we study how the black hole and the galaxy coevolve and what is the relative contribution of the AGNs and of the stellar populations to the luminosity budget of the system. We find that the feedback from the AGN has no strong effect on the properties of the galaxy, and does not increase the total ionizing luminosity of the host. The average escape fraction of our galaxy is around $f_{\rm esc} \sim 5{{\ \rm per\ cent}}$. While our galaxy would be selected as an AGN in deep X-ray surveys, most of the ultraviolet (UV) luminosity is originating from stellar populations. This confirms that there is a transition in the galaxy population from star-forming galaxies to quasar hosts, with bright Lyman-break galaxies with MUV around −22 falling in the overlap region. Our results also suggest that faint AGNs do not contribute significantly to reionizing the Universe.

APA, Harvard, Vancouver, ISO, and other styles

39

Koekemoer, Anton M. "Populations of candidate black holes at redshift 7 or above." Proceedings of the International Astronomical Union 2, no. 14 (August 2006): 258. http://dx.doi.org/10.1017/s1743921307010411.

Full text

Abstract:

AbstractI will describe recent results on constructing samples of candidate active galactic nuclei (AGN) at or beyond redshift 7, probing several orders of magnitude fainter than the top end of the quasar luminosity function at redshift 6. These advances have been made possible by the advent of deep, wide multi-waveband surveys that enable the selection of samples of sources that are detected at radio or X-ray wavelengths but completely undetected at optical wavelengths to very deep limits. A variety of multi-band selection criteria are used to identify the high-redshift candidates and eliminate lower-redshift interlopers by means of extensive spectral energy distribution modelling. The resulting constraints on the numbers of high-redshift AGN at or above redshift 7 are used to examine the evolution of the AGN luminosity function at high redshift, and help understand the properties of the first supermassive black holes in the universe.

APA, Harvard, Vancouver, ISO, and other styles

40

Oogi, Taira, Hikari Shirakata, Masahiro Nagashima, Takahiro Nishimichi, Toshihiro Kawaguchi, Takashi Okamoto, Tomoaki Ishiyama, and Motohiro Enoki. "Semi-analytic modelling of AGNs: autocorrelation function and halo occupation." Monthly Notices of the Royal Astronomical Society 497, no. 1 (July 7, 2020): 1–18. http://dx.doi.org/10.1093/mnras/staa1961.

Full text

Abstract:

ABSTRACT The spatial clustering of active galactic nuclei (AGNs) is considered to be one of the important diagnostics for the understanding of the underlying processes behind their activities complementary to measurements of the luminosity function (LF). We analyse the AGN clustering from a recent semi-analytic model performed on a large cosmological N-body simulation covering a cubic gigaparsec comoving volume. We have introduced a new time-scale of gas accretion on to the supermassive black holes to account for the loss of the angular momentum on small scales, which is required to match the faint end of the observed X-ray LF. The large simulation box allows us accurate determination of the autocorrelation function of the AGNs. The model prediction indicates that this time-scale plays a significant role in allowing massive haloes to host relatively faint population of AGNs, leading to a higher bias factor for those AGNs. The model predictions are in agreement with observations of X-ray selected AGNs in the luminosity range $10^{41.5}~\mathrm{erg} \ \mathrm{s}^{-1} \le L_{2{-}10\mathrm{keV}} \le 10^{44.5}~\mathrm{erg} \ \mathrm{s}^{-1}$, with the typical host halo mass of $10^{12.5-13.5} h^{-1}\, {\rm M}_{\odot }$ at $z \lesssim 1$. This result shows that the observational clustering measurements impose an independent constraint on the accretion time-scale complementary to the LF measurements. Moreover, we find that not only the effective halo mass corresponding to the overall bias factor, but the extended shape of the predicted AGN correlation function shows remarkable agreement with those from observations. Further observational efforts towards the low-luminosity end at $z$ ∼ 1 would give us stronger constraints on the triggering mechanisms of AGN activities through their clustering.

APA, Harvard, Vancouver, ISO, and other styles

41

Hardcastle, M. J., W. L. Williams, P. N. Best, J. H. Croston, K. J. Duncan, H. J. A. Röttgering, J. Sabater, et al. "Radio-loud AGN in the first LoTSS data release." Astronomy & Astrophysics 622 (February 2019): A12. http://dx.doi.org/10.1051/0004-6361/201833893.

Full text

Abstract:

We constructed a sample of 23 344 radio-loud active galactic nuclei (RLAGN) from the catalogue derived from the LOFAR Two-Metre Sky Survey (LoTSS) survey of the HETDEX Spring field. Although separating AGN from star-forming galaxies remains challenging, the combination of spectroscopic and photometric techniques we used gives us one of the largest available samples of candidate RLAGN. We used the sample, combined with recently developed analytical models, to investigate the lifetime distribution of RLAGN. We show that large or giant powerful RLAGN are probably the old tail of the general RLAGN population, but that the low-luminosity RLAGN candidates in our sample, many of which have sizes < 100 kpc, either require a very different lifetime distribution or have different jet physics from the more powerful objects. We then used analytical models to develop a method of estimating jet kinetic powers for our candidate objects and constructed a jet kinetic luminosity function based on these estimates. These values can be compared to observational quantities, such as the integrated radiative luminosity of groups and clusters, and to the predictions from models of RLAGN feedback in galaxy formation and evolution. In particular, we show that RLAGN in the local Universe are able to supply all the energy required per comoving unit volume to counterbalance X-ray radiative losses from groups and clusters and thus prevent the hot gas from cooling. Our computation of the kinetic luminosity density of local RLAGN is in good agreement with other recent observational estimates and with models of galaxy formation.

APA, Harvard, Vancouver, ISO, and other styles

42

Matute, Israel, Fabio La Franca, Carlotta Gruppioni, Francesca Pozzi, and Carlo Lari. "Unveiling the Evolution of Type I AGNs in the IR (15μm) — As Seen by ISO in the ELAIS-S1 Region." International Astronomical Union Colloquium 184 (2002): 167–72. http://dx.doi.org/10.1017/s0252921100030645.

Full text

Abstract:

AbstractWe present the first estimate of the evolution of type 1 AGNs in the IR (15 μm) obtained from the ELAIS survey in the S1 region. We find that the luminosity function (LF) of Type 1 AGNs at 15μm is fairly well represented by a double power-law function with a bright slope of 2.9 and a faint slope of 1.1. There is evidence for significant cosmological evolution according to a pure luminosity evolution model L15(z)α(l+z)k, with in a (Ωm,ΩΛ)=(1.0,0.0) cosmology. This evolution is similar to what is observed at other wavebands. From the luminosity function and its evolution, we estimate a contribution of ~ 2% from Type 1 AGN to the total Cosmic Infrared Background (CIRB) at 15 μm.

APA, Harvard, Vancouver, ISO, and other styles

43

Thorne, Jessica E., Aaron S. G. Robotham, Luke J. M. Davies, Sabine Bellstedt, Michael J. I. Brown, Scott M. Croom, Ivan Delvecchio, et al. "Deep Extragalactic VIsible Legacy Survey (DEVILS): identification of AGN through SED fitting and the evolution of the bolometric AGN luminosity function." Monthly Notices of the Royal Astronomical Society 509, no. 4 (December 14, 2021): 4940–61. http://dx.doi.org/10.1093/mnras/stab3208.

Full text

Abstract:

ABSTRACT Active galactic nuclei (AGN) are typically identified through radio, mid-infrared, or X-ray emission or through the presence of broad and/or narrow emission lines. AGN can also leave an imprint on a galaxy’s spectral energy distribution (SED) through the re-processing of photons by the dusty torus. Using the SED fitting code ProSpect with an incorporated AGN component, we fit the far-ultraviolet to far-infrared SEDs of ∼494 000 galaxies in the D10-COSMOS field and ∼230 000 galaxies from the GAMA survey. By combining an AGN component with a flexible star formation and metallicity implementation, we obtain estimates for the AGN luminosities, stellar masses, star formation histories, and metallicity histories for each of our galaxies. We find that ProSpect can identify AGN components in 91 per cent of galaxies pre-selected as containing AGN through narrow-emission line ratios and the presence of broad lines. Our ProSpect-derived AGN luminosities show close agreement with luminosities derived for X-ray selected AGN using both the X-ray flux and previous SED fitting results. We show that incorporating the flexibility of an AGN component when fitting the SEDs of galaxies with no AGN has no significant impact on the derived galaxy properties. However, in order to obtain accurate estimates of the stellar properties of AGN host galaxies, it is crucial to include an AGN component in the SED fitting process. We use our derived AGN luminosities to map the evolution of the AGN luminosity function for 0 < z < 2 and find good agreement with previous measurements and predictions from theoretical models.

APA, Harvard, Vancouver, ISO, and other styles

44

Shi, Yong, Patrick Ogle, George H. Rieke, Robert Antonucci, Dean C. Hines, Paul S. Smith, Frank J. Low, Jeroen Bouwman, and Christopher Willmer. "Aromatic Features in AGNs: Star‐forming Infrared Luminosity Function of AGN Host Galaxies." Astrophysical Journal 669, no. 2 (November 10, 2007): 841–61. http://dx.doi.org/10.1086/521594.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Bongiorno, A., G. Zamorani, I. Gavignaud, B. Marano, S. Paltani, G. Mathez, P. Møller, et al. "The VVDS type-1 AGN sample: the faint end of the luminosity function." Astronomy & Astrophysics 472, no. 2 (July 2, 2007): 443–54. http://dx.doi.org/10.1051/0004-6361:20077611.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

Miyaji, Takamitsu, M. Krumpe, A. Coil, H. Aceves, and B. Husemann. "Clustering and Halo Occupation Distribution of Active Galactic Nuclei." Proceedings of the International Astronomical Union 9, S304 (October 2013): 243. http://dx.doi.org/10.1017/s1743921314003937.

Full text

Abstract:

AbstractWe present the results of our series of studies on correlation function and halo occupation distribution of AGNs utilizing data the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) in the redshift range of 0.07<z<0.36. In order to improve the signal-to-noise ratio, we take cross-correlation approach, where cross-correlation functions (CCF) between AGNs and much more numerous AGNs are analyzed. The calculated CCFs are analyzed using the Halo Occupation Distribution (HOD) model, where the CCFs are divided into the term contributed by the AGN-galaxy pairs that reside in one dark matter halo (DMH), (the 1-halo term) and those from two different DMHs (the 2-halo term). The 2-halo term is the indicator of the bias parameter, which is a function of the typical mass of the DMHs in which AGNs reside. The combination of the 1-halo and 2-halo terms gives, not only the typical DMH mass, but also how the AGNs are distributed among the DMHs as a function of mass separately for those at the center of the DMHs and satellites. The main results are as follows: (1) the range of typical mass of the DMHs in various sub-samples of AGNs log (MDMH/h−1MΘ) ~ 12.4–13.4, (2) we found a dependence of the AGN bias parameter on the X-ray luminosity of AGNs, while the optical luminosity dependence is not significant probably due to smaller dynamic range in luminosity for the optically-selected sample, and (3) the growth of the number of AGNs per DMH (N (MDMH)) with MDMH is shallow, or even may be flat, contrary to that of the galaxy population in general, which grows with MDMH proportionally, suggesting a suppression of AGN triggering in denser environment. In order to investigate the origin of the X-ray luminosity dependence, we are also investigating the dependence of clustering on the black hole mass and the Eddington ratio, we also present the results of this investigation.

APA, Harvard, Vancouver, ISO, and other styles

47

Pierce, J. C. S., C. N. Tadhunter, Y. Gordon, C. Ramos Almeida, S. L. Ellison, C. O’Dea, L. Grimmett, L. Makrygianni, P. S. Bessiere, and P. Doña Girón. "Do AGN triggering mechanisms vary with radio power? – II. The importance of mergers as a function of radio power and optical luminosity." Monthly Notices of the Royal Astronomical Society 510, no. 1 (November 10, 2021): 1163–83. http://dx.doi.org/10.1093/mnras/stab3231.

Full text

Abstract:

ABSTRACT Investigation of the triggering mechanisms of radio active galactic nuclei (radio AGN) is important for improving our general understanding of galaxy evolution. In the first paper in this series, detailed morphological analysis of high-excitation radio galaxies (HERGs) with intermediate radio powers suggested that the importance of triggering via galaxy mergers and interactions increases strongly with AGN radio power and weakly with optical emission-line luminosity. Here, we use an online classification interface to expand our morphological analysis to a much larger sample of 155 active galaxies (3CR radio galaxies, radio-intermediate HERGs, and Type 2 quasars) that covers a broad range in both 1.4 GHz radio power and [O iii] λ5007 emission-line luminosity. All active galaxy samples are found to exhibit excesses in their rates of morphological disturbance relative to 378 stellar-mass- and redshift-matched non-active control galaxies classified randomly and blindly alongside them. These excesses are highest for the 3CR HERGs (4.7σ) and Type 2 quasar hosts (3.9σ), supporting the idea that galaxy mergers provide the dominant triggering mechanism for these subgroups. When the full active galaxy sample is considered, there is clear evidence to suggest that the enhancement in the rate of disturbance relative to the controls increases strongly with [O iii] λ5007 emission-line luminosity but not with 1.4 GHz radio power. Evidence that the dominant AGN host types change from early-type galaxies at high radio powers to late-type galaxies at low radio powers is also found, suggesting that triggering by secular, disc-based processes holds more importance for lower-power radio AGN.

APA, Harvard, Vancouver, ISO, and other styles

48

Dey, Rajat K., Animesh Basak, and Sabyasachi Ray. "Diffuse flux of PeV neutrinos from centrifugally accelerated protons in active galactic nuclei." Europhysics Letters 136, no. 6 (December 1, 2021): 69001. http://dx.doi.org/10.1209/0295-5075/ac35bc.

Full text

Abstract:

Abstract Evidence for high-energy astrophysical PeV neutrinos has been found in the IceCube experiment from an analysis with 7.5-year (2010–2017) data. Active galactic nuclei (AGN) are among the most prominent objects in the universe, and are widely speculated to be emitters of ultra-high-energy (UHE) cosmic rays with proton domination. Based on the standard two-step LLCD mechanism of particle acceleration, a transformation of energy occurs from AGN's central super-massive black hole (SMBH) rotation to high-energy protons. Protons can be accelerated up to energies and above, and might generate PeV neutrinos in the energy range through plausible hadronic interactions. The theoretically estimated revised extragalactic diffuse muon neutrino flux employing the “luminosity-dependent density evolution (LDDE)” model for the AGN luminosity function (LF) is found consistent with the IceCube level if only a fraction, of the total bolometric luminosity (BL) of AGN is being realizable to power the PeV neutrinos. In the Λ CDM cosmological framework with the LDDE-modeled LF and photon index distribution, about of the total BL is enough to power the IceCube neutrinos.

APA, Harvard, Vancouver, ISO, and other styles

49

Aird, James, and Alison L. Coil. "The AGN–galaxy–halo connection: the distribution of AGN host halo masses to z = 2.5." Monthly Notices of the Royal Astronomical Society 502, no. 4 (February 4, 2021): 5962–80. http://dx.doi.org/10.1093/mnras/stab312.

Full text

Abstract:

ABSTRACT It is widely reported, based on clustering measurements of observed active galactic nucleus (AGN) samples, that AGNs reside in similar mass host dark matter haloes across the bulk of cosmic time, with log $\mathcal {M}/\mathcal {M}_{\odot }\sim 12.5\!-\!13.0$ to z ∼ 2.5. We show that this is due in part to the AGN fraction in galaxies rising with increasing stellar mass, combined with AGN observational selection effects that exacerbate this trend. Here, we use AGN specific accretion rate distribution functions determined as a function of stellar mass and redshift for star-forming and quiescent galaxies separately, combined with the latest galaxy–halo connection models, to determine the parent and subhalo mass distribution function of AGNs to various observational limits. We find that while the median (sub)halo mass of AGNs, $\approx 10^{12}\mathcal {M}_{\odot }$, is fairly constant with luminosity, specific accretion rate, and redshift, the full halo mass distribution function is broad, spanning several orders of magnitude. We show that widely used methods to infer a typical dark matter halo mass based on an observed AGN clustering amplitude can result in biased, systematically high host halo masses. While the AGN satellite fraction rises with increasing parent halo mass, we find that the central galaxy is often not an AGN. Our results elucidate the physical causes for the apparent uniformity of AGN host haloes across cosmic time and underscore the importance of accounting for AGN selection biases when interpreting observational AGN clustering results. We further show that AGN clustering is most easily interpreted in terms of the relative bias to galaxy samples, not from absolute bias measurements alone.

APA, Harvard, Vancouver, ISO, and other styles

50

Snellen, I. A. G., K. H. Mack, R. T. Schilizzi, and W. Tschager. "Constraining the Evolution of Young Radio-Loud AGN." Publications of the Astronomical Society of Australia 20, no. 1 (2003): 38–41. http://dx.doi.org/10.1071/as02041.

Full text

Abstract:

AbstractGPS and CSS radio sources are the objects of choice to investigate the evolution of young radio-loud AGN. Previous investigations, mainly based on number counts and source size distributions, indicate that GPS/CSS sources decrease significantly in radio power when evolving into old, extended objects. We suggest this is preceded by a period of increase in radio luminosity, which lasts as long as the radio source is confined within the core-radius of its host galaxy. We have selected a sample of nearby compact radio sources, unbiased by radio spectrum, to determine their luminosity function, size distribution, dynamical ages, and emission line properties in a complete and homogeneous way. First results indicate that the large majority of objects (>80%) exhibit classical GPS/CSS radio spectra, and show structures consistent with them being compact double or compact symmetric objects. This sample provides an ideal basis to further test and constrain possible evolution scenarios, and to investigate the relation between radio spectra and morphologies, orientation and Doppler boosting in samples of young radio-loud AGN, in an unbiased way.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'AGN luminosity function'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles