Hello,
I noticed that in the kinetic mode of TNG's black hole, momentum is added in random directions. Could this ultimately result in a bipolar jet (or radio lobe） perpendicular to the disk (for instance, there is more gas within the disk, and the momentum gets 'dissipated' by the high-density gas, while the momentum in the direction perpendicular to the disk is preserved, thus forming a bipolar outflow)?
Looking forward to your response, thank you very much！
Dylan Nelson
11 Oct
This is broadly true, the directionality and emerging features are discussed in several papers, including
OK!Thank you very much!
Additionally, I have two more questions I would like to ask you：
1.I want to study a transition in black hole activity (similar to the 'quench' of galaxies). For the criterion of transition,I planned:
① to use the transition from high accretion rate to low accretion rate as a criterion. However, I found that some black holes, after transitioning from high accretion at small mass (X < 0.1) to low accretion at small mass (denote as snapshot t), revert back to high accretion state. Therefore, the snapshot t cannot be considered the final cessation (or more dramatically, the death) of black hole activity.
② If I set the criterion as the black hole transitioning to a high-mass(M_BH > 10^8 M_sun), low-accretion state, there are very few such cases:for snapshot 99 (z=0), only 86 out of more than 20,000 samples meet this condition, with most remaining in a low-mass, high-accretion state.
Thus, I would like to ask if you have any insightful suggestions on how to define this 'quench' standard for black holes.
Additionally, I noticed that the black hole mass growth exhibits a bimodal distribution, but the two peaks differ by only about two orders of magnitude. Would it be problematic to use these two peaks as standards for black hole mass growth states?
2.I noticed that some central galaxy SMBHs might disappear in a few snapshots and then reappear later. ① Some may regain their pre-disappearance mass and continue evolving, ② while others might be reseeded. This poses a challenge for studying the evolution or mass growth of black holes, because the mass after reseeding starts from the seed mass does not reflect the true mass growth. Are there any good strategies to handle this situation? Is there a disappearance threshold, similar to merger tree, where we can allow for a maximum of three snapshot splashes? For ②, is the only option to discard such cases?
Finally, I would like to express my sincere gratitude for your patient responses every time. I wish you a pleasant life and success in your work！
Zhang
Dylan Nelson
14 Oct
(1) Most SMBHs are low-mass, i.e. near the seed mass, simply because of the seeding model together with the halo mass function (steepness). Perhaps you only want to consider SMBHs more massive than a factor of X from the seed mass.
While most massive (>1e8) SMBHs will be in low-state, this isn't guaranteed, since if the accretion rates become high enough, they can revert back to high state.
(2) It sounds like you describe the repositioning, i.e ."disappear" means leave the (sub)halo. I expect this in satellites (see discussion in https://arxiv.org/abs/2205.10376 Section 6), but otherwise it should be rare.
怡远 张
17 Oct
OK, thank you!
I am preparing to do some comparisons between TNG and Illustris, but I found that unlike TNG, there are no 'BH_MdotBondi' and 'BH_MdotEddington' in parttype5 in Illustris. So, how can I distinguish the two feedback modes without the value of the Eddington rate (the 'quasar mode' and 'radio mode', which are identified according to the MdotBondi/MdotEddington ratio)? Does this mean I need to calculate the corresponding Eddington rates myself? To ensure consistency with the values (especially the order of magnitude) used in the Illustris subgrid model, could you provide me with the constants used in the Eddington accretion rate?
Best Wishes,
Zhang
Dylan Nelson
17 Oct
Dear Zhang,
The BH_Mdot field is what is relevant (this is calculated using the Bondi formula). If the Eddington rate is missing in Illustris, you can calculate it - you'll find the equation on e.g. wikipedia.
Hello,
I noticed that in the kinetic mode of TNG's black hole, momentum is added in random directions. Could this ultimately result in a bipolar jet (or radio lobe） perpendicular to the disk (for instance, there is more gas within the disk, and the momentum gets 'dissipated' by the high-density gas, while the momentum in the direction perpendicular to the disk is preserved, thus forming a bipolar outflow)?
Looking forward to your response, thank you very much！
This is broadly true, the directionality and emerging features are discussed in several papers, including
OK!Thank you very much!
Additionally, I have two more questions I would like to ask you：
1.I want to study a transition in black hole activity (similar to the 'quench' of galaxies). For the criterion of transition,I planned:
① to use the transition from high accretion rate to low accretion rate as a criterion. However, I found that some black holes, after transitioning from high accretion at small mass (X < 0.1) to low accretion at small mass (denote as snapshot t), revert back to high accretion state. Therefore, the snapshot t cannot be considered the final cessation (or more dramatically, the death) of black hole activity.
② If I set the criterion as the black hole transitioning to a high-mass(M_BH > 10^8 M_sun), low-accretion state, there are very few such cases:for snapshot 99 (z=0), only 86 out of more than 20,000 samples meet this condition, with most remaining in a low-mass, high-accretion state.
Thus, I would like to ask if you have any insightful suggestions on how to define this 'quench' standard for black holes.
Additionally, I noticed that the black hole mass growth exhibits a bimodal distribution, but the two peaks differ by only about two orders of magnitude. Would it be problematic to use these two peaks as standards for black hole mass growth states?
2.I noticed that some central galaxy SMBHs might disappear in a few snapshots and then reappear later. ① Some may regain their pre-disappearance mass and continue evolving, ② while others might be reseeded. This poses a challenge for studying the evolution or mass growth of black holes, because the mass after reseeding starts from the seed mass does not reflect the true mass growth. Are there any good strategies to handle this situation? Is there a disappearance threshold, similar to merger tree, where we can allow for a maximum of three snapshot splashes? For ②, is the only option to discard such cases?
Finally, I would like to express my sincere gratitude for your patient responses every time. I wish you a pleasant life and success in your work！
Zhang
(1) Most SMBHs are low-mass, i.e. near the seed mass, simply because of the seeding model together with the halo mass function (steepness). Perhaps you only want to consider SMBHs more massive than a factor of X from the seed mass.
While most massive (>1e8) SMBHs will be in low-state, this isn't guaranteed, since if the accretion rates become high enough, they can revert back to high state.
(2) It sounds like you describe the repositioning, i.e ."disappear" means leave the (sub)halo. I expect this in satellites (see discussion in https://arxiv.org/abs/2205.10376 Section 6), but otherwise it should be rare.
OK, thank you!
I am preparing to do some comparisons between TNG and Illustris, but I found that unlike TNG, there are no 'BH_MdotBondi' and 'BH_MdotEddington' in parttype5 in Illustris. So, how can I distinguish the two feedback modes without the value of the Eddington rate (the 'quasar mode' and 'radio mode', which are identified according to the MdotBondi/MdotEddington ratio)? Does this mean I need to calculate the corresponding Eddington rates myself? To ensure consistency with the values (especially the order of magnitude) used in the Illustris subgrid model, could you provide me with the constants used in the Eddington accretion rate?
Best Wishes,
Zhang
Dear Zhang,
The BH_Mdot field is what is relevant (this is calculated using the Bondi formula). If the Eddington rate is missing in Illustris, you can calculate it - you'll find the equation on e.g. wikipedia.